TUN-9467: bump coredns to solve CVE

* TUN-9467: bump coredns to solve CVE

vendor/google.golang.org/grpc/internal/backoff/backoff.go

@@ -25,10 +25,10 @@ package backoff
 import (
 	"context"
 	"errors"
+	rand "math/rand/v2"
 	"time"
 
 	grpcbackoff "google.golang.org/grpc/backoff"
-	"google.golang.org/grpc/internal/grpcrand"
 )
 
 // Strategy defines the methodology for backing off after a grpc connection
@@ -67,7 +67,7 @@ func (bc Exponential) Backoff(retries int) time.Duration {
 	}
 	// Randomize backoff delays so that if a cluster of requests start at
 	// the same time, they won't operate in lockstep.
-	backoff *= 1 + bc.Config.Jitter*(grpcrand.Float64()*2-1)
+	backoff *= 1 + bc.Config.Jitter*(rand.Float64()*2-1)
 	if backoff < 0 {
 		return 0
 	}

vendor/google.golang.org/grpc/internal/balancer/gracefulswitch/config.go

@@ -33,6 +33,8 @@ type lbConfig struct {
 	childConfig  serviceconfig.LoadBalancingConfig
 }
 
+// ChildName returns the name of the child balancer of the gracefulswitch
+// Balancer.
 func ChildName(l serviceconfig.LoadBalancingConfig) string {
 	return l.(*lbConfig).childBuilder.Name()
 }
@@ -75,7 +77,6 @@ func ParseConfig(cfg json.RawMessage) (serviceconfig.LoadBalancingConfig, error)
 		if err != nil {
 			return nil, fmt.Errorf("error parsing config for policy %q: %v", name, err)
 		}
-
 		return &lbConfig{childBuilder: builder, childConfig: cfg}, nil
 	}
 

vendor/google.golang.org/grpc/internal/balancer/gracefulswitch/gracefulswitch.go

@@ -109,8 +109,9 @@ func (gsb *Balancer) switchTo(builder balancer.Builder) (*balancerWrapper, error
 		return nil, errBalancerClosed
 	}
 	bw := &balancerWrapper{
-		builder: builder,
-		gsb:     gsb,
+		ClientConn: gsb.cc,
+		builder:    builder,
+		gsb:        gsb,
 		lastState: balancer.State{
 			ConnectivityState: connectivity.Connecting,
 			Picker:            base.NewErrPicker(balancer.ErrNoSubConnAvailable),
@@ -169,7 +170,6 @@ func (gsb *Balancer) latestBalancer() *balancerWrapper {
 func (gsb *Balancer) UpdateClientConnState(state balancer.ClientConnState) error {
 	// The resolver data is only relevant to the most recent LB Policy.
 	balToUpdate := gsb.latestBalancer()
-
 	gsbCfg, ok := state.BalancerConfig.(*lbConfig)
 	if ok {
 		// Switch to the child in the config unless it is already active.
@@ -294,6 +294,7 @@ func (gsb *Balancer) Close() {
 // State updates from the wrapped balancer can result in invocation of the
 // graceful switch logic.
 type balancerWrapper struct {
+	balancer.ClientConn
 	balancer.Balancer
 	gsb     *Balancer
 	builder balancer.Builder
@@ -414,7 +415,3 @@ func (bw *balancerWrapper) UpdateAddresses(sc balancer.SubConn, addrs []resolver
 	bw.gsb.mu.Unlock()
 	bw.gsb.cc.UpdateAddresses(sc, addrs)
 }
-
-func (bw *balancerWrapper) Target() string {
-	return bw.gsb.cc.Target()
-}

vendor/google.golang.org/grpc/internal/binarylog/method_logger.go

@@ -65,7 +65,7 @@ type TruncatingMethodLogger struct {
 	callID          uint64
 	idWithinCallGen *callIDGenerator
 
-	sink Sink // TODO(blog): make this plugable.
+	sink Sink // TODO(blog): make this pluggable.
 }
 
 // NewTruncatingMethodLogger returns a new truncating method logger.
@@ -80,7 +80,7 @@ func NewTruncatingMethodLogger(h, m uint64) *TruncatingMethodLogger {
 		callID:          idGen.next(),
 		idWithinCallGen: &callIDGenerator{},
 
-		sink: DefaultSink, // TODO(blog): make it plugable.
+		sink: DefaultSink, // TODO(blog): make it pluggable.
 	}
 }
 
@@ -106,7 +106,7 @@ func (ml *TruncatingMethodLogger) Build(c LogEntryConfig) *binlogpb.GrpcLogEntry
 }
 
 // Log creates a proto binary log entry, and logs it to the sink.
-func (ml *TruncatingMethodLogger) Log(ctx context.Context, c LogEntryConfig) {
+func (ml *TruncatingMethodLogger) Log(_ context.Context, c LogEntryConfig) {
 	ml.sink.Write(ml.Build(c))
 }
 
@@ -397,7 +397,7 @@ func metadataKeyOmit(key string) bool {
 	switch key {
 	case "lb-token", ":path", ":authority", "content-encoding", "content-type", "user-agent", "te":
 		return true
-	case "grpc-trace-bin": // grpc-trace-bin is special because it's visiable to users.
+	case "grpc-trace-bin": // grpc-trace-bin is special because it's visible to users.
 		return false
 	}
 	return strings.HasPrefix(key, "grpc-")

vendor/google.golang.org/grpc/internal/channelz/channel.go

@@ -43,6 +43,8 @@ type Channel struct {
 	// Non-zero traceRefCount means the trace of this channel cannot be deleted.
 	traceRefCount int32
 
+	// ChannelMetrics holds connectivity state, target and call metrics for the
+	// channel within channelz.
 	ChannelMetrics ChannelMetrics
 }
 
@@ -50,6 +52,8 @@ type Channel struct {
 // nesting.
 func (c *Channel) channelzIdentifier() {}
 
+// String returns a string representation of the Channel, including its parent
+// entity and ID.
 func (c *Channel) String() string {
 	if c.Parent == nil {
 		return fmt.Sprintf("Channel #%d", c.ID)
@@ -61,24 +65,31 @@ func (c *Channel) id() int64 {
 	return c.ID
 }
 
+// SubChans returns a copy of the map of sub-channels associated with the
+// Channel.
 func (c *Channel) SubChans() map[int64]string {
 	db.mu.RLock()
 	defer db.mu.RUnlock()
 	return copyMap(c.subChans)
 }
 
+// NestedChans returns a copy of the map of nested channels associated with the
+// Channel.
 func (c *Channel) NestedChans() map[int64]string {
 	db.mu.RLock()
 	defer db.mu.RUnlock()
 	return copyMap(c.nestedChans)
 }
 
+// Trace returns a copy of the Channel's trace data.
 func (c *Channel) Trace() *ChannelTrace {
 	db.mu.RLock()
 	defer db.mu.RUnlock()
 	return c.trace.copy()
 }
 
+// ChannelMetrics holds connectivity state, target and call metrics for the
+// channel within channelz.
 type ChannelMetrics struct {
 	// The current connectivity state of the channel.
 	State atomic.Pointer[connectivity.State]
@@ -136,12 +147,16 @@ func strFromPointer(s *string) string {
 	return *s
 }
 
+// String returns a string representation of the ChannelMetrics, including its
+// state, target, and call metrics.
 func (c *ChannelMetrics) String() string {
 	return fmt.Sprintf("State: %v, Target: %s, CallsStarted: %v, CallsSucceeded: %v, CallsFailed: %v, LastCallStartedTimestamp: %v",
 		c.State.Load(), strFromPointer(c.Target.Load()), c.CallsStarted.Load(), c.CallsSucceeded.Load(), c.CallsFailed.Load(), c.LastCallStartedTimestamp.Load(),
 	)
 }
 
+// NewChannelMetricForTesting creates a new instance of ChannelMetrics with
+// specified initial values for testing purposes.
 func NewChannelMetricForTesting(state connectivity.State, target string, started, succeeded, failed, timestamp int64) *ChannelMetrics {
 	c := &ChannelMetrics{}
 	c.State.Store(&state)

vendor/google.golang.org/grpc/internal/channelz/channelmap.go

@@ -46,7 +46,7 @@ type entry interface {
 
 // channelMap is the storage data structure for channelz.
 //
-// Methods of channelMap can be divided in two two categories with respect to
+// Methods of channelMap can be divided into two categories with respect to
 // locking.
 //
 // 1. Methods acquire the global lock.
@@ -234,13 +234,6 @@ func copyMap(m map[int64]string) map[int64]string {
 	return n
 }
 
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 func (c *channelMap) getTopChannels(id int64, maxResults int) ([]*Channel, bool) {
 	if maxResults <= 0 {
 		maxResults = EntriesPerPage

vendor/google.golang.org/grpc/internal/channelz/funcs.go

@@ -33,7 +33,7 @@ var (
 	// outside this package except by tests.
 	IDGen IDGenerator
 
-	db *channelMap = newChannelMap()
+	db = newChannelMap()
 	// EntriesPerPage defines the number of channelz entries to be shown on a web page.
 	EntriesPerPage = 50
 	curState       int32

vendor/google.golang.org/grpc/internal/channelz/server.go

@@ -59,6 +59,8 @@ func NewServerMetricsForTesting(started, succeeded, failed, timestamp int64) *Se
 	return sm
 }
 
+// CopyFrom copies the metrics data from the provided ServerMetrics
+// instance into the current instance.
 func (sm *ServerMetrics) CopyFrom(o *ServerMetrics) {
 	sm.CallsStarted.Store(o.CallsStarted.Load())
 	sm.CallsSucceeded.Store(o.CallsSucceeded.Load())

vendor/google.golang.org/grpc/internal/channelz/socket.go

@@ -70,13 +70,18 @@ type EphemeralSocketMetrics struct {
 	RemoteFlowControlWindow int64
 }
 
+// SocketType represents the type of socket.
 type SocketType string
 
+// SocketType can be one of these.
 const (
 	SocketTypeNormal = "NormalSocket"
 	SocketTypeListen = "ListenSocket"
 )
 
+// Socket represents a socket within channelz which includes socket
+// metrics and data related to socket activity and provides methods
+// for managing and interacting with sockets.
 type Socket struct {
 	Entity
 	SocketType       SocketType
@@ -100,6 +105,8 @@ type Socket struct {
 	Security credentials.ChannelzSecurityValue
 }
 
+// String returns a string representation of the Socket, including its parent
+// entity, socket type, and ID.
 func (ls *Socket) String() string {
 	return fmt.Sprintf("%s %s #%d", ls.Parent, ls.SocketType, ls.ID)
 }

vendor/google.golang.org/grpc/internal/channelz/subchannel.go

@@ -47,12 +47,14 @@ func (sc *SubChannel) id() int64 {
 	return sc.ID
 }
 
+// Sockets returns a copy of the sockets map associated with the SubChannel.
 func (sc *SubChannel) Sockets() map[int64]string {
 	db.mu.RLock()
 	defer db.mu.RUnlock()
 	return copyMap(sc.sockets)
 }
 
+// Trace returns a copy of the ChannelTrace associated with the SubChannel.
 func (sc *SubChannel) Trace() *ChannelTrace {
 	db.mu.RLock()
 	defer db.mu.RUnlock()

vendor/google.golang.org/grpc/internal/channelz/syscall_nonlinux.go

@@ -35,13 +35,13 @@ type SocketOptionData struct {
 // Getsockopt defines the function to get socket options requested by channelz.
 // It is to be passed to syscall.RawConn.Control().
 // Windows OS doesn't support Socket Option
-func (s *SocketOptionData) Getsockopt(fd uintptr) {
+func (s *SocketOptionData) Getsockopt(uintptr) {
 	once.Do(func() {
 		logger.Warning("Channelz: socket options are not supported on non-linux environments")
 	})
 }
 
 // GetSocketOption gets the socket option info of the conn.
-func GetSocketOption(c any) *SocketOptionData {
+func GetSocketOption(any) *SocketOptionData {
 	return nil
 }

vendor/google.golang.org/grpc/internal/channelz/trace.go

@@ -79,13 +79,21 @@ type TraceEvent struct {
 	Parent   *TraceEvent
 }
 
+// ChannelTrace provides tracing information for a channel.
+// It tracks various events and metadata related to the channel's lifecycle
+// and operations.
 type ChannelTrace struct {
-	cm           *channelMap
-	clearCalled  bool
+	cm          *channelMap
+	clearCalled bool
+	// The time when the trace was created.
 	CreationTime time.Time
-	EventNum     int64
-	mu           sync.Mutex
-	Events       []*traceEvent
+	// A counter for the number of events recorded in the
+	// trace.
+	EventNum int64
+	mu       sync.Mutex
+	// A slice of traceEvent pointers representing the events recorded for
+	// this channel.
+	Events []*traceEvent
 }
 
 func (c *ChannelTrace) copy() *ChannelTrace {
@@ -175,6 +183,7 @@ var refChannelTypeToString = map[RefChannelType]string{
 	RefNormalSocket: "NormalSocket",
 }
 
+// String returns a string representation of the RefChannelType
 func (r RefChannelType) String() string {
 	return refChannelTypeToString[r]
 }

vendor/google.golang.org/grpc/internal/envconfig/envconfig.go

@@ -28,9 +28,6 @@ import (
 var (
 	// TXTErrIgnore is set if TXT errors should be ignored ("GRPC_GO_IGNORE_TXT_ERRORS" is not "false").
 	TXTErrIgnore = boolFromEnv("GRPC_GO_IGNORE_TXT_ERRORS", true)
-	// AdvertiseCompressors is set if registered compressor should be advertised
-	// ("GRPC_GO_ADVERTISE_COMPRESSORS" is not "false").
-	AdvertiseCompressors = boolFromEnv("GRPC_GO_ADVERTISE_COMPRESSORS", true)
 	// RingHashCap indicates the maximum ring size which defaults to 4096
 	// entries but may be overridden by setting the environment variable
 	// "GRPC_RING_HASH_CAP".  This does not override the default bounds
@@ -43,6 +40,35 @@ var (
 	// ALTSMaxConcurrentHandshakes is the maximum number of concurrent ALTS
 	// handshakes that can be performed.
 	ALTSMaxConcurrentHandshakes = uint64FromEnv("GRPC_ALTS_MAX_CONCURRENT_HANDSHAKES", 100, 1, 100)
+	// EnforceALPNEnabled is set if TLS connections to servers with ALPN disabled
+	// should be rejected. The HTTP/2 protocol requires ALPN to be enabled, this
+	// option is present for backward compatibility. This option may be overridden
+	// by setting the environment variable "GRPC_ENFORCE_ALPN_ENABLED" to "true"
+	// or "false".
+	EnforceALPNEnabled = boolFromEnv("GRPC_ENFORCE_ALPN_ENABLED", true)
+	// XDSFallbackSupport is the env variable that controls whether support for
+	// xDS fallback is turned on. If this is unset or is false, only the first
+	// xDS server in the list of server configs will be used.
+	XDSFallbackSupport = boolFromEnv("GRPC_EXPERIMENTAL_XDS_FALLBACK", true)
+	// NewPickFirstEnabled is set if the new pickfirst leaf policy is to be used
+	// instead of the exiting pickfirst implementation. This can be disabled by
+	// setting the environment variable "GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST"
+	// to "false".
+	NewPickFirstEnabled = boolFromEnv("GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST", true)
+
+	// XDSEndpointHashKeyBackwardCompat controls the parsing of the endpoint hash
+	// key from EDS LbEndpoint metadata. Endpoint hash keys can be disabled by
+	// setting "GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT" to "true". When the
+	// implementation of A76 is stable, we will flip the default value to false
+	// in a subsequent release. A final release will remove this environment
+	// variable, enabling the new behavior unconditionally.
+	XDSEndpointHashKeyBackwardCompat = boolFromEnv("GRPC_XDS_ENDPOINT_HASH_KEY_BACKWARD_COMPAT", true)
+
+	// RingHashSetRequestHashKey is set if the ring hash balancer can get the
+	// request hash header by setting the "requestHashHeader" field, according
+	// to gRFC A76. It can be enabled by setting the environment variable
+	// "GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY" to "true".
+	RingHashSetRequestHashKey = boolFromEnv("GRPC_EXPERIMENTAL_RING_HASH_SET_REQUEST_HASH_KEY", false)
 )
 
 func boolFromEnv(envVar string, def bool) bool {

vendor/google.golang.org/grpc/internal/envconfig/xds.go

@@ -53,4 +53,14 @@ var (
 
 	// C2PResolverTestOnlyTrafficDirectorURI is the TD URI for testing.
 	C2PResolverTestOnlyTrafficDirectorURI = os.Getenv("GRPC_TEST_ONLY_GOOGLE_C2P_RESOLVER_TRAFFIC_DIRECTOR_URI")
+
+	// XDSDualstackEndpointsEnabled is true if gRPC should read the
+	// "additional addresses" in the xDS endpoint resource.
+	XDSDualstackEndpointsEnabled = boolFromEnv("GRPC_EXPERIMENTAL_XDS_DUALSTACK_ENDPOINTS", true)
+
+	// XDSSystemRootCertsEnabled is true when xDS enabled gRPC clients can use
+	// the system's default root certificates for TLS certificate validation.
+	// For more details, see:
+	// https://github.com/grpc/proposal/blob/master/A82-xds-system-root-certs.md.
+	XDSSystemRootCertsEnabled = boolFromEnv("GRPC_EXPERIMENTAL_XDS_SYSTEM_ROOT_CERTS", false)
 )

vendor/google.golang.org/grpc/internal/experimental.go

@@ -18,11 +18,11 @@
 package internal
 
 var (
-	// WithRecvBufferPool is implemented by the grpc package and returns a dial
+	// WithBufferPool is implemented by the grpc package and returns a dial
 	// option to configure a shared buffer pool for a grpc.ClientConn.
-	WithRecvBufferPool any // func (grpc.SharedBufferPool) grpc.DialOption
+	WithBufferPool any // func (grpc.SharedBufferPool) grpc.DialOption
 
-	// RecvBufferPool is implemented by the grpc package and returns a server
+	// BufferPool is implemented by the grpc package and returns a server
 	// option to configure a shared buffer pool for a grpc.Server.
-	RecvBufferPool any // func (grpc.SharedBufferPool) grpc.ServerOption
+	BufferPool any // func (grpc.SharedBufferPool) grpc.ServerOption
 )

vendor/google.golang.org/grpc/internal/grpclog/grpclog.go

@@ -1,126 +0,0 @@
-/*
- *
- * Copyright 2020 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-// Package grpclog (internal) defines depth logging for grpc.
-package grpclog
-
-import (
-	"os"
-)
-
-// Logger is the logger used for the non-depth log functions.
-var Logger LoggerV2
-
-// DepthLogger is the logger used for the depth log functions.
-var DepthLogger DepthLoggerV2
-
-// InfoDepth logs to the INFO log at the specified depth.
-func InfoDepth(depth int, args ...any) {
-	if DepthLogger != nil {
-		DepthLogger.InfoDepth(depth, args...)
-	} else {
-		Logger.Infoln(args...)
-	}
-}
-
-// WarningDepth logs to the WARNING log at the specified depth.
-func WarningDepth(depth int, args ...any) {
-	if DepthLogger != nil {
-		DepthLogger.WarningDepth(depth, args...)
-	} else {
-		Logger.Warningln(args...)
-	}
-}
-
-// ErrorDepth logs to the ERROR log at the specified depth.
-func ErrorDepth(depth int, args ...any) {
-	if DepthLogger != nil {
-		DepthLogger.ErrorDepth(depth, args...)
-	} else {
-		Logger.Errorln(args...)
-	}
-}
-
-// FatalDepth logs to the FATAL log at the specified depth.
-func FatalDepth(depth int, args ...any) {
-	if DepthLogger != nil {
-		DepthLogger.FatalDepth(depth, args...)
-	} else {
-		Logger.Fatalln(args...)
-	}
-	os.Exit(1)
-}
-
-// LoggerV2 does underlying logging work for grpclog.
-// This is a copy of the LoggerV2 defined in the external grpclog package. It
-// is defined here to avoid a circular dependency.
-type LoggerV2 interface {
-	// Info logs to INFO log. Arguments are handled in the manner of fmt.Print.
-	Info(args ...any)
-	// Infoln logs to INFO log. Arguments are handled in the manner of fmt.Println.
-	Infoln(args ...any)
-	// Infof logs to INFO log. Arguments are handled in the manner of fmt.Printf.
-	Infof(format string, args ...any)
-	// Warning logs to WARNING log. Arguments are handled in the manner of fmt.Print.
-	Warning(args ...any)
-	// Warningln logs to WARNING log. Arguments are handled in the manner of fmt.Println.
-	Warningln(args ...any)
-	// Warningf logs to WARNING log. Arguments are handled in the manner of fmt.Printf.
-	Warningf(format string, args ...any)
-	// Error logs to ERROR log. Arguments are handled in the manner of fmt.Print.
-	Error(args ...any)
-	// Errorln logs to ERROR log. Arguments are handled in the manner of fmt.Println.
-	Errorln(args ...any)
-	// Errorf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
-	Errorf(format string, args ...any)
-	// Fatal logs to ERROR log. Arguments are handled in the manner of fmt.Print.
-	// gRPC ensures that all Fatal logs will exit with os.Exit(1).
-	// Implementations may also call os.Exit() with a non-zero exit code.
-	Fatal(args ...any)
-	// Fatalln logs to ERROR log. Arguments are handled in the manner of fmt.Println.
-	// gRPC ensures that all Fatal logs will exit with os.Exit(1).
-	// Implementations may also call os.Exit() with a non-zero exit code.
-	Fatalln(args ...any)
-	// Fatalf logs to ERROR log. Arguments are handled in the manner of fmt.Printf.
-	// gRPC ensures that all Fatal logs will exit with os.Exit(1).
-	// Implementations may also call os.Exit() with a non-zero exit code.
-	Fatalf(format string, args ...any)
-	// V reports whether verbosity level l is at least the requested verbose level.
-	V(l int) bool
-}
-
-// DepthLoggerV2 logs at a specified call frame. If a LoggerV2 also implements
-// DepthLoggerV2, the below functions will be called with the appropriate stack
-// depth set for trivial functions the logger may ignore.
-// This is a copy of the DepthLoggerV2 defined in the external grpclog package.
-// It is defined here to avoid a circular dependency.
-//
-// # Experimental
-//
-// Notice: This type is EXPERIMENTAL and may be changed or removed in a
-// later release.
-type DepthLoggerV2 interface {
-	// InfoDepth logs to INFO log at the specified depth. Arguments are handled in the manner of fmt.Println.
-	InfoDepth(depth int, args ...any)
-	// WarningDepth logs to WARNING log at the specified depth. Arguments are handled in the manner of fmt.Println.
-	WarningDepth(depth int, args ...any)
-	// ErrorDepth logs to ERROR log at the specified depth. Arguments are handled in the manner of fmt.Println.
-	ErrorDepth(depth int, args ...any)
-	// FatalDepth logs to FATAL log at the specified depth. Arguments are handled in the manner of fmt.Println.
-	FatalDepth(depth int, args ...any)
-}

vendor/google.golang.org/grpc/internal/grpclog/prefix_logger.go

@@ -16,17 +16,21 @@
  *
  */
 
+// Package grpclog provides logging functionality for internal gRPC packages,
+// outside of the functionality provided by the external `grpclog` package.
 package grpclog
 
 import (
 	"fmt"
+
+	"google.golang.org/grpc/grpclog"
 )
 
 // PrefixLogger does logging with a prefix.
 //
 // Logging method on a nil logs without any prefix.
 type PrefixLogger struct {
-	logger DepthLoggerV2
+	logger grpclog.DepthLoggerV2
 	prefix string
 }
 
@@ -38,7 +42,7 @@ func (pl *PrefixLogger) Infof(format string, args ...any) {
 		pl.logger.InfoDepth(1, fmt.Sprintf(format, args...))
 		return
 	}
-	InfoDepth(1, fmt.Sprintf(format, args...))
+	grpclog.InfoDepth(1, fmt.Sprintf(format, args...))
 }
 
 // Warningf does warning logging.
@@ -48,7 +52,7 @@ func (pl *PrefixLogger) Warningf(format string, args ...any) {
 		pl.logger.WarningDepth(1, fmt.Sprintf(format, args...))
 		return
 	}
-	WarningDepth(1, fmt.Sprintf(format, args...))
+	grpclog.WarningDepth(1, fmt.Sprintf(format, args...))
 }
 
 // Errorf does error logging.
@@ -58,36 +62,18 @@ func (pl *PrefixLogger) Errorf(format string, args ...any) {
 		pl.logger.ErrorDepth(1, fmt.Sprintf(format, args...))
 		return
 	}
-	ErrorDepth(1, fmt.Sprintf(format, args...))
-}
-
-// Debugf does info logging at verbose level 2.
-func (pl *PrefixLogger) Debugf(format string, args ...any) {
-	// TODO(6044): Refactor interfaces LoggerV2 and DepthLogger, and maybe
-	// rewrite PrefixLogger a little to ensure that we don't use the global
-	// `Logger` here, and instead use the `logger` field.
-	if !Logger.V(2) {
-		return
-	}
-	if pl != nil {
-		// Handle nil, so the tests can pass in a nil logger.
-		format = pl.prefix + format
-		pl.logger.InfoDepth(1, fmt.Sprintf(format, args...))
-		return
-	}
-	InfoDepth(1, fmt.Sprintf(format, args...))
-
+	grpclog.ErrorDepth(1, fmt.Sprintf(format, args...))
 }
 
 // V reports whether verbosity level l is at least the requested verbose level.
 func (pl *PrefixLogger) V(l int) bool {
-	// TODO(6044): Refactor interfaces LoggerV2 and DepthLogger, and maybe
-	// rewrite PrefixLogger a little to ensure that we don't use the global
-	// `Logger` here, and instead use the `logger` field.
-	return Logger.V(l)
+	if pl != nil {
+		return pl.logger.V(l)
+	}
+	return true
 }
 
 // NewPrefixLogger creates a prefix logger with the given prefix.
-func NewPrefixLogger(logger DepthLoggerV2, prefix string) *PrefixLogger {
+func NewPrefixLogger(logger grpclog.DepthLoggerV2, prefix string) *PrefixLogger {
 	return &PrefixLogger{logger: logger, prefix: prefix}
 }

vendor/google.golang.org/grpc/internal/grpcrand/grpcrand.go

@@ -1,100 +0,0 @@
-//go:build !go1.21
-
-// TODO: when this file is deleted (after Go 1.20 support is dropped), delete
-// all of grpcrand and call the rand package directly.
-
-/*
- *
- * Copyright 2018 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-// Package grpcrand implements math/rand functions in a concurrent-safe way
-// with a global random source, independent of math/rand's global source.
-package grpcrand
-
-import (
-	"math/rand"
-	"sync"
-	"time"
-)
-
-var (
-	r  = rand.New(rand.NewSource(time.Now().UnixNano()))
-	mu sync.Mutex
-)
-
-// Int implements rand.Int on the grpcrand global source.
-func Int() int {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Int()
-}
-
-// Int63n implements rand.Int63n on the grpcrand global source.
-func Int63n(n int64) int64 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Int63n(n)
-}
-
-// Intn implements rand.Intn on the grpcrand global source.
-func Intn(n int) int {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Intn(n)
-}
-
-// Int31n implements rand.Int31n on the grpcrand global source.
-func Int31n(n int32) int32 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Int31n(n)
-}
-
-// Float64 implements rand.Float64 on the grpcrand global source.
-func Float64() float64 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Float64()
-}
-
-// Uint64 implements rand.Uint64 on the grpcrand global source.
-func Uint64() uint64 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Uint64()
-}
-
-// Uint32 implements rand.Uint32 on the grpcrand global source.
-func Uint32() uint32 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.Uint32()
-}
-
-// ExpFloat64 implements rand.ExpFloat64 on the grpcrand global source.
-func ExpFloat64() float64 {
-	mu.Lock()
-	defer mu.Unlock()
-	return r.ExpFloat64()
-}
-
-// Shuffle implements rand.Shuffle on the grpcrand global source.
-var Shuffle = func(n int, f func(int, int)) {
-	mu.Lock()
-	defer mu.Unlock()
-	r.Shuffle(n, f)
-}

vendor/google.golang.org/grpc/internal/grpcrand/grpcrand_go1.21.go

@@ -1,73 +0,0 @@
-//go:build go1.21
-
-/*
- *
- * Copyright 2024 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-// Package grpcrand implements math/rand functions in a concurrent-safe way
-// with a global random source, independent of math/rand's global source.
-package grpcrand
-
-import "math/rand"
-
-// This implementation will be used for Go version 1.21 or newer.
-// For older versions, the original implementation with mutex will be used.
-
-// Int implements rand.Int on the grpcrand global source.
-func Int() int {
-	return rand.Int()
-}
-
-// Int63n implements rand.Int63n on the grpcrand global source.
-func Int63n(n int64) int64 {
-	return rand.Int63n(n)
-}
-
-// Intn implements rand.Intn on the grpcrand global source.
-func Intn(n int) int {
-	return rand.Intn(n)
-}
-
-// Int31n implements rand.Int31n on the grpcrand global source.
-func Int31n(n int32) int32 {
-	return rand.Int31n(n)
-}
-
-// Float64 implements rand.Float64 on the grpcrand global source.
-func Float64() float64 {
-	return rand.Float64()
-}
-
-// Uint64 implements rand.Uint64 on the grpcrand global source.
-func Uint64() uint64 {
-	return rand.Uint64()
-}
-
-// Uint32 implements rand.Uint32 on the grpcrand global source.
-func Uint32() uint32 {
-	return rand.Uint32()
-}
-
-// ExpFloat64 implements rand.ExpFloat64 on the grpcrand global source.
-func ExpFloat64() float64 {
-	return rand.ExpFloat64()
-}
-
-// Shuffle implements rand.Shuffle on the grpcrand global source.
-var Shuffle = func(n int, f func(int, int)) {
-	rand.Shuffle(n, f)
-}

vendor/google.golang.org/grpc/internal/grpcsync/callback_serializer.go

@@ -53,16 +53,28 @@ func NewCallbackSerializer(ctx context.Context) *CallbackSerializer {
 	return cs
 }
 
-// Schedule adds a callback to be scheduled after existing callbacks are run.
+// TrySchedule tries to schedule the provided callback function f to be
+// executed in the order it was added. This is a best-effort operation. If the
+// context passed to NewCallbackSerializer was canceled before this method is
+// called, the callback will not be scheduled.
 //
 // Callbacks are expected to honor the context when performing any blocking
 // operations, and should return early when the context is canceled.
+func (cs *CallbackSerializer) TrySchedule(f func(ctx context.Context)) {
+	cs.callbacks.Put(f)
+}
+
+// ScheduleOr schedules the provided callback function f to be executed in the
+// order it was added. If the context passed to NewCallbackSerializer has been
+// canceled before this method is called, the onFailure callback will be
+// executed inline instead.
 //
-// Return value indicates if the callback was successfully added to the list of
-// callbacks to be executed by the serializer. It is not possible to add
-// callbacks once the context passed to NewCallbackSerializer is cancelled.
-func (cs *CallbackSerializer) Schedule(f func(ctx context.Context)) bool {
-	return cs.callbacks.Put(f) == nil
+// Callbacks are expected to honor the context when performing any blocking
+// operations, and should return early when the context is canceled.
+func (cs *CallbackSerializer) ScheduleOr(f func(ctx context.Context), onFailure func()) {
+	if cs.callbacks.Put(f) != nil {
+		onFailure()
+	}
 }
 
 func (cs *CallbackSerializer) run(ctx context.Context) {

vendor/google.golang.org/grpc/internal/grpcsync/oncefunc.go

@@ -1,32 +0,0 @@
-/*
- *
- * Copyright 2022 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-package grpcsync
-
-import (
-	"sync"
-)
-
-// OnceFunc returns a function wrapping f which ensures f is only executed
-// once even if the returned function is executed multiple times.
-func OnceFunc(f func()) func() {
-	var once sync.Once
-	return func() {
-		once.Do(f)
-	}
-}

vendor/google.golang.org/grpc/internal/grpcsync/pubsub.go

@@ -77,7 +77,7 @@ func (ps *PubSub) Subscribe(sub Subscriber) (cancel func()) {
 
 	if ps.msg != nil {
 		msg := ps.msg
-		ps.cs.Schedule(func(context.Context) {
+		ps.cs.TrySchedule(func(context.Context) {
 			ps.mu.Lock()
 			defer ps.mu.Unlock()
 			if !ps.subscribers[sub] {
@@ -103,7 +103,7 @@ func (ps *PubSub) Publish(msg any) {
 	ps.msg = msg
 	for sub := range ps.subscribers {
 		s := sub
-		ps.cs.Schedule(func(context.Context) {
+		ps.cs.TrySchedule(func(context.Context) {
 			ps.mu.Lock()
 			defer ps.mu.Unlock()
 			if !ps.subscribers[s] {

vendor/google.golang.org/grpc/internal/grpcutil/compressor.go

@@ -20,8 +20,6 @@ package grpcutil
 
 import (
 	"strings"
-
-	"google.golang.org/grpc/internal/envconfig"
 )
 
 // RegisteredCompressorNames holds names of the registered compressors.
@@ -40,8 +38,5 @@ func IsCompressorNameRegistered(name string) bool {
 // RegisteredCompressors returns a string of registered compressor names
 // separated by comma.
 func RegisteredCompressors() string {
-	if !envconfig.AdvertiseCompressors {
-		return ""
-	}
 	return strings.Join(RegisteredCompressorNames, ",")
 }

vendor/google.golang.org/grpc/internal/grpcutil/method.go

@@ -39,7 +39,7 @@ func ParseMethod(methodName string) (service, method string, _ error) {
 }
 
 // baseContentType is the base content-type for gRPC.  This is a valid
-// content-type on it's own, but can also include a content-subtype such as
+// content-type on its own, but can also include a content-subtype such as
 // "proto" as a suffix after "+" or ";".  See
 // https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests
 // for more details.

vendor/google.golang.org/grpc/internal/idle/idle.go

@@ -182,6 +182,7 @@ func (m *Manager) tryEnterIdleMode() bool {
 	return true
 }
 
+// EnterIdleModeForTesting instructs the channel to enter idle mode.
 func (m *Manager) EnterIdleModeForTesting() {
 	m.tryEnterIdleMode()
 }
@@ -225,7 +226,7 @@ func (m *Manager) ExitIdleMode() error {
 		//   came in and OnCallBegin() noticed that the calls count is negative.
 		// - Channel is in idle mode, and multiple new RPCs come in at the same
 		//   time, all of them notice a negative calls count in OnCallBegin and get
-		//   here. The first one to get the lock would got the channel to exit idle.
+		//   here. The first one to get the lock would get the channel to exit idle.
 		// - Channel is not in idle mode, and the user calls Connect which calls
 		//   m.ExitIdleMode.
 		//
@@ -266,6 +267,7 @@ func (m *Manager) isClosed() bool {
 	return atomic.LoadInt32(&m.closed) == 1
 }
 
+// Close stops the timer associated with the Manager, if it exists.
 func (m *Manager) Close() {
 	atomic.StoreInt32(&m.closed, 1)
 

vendor/google.golang.org/grpc/internal/internal.go

@@ -29,10 +29,12 @@ import (
 )
 
 var (
-	// WithHealthCheckFunc is set by dialoptions.go
-	WithHealthCheckFunc any // func (HealthChecker) DialOption
 	// HealthCheckFunc is used to provide client-side LB channel health checking
 	HealthCheckFunc HealthChecker
+	// RegisterClientHealthCheckListener is used to provide a listener for
+	// updates from the client-side health checking service. It returns a
+	// function that can be called to stop the health producer.
+	RegisterClientHealthCheckListener any // func(ctx context.Context, sc balancer.SubConn, serviceName string, listener func(balancer.SubConnState)) func()
 	// BalancerUnregister is exported by package balancer to unregister a balancer.
 	BalancerUnregister func(name string)
 	// KeepaliveMinPingTime is the minimum ping interval.  This must be 10s by
@@ -62,6 +64,9 @@ var (
 	// gRPC server. An xDS-enabled server needs to know what type of credentials
 	// is configured on the underlying gRPC server. This is set by server.go.
 	GetServerCredentials any // func (*grpc.Server) credentials.TransportCredentials
+	// MetricsRecorderForServer returns the MetricsRecorderList derived from a
+	// server's stats handlers.
+	MetricsRecorderForServer any // func (*grpc.Server) estats.MetricsRecorder
 	// CanonicalString returns the canonical string of the code defined here:
 	// https://github.com/grpc/grpc/blob/master/doc/statuscodes.md.
 	//
@@ -106,6 +111,14 @@ var (
 	// This is used in the 1.0 release of gcp/observability, and thus must not be
 	// deleted or changed.
 	ClearGlobalDialOptions func()
+
+	// AddGlobalPerTargetDialOptions adds a PerTargetDialOption that will be
+	// configured for newly created ClientConns.
+	AddGlobalPerTargetDialOptions any // func (opt any)
+	// ClearGlobalPerTargetDialOptions clears the slice of global late apply
+	// dial options.
+	ClearGlobalPerTargetDialOptions func()
+
 	// JoinDialOptions combines the dial options passed as arguments into a
 	// single dial option.
 	JoinDialOptions any // func(...grpc.DialOption) grpc.DialOption
@@ -126,7 +139,8 @@ var (
 	// deleted or changed.
 	BinaryLogger any // func(binarylog.Logger) grpc.ServerOption
 
-	// SubscribeToConnectivityStateChanges adds a grpcsync.Subscriber to a provided grpc.ClientConn
+	// SubscribeToConnectivityStateChanges adds a grpcsync.Subscriber to a
+	// provided grpc.ClientConn.
 	SubscribeToConnectivityStateChanges any // func(*grpc.ClientConn, grpcsync.Subscriber)
 
 	// NewXDSResolverWithConfigForTesting creates a new xds resolver builder using
@@ -140,6 +154,34 @@ var (
 	// other features, including the CSDS service.
 	NewXDSResolverWithConfigForTesting any // func([]byte) (resolver.Builder, error)
 
+	// NewXDSResolverWithPoolForTesting creates a new xDS resolver builder
+	// using the provided xDS pool instead of creating a new one using the
+	// bootstrap configuration specified by the supported environment variables.
+	// The resolver.Builder is meant to be used in conjunction with the
+	// grpc.WithResolvers DialOption. The resolver.Builder does not take
+	// ownership of the provided xDS client and it is the responsibility of the
+	// caller to close the client when no longer required.
+	//
+	// Testing Only
+	//
+	// This function should ONLY be used for testing and may not work with some
+	// other features, including the CSDS service.
+	NewXDSResolverWithPoolForTesting any // func(*xdsclient.Pool) (resolver.Builder, error)
+
+	// NewXDSResolverWithClientForTesting creates a new xDS resolver builder
+	// using the provided xDS client instead of creating a new one using the
+	// bootstrap configuration specified by the supported environment variables.
+	// The resolver.Builder is meant to be used in conjunction with the
+	// grpc.WithResolvers DialOption. The resolver.Builder does not take
+	// ownership of the provided xDS client and it is the responsibility of the
+	// caller to close the client when no longer required.
+	//
+	// Testing Only
+	//
+	// This function should ONLY be used for testing and may not work with some
+	// other features, including the CSDS service.
+	NewXDSResolverWithClientForTesting any // func(xdsclient.XDSClient) (resolver.Builder, error)
+
 	// RegisterRLSClusterSpecifierPluginForTesting registers the RLS Cluster
 	// Specifier Plugin for testing purposes, regardless of the XDSRLS environment
 	// variable.
@@ -174,7 +216,7 @@ var (
 
 	// GRPCResolverSchemeExtraMetadata determines when gRPC will add extra
 	// metadata to RPCs.
-	GRPCResolverSchemeExtraMetadata string = "xds"
+	GRPCResolverSchemeExtraMetadata = "xds"
 
 	// EnterIdleModeForTesting gets the ClientConn to enter IDLE mode.
 	EnterIdleModeForTesting any // func(*grpc.ClientConn)
@@ -182,31 +224,56 @@ var (
 	// ExitIdleModeForTesting gets the ClientConn to exit IDLE mode.
 	ExitIdleModeForTesting any // func(*grpc.ClientConn) error
 
+	// ChannelzTurnOffForTesting disables the Channelz service for testing
+	// purposes.
 	ChannelzTurnOffForTesting func()
 
-	// TriggerXDSResourceNameNotFoundForTesting triggers the resource-not-found
-	// error for a given resource type and name. This is usually triggered when
-	// the associated watch timer fires. For testing purposes, having this
-	// function makes events more predictable than relying on timer events.
-	TriggerXDSResourceNameNotFoundForTesting any // func(func(xdsresource.Type, string), string, string) error
+	// TriggerXDSResourceNotFoundForTesting causes the provided xDS Client to
+	// invoke resource-not-found error for the given resource type and name.
+	TriggerXDSResourceNotFoundForTesting any // func(xdsclient.XDSClient, xdsresource.Type, string) error
 
-	// TriggerXDSResourceNameNotFoundClient invokes the testing xDS Client
-	// singleton to invoke resource not found for a resource type name and
-	// resource name.
-	TriggerXDSResourceNameNotFoundClient any // func(string, string) error
-
-	// FromOutgoingContextRaw returns the un-merged, intermediary contents of metadata.rawMD.
+	// FromOutgoingContextRaw returns the un-merged, intermediary contents of
+	// metadata.rawMD.
 	FromOutgoingContextRaw any // func(context.Context) (metadata.MD, [][]string, bool)
 
-	// UserSetDefaultScheme is set to true if the user has overridden the default resolver scheme.
-	UserSetDefaultScheme bool = false
+	// UserSetDefaultScheme is set to true if the user has overridden the
+	// default resolver scheme.
+	UserSetDefaultScheme = false
+
+	// ConnectedAddress returns the connected address for a SubConnState. The
+	// address is only valid if the state is READY.
+	ConnectedAddress any // func (scs SubConnState) resolver.Address
+
+	// SetConnectedAddress sets the connected address for a SubConnState.
+	SetConnectedAddress any // func(scs *SubConnState, addr resolver.Address)
+
+	// SnapshotMetricRegistryForTesting snapshots the global data of the metric
+	// registry. Returns a cleanup function that sets the metric registry to its
+	// original state. Only called in testing functions.
+	SnapshotMetricRegistryForTesting func() func()
+
+	// SetDefaultBufferPoolForTesting updates the default buffer pool, for
+	// testing purposes.
+	SetDefaultBufferPoolForTesting any // func(mem.BufferPool)
+
+	// SetBufferPoolingThresholdForTesting updates the buffer pooling threshold, for
+	// testing purposes.
+	SetBufferPoolingThresholdForTesting any // func(int)
+
+	// TimeAfterFunc is used to create timers. During tests the function is
+	// replaced to track allocated timers and fail the test if a timer isn't
+	// cancelled.
+	TimeAfterFunc = func(d time.Duration, f func()) Timer {
+		return time.AfterFunc(d, f)
+	}
 )
 
-// HealthChecker defines the signature of the client-side LB channel health checking function.
+// HealthChecker defines the signature of the client-side LB channel health
+// checking function.
 //
 // The implementation is expected to create a health checking RPC stream by
 // calling newStream(), watch for the health status of serviceName, and report
-// it's health back by calling setConnectivityState().
+// its health back by calling setConnectivityState().
 //
 // The health checking protocol is defined at:
 // https://github.com/grpc/grpc/blob/master/doc/health-checking.md
@@ -228,3 +295,21 @@ const (
 // It currently has an experimental suffix which would be removed once
 // end-to-end testing of the policy is completed.
 const RLSLoadBalancingPolicyName = "rls_experimental"
+
+// EnforceSubConnEmbedding is used to enforce proper SubConn implementation
+// embedding.
+type EnforceSubConnEmbedding interface {
+	enforceSubConnEmbedding()
+}
+
+// EnforceClientConnEmbedding is used to enforce proper ClientConn implementation
+// embedding.
+type EnforceClientConnEmbedding interface {
+	enforceClientConnEmbedding()
+}
+
+// Timer is an interface to allow injecting different time.Timer implementations
+// during tests.
+type Timer interface {
+	Stop() bool
+}

vendor/google.golang.org/grpc/internal/metadata/metadata.go

@@ -97,13 +97,11 @@ func hasNotPrintable(msg string) bool {
 	return false
 }
 
-// ValidatePair validate a key-value pair with the following rules (the pseudo-header will be skipped) :
-//
-// - key must contain one or more characters.
-// - the characters in the key must be contained in [0-9 a-z _ - .].
-// - if the key ends with a "-bin" suffix, no validation of the corresponding value is performed.
-// - the characters in the every value must be printable (in [%x20-%x7E]).
-func ValidatePair(key string, vals ...string) error {
+// ValidateKey validates a key with the following rules (pseudo-headers are
+// skipped):
+// - the key must contain one or more characters.
+// - the characters in the key must be in [0-9 a-z _ - .].
+func ValidateKey(key string) error {
 	// key should not be empty
 	if key == "" {
 		return fmt.Errorf("there is an empty key in the header")
@@ -119,6 +117,20 @@ func ValidatePair(key string, vals ...string) error {
 			return fmt.Errorf("header key %q contains illegal characters not in [0-9a-z-_.]", key)
 		}
 	}
+	return nil
+}
+
+// ValidatePair validates a key-value pair with the following rules
+// (pseudo-header are skipped):
+//   - the key must contain one or more characters.
+//   - the characters in the key must be in [0-9 a-z _ - .].
+//   - if the key ends with a "-bin" suffix, no validation of the corresponding
+//     value is performed.
+//   - the characters in every value must be printable (in [%x20-%x7E]).
+func ValidatePair(key string, vals ...string) error {
+	if err := ValidateKey(key); err != nil {
+		return err
+	}
 	if strings.HasSuffix(key, "-bin") {
 		return nil
 	}

vendor/google.golang.org/grpc/internal/proxyattributes/proxyattributes.go

@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package proxyattributes contains functions for getting and setting proxy
+// attributes like the CONNECT address and user info.
+package proxyattributes
+
+import (
+	"net/url"
+
+	"google.golang.org/grpc/resolver"
+)
+
+type keyType string
+
+const proxyOptionsKey = keyType("grpc.resolver.delegatingresolver.proxyOptions")
+
+// Options holds the proxy connection details needed during the CONNECT
+// handshake.
+type Options struct {
+	User        *url.Userinfo
+	ConnectAddr string
+}
+
+// Set returns a copy of addr with opts set in its attributes.
+func Set(addr resolver.Address, opts Options) resolver.Address {
+	addr.Attributes = addr.Attributes.WithValue(proxyOptionsKey, opts)
+	return addr
+}
+
+// Get returns the Options for the proxy [resolver.Address] and a boolean
+// value representing if the attribute is present or not. The returned data
+// should not be mutated.
+func Get(addr resolver.Address) (Options, bool) {
+	if a := addr.Attributes.Value(proxyOptionsKey); a != nil {
+		return a.(Options), true
+	}
+	return Options{}, false
+}

vendor/google.golang.org/grpc/internal/resolver/delegatingresolver/delegatingresolver.go

@@ -0,0 +1,427 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package delegatingresolver implements a resolver capable of resolving both
+// target URIs and proxy addresses.
+package delegatingresolver
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"sync"
+
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal/proxyattributes"
+	"google.golang.org/grpc/internal/transport"
+	"google.golang.org/grpc/internal/transport/networktype"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/serviceconfig"
+)
+
+var (
+	logger = grpclog.Component("delegating-resolver")
+	// HTTPSProxyFromEnvironment will be overwritten in the tests
+	HTTPSProxyFromEnvironment = http.ProxyFromEnvironment
+)
+
+// delegatingResolver manages both target URI and proxy address resolution by
+// delegating these tasks to separate child resolvers. Essentially, it acts as
+// an intermediary between the gRPC ClientConn and the child resolvers.
+//
+// It implements the [resolver.Resolver] interface.
+type delegatingResolver struct {
+	target   resolver.Target     // parsed target URI to be resolved
+	cc       resolver.ClientConn // gRPC ClientConn
+	proxyURL *url.URL            // proxy URL, derived from proxy environment and target
+
+	// We do not hold both mu and childMu in the same goroutine. Avoid holding
+	// both locks when calling into the child, as the child resolver may
+	// synchronously callback into the channel.
+	mu                  sync.Mutex         // protects all the fields below
+	targetResolverState *resolver.State    // state of the target resolver
+	proxyAddrs          []resolver.Address // resolved proxy addresses; empty if no proxy is configured
+
+	// childMu serializes calls into child resolvers. It also protects access to
+	// the following fields.
+	childMu        sync.Mutex
+	targetResolver resolver.Resolver // resolver for the target URI, based on its scheme
+	proxyResolver  resolver.Resolver // resolver for the proxy URI; nil if no proxy is configured
+}
+
+// nopResolver is a resolver that does nothing.
+type nopResolver struct{}
+
+func (nopResolver) ResolveNow(resolver.ResolveNowOptions) {}
+
+func (nopResolver) Close() {}
+
+// proxyURLForTarget determines the proxy URL for the given address based on the
+// environment. It can return the following:
+//   - nil URL, nil error: No proxy is configured or the address is excluded
+//     using the `NO_PROXY` environment variable or if req.URL.Host is
+//     "localhost" (with or without // a port number)
+//   - nil URL, non-nil error: An error occurred while retrieving the proxy URL.
+//   - non-nil URL, nil error: A proxy is configured, and the proxy URL was
+//     retrieved successfully without any errors.
+func proxyURLForTarget(address string) (*url.URL, error) {
+	req := &http.Request{URL: &url.URL{
+		Scheme: "https",
+		Host:   address,
+	}}
+	return HTTPSProxyFromEnvironment(req)
+}
+
+// New creates a new delegating resolver that can create up to two child
+// resolvers:
+//   - one to resolve the proxy address specified using the supported
+//     environment variables. This uses the registered resolver for the "dns"
+//     scheme. It is lazily built when a target resolver update contains at least
+//     one TCP address.
+//   - one to resolve the target URI using the resolver specified by the scheme
+//     in the target URI or specified by the user using the WithResolvers dial
+//     option. As a special case, if the target URI's scheme is "dns" and a
+//     proxy is specified using the supported environment variables, the target
+//     URI's path portion is used as the resolved address unless target
+//     resolution is enabled using the dial option.
+func New(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions, targetResolverBuilder resolver.Builder, targetResolutionEnabled bool) (resolver.Resolver, error) {
+	r := &delegatingResolver{
+		target:         target,
+		cc:             cc,
+		proxyResolver:  nopResolver{},
+		targetResolver: nopResolver{},
+	}
+
+	var err error
+	r.proxyURL, err = proxyURLForTarget(target.Endpoint())
+	if err != nil {
+		return nil, fmt.Errorf("delegating_resolver: failed to determine proxy URL for target %s: %v", target, err)
+	}
+
+	// proxy is not configured or proxy address excluded using `NO_PROXY` env
+	// var, so only target resolver is used.
+	if r.proxyURL == nil {
+		return targetResolverBuilder.Build(target, cc, opts)
+	}
+
+	if logger.V(2) {
+		logger.Infof("Proxy URL detected : %s", r.proxyURL)
+	}
+
+	// Resolver updates from one child may trigger calls into the other. Block
+	// updates until the children are initialized.
+	r.childMu.Lock()
+	defer r.childMu.Unlock()
+	// When the scheme is 'dns' and target resolution on client is not enabled,
+	// resolution should be handled by the proxy, not the client. Therefore, we
+	// bypass the target resolver and store the unresolved target address.
+	if target.URL.Scheme == "dns" && !targetResolutionEnabled {
+		r.targetResolverState = &resolver.State{
+			Addresses: []resolver.Address{{Addr: target.Endpoint()}},
+			Endpoints: []resolver.Endpoint{{Addresses: []resolver.Address{{Addr: target.Endpoint()}}}},
+		}
+		r.updateTargetResolverState(*r.targetResolverState)
+		return r, nil
+	}
+	wcc := &wrappingClientConn{
+		stateListener: r.updateTargetResolverState,
+		parent:        r,
+	}
+	if r.targetResolver, err = targetResolverBuilder.Build(target, wcc, opts); err != nil {
+		return nil, fmt.Errorf("delegating_resolver: unable to build the resolver for target %s: %v", target, err)
+	}
+	return r, nil
+}
+
+// proxyURIResolver creates a resolver for resolving proxy URIs using the "dns"
+// scheme. It adjusts the proxyURL to conform to the "dns:///" format and builds
+// a resolver with a wrappingClientConn to capture resolved addresses.
+func (r *delegatingResolver) proxyURIResolver(opts resolver.BuildOptions) (resolver.Resolver, error) {
+	proxyBuilder := resolver.Get("dns")
+	if proxyBuilder == nil {
+		panic("delegating_resolver: resolver for proxy not found for scheme dns")
+	}
+	url := *r.proxyURL
+	url.Scheme = "dns"
+	url.Path = "/" + r.proxyURL.Host
+	url.Host = "" // Clear the Host field to conform to the "dns:///" format
+
+	proxyTarget := resolver.Target{URL: url}
+	wcc := &wrappingClientConn{
+		stateListener: r.updateProxyResolverState,
+		parent:        r,
+	}
+	return proxyBuilder.Build(proxyTarget, wcc, opts)
+}
+
+func (r *delegatingResolver) ResolveNow(o resolver.ResolveNowOptions) {
+	r.childMu.Lock()
+	defer r.childMu.Unlock()
+	r.targetResolver.ResolveNow(o)
+	r.proxyResolver.ResolveNow(o)
+}
+
+func (r *delegatingResolver) Close() {
+	r.childMu.Lock()
+	defer r.childMu.Unlock()
+	r.targetResolver.Close()
+	r.targetResolver = nil
+
+	r.proxyResolver.Close()
+	r.proxyResolver = nil
+}
+
+func needsProxyResolver(state *resolver.State) bool {
+	for _, addr := range state.Addresses {
+		if !skipProxy(addr) {
+			return true
+		}
+	}
+	for _, endpoint := range state.Endpoints {
+		for _, addr := range endpoint.Addresses {
+			if !skipProxy(addr) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func skipProxy(address resolver.Address) bool {
+	// Avoid proxy when network is not tcp.
+	networkType, ok := networktype.Get(address)
+	if !ok {
+		networkType, _ = transport.ParseDialTarget(address.Addr)
+	}
+	if networkType != "tcp" {
+		return true
+	}
+
+	req := &http.Request{URL: &url.URL{
+		Scheme: "https",
+		Host:   address.Addr,
+	}}
+	// Avoid proxy when address included in `NO_PROXY` environment variable or
+	// fails to get the proxy address.
+	url, err := HTTPSProxyFromEnvironment(req)
+	if err != nil || url == nil {
+		return true
+	}
+	return false
+}
+
+// updateClientConnStateLocked constructs a combined list of addresses by
+// pairing each proxy address with every target address of type TCP. For each
+// pair, it creates a new [resolver.Address] using the proxy address and
+// attaches the corresponding target address and user info as attributes. Target
+// addresses that are not of type TCP are appended to the list as-is. The
+// function returns nil if either resolver has not yet provided an update, and
+// returns the result of ClientConn.UpdateState once both resolvers have
+// provided at least one update.
+func (r *delegatingResolver) updateClientConnStateLocked() error {
+	if r.targetResolverState == nil || r.proxyAddrs == nil {
+		return nil
+	}
+
+	// If multiple resolved proxy addresses are present, we send only the
+	// unresolved proxy host and let net.Dial handle the proxy host name
+	// resolution when creating the transport. Sending all resolved addresses
+	// would increase the number of addresses passed to the ClientConn and
+	// subsequently to load balancing (LB) policies like Round Robin, leading
+	// to additional TCP connections. However, if there's only one resolved
+	// proxy address, we send it directly, as it doesn't affect the address
+	// count returned by the target resolver and the address count sent to the
+	// ClientConn.
+	var proxyAddr resolver.Address
+	if len(r.proxyAddrs) == 1 {
+		proxyAddr = r.proxyAddrs[0]
+	} else {
+		proxyAddr = resolver.Address{Addr: r.proxyURL.Host}
+	}
+	var addresses []resolver.Address
+	for _, targetAddr := range (*r.targetResolverState).Addresses {
+		if skipProxy(targetAddr) {
+			addresses = append(addresses, targetAddr)
+			continue
+		}
+		addresses = append(addresses, proxyattributes.Set(proxyAddr, proxyattributes.Options{
+			User:        r.proxyURL.User,
+			ConnectAddr: targetAddr.Addr,
+		}))
+	}
+
+	// For each target endpoint, construct a new [resolver.Endpoint] that
+	// includes all addresses from all proxy endpoints and the addresses from
+	// that target endpoint, preserving the number of target endpoints.
+	var endpoints []resolver.Endpoint
+	for _, endpt := range (*r.targetResolverState).Endpoints {
+		var addrs []resolver.Address
+		for _, targetAddr := range endpt.Addresses {
+			// Avoid proxy when network is not tcp.
+			if skipProxy(targetAddr) {
+				addrs = append(addrs, targetAddr)
+				continue
+			}
+			for _, proxyAddr := range r.proxyAddrs {
+				addrs = append(addrs, proxyattributes.Set(proxyAddr, proxyattributes.Options{
+					User:        r.proxyURL.User,
+					ConnectAddr: targetAddr.Addr,
+				}))
+			}
+		}
+		endpoints = append(endpoints, resolver.Endpoint{Addresses: addrs})
+	}
+	// Use the targetResolverState for its service config and attributes
+	// contents. The state update is only sent after both the target and proxy
+	// resolvers have sent their updates, and curState has been updated with the
+	// combined addresses.
+	curState := *r.targetResolverState
+	curState.Addresses = addresses
+	curState.Endpoints = endpoints
+	return r.cc.UpdateState(curState)
+}
+
+// updateProxyResolverState updates the proxy resolver state by storing proxy
+// addresses and endpoints, marking the resolver as ready, and triggering a
+// state update if both proxy and target resolvers are ready. If the ClientConn
+// returns a non-nil error, it calls `ResolveNow()` on the target resolver.  It
+// is a StateListener function of wrappingClientConn passed to the proxy
+// resolver.
+func (r *delegatingResolver) updateProxyResolverState(state resolver.State) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if logger.V(2) {
+		logger.Infof("Addresses received from proxy resolver: %s", state.Addresses)
+	}
+	if len(state.Endpoints) > 0 {
+		// We expect exactly one address per endpoint because the proxy resolver
+		// uses "dns" resolution.
+		r.proxyAddrs = make([]resolver.Address, 0, len(state.Endpoints))
+		for _, endpoint := range state.Endpoints {
+			r.proxyAddrs = append(r.proxyAddrs, endpoint.Addresses...)
+		}
+	} else if state.Addresses != nil {
+		r.proxyAddrs = state.Addresses
+	} else {
+		r.proxyAddrs = []resolver.Address{} // ensure proxyAddrs is non-nil to indicate an update has been received
+	}
+	err := r.updateClientConnStateLocked()
+	// Another possible approach was to block until updates are received from
+	// both resolvers. But this is not used because calling `New()` triggers
+	// `Build()` for the first resolver, which calls `UpdateState()`. And the
+	// second resolver hasn't sent an update yet, so it would cause `New()` to
+	// block indefinitely.
+	if err != nil {
+		go func() {
+			r.childMu.Lock()
+			defer r.childMu.Unlock()
+			if r.targetResolver != nil {
+				r.targetResolver.ResolveNow(resolver.ResolveNowOptions{})
+			}
+		}()
+	}
+	return err
+}
+
+// updateTargetResolverState is the StateListener function provided to the
+// target resolver via wrappingClientConn. It updates the resolver state and
+// marks the target resolver as ready. If the update includes at least one TCP
+// address and the proxy resolver has not yet been constructed, it initializes
+// the proxy resolver. A combined state update is triggered once both resolvers
+// are ready. If all addresses are non-TCP, it proceeds without waiting for the
+// proxy resolver. If ClientConn.UpdateState returns a non-nil error,
+// ResolveNow() is called on the proxy resolver.
+func (r *delegatingResolver) updateTargetResolverState(state resolver.State) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if logger.V(2) {
+		logger.Infof("Addresses received from target resolver: %v", state.Addresses)
+	}
+	r.targetResolverState = &state
+	// If all addresses returned by the target resolver have a non-TCP network
+	// type, or are listed in the `NO_PROXY` environment variable, do not wait
+	// for proxy update.
+	if !needsProxyResolver(r.targetResolverState) {
+		return r.cc.UpdateState(*r.targetResolverState)
+	}
+
+	// The proxy resolver may be rebuilt multiple times, specifically each time
+	// the target resolver sends an update, even if the target resolver is built
+	// successfully but building the proxy resolver fails.
+	if len(r.proxyAddrs) == 0 {
+		go func() {
+			r.childMu.Lock()
+			defer r.childMu.Unlock()
+			if _, ok := r.proxyResolver.(nopResolver); !ok {
+				return
+			}
+			proxyResolver, err := r.proxyURIResolver(resolver.BuildOptions{})
+			if err != nil {
+				r.cc.ReportError(fmt.Errorf("delegating_resolver: unable to build the proxy resolver: %v", err))
+				return
+			}
+			r.proxyResolver = proxyResolver
+		}()
+	}
+
+	err := r.updateClientConnStateLocked()
+	if err != nil {
+		go func() {
+			r.childMu.Lock()
+			defer r.childMu.Unlock()
+			if r.proxyResolver != nil {
+				r.proxyResolver.ResolveNow(resolver.ResolveNowOptions{})
+			}
+		}()
+	}
+	return nil
+}
+
+// wrappingClientConn serves as an intermediary between the parent ClientConn
+// and the child resolvers created here. It implements the resolver.ClientConn
+// interface and is passed in that capacity to the child resolvers.
+type wrappingClientConn struct {
+	// Callback to deliver resolver state updates
+	stateListener func(state resolver.State) error
+	parent        *delegatingResolver
+}
+
+// UpdateState receives resolver state updates and forwards them to the
+// appropriate listener function (either for the proxy or target resolver).
+func (wcc *wrappingClientConn) UpdateState(state resolver.State) error {
+	return wcc.stateListener(state)
+}
+
+// ReportError intercepts errors from the child resolvers and passes them to
+// ClientConn.
+func (wcc *wrappingClientConn) ReportError(err error) {
+	wcc.parent.cc.ReportError(err)
+}
+
+// NewAddress intercepts the new resolved address from the child resolvers and
+// passes them to ClientConn.
+func (wcc *wrappingClientConn) NewAddress(addrs []resolver.Address) {
+	wcc.UpdateState(resolver.State{Addresses: addrs})
+}
+
+// ParseServiceConfig parses the provided service config and returns an object
+// that provides the parsed config.
+func (wcc *wrappingClientConn) ParseServiceConfig(serviceConfigJSON string) *serviceconfig.ParseResult {
+	return wcc.parent.cc.ParseServiceConfig(serviceConfigJSON)
+}

vendor/google.golang.org/grpc/internal/resolver/dns/dns_resolver.go

@@ -24,7 +24,9 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	rand "math/rand/v2"
 	"net"
+	"net/netip"
 	"os"
 	"strconv"
 	"strings"
@@ -35,28 +37,35 @@ import (
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/internal/backoff"
 	"google.golang.org/grpc/internal/envconfig"
-	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/internal/resolver/dns/internal"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/serviceconfig"
 )
 
-// EnableSRVLookups controls whether the DNS resolver attempts to fetch gRPCLB
-// addresses from SRV records.  Must not be changed after init time.
-var EnableSRVLookups = false
+var (
+	// EnableSRVLookups controls whether the DNS resolver attempts to fetch gRPCLB
+	// addresses from SRV records.  Must not be changed after init time.
+	EnableSRVLookups = false
 
-// ResolvingTimeout specifies the maximum duration for a DNS resolution request.
-// If the timeout expires before a response is received, the request will be canceled.
-//
-// It is recommended to set this value at application startup. Avoid modifying this variable
-// after initialization as it's not thread-safe for concurrent modification.
-var ResolvingTimeout = 30 * time.Second
+	// MinResolutionInterval is the minimum interval at which re-resolutions are
+	// allowed. This helps to prevent excessive re-resolution.
+	MinResolutionInterval = 30 * time.Second
 
-var logger = grpclog.Component("dns")
+	// ResolvingTimeout specifies the maximum duration for a DNS resolution request.
+	// If the timeout expires before a response is received, the request will be canceled.
+	//
+	// It is recommended to set this value at application startup. Avoid modifying this variable
+	// after initialization as it's not thread-safe for concurrent modification.
+	ResolvingTimeout = 30 * time.Second
+
+	logger = grpclog.Component("dns")
+)
 
 func init() {
 	resolver.Register(NewBuilder())
 	internal.TimeAfterFunc = time.After
+	internal.TimeNowFunc = time.Now
+	internal.TimeUntilFunc = time.Until
 	internal.NewNetResolver = newNetResolver
 	internal.AddressDialer = addressDialer
 }
@@ -114,7 +123,7 @@ func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts
 	}
 
 	// IP address.
-	if ipAddr, ok := formatIP(host); ok {
+	if ipAddr, err := formatIP(host); err == nil {
 		addr := []resolver.Address{{Addr: ipAddr + ":" + port}}
 		cc.UpdateState(resolver.State{Addresses: addr})
 		return deadResolver{}, nil
@@ -169,7 +178,7 @@ type dnsResolver struct {
 	// finished. Otherwise, data race will be possible. [Race Example] in
 	// dns_resolver_test we replace the real lookup functions with mocked ones to
 	// facilitate testing. If Close() doesn't wait for watcher() goroutine
-	// finishes, race detector sometimes will warns lookup (READ the lookup
+	// finishes, race detector sometimes will warn lookup (READ the lookup
 	// function pointers) inside watcher() goroutine has data race with
 	// replaceNetFunc (WRITE the lookup function pointers).
 	wg                   sync.WaitGroup
@@ -203,12 +212,12 @@ func (d *dnsResolver) watcher() {
 			err = d.cc.UpdateState(*state)
 		}
 
-		var waitTime time.Duration
+		var nextResolutionTime time.Time
 		if err == nil {
 			// Success resolving, wait for the next ResolveNow. However, also wait 30
 			// seconds at the very least to prevent constantly re-resolving.
 			backoffIndex = 1
-			waitTime = internal.MinResolutionRate
+			nextResolutionTime = internal.TimeNowFunc().Add(MinResolutionInterval)
 			select {
 			case <-d.ctx.Done():
 				return
@@ -217,19 +226,21 @@ func (d *dnsResolver) watcher() {
 		} else {
 			// Poll on an error found in DNS Resolver or an error received from
 			// ClientConn.
-			waitTime = backoff.DefaultExponential.Backoff(backoffIndex)
+			nextResolutionTime = internal.TimeNowFunc().Add(backoff.DefaultExponential.Backoff(backoffIndex))
 			backoffIndex++
 		}
 		select {
 		case <-d.ctx.Done():
 			return
-		case <-internal.TimeAfterFunc(waitTime):
+		case <-internal.TimeAfterFunc(internal.TimeUntilFunc(nextResolutionTime)):
 		}
 	}
 }
 
 func (d *dnsResolver) lookupSRV(ctx context.Context) ([]resolver.Address, error) {
-	if !EnableSRVLookups {
+	// Skip this particular host to avoid timeouts with some versions of
+	// systemd-resolved.
+	if !EnableSRVLookups || d.host == "metadata.google.internal." {
 		return nil, nil
 	}
 	var newAddrs []resolver.Address
@@ -250,9 +261,9 @@ func (d *dnsResolver) lookupSRV(ctx context.Context) ([]resolver.Address, error)
 			return nil, err
 		}
 		for _, a := range lbAddrs {
-			ip, ok := formatIP(a)
-			if !ok {
-				return nil, fmt.Errorf("dns: error parsing A record IP address %v", a)
+			ip, err := formatIP(a)
+			if err != nil {
+				return nil, fmt.Errorf("dns: error parsing A record IP address %v: %v", a, err)
 			}
 			addr := ip + ":" + strconv.Itoa(int(s.Port))
 			newAddrs = append(newAddrs, resolver.Address{Addr: addr, ServerName: s.Target})
@@ -312,9 +323,9 @@ func (d *dnsResolver) lookupHost(ctx context.Context) ([]resolver.Address, error
 	}
 	newAddrs := make([]resolver.Address, 0, len(addrs))
 	for _, a := range addrs {
-		ip, ok := formatIP(a)
-		if !ok {
-			return nil, fmt.Errorf("dns: error parsing A record IP address %v", a)
+		ip, err := formatIP(a)
+		if err != nil {
+			return nil, fmt.Errorf("dns: error parsing A record IP address %v: %v", a, err)
 		}
 		addr := ip + ":" + d.port
 		newAddrs = append(newAddrs, resolver.Address{Addr: addr})
@@ -341,19 +352,19 @@ func (d *dnsResolver) lookup() (*resolver.State, error) {
 	return &state, nil
 }
 
-// formatIP returns ok = false if addr is not a valid textual representation of
-// an IP address. If addr is an IPv4 address, return the addr and ok = true.
+// formatIP returns an error if addr is not a valid textual representation of
+// an IP address. If addr is an IPv4 address, return the addr and error = nil.
 // If addr is an IPv6 address, return the addr enclosed in square brackets and
-// ok = true.
-func formatIP(addr string) (addrIP string, ok bool) {
-	ip := net.ParseIP(addr)
-	if ip == nil {
-		return "", false
+// error = nil.
+func formatIP(addr string) (string, error) {
+	ip, err := netip.ParseAddr(addr)
+	if err != nil {
+		return "", err
 	}
-	if ip.To4() != nil {
-		return addr, true
+	if ip.Is4() {
+		return addr, nil
 	}
-	return "[" + addr + "]", true
+	return "[" + addr + "]", nil
 }
 
 // parseTarget takes the user input target string and default port, returns
@@ -369,7 +380,7 @@ func parseTarget(target, defaultPort string) (host, port string, err error) {
 	if target == "" {
 		return "", "", internal.ErrMissingAddr
 	}
-	if ip := net.ParseIP(target); ip != nil {
+	if _, err := netip.ParseAddr(target); err == nil {
 		// target is an IPv4 or IPv6(without brackets) address
 		return target, defaultPort, nil
 	}
@@ -417,7 +428,7 @@ func chosenByPercentage(a *int) bool {
 	if a == nil {
 		return true
 	}
-	return grpcrand.Intn(100)+1 <= *a
+	return rand.IntN(100)+1 <= *a
 }
 
 func canaryingSC(js string) string {

vendor/google.golang.org/grpc/internal/resolver/dns/internal/internal.go

@@ -28,7 +28,7 @@ import (
 
 // NetResolver groups the methods on net.Resolver that are used by the DNS
 // resolver implementation. This allows the default net.Resolver instance to be
-// overidden from tests.
+// overridden from tests.
 type NetResolver interface {
 	LookupHost(ctx context.Context, host string) (addrs []string, err error)
 	LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*net.SRV, err error)
@@ -50,16 +50,23 @@ var (
 
 // The following vars are overridden from tests.
 var (
-	// MinResolutionRate is the minimum rate at which re-resolutions are
-	// allowed. This helps to prevent excessive re-resolution.
-	MinResolutionRate = 30 * time.Second
-
 	// TimeAfterFunc is used by the DNS resolver to wait for the given duration
-	// to elapse. In non-test code, this is implemented by time.After.  In test
+	// to elapse. In non-test code, this is implemented by time.After. In test
 	// code, this can be used to control the amount of time the resolver is
 	// blocked waiting for the duration to elapse.
 	TimeAfterFunc func(time.Duration) <-chan time.Time
 
+	// TimeNowFunc is used by the DNS resolver to get the current time.
+	// In non-test code, this is implemented by time.Now. In test code,
+	// this can be used to control the current time for the resolver.
+	TimeNowFunc func() time.Time
+
+	// TimeUntilFunc is used by the DNS resolver to calculate the remaining
+	// wait time for re-resolution. In non-test code, this is implemented by
+	// time.Until. In test code, this can be used to control the remaining
+	// time for resolver to wait for re-resolution.
+	TimeUntilFunc func(time.Time) time.Duration
+
 	// NewNetResolver returns the net.Resolver instance for the given target.
 	NewNetResolver func(string) (NetResolver, error)
 

vendor/google.golang.org/grpc/internal/resolver/passthrough/passthrough.go

@@ -55,7 +55,7 @@ func (r *passthroughResolver) start() {
 	r.cc.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: r.target.Endpoint()}}})
 }
 
-func (*passthroughResolver) ResolveNow(o resolver.ResolveNowOptions) {}
+func (*passthroughResolver) ResolveNow(resolver.ResolveNowOptions) {}
 
 func (*passthroughResolver) Close() {}
 

vendor/google.golang.org/grpc/internal/stats/labels.go

@@ -0,0 +1,42 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package stats provides internal stats related functionality.
+package stats
+
+import "context"
+
+// Labels are the labels for metrics.
+type Labels struct {
+	// TelemetryLabels are the telemetry labels to record.
+	TelemetryLabels map[string]string
+}
+
+type labelsKey struct{}
+
+// GetLabels returns the Labels stored in the context, or nil if there is one.
+func GetLabels(ctx context.Context) *Labels {
+	labels, _ := ctx.Value(labelsKey{}).(*Labels)
+	return labels
+}
+
+// SetLabels sets the Labels in the context.
+func SetLabels(ctx context.Context, labels *Labels) context.Context {
+	// could also append
+	return context.WithValue(ctx, labelsKey{}, labels)
+}

vendor/google.golang.org/grpc/internal/stats/metrics_recorder_list.go

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package stats
+
+import (
+	"fmt"
+
+	estats "google.golang.org/grpc/experimental/stats"
+	"google.golang.org/grpc/stats"
+)
+
+// MetricsRecorderList forwards Record calls to all of its metricsRecorders.
+//
+// It eats any record calls where the label values provided do not match the
+// number of label keys.
+type MetricsRecorderList struct {
+	// metricsRecorders are the metrics recorders this list will forward to.
+	metricsRecorders []estats.MetricsRecorder
+}
+
+// NewMetricsRecorderList creates a new metric recorder list with all the stats
+// handlers provided which implement the MetricsRecorder interface.
+// If no stats handlers provided implement the MetricsRecorder interface,
+// the MetricsRecorder list returned is a no-op.
+func NewMetricsRecorderList(shs []stats.Handler) *MetricsRecorderList {
+	var mrs []estats.MetricsRecorder
+	for _, sh := range shs {
+		if mr, ok := sh.(estats.MetricsRecorder); ok {
+			mrs = append(mrs, mr)
+		}
+	}
+	return &MetricsRecorderList{
+		metricsRecorders: mrs,
+	}
+}
+
+func verifyLabels(desc *estats.MetricDescriptor, labelsRecv ...string) {
+	if got, want := len(labelsRecv), len(desc.Labels)+len(desc.OptionalLabels); got != want {
+		panic(fmt.Sprintf("Received %d labels in call to record metric %q, but expected %d.", got, desc.Name, want))
+	}
+}
+
+// RecordInt64Count records the measurement alongside labels on the int
+// count associated with the provided handle.
+func (l *MetricsRecorderList) RecordInt64Count(handle *estats.Int64CountHandle, incr int64, labels ...string) {
+	verifyLabels(handle.Descriptor(), labels...)
+
+	for _, metricRecorder := range l.metricsRecorders {
+		metricRecorder.RecordInt64Count(handle, incr, labels...)
+	}
+}
+
+// RecordFloat64Count records the measurement alongside labels on the float
+// count associated with the provided handle.
+func (l *MetricsRecorderList) RecordFloat64Count(handle *estats.Float64CountHandle, incr float64, labels ...string) {
+	verifyLabels(handle.Descriptor(), labels...)
+
+	for _, metricRecorder := range l.metricsRecorders {
+		metricRecorder.RecordFloat64Count(handle, incr, labels...)
+	}
+}
+
+// RecordInt64Histo records the measurement alongside labels on the int
+// histo associated with the provided handle.
+func (l *MetricsRecorderList) RecordInt64Histo(handle *estats.Int64HistoHandle, incr int64, labels ...string) {
+	verifyLabels(handle.Descriptor(), labels...)
+
+	for _, metricRecorder := range l.metricsRecorders {
+		metricRecorder.RecordInt64Histo(handle, incr, labels...)
+	}
+}
+
+// RecordFloat64Histo records the measurement alongside labels on the float
+// histo associated with the provided handle.
+func (l *MetricsRecorderList) RecordFloat64Histo(handle *estats.Float64HistoHandle, incr float64, labels ...string) {
+	verifyLabels(handle.Descriptor(), labels...)
+
+	for _, metricRecorder := range l.metricsRecorders {
+		metricRecorder.RecordFloat64Histo(handle, incr, labels...)
+	}
+}
+
+// RecordInt64Gauge records the measurement alongside labels on the int
+// gauge associated with the provided handle.
+func (l *MetricsRecorderList) RecordInt64Gauge(handle *estats.Int64GaugeHandle, incr int64, labels ...string) {
+	verifyLabels(handle.Descriptor(), labels...)
+
+	for _, metricRecorder := range l.metricsRecorders {
+		metricRecorder.RecordInt64Gauge(handle, incr, labels...)
+	}
+}

vendor/google.golang.org/grpc/internal/status/status.go

@@ -138,17 +138,19 @@ func (s *Status) WithDetails(details ...protoadapt.MessageV1) (*Status, error) {
 	// s.Code() != OK implies that s.Proto() != nil.
 	p := s.Proto()
 	for _, detail := range details {
-		any, err := anypb.New(protoadapt.MessageV2Of(detail))
+		m, err := anypb.New(protoadapt.MessageV2Of(detail))
 		if err != nil {
 			return nil, err
 		}
-		p.Details = append(p.Details, any)
+		p.Details = append(p.Details, m)
 	}
 	return &Status{s: p}, nil
 }
 
 // Details returns a slice of details messages attached to the status.
 // If a detail cannot be decoded, the error is returned in place of the detail.
+// If the detail can be decoded, the proto message returned is of the same
+// type that was given to WithDetails().
 func (s *Status) Details() []any {
 	if s == nil || s.s == nil {
 		return nil
@@ -160,7 +162,38 @@ func (s *Status) Details() []any {
 			details = append(details, err)
 			continue
 		}
-		details = append(details, detail)
+		// The call to MessageV1Of is required to unwrap the proto message if
+		// it implemented only the MessageV1 API. The proto message would have
+		// been wrapped in a V2 wrapper in Status.WithDetails. V2 messages are
+		// added to a global registry used by any.UnmarshalNew().
+		// MessageV1Of has the following behaviour:
+		// 1. If the given message is a wrapped MessageV1, it returns the
+		//   unwrapped value.
+		// 2. If the given message already implements MessageV1, it returns it
+		//   as is.
+		// 3. Else, it wraps the MessageV2 in a MessageV1 wrapper.
+		//
+		// Since the Status.WithDetails() API only accepts MessageV1, calling
+		// MessageV1Of ensures we return the same type that was given to
+		// WithDetails:
+		// * If the give type implemented only MessageV1, the unwrapping from
+		//   point 1 above will restore the type.
+		// * If the given type implemented both MessageV1 and MessageV2, point 2
+		//   above will ensure no wrapping is performed.
+		// * If the given type implemented only MessageV2 and was wrapped using
+		//   MessageV1Of before passing to WithDetails(), it would be unwrapped
+		//   in WithDetails by calling MessageV2Of(). Point 3 above will ensure
+		//   that the type is wrapped in a MessageV1 wrapper again before
+		//   returning. Note that protoc-gen-go doesn't generate code which
+		//   implements ONLY MessageV2 at the time of writing.
+		//
+		// NOTE: Status details can also be added using the FromProto method.
+		// This could theoretically allow passing a Detail message that only
+		// implements the V2 API. In such a case the message will be wrapped in
+		// a MessageV1 wrapper when fetched using Details().
+		// Since protoc-gen-go generates only code that implements both V1 and
+		// V2 APIs for backward compatibility, this is not a concern.
+		details = append(details, protoadapt.MessageV1Of(detail))
 	}
 	return details
 }

vendor/google.golang.org/grpc/internal/syscall/syscall_nonlinux.go

@@ -58,20 +58,20 @@ func GetRusage() *Rusage {
 
 // CPUTimeDiff returns the differences of user CPU time and system CPU time used
 // between two Rusage structs. It a no-op function for non-linux environments.
-func CPUTimeDiff(first *Rusage, latest *Rusage) (float64, float64) {
+func CPUTimeDiff(*Rusage, *Rusage) (float64, float64) {
 	log()
 	return 0, 0
 }
 
 // SetTCPUserTimeout is a no-op function under non-linux environments.
-func SetTCPUserTimeout(conn net.Conn, timeout time.Duration) error {
+func SetTCPUserTimeout(net.Conn, time.Duration) error {
 	log()
 	return nil
 }
 
 // GetTCPUserTimeout is a no-op function under non-linux environments.
 // A negative return value indicates the operation is not supported
-func GetTCPUserTimeout(conn net.Conn) (int, error) {
+func GetTCPUserTimeout(net.Conn) (int, error) {
 	log()
 	return -1, nil
 }

vendor/google.golang.org/grpc/internal/tcp_keepalive_unix.go

@@ -44,7 +44,7 @@ func NetDialerWithTCPKeepalive() *net.Dialer {
 		// combination of unconditionally enabling TCP keepalives here, and
 		// disabling the overriding of TCP keepalive parameters by setting the
 		// KeepAlive field to a negative value above, results in OS defaults for
-		// the TCP keealive interval and time parameters.
+		// the TCP keepalive interval and time parameters.
 		Control: func(_, _ string, c syscall.RawConn) error {
 			return c.Control(func(fd uintptr) {
 				unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)

vendor/google.golang.org/grpc/internal/tcp_keepalive_windows.go

@@ -44,7 +44,7 @@ func NetDialerWithTCPKeepalive() *net.Dialer {
 		// combination of unconditionally enabling TCP keepalives here, and
 		// disabling the overriding of TCP keepalive parameters by setting the
 		// KeepAlive field to a negative value above, results in OS defaults for
-		// the TCP keealive interval and time parameters.
+		// the TCP keepalive interval and time parameters.
 		Control: func(_, _ string, c syscall.RawConn) error {
 			return c.Control(func(fd uintptr) {
 				windows.SetsockoptInt(windows.Handle(fd), windows.SOL_SOCKET, windows.SO_KEEPALIVE, 1)

vendor/google.golang.org/grpc/internal/transport/client_stream.go

@@ -0,0 +1,144 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+	"sync/atomic"
+
+	"golang.org/x/net/http2"
+	"google.golang.org/grpc/mem"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+// ClientStream implements streaming functionality for a gRPC client.
+type ClientStream struct {
+	*Stream // Embed for common stream functionality.
+
+	ct       *http2Client
+	done     chan struct{} // closed at the end of stream to unblock writers.
+	doneFunc func()        // invoked at the end of stream.
+
+	headerChan       chan struct{} // closed to indicate the end of header metadata.
+	headerChanClosed uint32        // set when headerChan is closed. Used to avoid closing headerChan multiple times.
+	// headerValid indicates whether a valid header was received.  Only
+	// meaningful after headerChan is closed (always call waitOnHeader() before
+	// reading its value).
+	headerValid bool
+	header      metadata.MD // the received header metadata
+	noHeaders   bool        // set if the client never received headers (set only after the stream is done).
+
+	bytesReceived atomic.Bool // indicates whether any bytes have been received on this stream
+	unprocessed   atomic.Bool // set if the server sends a refused stream or GOAWAY including this stream
+
+	status *status.Status // the status error received from the server
+}
+
+// Read reads an n byte message from the input stream.
+func (s *ClientStream) Read(n int) (mem.BufferSlice, error) {
+	b, err := s.Stream.read(n)
+	if err == nil {
+		s.ct.incrMsgRecv()
+	}
+	return b, err
+}
+
+// Close closes the stream and propagates err to any readers.
+func (s *ClientStream) Close(err error) {
+	var (
+		rst     bool
+		rstCode http2.ErrCode
+	)
+	if err != nil {
+		rst = true
+		rstCode = http2.ErrCodeCancel
+	}
+	s.ct.closeStream(s, err, rst, rstCode, status.Convert(err), nil, false)
+}
+
+// Write writes the hdr and data bytes to the output stream.
+func (s *ClientStream) Write(hdr []byte, data mem.BufferSlice, opts *WriteOptions) error {
+	return s.ct.write(s, hdr, data, opts)
+}
+
+// BytesReceived indicates whether any bytes have been received on this stream.
+func (s *ClientStream) BytesReceived() bool {
+	return s.bytesReceived.Load()
+}
+
+// Unprocessed indicates whether the server did not process this stream --
+// i.e. it sent a refused stream or GOAWAY including this stream ID.
+func (s *ClientStream) Unprocessed() bool {
+	return s.unprocessed.Load()
+}
+
+func (s *ClientStream) waitOnHeader() {
+	select {
+	case <-s.ctx.Done():
+		// Close the stream to prevent headers/trailers from changing after
+		// this function returns.
+		s.Close(ContextErr(s.ctx.Err()))
+		// headerChan could possibly not be closed yet if closeStream raced
+		// with operateHeaders; wait until it is closed explicitly here.
+		<-s.headerChan
+	case <-s.headerChan:
+	}
+}
+
+// RecvCompress returns the compression algorithm applied to the inbound
+// message. It is empty string if there is no compression applied.
+func (s *ClientStream) RecvCompress() string {
+	s.waitOnHeader()
+	return s.recvCompress
+}
+
+// Done returns a channel which is closed when it receives the final status
+// from the server.
+func (s *ClientStream) Done() <-chan struct{} {
+	return s.done
+}
+
+// Header returns the header metadata of the stream. Acquires the key-value
+// pairs of header metadata once it is available. It blocks until i) the
+// metadata is ready or ii) there is no header metadata or iii) the stream is
+// canceled/expired.
+func (s *ClientStream) Header() (metadata.MD, error) {
+	s.waitOnHeader()
+
+	if !s.headerValid || s.noHeaders {
+		return nil, s.status.Err()
+	}
+
+	return s.header.Copy(), nil
+}
+
+// TrailersOnly blocks until a header or trailers-only frame is received and
+// then returns true if the stream was trailers-only.  If the stream ends
+// before headers are received, returns true, nil.
+func (s *ClientStream) TrailersOnly() bool {
+	s.waitOnHeader()
+	return s.noHeaders
+}
+
+// Status returns the status received from the server.
+// Status can be read safely only after the stream has ended,
+// that is, after Done() is closed.
+func (s *ClientStream) Status() *status.Status {
+	return s.status
+}

vendor/google.golang.org/grpc/internal/transport/controlbuf.go

@@ -32,6 +32,7 @@ import (
 	"golang.org/x/net/http2/hpack"
 	"google.golang.org/grpc/internal/grpclog"
 	"google.golang.org/grpc/internal/grpcutil"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/status"
 )
 
@@ -148,9 +149,9 @@ type dataFrame struct {
 	streamID  uint32
 	endStream bool
 	h         []byte
-	d         []byte
+	reader    mem.Reader
 	// onEachWrite is called every time
-	// a part of d is written out.
+	// a part of data is written out.
 	onEachWrite func()
 }
 
@@ -193,7 +194,7 @@ type goAway struct {
 	code      http2.ErrCode
 	debugData []byte
 	headsUp   bool
-	closeConn error // if set, loopyWriter will exit, resulting in conn closure
+	closeConn error // if set, loopyWriter will exit with this error
 }
 
 func (*goAway) isTransportResponseFrame() bool { return false }
@@ -289,18 +290,22 @@ func (l *outStreamList) dequeue() *outStream {
 }
 
 // controlBuffer is a way to pass information to loopy.
-// Information is passed as specific struct types called control frames.
-// A control frame not only represents data, messages or headers to be sent out
-// but can also be used to instruct loopy to update its internal state.
-// It shouldn't be confused with an HTTP2 frame, although some of the control frames
-// like dataFrame and headerFrame do go out on wire as HTTP2 frames.
+//
+// Information is passed as specific struct types called control frames. A
+// control frame not only represents data, messages or headers to be sent out
+// but can also be used to instruct loopy to update its internal state. It
+// shouldn't be confused with an HTTP2 frame, although some of the control
+// frames like dataFrame and headerFrame do go out on wire as HTTP2 frames.
 type controlBuffer struct {
-	ch              chan struct{}
-	done            <-chan struct{}
+	wakeupCh chan struct{}   // Unblocks readers waiting for something to read.
+	done     <-chan struct{} // Closed when the transport is done.
+
+	// Mutex guards all the fields below, except trfChan which can be read
+	// atomically without holding mu.
 	mu              sync.Mutex
-	consumerWaiting bool
-	list            *itemList
-	err             error
+	consumerWaiting bool      // True when readers are blocked waiting for new data.
+	closed          bool      // True when the controlbuf is finished.
+	list            *itemList // List of queued control frames.
 
 	// transportResponseFrames counts the number of queued items that represent
 	// the response of an action initiated by the peer.  trfChan is created
@@ -308,47 +313,59 @@ type controlBuffer struct {
 	// closed and nilled when transportResponseFrames drops below the
 	// threshold.  Both fields are protected by mu.
 	transportResponseFrames int
-	trfChan                 atomic.Value // chan struct{}
+	trfChan                 atomic.Pointer[chan struct{}]
 }
 
 func newControlBuffer(done <-chan struct{}) *controlBuffer {
 	return &controlBuffer{
-		ch:   make(chan struct{}, 1),
-		list: &itemList{},
-		done: done,
+		wakeupCh: make(chan struct{}, 1),
+		list:     &itemList{},
+		done:     done,
 	}
 }
 
-// throttle blocks if there are too many incomingSettings/cleanupStreams in the
-// controlbuf.
+// throttle blocks if there are too many frames in the control buf that
+// represent the response of an action initiated by the peer, like
+// incomingSettings cleanupStreams etc.
 func (c *controlBuffer) throttle() {
-	ch, _ := c.trfChan.Load().(chan struct{})
-	if ch != nil {
+	if ch := c.trfChan.Load(); ch != nil {
 		select {
-		case <-ch:
+		case <-(*ch):
 		case <-c.done:
 		}
 	}
 }
 
+// put adds an item to the controlbuf.
 func (c *controlBuffer) put(it cbItem) error {
 	_, err := c.executeAndPut(nil, it)
 	return err
 }
 
-func (c *controlBuffer) executeAndPut(f func(it any) bool, it cbItem) (bool, error) {
-	var wakeUp bool
+// executeAndPut runs f, and if the return value is true, adds the given item to
+// the controlbuf. The item could be nil, in which case, this method simply
+// executes f and does not add the item to the controlbuf.
+//
+// The first return value indicates whether the item was successfully added to
+// the control buffer. A non-nil error, specifically ErrConnClosing, is returned
+// if the control buffer is already closed.
+func (c *controlBuffer) executeAndPut(f func() bool, it cbItem) (bool, error) {
 	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
-		return false, c.err
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return false, ErrConnClosing
 	}
 	if f != nil {
-		if !f(it) { // f wasn't successful
-			c.mu.Unlock()
+		if !f() { // f wasn't successful
 			return false, nil
 		}
 	}
+	if it == nil {
+		return true, nil
+	}
+
+	var wakeUp bool
 	if c.consumerWaiting {
 		wakeUp = true
 		c.consumerWaiting = false
@@ -359,98 +376,102 @@ func (c *controlBuffer) executeAndPut(f func(it any) bool, it cbItem) (bool, err
 		if c.transportResponseFrames == maxQueuedTransportResponseFrames {
 			// We are adding the frame that puts us over the threshold; create
 			// a throttling channel.
-			c.trfChan.Store(make(chan struct{}))
+			ch := make(chan struct{})
+			c.trfChan.Store(&ch)
 		}
 	}
-	c.mu.Unlock()
 	if wakeUp {
 		select {
-		case c.ch <- struct{}{}:
+		case c.wakeupCh <- struct{}{}:
 		default:
 		}
 	}
 	return true, nil
 }
 
-// Note argument f should never be nil.
-func (c *controlBuffer) execute(f func(it any) bool, it any) (bool, error) {
-	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
-		return false, c.err
-	}
-	if !f(it) { // f wasn't successful
-		c.mu.Unlock()
-		return false, nil
-	}
-	c.mu.Unlock()
-	return true, nil
-}
-
+// get returns the next control frame from the control buffer. If block is true
+// **and** there are no control frames in the control buffer, the call blocks
+// until one of the conditions is met: there is a frame to return or the
+// transport is closed.
 func (c *controlBuffer) get(block bool) (any, error) {
 	for {
 		c.mu.Lock()
-		if c.err != nil {
+		frame, err := c.getOnceLocked()
+		if frame != nil || err != nil || !block {
+			// If we read a frame or an error, we can return to the caller. The
+			// call to getOnceLocked() returns a nil frame and a nil error if
+			// there is nothing to read, and in that case, if the caller asked
+			// us not to block, we can return now as well.
 			c.mu.Unlock()
-			return nil, c.err
-		}
-		if !c.list.isEmpty() {
-			h := c.list.dequeue().(cbItem)
-			if h.isTransportResponseFrame() {
-				if c.transportResponseFrames == maxQueuedTransportResponseFrames {
-					// We are removing the frame that put us over the
-					// threshold; close and clear the throttling channel.
-					ch := c.trfChan.Load().(chan struct{})
-					close(ch)
-					c.trfChan.Store((chan struct{})(nil))
-				}
-				c.transportResponseFrames--
-			}
-			c.mu.Unlock()
-			return h, nil
-		}
-		if !block {
-			c.mu.Unlock()
-			return nil, nil
+			return frame, err
 		}
 		c.consumerWaiting = true
 		c.mu.Unlock()
+
+		// Release the lock above and wait to be woken up.
 		select {
-		case <-c.ch:
+		case <-c.wakeupCh:
 		case <-c.done:
 			return nil, errors.New("transport closed by client")
 		}
 	}
 }
 
+// Callers must not use this method, but should instead use get().
+//
+// Caller must hold c.mu.
+func (c *controlBuffer) getOnceLocked() (any, error) {
+	if c.closed {
+		return false, ErrConnClosing
+	}
+	if c.list.isEmpty() {
+		return nil, nil
+	}
+	h := c.list.dequeue().(cbItem)
+	if h.isTransportResponseFrame() {
+		if c.transportResponseFrames == maxQueuedTransportResponseFrames {
+			// We are removing the frame that put us over the
+			// threshold; close and clear the throttling channel.
+			ch := c.trfChan.Swap(nil)
+			close(*ch)
+		}
+		c.transportResponseFrames--
+	}
+	return h, nil
+}
+
+// finish closes the control buffer, cleaning up any streams that have queued
+// header frames. Once this method returns, no more frames can be added to the
+// control buffer, and attempts to do so will return ErrConnClosing.
 func (c *controlBuffer) finish() {
 	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
+	defer c.mu.Unlock()
+
+	if c.closed {
 		return
 	}
-	c.err = ErrConnClosing
+	c.closed = true
 	// There may be headers for streams in the control buffer.
 	// These streams need to be cleaned out since the transport
 	// is still not aware of these yet.
 	for head := c.list.dequeueAll(); head != nil; head = head.next {
-		hdr, ok := head.it.(*headerFrame)
-		if !ok {
-			continue
-		}
-		if hdr.onOrphaned != nil { // It will be nil on the server-side.
-			hdr.onOrphaned(ErrConnClosing)
+		switch v := head.it.(type) {
+		case *headerFrame:
+			if v.onOrphaned != nil { // It will be nil on the server-side.
+				v.onOrphaned(ErrConnClosing)
+			}
+		case *dataFrame:
+			_ = v.reader.Close()
 		}
 	}
+
 	// In case throttle() is currently in flight, it needs to be unblocked.
 	// Otherwise, the transport may not close, since the transport is closed by
 	// the reader encountering the connection error.
-	ch, _ := c.trfChan.Load().(chan struct{})
+	ch := c.trfChan.Swap(nil)
 	if ch != nil {
-		close(ch)
+		close(*ch)
 	}
-	c.trfChan.Store((chan struct{})(nil))
-	c.mu.Unlock()
 }
 
 type side int
@@ -466,7 +487,7 @@ const (
 // stream maintains a queue of data frames; as loopy receives data frames
 // it gets added to the queue of the relevant stream.
 // Loopy goes over this list of active streams by processing one node every iteration,
-// thereby closely resemebling to a round-robin scheduling over all streams. While
+// thereby closely resembling a round-robin scheduling over all streams. While
 // processing a stream, loopy writes out data bytes from this stream capped by the min
 // of http2MaxFrameLen, connection-level flow control and stream-level flow control.
 type loopyWriter struct {
@@ -490,26 +511,29 @@ type loopyWriter struct {
 	draining      bool
 	conn          net.Conn
 	logger        *grpclog.PrefixLogger
+	bufferPool    mem.BufferPool
 
 	// Side-specific handlers
 	ssGoAwayHandler func(*goAway) (bool, error)
 }
 
-func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimator, conn net.Conn, logger *grpclog.PrefixLogger) *loopyWriter {
+func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimator, conn net.Conn, logger *grpclog.PrefixLogger, goAwayHandler func(*goAway) (bool, error), bufferPool mem.BufferPool) *loopyWriter {
 	var buf bytes.Buffer
 	l := &loopyWriter{
-		side:          s,
-		cbuf:          cbuf,
-		sendQuota:     defaultWindowSize,
-		oiws:          defaultWindowSize,
-		estdStreams:   make(map[uint32]*outStream),
-		activeStreams: newOutStreamList(),
-		framer:        fr,
-		hBuf:          &buf,
-		hEnc:          hpack.NewEncoder(&buf),
-		bdpEst:        bdpEst,
-		conn:          conn,
-		logger:        logger,
+		side:            s,
+		cbuf:            cbuf,
+		sendQuota:       defaultWindowSize,
+		oiws:            defaultWindowSize,
+		estdStreams:     make(map[uint32]*outStream),
+		activeStreams:   newOutStreamList(),
+		framer:          fr,
+		hBuf:            &buf,
+		hEnc:            hpack.NewEncoder(&buf),
+		bdpEst:          bdpEst,
+		conn:            conn,
+		logger:          logger,
+		ssGoAwayHandler: goAwayHandler,
+		bufferPool:      bufferPool,
 	}
 	return l
 }
@@ -767,6 +791,11 @@ func (l *loopyWriter) cleanupStreamHandler(c *cleanupStream) error {
 		// not be established yet.
 		delete(l.estdStreams, c.streamID)
 		str.deleteSelf()
+		for head := str.itl.dequeueAll(); head != nil; head = head.next {
+			if df, ok := head.it.(*dataFrame); ok {
+				_ = df.reader.Close()
+			}
+		}
 	}
 	if c.rst { // If RST_STREAM needs to be sent.
 		if err := l.framer.fr.WriteRSTStream(c.streamID, c.rstCode); err != nil {
@@ -902,16 +931,18 @@ func (l *loopyWriter) processData() (bool, error) {
 	dataItem := str.itl.peek().(*dataFrame) // Peek at the first data item this stream.
 	// A data item is represented by a dataFrame, since it later translates into
 	// multiple HTTP2 data frames.
-	// Every dataFrame has two buffers; h that keeps grpc-message header and d that is actual data.
-	// As an optimization to keep wire traffic low, data from d is copied to h to make as big as the
-	// maximum possible HTTP2 frame size.
+	// Every dataFrame has two buffers; h that keeps grpc-message header and data
+	// that is the actual message. As an optimization to keep wire traffic low, data
+	// from data is copied to h to make as big as the maximum possible HTTP2 frame
+	// size.
 
-	if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // Empty data frame
+	if len(dataItem.h) == 0 && dataItem.reader.Remaining() == 0 { // Empty data frame
 		// Client sends out empty data frame with endStream = true
 		if err := l.framer.fr.WriteData(dataItem.streamID, dataItem.endStream, nil); err != nil {
 			return false, err
 		}
 		str.itl.dequeue() // remove the empty data item from stream
+		_ = dataItem.reader.Close()
 		if str.itl.isEmpty() {
 			str.state = empty
 		} else if trailer, ok := str.itl.peek().(*headerFrame); ok { // the next item is trailers.
@@ -926,9 +957,7 @@ func (l *loopyWriter) processData() (bool, error) {
 		}
 		return false, nil
 	}
-	var (
-		buf []byte
-	)
+
 	// Figure out the maximum size we can send
 	maxSize := http2MaxFrameLen
 	if strQuota := int(l.oiws) - str.bytesOutStanding; strQuota <= 0 { // stream-level flow control.
@@ -942,43 +971,50 @@ func (l *loopyWriter) processData() (bool, error) {
 	}
 	// Compute how much of the header and data we can send within quota and max frame length
 	hSize := min(maxSize, len(dataItem.h))
-	dSize := min(maxSize-hSize, len(dataItem.d))
-	if hSize != 0 {
-		if dSize == 0 {
-			buf = dataItem.h
-		} else {
-			// We can add some data to grpc message header to distribute bytes more equally across frames.
-			// Copy on the stack to avoid generating garbage
-			var localBuf [http2MaxFrameLen]byte
-			copy(localBuf[:hSize], dataItem.h)
-			copy(localBuf[hSize:], dataItem.d[:dSize])
-			buf = localBuf[:hSize+dSize]
-		}
-	} else {
-		buf = dataItem.d
-	}
-
+	dSize := min(maxSize-hSize, dataItem.reader.Remaining())
+	remainingBytes := len(dataItem.h) + dataItem.reader.Remaining() - hSize - dSize
 	size := hSize + dSize
 
+	var buf *[]byte
+
+	if hSize != 0 && dSize == 0 {
+		buf = &dataItem.h
+	} else {
+		// Note: this is only necessary because the http2.Framer does not support
+		// partially writing a frame, so the sequence must be materialized into a buffer.
+		// TODO: Revisit once https://github.com/golang/go/issues/66655 is addressed.
+		pool := l.bufferPool
+		if pool == nil {
+			// Note that this is only supposed to be nil in tests. Otherwise, stream is
+			// always initialized with a BufferPool.
+			pool = mem.DefaultBufferPool()
+		}
+		buf = pool.Get(size)
+		defer pool.Put(buf)
+
+		copy((*buf)[:hSize], dataItem.h)
+		_, _ = dataItem.reader.Read((*buf)[hSize:])
+	}
+
 	// Now that outgoing flow controls are checked we can replenish str's write quota
 	str.wq.replenish(size)
 	var endStream bool
 	// If this is the last data message on this stream and all of it can be written in this iteration.
-	if dataItem.endStream && len(dataItem.h)+len(dataItem.d) <= size {
+	if dataItem.endStream && remainingBytes == 0 {
 		endStream = true
 	}
 	if dataItem.onEachWrite != nil {
 		dataItem.onEachWrite()
 	}
-	if err := l.framer.fr.WriteData(dataItem.streamID, endStream, buf[:size]); err != nil {
+	if err := l.framer.fr.WriteData(dataItem.streamID, endStream, (*buf)[:size]); err != nil {
 		return false, err
 	}
 	str.bytesOutStanding += size
 	l.sendQuota -= uint32(size)
 	dataItem.h = dataItem.h[hSize:]
-	dataItem.d = dataItem.d[dSize:]
 
-	if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // All the data from that message was written out.
+	if remainingBytes == 0 { // All the data from that message was written out.
+		_ = dataItem.reader.Close()
 		str.itl.dequeue()
 	}
 	if str.itl.isEmpty() {
@@ -997,10 +1033,3 @@ func (l *loopyWriter) processData() (bool, error) {
 	}
 	return false, nil
 }
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}

vendor/google.golang.org/grpc/internal/transport/flowcontrol.go

@@ -92,14 +92,11 @@ func (f *trInFlow) newLimit(n uint32) uint32 {
 
 func (f *trInFlow) onData(n uint32) uint32 {
 	f.unacked += n
-	if f.unacked >= f.limit/4 {
-		w := f.unacked
-		f.unacked = 0
+	if f.unacked < f.limit/4 {
 		f.updateEffectiveWindowSize()
-		return w
+		return 0
 	}
-	f.updateEffectiveWindowSize()
-	return 0
+	return f.reset()
 }
 
 func (f *trInFlow) reset() uint32 {

vendor/google.golang.org/grpc/internal/transport/handler_server.go

@@ -24,7 +24,6 @@
 package transport
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -40,6 +39,7 @@ import (
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/grpclog"
 	"google.golang.org/grpc/internal/grpcutil"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/stats"
@@ -50,7 +50,7 @@ import (
 // NewServerHandlerTransport returns a ServerTransport handling gRPC from
 // inside an http.Handler, or writes an HTTP error to w and returns an error.
 // It requires that the http Server supports HTTP/2.
-func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []stats.Handler) (ServerTransport, error) {
+func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []stats.Handler, bufferPool mem.BufferPool) (ServerTransport, error) {
 	if r.Method != http.MethodPost {
 		w.Header().Set("Allow", http.MethodPost)
 		msg := fmt.Sprintf("invalid gRPC request method %q", r.Method)
@@ -98,6 +98,7 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []s
 		contentType:    contentType,
 		contentSubtype: contentSubtype,
 		stats:          stats,
+		bufferPool:     bufferPool,
 	}
 	st.logger = prefixLoggerForServerHandlerTransport(st)
 
@@ -171,6 +172,8 @@ type serverHandlerTransport struct {
 
 	stats  []stats.Handler
 	logger *grpclog.PrefixLogger
+
+	bufferPool mem.BufferPool
 }
 
 func (ht *serverHandlerTransport) Close(err error) {
@@ -222,7 +225,7 @@ func (ht *serverHandlerTransport) do(fn func()) error {
 	}
 }
 
-func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) error {
+func (ht *serverHandlerTransport) writeStatus(s *ServerStream, st *status.Status) error {
 	ht.writeStatusMu.Lock()
 	defer ht.writeStatusMu.Unlock()
 
@@ -244,6 +247,7 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 		}
 
 		s.hdrMu.Lock()
+		defer s.hdrMu.Unlock()
 		if p := st.Proto(); p != nil && len(p.Details) > 0 {
 			delete(s.trailer, grpcStatusDetailsBinHeader)
 			stBytes, err := proto.Marshal(p)
@@ -268,7 +272,6 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 				}
 			}
 		}
-		s.hdrMu.Unlock()
 	})
 
 	if err == nil { // transport has not been closed
@@ -286,14 +289,14 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 
 // writePendingHeaders sets common and custom headers on the first
 // write call (Write, WriteHeader, or WriteStatus)
-func (ht *serverHandlerTransport) writePendingHeaders(s *Stream) {
+func (ht *serverHandlerTransport) writePendingHeaders(s *ServerStream) {
 	ht.writeCommonHeaders(s)
 	ht.writeCustomHeaders(s)
 }
 
 // writeCommonHeaders sets common headers on the first write
 // call (Write, WriteHeader, or WriteStatus).
-func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
+func (ht *serverHandlerTransport) writeCommonHeaders(s *ServerStream) {
 	h := ht.rw.Header()
 	h["Date"] = nil // suppress Date to make tests happy; TODO: restore
 	h.Set("Content-Type", ht.contentType)
@@ -314,7 +317,7 @@ func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
 
 // writeCustomHeaders sets custom headers set on the stream via SetHeader
 // on the first write call (Write, WriteHeader, or WriteStatus)
-func (ht *serverHandlerTransport) writeCustomHeaders(s *Stream) {
+func (ht *serverHandlerTransport) writeCustomHeaders(s *ServerStream) {
 	h := ht.rw.Header()
 
 	s.hdrMu.Lock()
@@ -330,19 +333,31 @@ func (ht *serverHandlerTransport) writeCustomHeaders(s *Stream) {
 	s.hdrMu.Unlock()
 }
 
-func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (ht *serverHandlerTransport) write(s *ServerStream, hdr []byte, data mem.BufferSlice, _ *WriteOptions) error {
+	// Always take a reference because otherwise there is no guarantee the data will
+	// be available after this function returns. This is what callers to Write
+	// expect.
+	data.Ref()
 	headersWritten := s.updateHeaderSent()
-	return ht.do(func() {
+	err := ht.do(func() {
+		defer data.Free()
 		if !headersWritten {
 			ht.writePendingHeaders(s)
 		}
 		ht.rw.Write(hdr)
-		ht.rw.Write(data)
+		for _, b := range data {
+			_, _ = ht.rw.Write(b.ReadOnlyData())
+		}
 		ht.rw.(http.Flusher).Flush()
 	})
+	if err != nil {
+		data.Free()
+		return err
+	}
+	return nil
 }
 
-func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
+func (ht *serverHandlerTransport) writeHeader(s *ServerStream, md metadata.MD) error {
 	if err := s.SetHeader(md); err != nil {
 		return err
 	}
@@ -370,7 +385,7 @@ func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
 	return err
 }
 
-func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream func(*Stream)) {
+func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream func(*ServerStream)) {
 	// With this transport type there will be exactly 1 stream: this HTTP request.
 	var cancel context.CancelFunc
 	if ht.timeoutSet {
@@ -393,20 +408,22 @@ func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream
 
 	ctx = metadata.NewIncomingContext(ctx, ht.headerMD)
 	req := ht.req
-	s := &Stream{
-		id:               0, // irrelevant
-		ctx:              ctx,
-		requestRead:      func(int) {},
+	s := &ServerStream{
+		Stream: &Stream{
+			id:             0, // irrelevant
+			ctx:            ctx,
+			requestRead:    func(int) {},
+			buf:            newRecvBuffer(),
+			method:         req.URL.Path,
+			recvCompress:   req.Header.Get("grpc-encoding"),
+			contentSubtype: ht.contentSubtype,
+		},
 		cancel:           cancel,
-		buf:              newRecvBuffer(),
 		st:               ht,
-		method:           req.URL.Path,
-		recvCompress:     req.Header.Get("grpc-encoding"),
-		contentSubtype:   ht.contentSubtype,
 		headerWireLength: 0, // won't have access to header wire length until golang/go#18997.
 	}
 	s.trReader = &transportReader{
-		reader:        &recvBufferReader{ctx: s.ctx, ctxDone: s.ctx.Done(), recv: s.buf, freeBuffer: func(*bytes.Buffer) {}},
+		reader:        &recvBufferReader{ctx: s.ctx, ctxDone: s.ctx.Done(), recv: s.buf},
 		windowHandler: func(int) {},
 	}
 
@@ -415,21 +432,19 @@ func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream
 	go func() {
 		defer close(readerDone)
 
-		// TODO: minimize garbage, optimize recvBuffer code/ownership
-		const readSize = 8196
-		for buf := make([]byte, readSize); ; {
-			n, err := req.Body.Read(buf)
+		for {
+			buf := ht.bufferPool.Get(http2MaxFrameLen)
+			n, err := req.Body.Read(*buf)
 			if n > 0 {
-				s.buf.put(recvMsg{buffer: bytes.NewBuffer(buf[:n:n])})
-				buf = buf[n:]
+				*buf = (*buf)[:n]
+				s.buf.put(recvMsg{buffer: mem.NewBuffer(buf, ht.bufferPool)})
+			} else {
+				ht.bufferPool.Put(buf)
 			}
 			if err != nil {
 				s.buf.put(recvMsg{err: mapRecvMsgError(err)})
 				return
 			}
-			if len(buf) == 0 {
-				buf = make([]byte, readSize)
-			}
 		}
 	}()
 
@@ -458,11 +473,9 @@ func (ht *serverHandlerTransport) runStream() {
 	}
 }
 
-func (ht *serverHandlerTransport) IncrMsgSent() {}
+func (ht *serverHandlerTransport) incrMsgRecv() {}
 
-func (ht *serverHandlerTransport) IncrMsgRecv() {}
-
-func (ht *serverHandlerTransport) Drain(debugData string) {
+func (ht *serverHandlerTransport) Drain(string) {
 	panic("Drain() is not implemented")
 }
 
@@ -485,5 +498,5 @@ func mapRecvMsgError(err error) error {
 	if strings.Contains(err.Error(), "body closed by handler") {
 		return status.Error(codes.Canceled, err.Error())
 	}
-	return connectionErrorf(true, err, err.Error())
+	return connectionErrorf(true, err, "%s", err.Error())
 }

vendor/google.golang.org/grpc/internal/transport/http2_client.go

@@ -43,10 +43,12 @@ import (
 	"google.golang.org/grpc/internal/grpcsync"
 	"google.golang.org/grpc/internal/grpcutil"
 	imetadata "google.golang.org/grpc/internal/metadata"
+	"google.golang.org/grpc/internal/proxyattributes"
 	istatus "google.golang.org/grpc/internal/status"
 	isyscall "google.golang.org/grpc/internal/syscall"
 	"google.golang.org/grpc/internal/transport/networktype"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/resolver"
@@ -59,6 +61,8 @@ import (
 // atomically.
 var clientConnectionCounter uint64
 
+var goAwayLoopyWriterTimeout = 5 * time.Second
+
 var metadataFromOutgoingContextRaw = internal.FromOutgoingContextRaw.(func(context.Context) (metadata.MD, [][]string, bool))
 
 // http2Client implements the ClientTransport interface with HTTP2.
@@ -83,9 +87,9 @@ type http2Client struct {
 	writerDone chan struct{} // sync point to enable testing.
 	// goAway is closed to notify the upper layer (i.e., addrConn.transportMonitor)
 	// that the server sent GoAway on this transport.
-	goAway chan struct{}
-
-	framer *framer
+	goAway        chan struct{}
+	keepaliveDone chan struct{} // Closed when the keepalive goroutine exits.
+	framer        *framer
 	// controlBuf delivers all the control related tasks (e.g., window
 	// updates, reset streams, and various settings) to the controller.
 	// Do not access controlBuf with mu held.
@@ -114,13 +118,13 @@ type http2Client struct {
 	streamQuota           int64
 	streamsQuotaAvailable chan struct{}
 	waitingStreams        uint32
-	nextID                uint32
 	registeredCompressors string
 
 	// Do not access controlBuf with mu held.
 	mu            sync.Mutex // guard the following variables
+	nextID        uint32
 	state         transportState
-	activeStreams map[uint32]*Stream
+	activeStreams map[uint32]*ClientStream
 	// prevGoAway ID records the Last-Stream-ID in the previous GOAway frame.
 	prevGoAwayID uint32
 	// goAwayReason records the http2.ErrCode and debug data received with the
@@ -144,13 +148,13 @@ type http2Client struct {
 
 	onClose func(GoAwayReason)
 
-	bufferPool *bufferPool
+	bufferPool mem.BufferPool
 
 	connectionID uint64
 	logger       *grpclog.PrefixLogger
 }
 
-func dial(ctx context.Context, fn func(context.Context, string) (net.Conn, error), addr resolver.Address, useProxy bool, grpcUA string) (net.Conn, error) {
+func dial(ctx context.Context, fn func(context.Context, string) (net.Conn, error), addr resolver.Address, grpcUA string) (net.Conn, error) {
 	address := addr.Addr
 	networkType, ok := networktype.Get(addr)
 	if fn != nil {
@@ -172,10 +176,10 @@ func dial(ctx context.Context, fn func(context.Context, string) (net.Conn, error
 		return fn(ctx, address)
 	}
 	if !ok {
-		networkType, address = parseDialTarget(address)
+		networkType, address = ParseDialTarget(address)
 	}
-	if networkType == "tcp" && useProxy {
-		return proxyDial(ctx, address, grpcUA)
+	if opts, present := proxyattributes.Get(addr); present {
+		return proxyDial(ctx, addr, grpcUA, opts)
 	}
 	return internal.NetDialerWithTCPKeepalive().DialContext(ctx, networkType, address)
 }
@@ -196,10 +200,10 @@ func isTemporary(err error) bool {
 	return true
 }
 
-// newHTTP2Client constructs a connected ClientTransport to addr based on HTTP2
+// NewHTTP2Client constructs a connected ClientTransport to addr based on HTTP2
 // and starts to receive messages on it. Non-nil error returns if construction
 // fails.
-func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts ConnectOptions, onClose func(GoAwayReason)) (_ *http2Client, err error) {
+func NewHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts ConnectOptions, onClose func(GoAwayReason)) (_ ClientTransport, err error) {
 	scheme := "http"
 	ctx, cancel := context.WithCancel(ctx)
 	defer func() {
@@ -214,7 +218,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 	// address specific arbitrary data to reach custom dialers and credential handshakers.
 	connectCtx = icredentials.NewClientHandshakeInfoContext(connectCtx, credentials.ClientHandshakeInfo{Attributes: addr.Attributes})
 
-	conn, err := dial(connectCtx, opts.Dialer, addr, opts.UseProxy, opts.UserAgent)
+	conn, err := dial(connectCtx, opts.Dialer, addr, opts.UserAgent)
 	if err != nil {
 		if opts.FailOnNonTempDialError {
 			return nil, connectionErrorf(isTemporary(err), err, "transport: error while dialing: %v", err)
@@ -229,7 +233,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		}
 	}(conn)
 
-	// The following defer and goroutine monitor the connectCtx for cancelation
+	// The following defer and goroutine monitor the connectCtx for cancellation
 	// and deadline.  On context expiration, the connection is hard closed and
 	// this function will naturally fail as a result.  Otherwise, the defer
 	// waits for the goroutine to exit to prevent the context from being
@@ -332,10 +336,11 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		readerDone:            make(chan struct{}),
 		writerDone:            make(chan struct{}),
 		goAway:                make(chan struct{}),
+		keepaliveDone:         make(chan struct{}),
 		framer:                newFramer(conn, writeBufSize, readBufSize, opts.SharedWriteBuffer, maxHeaderListSize),
 		fc:                    &trInFlow{limit: uint32(icwz)},
 		scheme:                scheme,
-		activeStreams:         make(map[uint32]*Stream),
+		activeStreams:         make(map[uint32]*ClientStream),
 		isSecure:              isSecure,
 		perRPCCreds:           perRPCCreds,
 		kp:                    kp,
@@ -346,7 +351,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		streamQuota:           defaultMaxStreamsClient,
 		streamsQuotaAvailable: make(chan struct{}, 1),
 		keepaliveEnabled:      keepaliveEnabled,
-		bufferPool:            newBufferPool(),
+		bufferPool:            opts.BufferPool,
 		onClose:               onClose,
 	}
 	var czSecurity credentials.ChannelzSecurityValue
@@ -408,10 +413,10 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 	readerErrCh := make(chan error, 1)
 	go t.reader(readerErrCh)
 	defer func() {
-		if err == nil {
-			err = <-readerErrCh
-		}
 		if err != nil {
+			// writerDone should be closed since the loopy goroutine
+			// wouldn't have started in the case this function returns an error.
+			close(t.writerDone)
 			t.Close(err)
 		}
 	}()
@@ -458,8 +463,12 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 	if err := t.framer.writer.Flush(); err != nil {
 		return nil, err
 	}
+	// Block until the server preface is received successfully or an error occurs.
+	if err = <-readerErrCh; err != nil {
+		return nil, err
+	}
 	go func() {
-		t.loopy = newLoopyWriter(clientSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger)
+		t.loopy = newLoopyWriter(clientSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler, t.bufferPool)
 		if err := t.loopy.run(); !isIOError(err) {
 			// Immediately close the connection, as the loopy writer returns
 			// when there are no more active streams and we were draining (the
@@ -472,17 +481,19 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 	return t, nil
 }
 
-func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
+func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *ClientStream {
 	// TODO(zhaoq): Handle uint32 overflow of Stream.id.
-	s := &Stream{
-		ct:             t,
-		done:           make(chan struct{}),
-		method:         callHdr.Method,
-		sendCompress:   callHdr.SendCompress,
-		buf:            newRecvBuffer(),
-		headerChan:     make(chan struct{}),
-		contentSubtype: callHdr.ContentSubtype,
-		doneFunc:       callHdr.DoneFunc,
+	s := &ClientStream{
+		Stream: &Stream{
+			method:         callHdr.Method,
+			sendCompress:   callHdr.SendCompress,
+			buf:            newRecvBuffer(),
+			contentSubtype: callHdr.ContentSubtype,
+		},
+		ct:         t,
+		done:       make(chan struct{}),
+		headerChan: make(chan struct{}),
+		doneFunc:   callHdr.DoneFunc,
 	}
 	s.wq = newWriteQuota(defaultWriteQuota, s.done)
 	s.requestRead = func(n int) {
@@ -498,9 +509,8 @@ func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
 			ctxDone: s.ctx.Done(),
 			recv:    s.buf,
 			closeStream: func(err error) {
-				t.CloseStream(s, err)
+				s.Close(err)
 			},
-			freeBuffer: t.bufferPool.put,
 		},
 		windowHandler: func(n int) {
 			t.updateWindow(s, uint32(n))
@@ -517,6 +527,18 @@ func (t *http2Client) getPeer() *peer.Peer {
 	}
 }
 
+// OutgoingGoAwayHandler writes a GOAWAY to the connection.  Always returns (false, err) as we want the GoAway
+// to be the last frame loopy writes to the transport.
+func (t *http2Client) outgoingGoAwayHandler(g *goAway) (bool, error) {
+	t.mu.Lock()
+	maxStreamID := t.nextID - 2
+	t.mu.Unlock()
+	if err := t.framer.fr.WriteGoAway(maxStreamID, http2.ErrCodeNo, g.debugData); err != nil {
+		return false, err
+	}
+	return false, g.closeConn
+}
+
 func (t *http2Client) createHeaderFields(ctx context.Context, callHdr *CallHdr) ([]hpack.HeaderField, error) {
 	aud := t.createAudience(callHdr)
 	ri := credentials.RequestInfo{
@@ -578,12 +600,6 @@ func (t *http2Client) createHeaderFields(ctx context.Context, callHdr *CallHdr)
 	for k, v := range callAuthData {
 		headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
 	}
-	if b := stats.OutgoingTags(ctx); b != nil {
-		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-tags-bin", Value: encodeBinHeader(b)})
-	}
-	if b := stats.OutgoingTrace(ctx); b != nil {
-		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-trace-bin", Value: encodeBinHeader(b)})
-	}
 
 	if md, added, ok := metadataFromOutgoingContextRaw(ctx); ok {
 		var k string
@@ -719,7 +735,7 @@ func (e NewStreamError) Error() string {
 
 // NewStream creates a stream and registers it into the transport as "active"
 // streams.  All non-nil errors returned will be *NewStreamError.
-func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error) {
+func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*ClientStream, error) {
 	ctx = peer.NewContext(ctx, t.getPeer())
 
 	// ServerName field of the resolver returned address takes precedence over
@@ -744,7 +760,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 			return
 		}
 		// The stream was unprocessed by the server.
-		atomic.StoreUint32(&s.unprocessed, 1)
+		s.unprocessed.Store(true)
 		s.write(recvMsg{err: err})
 		close(s.done)
 		// If headerChan isn't closed, then close it.
@@ -755,7 +771,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 	hdr := &headerFrame{
 		hf:        headerFields,
 		endStream: false,
-		initStream: func(id uint32) error {
+		initStream: func(uint32) error {
 			t.mu.Lock()
 			// TODO: handle transport closure in loopy instead and remove this
 			// initStream is never called when transport is draining.
@@ -781,7 +797,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 	firstTry := true
 	var ch chan struct{}
 	transportDrainRequired := false
-	checkForStreamQuota := func(it any) bool {
+	checkForStreamQuota := func() bool {
 		if t.streamQuota <= 0 { // Can go negative if server decreases it.
 			if firstTry {
 				t.waitingStreams++
@@ -793,23 +809,24 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 			t.waitingStreams--
 		}
 		t.streamQuota--
-		h := it.(*headerFrame)
-		h.streamID = t.nextID
-		t.nextID += 2
 
-		// Drain client transport if nextID > MaxStreamID which signals gRPC that
-		// the connection is closed and a new one must be created for subsequent RPCs.
-		transportDrainRequired = t.nextID > MaxStreamID
-
-		s.id = h.streamID
-		s.fc = &inFlow{limit: uint32(t.initialWindowSize)}
 		t.mu.Lock()
 		if t.state == draining || t.activeStreams == nil { // Can be niled from Close().
 			t.mu.Unlock()
 			return false // Don't create a stream if the transport is already closed.
 		}
+
+		hdr.streamID = t.nextID
+		t.nextID += 2
+		// Drain client transport if nextID > MaxStreamID which signals gRPC that
+		// the connection is closed and a new one must be created for subsequent RPCs.
+		transportDrainRequired = t.nextID > MaxStreamID
+
+		s.id = hdr.streamID
+		s.fc = &inFlow{limit: uint32(t.initialWindowSize)}
 		t.activeStreams[s.id] = s
 		t.mu.Unlock()
+
 		if t.streamQuota > 0 && t.waitingStreams > 0 {
 			select {
 			case t.streamsQuotaAvailable <- struct{}{}:
@@ -819,13 +836,12 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 		return true
 	}
 	var hdrListSizeErr error
-	checkForHeaderListSize := func(it any) bool {
+	checkForHeaderListSize := func() bool {
 		if t.maxSendHeaderListSize == nil {
 			return true
 		}
-		hdrFrame := it.(*headerFrame)
 		var sz int64
-		for _, f := range hdrFrame.hf {
+		for _, f := range hdr.hf {
 			if sz += int64(f.Size()); sz > int64(*t.maxSendHeaderListSize) {
 				hdrListSizeErr = status.Errorf(codes.Internal, "header list size to send violates the maximum size (%d bytes) set by server", *t.maxSendHeaderListSize)
 				return false
@@ -834,8 +850,8 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 		return true
 	}
 	for {
-		success, err := t.controlBuf.executeAndPut(func(it any) bool {
-			return checkForHeaderListSize(it) && checkForStreamQuota(it)
+		success, err := t.controlBuf.executeAndPut(func() bool {
+			return checkForHeaderListSize() && checkForStreamQuota()
 		}, hdr)
 		if err != nil {
 			// Connection closed.
@@ -889,21 +905,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (*Stream,
 	return s, nil
 }
 
-// CloseStream clears the footprint of a stream when the stream is not needed any more.
-// This must not be executed in reader's goroutine.
-func (t *http2Client) CloseStream(s *Stream, err error) {
-	var (
-		rst     bool
-		rstCode http2.ErrCode
-	)
-	if err != nil {
-		rst = true
-		rstCode = http2.ErrCodeCancel
-	}
-	t.closeStream(s, err, rst, rstCode, status.Convert(err), nil, false)
-}
-
-func (t *http2Client) closeStream(s *Stream, err error, rst bool, rstCode http2.ErrCode, st *status.Status, mdata map[string][]string, eosReceived bool) {
+func (t *http2Client) closeStream(s *ClientStream, err error, rst bool, rstCode http2.ErrCode, st *status.Status, mdata map[string][]string, eosReceived bool) {
 	// Set stream status to done.
 	if s.swapState(streamDone) == streamDone {
 		// If it was already done, return.  If multiple closeStream calls
@@ -946,7 +948,7 @@ func (t *http2Client) closeStream(s *Stream, err error, rst bool, rstCode http2.
 		rst:     rst,
 		rstCode: rstCode,
 	}
-	addBackStreamQuota := func(any) bool {
+	addBackStreamQuota := func() bool {
 		t.streamQuota++
 		if t.streamQuota > 0 && t.waitingStreams > 0 {
 			select {
@@ -966,8 +968,9 @@ func (t *http2Client) closeStream(s *Stream, err error, rst bool, rstCode http2.
 
 // Close kicks off the shutdown process of the transport. This should be called
 // only once on a transport. Once it is called, the transport should not be
-// accessed any more.
+// accessed anymore.
 func (t *http2Client) Close(err error) {
+	t.conn.SetWriteDeadline(time.Now().Add(time.Second * 10))
 	t.mu.Lock()
 	// Make sure we only close once.
 	if t.state == closing {
@@ -990,15 +993,33 @@ func (t *http2Client) Close(err error) {
 		// should unblock it so that the goroutine eventually exits.
 		t.kpDormancyCond.Signal()
 	}
-	t.mu.Unlock()
-	t.controlBuf.finish()
-	t.cancel()
-	t.conn.Close()
-	channelz.RemoveEntry(t.channelz.ID)
 	// Append info about previous goaways if there were any, since this may be important
 	// for understanding the root cause for this connection to be closed.
-	_, goAwayDebugMessage := t.GetGoAwayReason()
+	goAwayDebugMessage := t.goAwayDebugMessage
+	t.mu.Unlock()
 
+	// Per HTTP/2 spec, a GOAWAY frame must be sent before closing the
+	// connection. See https://httpwg.org/specs/rfc7540.html#GOAWAY. It
+	// also waits for loopyWriter to be closed with a timer to avoid the
+	// long blocking in case the connection is blackholed, i.e. TCP is
+	// just stuck.
+	t.controlBuf.put(&goAway{code: http2.ErrCodeNo, debugData: []byte("client transport shutdown"), closeConn: err})
+	timer := time.NewTimer(goAwayLoopyWriterTimeout)
+	defer timer.Stop()
+	select {
+	case <-t.writerDone: // success
+	case <-timer.C:
+		t.logger.Infof("Failed to write a GOAWAY frame as part of connection close after %s. Giving up and closing the transport.", goAwayLoopyWriterTimeout)
+	}
+	t.cancel()
+	t.conn.Close()
+	// Waits for the reader and keepalive goroutines to exit before returning to
+	// ensure all resources are cleaned up before Close can return.
+	<-t.readerDone
+	if t.keepaliveEnabled {
+		<-t.keepaliveDone
+	}
+	channelz.RemoveEntry(t.channelz.ID)
 	var st *status.Status
 	if len(goAwayDebugMessage) > 0 {
 		st = status.Newf(codes.Unavailable, "closing transport due to: %v, received prior goaway: %v", err, goAwayDebugMessage)
@@ -1047,30 +1068,40 @@ func (t *http2Client) GracefulClose() {
 
 // Write formats the data into HTTP2 data frame(s) and sends it out. The caller
 // should proceed only if Write returns nil.
-func (t *http2Client) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (t *http2Client) write(s *ClientStream, hdr []byte, data mem.BufferSlice, opts *WriteOptions) error {
+	reader := data.Reader()
+
 	if opts.Last {
 		// If it's the last message, update stream state.
 		if !s.compareAndSwapState(streamActive, streamWriteDone) {
+			_ = reader.Close()
 			return errStreamDone
 		}
 	} else if s.getState() != streamActive {
+		_ = reader.Close()
 		return errStreamDone
 	}
 	df := &dataFrame{
 		streamID:  s.id,
 		endStream: opts.Last,
 		h:         hdr,
-		d:         data,
+		reader:    reader,
 	}
-	if hdr != nil || data != nil { // If it's not an empty data frame, check quota.
-		if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+	if hdr != nil || df.reader.Remaining() != 0 { // If it's not an empty data frame, check quota.
+		if err := s.wq.get(int32(len(hdr) + df.reader.Remaining())); err != nil {
+			_ = reader.Close()
 			return err
 		}
 	}
-	return t.controlBuf.put(df)
+	if err := t.controlBuf.put(df); err != nil {
+		_ = reader.Close()
+		return err
+	}
+	t.incrMsgSent()
+	return nil
 }
 
-func (t *http2Client) getStream(f http2.Frame) *Stream {
+func (t *http2Client) getStream(f http2.Frame) *ClientStream {
 	t.mu.Lock()
 	s := t.activeStreams[f.Header().StreamID]
 	t.mu.Unlock()
@@ -1080,7 +1111,7 @@ func (t *http2Client) getStream(f http2.Frame) *Stream {
 // adjustWindow sends out extra window update over the initial window size
 // of stream if the application is requesting data larger in size than
 // the window.
-func (t *http2Client) adjustWindow(s *Stream, n uint32) {
+func (t *http2Client) adjustWindow(s *ClientStream, n uint32) {
 	if w := s.fc.maybeAdjust(n); w > 0 {
 		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
 	}
@@ -1089,7 +1120,7 @@ func (t *http2Client) adjustWindow(s *Stream, n uint32) {
 // updateWindow adjusts the inbound quota for the stream.
 // Window updates will be sent out when the cumulative quota
 // exceeds the corresponding threshold.
-func (t *http2Client) updateWindow(s *Stream, n uint32) {
+func (t *http2Client) updateWindow(s *ClientStream, n uint32) {
 	if w := s.fc.onRead(n); w > 0 {
 		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
 	}
@@ -1099,7 +1130,7 @@ func (t *http2Client) updateWindow(s *Stream, n uint32) {
 // for the transport and the stream based on the current bdp
 // estimation.
 func (t *http2Client) updateFlowControl(n uint32) {
-	updateIWS := func(any) bool {
+	updateIWS := func() bool {
 		t.initialWindowSize = int32(n)
 		t.mu.Lock()
 		for _, s := range t.activeStreams {
@@ -1172,10 +1203,13 @@ func (t *http2Client) handleData(f *http2.DataFrame) {
 		// guarantee f.Data() is consumed before the arrival of next frame.
 		// Can this copy be eliminated?
 		if len(f.Data()) > 0 {
-			buffer := t.bufferPool.get()
-			buffer.Reset()
-			buffer.Write(f.Data())
-			s.write(recvMsg{buffer: buffer})
+			pool := t.bufferPool
+			if pool == nil {
+				// Note that this is only supposed to be nil in tests. Otherwise, stream is
+				// always initialized with a BufferPool.
+				pool = mem.DefaultBufferPool()
+			}
+			s.write(recvMsg{buffer: mem.Copy(f.Data(), pool)})
 		}
 	}
 	// The server has closed the stream without sending trailers.  Record that
@@ -1192,7 +1226,7 @@ func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
 	}
 	if f.ErrCode == http2.ErrCodeRefusedStream {
 		// The stream was unprocessed by the server.
-		atomic.StoreUint32(&s.unprocessed, 1)
+		s.unprocessed.Store(true)
 	}
 	statusCode, ok := http2ErrConvTab[f.ErrCode]
 	if !ok {
@@ -1204,11 +1238,12 @@ func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
 	if statusCode == codes.Canceled {
 		if d, ok := s.ctx.Deadline(); ok && !d.After(time.Now()) {
 			// Our deadline was already exceeded, and that was likely the cause
-			// of this cancelation.  Alter the status code accordingly.
+			// of this cancellation.  Alter the status code accordingly.
 			statusCode = codes.DeadlineExceeded
 		}
 	}
-	t.closeStream(s, io.EOF, false, http2.ErrCodeNo, status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %v", f.ErrCode), nil, false)
+	st := status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %v", f.ErrCode)
+	t.closeStream(s, st.Err(), false, http2.ErrCodeNo, st, nil, false)
 }
 
 func (t *http2Client) handleSettings(f *http2.SettingsFrame, isFirst bool) {
@@ -1252,7 +1287,7 @@ func (t *http2Client) handleSettings(f *http2.SettingsFrame, isFirst bool) {
 		}
 		updateFuncs = append(updateFuncs, updateStreamQuota)
 	}
-	t.controlBuf.executeAndPut(func(any) bool {
+	t.controlBuf.executeAndPut(func() bool {
 		for _, f := range updateFuncs {
 			f()
 		}
@@ -1273,11 +1308,11 @@ func (t *http2Client) handlePing(f *http2.PingFrame) {
 	t.controlBuf.put(pingAck)
 }
 
-func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
+func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) error {
 	t.mu.Lock()
 	if t.state == closing {
 		t.mu.Unlock()
-		return
+		return nil
 	}
 	if f.ErrCode == http2.ErrCodeEnhanceYourCalm && string(f.DebugData()) == "too_many_pings" {
 		// When a client receives a GOAWAY with error code ENHANCE_YOUR_CALM and debug
@@ -1289,8 +1324,7 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 	id := f.LastStreamID
 	if id > 0 && id%2 == 0 {
 		t.mu.Unlock()
-		t.Close(connectionErrorf(true, nil, "received goaway with non-zero even-numbered numbered stream id: %v", id))
-		return
+		return connectionErrorf(true, nil, "received goaway with non-zero even-numbered stream id: %v", id)
 	}
 	// A client can receive multiple GoAways from the server (see
 	// https://github.com/grpc/grpc-go/issues/1387).  The idea is that the first
@@ -1307,8 +1341,7 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 		// If there are multiple GoAways the first one should always have an ID greater than the following ones.
 		if id > t.prevGoAwayID {
 			t.mu.Unlock()
-			t.Close(connectionErrorf(true, nil, "received goaway with stream id: %v, which exceeds stream id of previous goaway: %v", id, t.prevGoAwayID))
-			return
+			return connectionErrorf(true, nil, "received goaway with stream id: %v, which exceeds stream id of previous goaway: %v", id, t.prevGoAwayID)
 		}
 	default:
 		t.setGoAwayReason(f)
@@ -1332,15 +1365,14 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 	t.prevGoAwayID = id
 	if len(t.activeStreams) == 0 {
 		t.mu.Unlock()
-		t.Close(connectionErrorf(true, nil, "received goaway and there are no active streams"))
-		return
+		return connectionErrorf(true, nil, "received goaway and there are no active streams")
 	}
 
-	streamsToClose := make([]*Stream, 0)
+	streamsToClose := make([]*ClientStream, 0)
 	for streamID, stream := range t.activeStreams {
 		if streamID > id && streamID <= upperLimit {
 			// The stream was unprocessed by the server.
-			atomic.StoreUint32(&stream.unprocessed, 1)
+			stream.unprocessed.Store(true)
 			streamsToClose = append(streamsToClose, stream)
 		}
 	}
@@ -1350,6 +1382,7 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 	for _, stream := range streamsToClose {
 		t.closeStream(stream, errStreamDrain, false, http2.ErrCodeNo, statusGoAway, nil, false)
 	}
+	return nil
 }
 
 // setGoAwayReason sets the value of t.goAwayReason based
@@ -1358,8 +1391,7 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 // the caller.
 func (t *http2Client) setGoAwayReason(f *http2.GoAwayFrame) {
 	t.goAwayReason = GoAwayNoReason
-	switch f.ErrCode {
-	case http2.ErrCodeEnhanceYourCalm:
+	if f.ErrCode == http2.ErrCodeEnhanceYourCalm {
 		if string(f.DebugData()) == "too_many_pings" {
 			t.goAwayReason = GoAwayTooManyPings
 		}
@@ -1391,7 +1423,7 @@ func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
 		return
 	}
 	endStream := frame.StreamEnded()
-	atomic.StoreUint32(&s.bytesReceived, 1)
+	s.bytesReceived.Store(true)
 	initialHeader := atomic.LoadUint32(&s.headerChanClosed) == 0
 
 	if !initialHeader && !endStream {
@@ -1585,7 +1617,13 @@ func (t *http2Client) readServerPreface() error {
 // network connection.  If the server preface is not read successfully, an
 // error is pushed to errCh; otherwise errCh is closed with no error.
 func (t *http2Client) reader(errCh chan<- error) {
-	defer close(t.readerDone)
+	var errClose error
+	defer func() {
+		close(t.readerDone)
+		if errClose != nil {
+			t.Close(errClose)
+		}
+	}()
 
 	if err := t.readServerPreface(); err != nil {
 		errCh <- err
@@ -1624,11 +1662,10 @@ func (t *http2Client) reader(errCh chan<- error) {
 					t.closeStream(s, status.Error(code, msg), true, http2.ErrCodeProtocol, status.New(code, msg), nil, false)
 				}
 				continue
-			} else {
-				// Transport error.
-				t.Close(connectionErrorf(true, err, "error reading from server: %v", err))
-				return
 			}
+			// Transport error.
+			errClose = connectionErrorf(true, err, "error reading from server: %v", err)
+			return
 		}
 		switch frame := frame.(type) {
 		case *http2.MetaHeadersFrame:
@@ -1642,7 +1679,7 @@ func (t *http2Client) reader(errCh chan<- error) {
 		case *http2.PingFrame:
 			t.handlePing(frame)
 		case *http2.GoAwayFrame:
-			t.handleGoAway(frame)
+			errClose = t.handleGoAway(frame)
 		case *http2.WindowUpdateFrame:
 			t.handleWindowUpdate(frame)
 		default:
@@ -1653,15 +1690,15 @@ func (t *http2Client) reader(errCh chan<- error) {
 	}
 }
 
-func minTime(a, b time.Duration) time.Duration {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 // keepalive running in a separate goroutine makes sure the connection is alive by sending pings.
 func (t *http2Client) keepalive() {
+	var err error
+	defer func() {
+		close(t.keepaliveDone)
+		if err != nil {
+			t.Close(err)
+		}
+	}()
 	p := &ping{data: [8]byte{}}
 	// True iff a ping has been sent, and no data has been received since then.
 	outstandingPing := false
@@ -1685,7 +1722,7 @@ func (t *http2Client) keepalive() {
 				continue
 			}
 			if outstandingPing && timeoutLeft <= 0 {
-				t.Close(connectionErrorf(true, nil, "keepalive ping failed to receive ACK within timeout"))
+				err = connectionErrorf(true, nil, "keepalive ping failed to receive ACK within timeout")
 				return
 			}
 			t.mu.Lock()
@@ -1727,7 +1764,7 @@ func (t *http2Client) keepalive() {
 			// timeoutLeft. This will ensure that we wait only for kp.Time
 			// before sending out the next ping (for cases where the ping is
 			// acked).
-			sleepDuration := minTime(t.kp.Time, timeoutLeft)
+			sleepDuration := min(t.kp.Time, timeoutLeft)
 			timeoutLeft -= sleepDuration
 			timer.Reset(sleepDuration)
 		case <-t.ctx.Done():
@@ -1756,14 +1793,18 @@ func (t *http2Client) socketMetrics() *channelz.EphemeralSocketMetrics {
 
 func (t *http2Client) RemoteAddr() net.Addr { return t.remoteAddr }
 
-func (t *http2Client) IncrMsgSent() {
-	t.channelz.SocketMetrics.MessagesSent.Add(1)
-	t.channelz.SocketMetrics.LastMessageSentTimestamp.Store(time.Now().UnixNano())
+func (t *http2Client) incrMsgSent() {
+	if channelz.IsOn() {
+		t.channelz.SocketMetrics.MessagesSent.Add(1)
+		t.channelz.SocketMetrics.LastMessageSentTimestamp.Store(time.Now().UnixNano())
+	}
 }
 
-func (t *http2Client) IncrMsgRecv() {
-	t.channelz.SocketMetrics.MessagesReceived.Add(1)
-	t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Store(time.Now().UnixNano())
+func (t *http2Client) incrMsgRecv() {
+	if channelz.IsOn() {
+		t.channelz.SocketMetrics.MessagesReceived.Add(1)
+		t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Store(time.Now().UnixNano())
+	}
 }
 
 func (t *http2Client) getOutFlowWindow() int64 {

vendor/google.golang.org/grpc/internal/transport/http2_server.go

@@ -25,6 +25,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	rand "math/rand/v2"
 	"net"
 	"net/http"
 	"strconv"
@@ -34,16 +35,17 @@ import (
 
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/hpack"
+	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/internal/grpclog"
 	"google.golang.org/grpc/internal/grpcutil"
 	"google.golang.org/grpc/internal/pretty"
 	"google.golang.org/grpc/internal/syscall"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/protobuf/proto"
 
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/channelz"
-	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/internal/grpcsync"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
@@ -110,7 +112,7 @@ type http2Server struct {
 	// already initialized since draining is already underway.
 	drainEvent    *grpcsync.Event
 	state         transportState
-	activeStreams map[uint32]*Stream
+	activeStreams map[uint32]*ServerStream
 	// idle is the time instant when the connection went idle.
 	// This is either the beginning of the connection or when the number of
 	// RPCs go down to 0.
@@ -119,7 +121,7 @@ type http2Server struct {
 
 	// Fields below are for channelz metric collection.
 	channelz   *channelz.Socket
-	bufferPool *bufferPool
+	bufferPool mem.BufferPool
 
 	connectionID uint64
 
@@ -255,13 +257,13 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 		inTapHandle:       config.InTapHandle,
 		fc:                &trInFlow{limit: uint32(icwz)},
 		state:             reachable,
-		activeStreams:     make(map[uint32]*Stream),
+		activeStreams:     make(map[uint32]*ServerStream),
 		stats:             config.StatsHandlers,
 		kp:                kp,
 		idle:              time.Now(),
 		kep:               kep,
 		initialWindowSize: iwz,
-		bufferPool:        newBufferPool(),
+		bufferPool:        config.BufferPool,
 	}
 	var czSecurity credentials.ChannelzSecurityValue
 	if au, ok := authInfo.(credentials.ChannelzSecurityInfo); ok {
@@ -330,8 +332,7 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 	t.handleSettings(sf)
 
 	go func() {
-		t.loopy = newLoopyWriter(serverSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger)
-		t.loopy.ssGoAwayHandler = t.outgoingGoAwayHandler
+		t.loopy = newLoopyWriter(serverSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler, t.bufferPool)
 		err := t.loopy.run()
 		close(t.loopyWriterDone)
 		if !isIOError(err) {
@@ -359,7 +360,7 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 
 // operateHeaders takes action on the decoded headers. Returns an error if fatal
 // error encountered and transport needs to close, otherwise returns nil.
-func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeadersFrame, handle func(*Stream)) error {
+func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeadersFrame, handle func(*ServerStream)) error {
 	// Acquire max stream ID lock for entire duration
 	t.maxStreamMu.Lock()
 	defer t.maxStreamMu.Unlock()
@@ -385,11 +386,13 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 	t.maxStreamID = streamID
 
 	buf := newRecvBuffer()
-	s := &Stream{
-		id:               streamID,
+	s := &ServerStream{
+		Stream: &Stream{
+			id:  streamID,
+			buf: buf,
+			fc:  &inFlow{limit: uint32(t.initialWindowSize)},
+		},
 		st:               t,
-		buf:              buf,
-		fc:               &inFlow{limit: uint32(t.initialWindowSize)},
 		headerWireLength: int(frame.Header().Length),
 	}
 	var (
@@ -537,12 +540,6 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 	// Attach the received metadata to the context.
 	if len(mdata) > 0 {
 		s.ctx = metadata.NewIncomingContext(s.ctx, mdata)
-		if statsTags := mdata["grpc-tags-bin"]; len(statsTags) > 0 {
-			s.ctx = stats.SetIncomingTags(s.ctx, []byte(statsTags[len(statsTags)-1]))
-		}
-		if statsTrace := mdata["grpc-trace-bin"]; len(statsTrace) > 0 {
-			s.ctx = stats.SetIncomingTrace(s.ctx, []byte(statsTrace[len(statsTrace)-1]))
-		}
 	}
 	t.mu.Lock()
 	if t.state != reachable {
@@ -568,7 +565,7 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 			t.logger.Infof("Aborting the stream early: %v", errMsg)
 		}
 		t.controlBuf.put(&earlyAbortStream{
-			httpStatus:     405,
+			httpStatus:     http.StatusMethodNotAllowed,
 			streamID:       streamID,
 			contentSubtype: s.contentSubtype,
 			status:         status.New(codes.Internal, errMsg),
@@ -589,7 +586,7 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 				stat = status.New(codes.PermissionDenied, err.Error())
 			}
 			t.controlBuf.put(&earlyAbortStream{
-				httpStatus:     200,
+				httpStatus:     http.StatusOK,
 				streamID:       s.id,
 				contentSubtype: s.contentSubtype,
 				status:         stat,
@@ -602,6 +599,22 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 	if len(t.activeStreams) == 1 {
 		t.idle = time.Time{}
 	}
+	// Start a timer to close the stream on reaching the deadline.
+	if timeoutSet {
+		// We need to wait for s.cancel to be updated before calling
+		// t.closeStream to avoid data races.
+		cancelUpdated := make(chan struct{})
+		timer := internal.TimeAfterFunc(timeout, func() {
+			<-cancelUpdated
+			t.closeStream(s, true, http2.ErrCodeCancel, false)
+		})
+		oldCancel := s.cancel
+		s.cancel = func() {
+			oldCancel()
+			timer.Stop()
+		}
+		close(cancelUpdated)
+	}
 	t.mu.Unlock()
 	if channelz.IsOn() {
 		t.channelz.SocketMetrics.StreamsStarted.Add(1)
@@ -614,10 +627,9 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 	s.wq = newWriteQuota(defaultWriteQuota, s.ctxDone)
 	s.trReader = &transportReader{
 		reader: &recvBufferReader{
-			ctx:        s.ctx,
-			ctxDone:    s.ctxDone,
-			recv:       s.buf,
-			freeBuffer: t.bufferPool.put,
+			ctx:     s.ctx,
+			ctxDone: s.ctxDone,
+			recv:    s.buf,
 		},
 		windowHandler: func(n int) {
 			t.updateWindow(s, uint32(n))
@@ -635,7 +647,7 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 // HandleStreams receives incoming streams using the given handler. This is
 // typically run in a separate goroutine.
 // traceCtx attaches trace to ctx and returns the new context.
-func (t *http2Server) HandleStreams(ctx context.Context, handle func(*Stream)) {
+func (t *http2Server) HandleStreams(ctx context.Context, handle func(*ServerStream)) {
 	defer func() {
 		close(t.readerDone)
 		<-t.loopyWriterDone
@@ -699,7 +711,7 @@ func (t *http2Server) HandleStreams(ctx context.Context, handle func(*Stream)) {
 	}
 }
 
-func (t *http2Server) getStream(f http2.Frame) (*Stream, bool) {
+func (t *http2Server) getStream(f http2.Frame) (*ServerStream, bool) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 	if t.activeStreams == nil {
@@ -717,7 +729,7 @@ func (t *http2Server) getStream(f http2.Frame) (*Stream, bool) {
 // adjustWindow sends out extra window update over the initial window size
 // of stream if the application is requesting data larger in size than
 // the window.
-func (t *http2Server) adjustWindow(s *Stream, n uint32) {
+func (t *http2Server) adjustWindow(s *ServerStream, n uint32) {
 	if w := s.fc.maybeAdjust(n); w > 0 {
 		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
 	}
@@ -727,7 +739,7 @@ func (t *http2Server) adjustWindow(s *Stream, n uint32) {
 // updateWindow adjusts the inbound quota for the stream and the transport.
 // Window updates will deliver to the controller for sending when
 // the cumulative quota exceeds the corresponding threshold.
-func (t *http2Server) updateWindow(s *Stream, n uint32) {
+func (t *http2Server) updateWindow(s *ServerStream, n uint32) {
 	if w := s.fc.onRead(n); w > 0 {
 		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id,
 			increment: w,
@@ -814,10 +826,13 @@ func (t *http2Server) handleData(f *http2.DataFrame) {
 		// guarantee f.Data() is consumed before the arrival of next frame.
 		// Can this copy be eliminated?
 		if len(f.Data()) > 0 {
-			buffer := t.bufferPool.get()
-			buffer.Reset()
-			buffer.Write(f.Data())
-			s.write(recvMsg{buffer: buffer})
+			pool := t.bufferPool
+			if pool == nil {
+				// Note that this is only supposed to be nil in tests. Otherwise, stream is
+				// always initialized with a BufferPool.
+				pool = mem.DefaultBufferPool()
+			}
+			s.write(recvMsg{buffer: mem.Copy(f.Data(), pool)})
 		}
 	}
 	if f.StreamEnded() {
@@ -860,7 +875,7 @@ func (t *http2Server) handleSettings(f *http2.SettingsFrame) {
 		}
 		return nil
 	})
-	t.controlBuf.executeAndPut(func(any) bool {
+	t.controlBuf.executeAndPut(func() bool {
 		for _, f := range updateFuncs {
 			f()
 		}
@@ -961,7 +976,7 @@ func (t *http2Server) checkForHeaderListSize(it any) bool {
 	return true
 }
 
-func (t *http2Server) streamContextErr(s *Stream) error {
+func (t *http2Server) streamContextErr(s *ServerStream) error {
 	select {
 	case <-t.done:
 		return ErrConnClosing
@@ -971,7 +986,7 @@ func (t *http2Server) streamContextErr(s *Stream) error {
 }
 
 // WriteHeader sends the header metadata md back to the client.
-func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
+func (t *http2Server) writeHeader(s *ServerStream, md metadata.MD) error {
 	s.hdrMu.Lock()
 	defer s.hdrMu.Unlock()
 	if s.getState() == streamDone {
@@ -1004,7 +1019,7 @@ func (t *http2Server) setResetPingStrikes() {
 	atomic.StoreUint32(&t.resetPingStrikes, 1)
 }
 
-func (t *http2Server) writeHeaderLocked(s *Stream) error {
+func (t *http2Server) writeHeaderLocked(s *ServerStream) error {
 	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
 	// first and create a slice of that exact size.
 	headerFields := make([]hpack.HeaderField, 0, 2) // at least :status, content-type will be there if none else.
@@ -1014,12 +1029,13 @@ func (t *http2Server) writeHeaderLocked(s *Stream) error {
 		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
 	}
 	headerFields = appendHeaderFieldsFromMD(headerFields, s.header)
-	success, err := t.controlBuf.executeAndPut(t.checkForHeaderListSize, &headerFrame{
+	hf := &headerFrame{
 		streamID:  s.id,
 		hf:        headerFields,
 		endStream: false,
 		onWrite:   t.setResetPingStrikes,
-	})
+	}
+	success, err := t.controlBuf.executeAndPut(func() bool { return t.checkForHeaderListSize(hf) }, hf)
 	if !success {
 		if err != nil {
 			return err
@@ -1043,7 +1059,7 @@ func (t *http2Server) writeHeaderLocked(s *Stream) error {
 // There is no further I/O operations being able to perform on this stream.
 // TODO(zhaoq): Now it indicates the end of entire stream. Revisit if early
 // OK is adopted.
-func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
+func (t *http2Server) writeStatus(s *ServerStream, st *status.Status) error {
 	s.hdrMu.Lock()
 	defer s.hdrMu.Unlock()
 
@@ -1089,7 +1105,9 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 		onWrite:   t.setResetPingStrikes,
 	}
 
-	success, err := t.controlBuf.execute(t.checkForHeaderListSize, trailingHeader)
+	success, err := t.controlBuf.executeAndPut(func() bool {
+		return t.checkForHeaderListSize(trailingHeader)
+	}, nil)
 	if !success {
 		if err != nil {
 			return err
@@ -1112,27 +1130,38 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 
 // Write converts the data into HTTP2 data frame and sends it out. Non-nil error
 // is returns if it fails (e.g., framing error, transport error).
-func (t *http2Server) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (t *http2Server) write(s *ServerStream, hdr []byte, data mem.BufferSlice, _ *WriteOptions) error {
+	reader := data.Reader()
+
 	if !s.isHeaderSent() { // Headers haven't been written yet.
-		if err := t.WriteHeader(s, nil); err != nil {
+		if err := t.writeHeader(s, nil); err != nil {
+			_ = reader.Close()
 			return err
 		}
 	} else {
 		// Writing headers checks for this condition.
 		if s.getState() == streamDone {
+			_ = reader.Close()
 			return t.streamContextErr(s)
 		}
 	}
+
 	df := &dataFrame{
 		streamID:    s.id,
 		h:           hdr,
-		d:           data,
+		reader:      reader,
 		onEachWrite: t.setResetPingStrikes,
 	}
-	if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+	if err := s.wq.get(int32(len(hdr) + df.reader.Remaining())); err != nil {
+		_ = reader.Close()
 		return t.streamContextErr(s)
 	}
-	return t.controlBuf.put(df)
+	if err := t.controlBuf.put(df); err != nil {
+		_ = reader.Close()
+		return err
+	}
+	t.incrMsgSent()
+	return nil
 }
 
 // keepalive running in a separate goroutine does the following:
@@ -1208,7 +1237,7 @@ func (t *http2Server) keepalive() {
 				continue
 			}
 			if outstandingPing && kpTimeoutLeft <= 0 {
-				t.Close(fmt.Errorf("keepalive ping not acked within timeout %s", t.kp.Time))
+				t.Close(fmt.Errorf("keepalive ping not acked within timeout %s", t.kp.Timeout))
 				return
 			}
 			if !outstandingPing {
@@ -1223,7 +1252,7 @@ func (t *http2Server) keepalive() {
 			// timeoutLeft. This will ensure that we wait only for kp.Time
 			// before sending out the next ping (for cases where the ping is
 			// acked).
-			sleepDuration := minTime(t.kp.Time, kpTimeoutLeft)
+			sleepDuration := min(t.kp.Time, kpTimeoutLeft)
 			kpTimeoutLeft -= sleepDuration
 			kpTimer.Reset(sleepDuration)
 		case <-t.done:
@@ -1261,8 +1290,7 @@ func (t *http2Server) Close(err error) {
 }
 
 // deleteStream deletes the stream s from transport's active streams.
-func (t *http2Server) deleteStream(s *Stream, eosReceived bool) {
-
+func (t *http2Server) deleteStream(s *ServerStream, eosReceived bool) {
 	t.mu.Lock()
 	if _, ok := t.activeStreams[s.id]; ok {
 		delete(t.activeStreams, s.id)
@@ -1282,7 +1310,7 @@ func (t *http2Server) deleteStream(s *Stream, eosReceived bool) {
 }
 
 // finishStream closes the stream and puts the trailing headerFrame into controlbuf.
-func (t *http2Server) finishStream(s *Stream, rst bool, rstCode http2.ErrCode, hdr *headerFrame, eosReceived bool) {
+func (t *http2Server) finishStream(s *ServerStream, rst bool, rstCode http2.ErrCode, hdr *headerFrame, eosReceived bool) {
 	// In case stream sending and receiving are invoked in separate
 	// goroutines (e.g., bi-directional streaming), cancel needs to be
 	// called to interrupt the potential blocking on other goroutines.
@@ -1306,13 +1334,16 @@ func (t *http2Server) finishStream(s *Stream, rst bool, rstCode http2.ErrCode, h
 }
 
 // closeStream clears the footprint of a stream when the stream is not needed any more.
-func (t *http2Server) closeStream(s *Stream, rst bool, rstCode http2.ErrCode, eosReceived bool) {
+func (t *http2Server) closeStream(s *ServerStream, rst bool, rstCode http2.ErrCode, eosReceived bool) {
 	// In case stream sending and receiving are invoked in separate
 	// goroutines (e.g., bi-directional streaming), cancel needs to be
 	// called to interrupt the potential blocking on other goroutines.
 	s.cancel()
 
-	s.swapState(streamDone)
+	oldState := s.swapState(streamDone)
+	if oldState == streamDone {
+		return
+	}
 	t.deleteStream(s, eosReceived)
 
 	t.controlBuf.put(&cleanupStream{
@@ -1400,14 +1431,18 @@ func (t *http2Server) socketMetrics() *channelz.EphemeralSocketMetrics {
 	}
 }
 
-func (t *http2Server) IncrMsgSent() {
-	t.channelz.SocketMetrics.MessagesSent.Add(1)
-	t.channelz.SocketMetrics.LastMessageSentTimestamp.Add(1)
+func (t *http2Server) incrMsgSent() {
+	if channelz.IsOn() {
+		t.channelz.SocketMetrics.MessagesSent.Add(1)
+		t.channelz.SocketMetrics.LastMessageSentTimestamp.Add(1)
+	}
 }
 
-func (t *http2Server) IncrMsgRecv() {
-	t.channelz.SocketMetrics.MessagesReceived.Add(1)
-	t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Add(1)
+func (t *http2Server) incrMsgRecv() {
+	if channelz.IsOn() {
+		t.channelz.SocketMetrics.MessagesReceived.Add(1)
+		t.channelz.SocketMetrics.LastMessageReceivedTimestamp.Add(1)
+	}
 }
 
 func (t *http2Server) getOutFlowWindow() int64 {
@@ -1440,7 +1475,7 @@ func getJitter(v time.Duration) time.Duration {
 	}
 	// Generate a jitter between +/- 10% of the value.
 	r := int64(v / 10)
-	j := grpcrand.Int63n(2*r) - r
+	j := rand.Int64N(2*r) - r
 	return time.Duration(j)
 }
 

vendor/google.golang.org/grpc/internal/transport/http_util.go

@@ -317,28 +317,32 @@ func newBufWriter(conn net.Conn, batchSize int, pool *sync.Pool) *bufWriter {
 	return w
 }
 
-func (w *bufWriter) Write(b []byte) (n int, err error) {
+func (w *bufWriter) Write(b []byte) (int, error) {
 	if w.err != nil {
 		return 0, w.err
 	}
 	if w.batchSize == 0 { // Buffer has been disabled.
-		n, err = w.conn.Write(b)
+		n, err := w.conn.Write(b)
 		return n, toIOError(err)
 	}
 	if w.buf == nil {
 		b := w.pool.Get().(*[]byte)
 		w.buf = *b
 	}
+	written := 0
 	for len(b) > 0 {
-		nn := copy(w.buf[w.offset:], b)
-		b = b[nn:]
-		w.offset += nn
-		n += nn
-		if w.offset >= w.batchSize {
-			err = w.flushKeepBuffer()
+		copied := copy(w.buf[w.offset:], b)
+		b = b[copied:]
+		written += copied
+		w.offset += copied
+		if w.offset < w.batchSize {
+			continue
+		}
+		if err := w.flushKeepBuffer(); err != nil {
+			return written, err
 		}
 	}
-	return n, err
+	return written, nil
 }
 
 func (w *bufWriter) Flush() error {
@@ -389,7 +393,7 @@ type framer struct {
 	fr     *http2.Framer
 }
 
-var writeBufferPoolMap map[int]*sync.Pool = make(map[int]*sync.Pool)
+var writeBufferPoolMap = make(map[int]*sync.Pool)
 var writeBufferMutex sync.Mutex
 
 func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, sharedWriteBuffer bool, maxHeaderListSize uint32) *framer {
@@ -435,8 +439,8 @@ func getWriteBufferPool(size int) *sync.Pool {
 	return pool
 }
 
-// parseDialTarget returns the network and address to pass to dialer.
-func parseDialTarget(target string) (string, string) {
+// ParseDialTarget returns the network and address to pass to dialer.
+func ParseDialTarget(target string) (string, string) {
 	net := "tcp"
 	m1 := strings.Index(target, ":")
 	m2 := strings.Index(target, ":/")

vendor/google.golang.org/grpc/internal/transport/proxy.go

@@ -30,34 +30,16 @@ import (
 	"net/url"
 
 	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/proxyattributes"
+	"google.golang.org/grpc/resolver"
 )
 
 const proxyAuthHeaderKey = "Proxy-Authorization"
 
-var (
-	// The following variable will be overwritten in the tests.
-	httpProxyFromEnvironment = http.ProxyFromEnvironment
-)
-
-func mapAddress(address string) (*url.URL, error) {
-	req := &http.Request{
-		URL: &url.URL{
-			Scheme: "https",
-			Host:   address,
-		},
-	}
-	url, err := httpProxyFromEnvironment(req)
-	if err != nil {
-		return nil, err
-	}
-	return url, nil
-}
-
 // To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
-// It's possible that this reader reads more than what's need for the response and stores
-// those bytes in the buffer.
-// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
-// bytes in the buffer.
+// It's possible that this reader reads more than what's need for the response
+// and stores those bytes in the buffer. bufConn wraps the original net.Conn
+// and the bufio.Reader to make sure we don't lose the bytes in the buffer.
 type bufConn struct {
 	net.Conn
 	r io.Reader
@@ -72,7 +54,7 @@ func basicAuth(username, password string) string {
 	return base64.StdEncoding.EncodeToString([]byte(auth))
 }
 
-func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr string, proxyURL *url.URL, grpcUA string) (_ net.Conn, err error) {
+func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, grpcUA string, opts proxyattributes.Options) (_ net.Conn, err error) {
 	defer func() {
 		if err != nil {
 			conn.Close()
@@ -81,15 +63,14 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr stri
 
 	req := &http.Request{
 		Method: http.MethodConnect,
-		URL:    &url.URL{Host: backendAddr},
+		URL:    &url.URL{Host: opts.ConnectAddr},
 		Header: map[string][]string{"User-Agent": {grpcUA}},
 	}
-	if t := proxyURL.User; t != nil {
-		u := t.Username()
-		p, _ := t.Password()
+	if user := opts.User; user != nil {
+		u := user.Username()
+		p, _ := user.Password()
 		req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
 	}
-
 	if err := sendHTTPRequest(ctx, req, conn); err != nil {
 		return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
 	}
@@ -107,32 +88,23 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr stri
 		}
 		return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
 	}
-
-	return &bufConn{Conn: conn, r: r}, nil
+	// The buffer could contain extra bytes from the target server, so we can't
+	// discard it. However, in many cases where the server waits for the client
+	// to send the first message (e.g. when TLS is being used), the buffer will
+	// be empty, so we can avoid the overhead of reading through this buffer.
+	if r.Buffered() != 0 {
+		return &bufConn{Conn: conn, r: r}, nil
+	}
+	return conn, nil
 }
 
-// proxyDial dials, connecting to a proxy first if necessary. Checks if a proxy
-// is necessary, dials, does the HTTP CONNECT handshake, and returns the
-// connection.
-func proxyDial(ctx context.Context, addr string, grpcUA string) (net.Conn, error) {
-	newAddr := addr
-	proxyURL, err := mapAddress(addr)
+// proxyDial establishes a TCP connection to the specified address and performs an HTTP CONNECT handshake.
+func proxyDial(ctx context.Context, addr resolver.Address, grpcUA string, opts proxyattributes.Options) (net.Conn, error) {
+	conn, err := internal.NetDialerWithTCPKeepalive().DialContext(ctx, "tcp", addr.Addr)
 	if err != nil {
 		return nil, err
 	}
-	if proxyURL != nil {
-		newAddr = proxyURL.Host
-	}
-
-	conn, err := internal.NetDialerWithTCPKeepalive().DialContext(ctx, "tcp", newAddr)
-	if err != nil {
-		return nil, err
-	}
-	if proxyURL == nil {
-		// proxy is disabled if proxyURL is nil.
-		return conn, err
-	}
-	return doHTTPConnectHandshake(ctx, conn, addr, proxyURL, grpcUA)
+	return doHTTPConnectHandshake(ctx, conn, grpcUA, opts)
 }
 
 func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {

vendor/google.golang.org/grpc/internal/transport/server_stream.go

@@ -0,0 +1,180 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"google.golang.org/grpc/mem"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+// ServerStream implements streaming functionality for a gRPC server.
+type ServerStream struct {
+	*Stream // Embed for common stream functionality.
+
+	st      internalServerTransport
+	ctxDone <-chan struct{} // closed at the end of stream.  Cache of ctx.Done() (for performance)
+	// cancel is invoked at the end of stream to cancel ctx. It also stops the
+	// timer for monitoring the rpc deadline if configured.
+	cancel func()
+
+	// Holds compressor names passed in grpc-accept-encoding metadata from the
+	// client.
+	clientAdvertisedCompressors string
+	headerWireLength            int
+
+	// hdrMu protects outgoing header and trailer metadata.
+	hdrMu      sync.Mutex
+	header     metadata.MD // the outgoing header metadata.  Updated by WriteHeader.
+	headerSent atomic.Bool // atomically set when the headers are sent out.
+}
+
+// Read reads an n byte message from the input stream.
+func (s *ServerStream) Read(n int) (mem.BufferSlice, error) {
+	b, err := s.Stream.read(n)
+	if err == nil {
+		s.st.incrMsgRecv()
+	}
+	return b, err
+}
+
+// SendHeader sends the header metadata for the given stream.
+func (s *ServerStream) SendHeader(md metadata.MD) error {
+	return s.st.writeHeader(s, md)
+}
+
+// Write writes the hdr and data bytes to the output stream.
+func (s *ServerStream) Write(hdr []byte, data mem.BufferSlice, opts *WriteOptions) error {
+	return s.st.write(s, hdr, data, opts)
+}
+
+// WriteStatus sends the status of a stream to the client.  WriteStatus is
+// the final call made on a stream and always occurs.
+func (s *ServerStream) WriteStatus(st *status.Status) error {
+	return s.st.writeStatus(s, st)
+}
+
+// isHeaderSent indicates whether headers have been sent.
+func (s *ServerStream) isHeaderSent() bool {
+	return s.headerSent.Load()
+}
+
+// updateHeaderSent updates headerSent and returns true
+// if it was already set.
+func (s *ServerStream) updateHeaderSent() bool {
+	return s.headerSent.Swap(true)
+}
+
+// RecvCompress returns the compression algorithm applied to the inbound
+// message. It is empty string if there is no compression applied.
+func (s *ServerStream) RecvCompress() string {
+	return s.recvCompress
+}
+
+// SendCompress returns the send compressor name.
+func (s *ServerStream) SendCompress() string {
+	return s.sendCompress
+}
+
+// ContentSubtype returns the content-subtype for a request. For example, a
+// content-subtype of "proto" will result in a content-type of
+// "application/grpc+proto". This will always be lowercase.  See
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
+// more details.
+func (s *ServerStream) ContentSubtype() string {
+	return s.contentSubtype
+}
+
+// SetSendCompress sets the compression algorithm to the stream.
+func (s *ServerStream) SetSendCompress(name string) error {
+	if s.isHeaderSent() || s.getState() == streamDone {
+		return errors.New("transport: set send compressor called after headers sent or stream done")
+	}
+
+	s.sendCompress = name
+	return nil
+}
+
+// SetContext sets the context of the stream. This will be deleted once the
+// stats handler callouts all move to gRPC layer.
+func (s *ServerStream) SetContext(ctx context.Context) {
+	s.ctx = ctx
+}
+
+// ClientAdvertisedCompressors returns the compressor names advertised by the
+// client via grpc-accept-encoding header.
+func (s *ServerStream) ClientAdvertisedCompressors() []string {
+	values := strings.Split(s.clientAdvertisedCompressors, ",")
+	for i, v := range values {
+		values[i] = strings.TrimSpace(v)
+	}
+	return values
+}
+
+// Header returns the header metadata of the stream.  It returns the out header
+// after t.WriteHeader is called.  It does not block and must not be called
+// until after WriteHeader.
+func (s *ServerStream) Header() (metadata.MD, error) {
+	// Return the header in stream. It will be the out
+	// header after t.WriteHeader is called.
+	return s.header.Copy(), nil
+}
+
+// HeaderWireLength returns the size of the headers of the stream as received
+// from the wire.
+func (s *ServerStream) HeaderWireLength() int {
+	return s.headerWireLength
+}
+
+// SetHeader sets the header metadata. This can be called multiple times.
+// This should not be called in parallel to other data writes.
+func (s *ServerStream) SetHeader(md metadata.MD) error {
+	if md.Len() == 0 {
+		return nil
+	}
+	if s.isHeaderSent() || s.getState() == streamDone {
+		return ErrIllegalHeaderWrite
+	}
+	s.hdrMu.Lock()
+	s.header = metadata.Join(s.header, md)
+	s.hdrMu.Unlock()
+	return nil
+}
+
+// SetTrailer sets the trailer metadata which will be sent with the RPC status
+// by the server. This can be called multiple times.
+// This should not be called parallel to other data writes.
+func (s *ServerStream) SetTrailer(md metadata.MD) error {
+	if md.Len() == 0 {
+		return nil
+	}
+	if s.getState() == streamDone {
+		return ErrIllegalHeaderWrite
+	}
+	s.hdrMu.Lock()
+	s.trailer = metadata.Join(s.trailer, md)
+	s.hdrMu.Unlock()
+	return nil
+}

vendor/google.golang.org/grpc/internal/transport/transport.go

@@ -22,13 +22,11 @@
 package transport
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io"
 	"net"
-	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -37,9 +35,9 @@ import (
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/channelz"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
-	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/stats"
 	"google.golang.org/grpc/status"
 	"google.golang.org/grpc/tap"
@@ -47,32 +45,10 @@ import (
 
 const logLevel = 2
 
-type bufferPool struct {
-	pool sync.Pool
-}
-
-func newBufferPool() *bufferPool {
-	return &bufferPool{
-		pool: sync.Pool{
-			New: func() any {
-				return new(bytes.Buffer)
-			},
-		},
-	}
-}
-
-func (p *bufferPool) get() *bytes.Buffer {
-	return p.pool.Get().(*bytes.Buffer)
-}
-
-func (p *bufferPool) put(b *bytes.Buffer) {
-	p.pool.Put(b)
-}
-
 // recvMsg represents the received msg from the transport. All transport
 // protocol specific info has been removed.
 type recvMsg struct {
-	buffer *bytes.Buffer
+	buffer mem.Buffer
 	// nil: received some data
 	// io.EOF: stream is completed. data is nil.
 	// other non-nil error: transport failure. data is nil.
@@ -102,6 +78,9 @@ func newRecvBuffer() *recvBuffer {
 func (b *recvBuffer) put(r recvMsg) {
 	b.mu.Lock()
 	if b.err != nil {
+		// drop the buffer on the floor. Since b.err is not nil, any subsequent reads
+		// will always return an error, making this buffer inaccessible.
+		r.buffer.Free()
 		b.mu.Unlock()
 		// An error had occurred earlier, don't accept more
 		// data or errors.
@@ -148,45 +127,70 @@ type recvBufferReader struct {
 	ctx         context.Context
 	ctxDone     <-chan struct{} // cache of ctx.Done() (for performance).
 	recv        *recvBuffer
-	last        *bytes.Buffer // Stores the remaining data in the previous calls.
+	last        mem.Buffer // Stores the remaining data in the previous calls.
 	err         error
-	freeBuffer  func(*bytes.Buffer)
 }
 
-// Read reads the next len(p) bytes from last. If last is drained, it tries to
-// read additional data from recv. It blocks if there no additional data available
-// in recv. If Read returns any non-nil error, it will continue to return that error.
-func (r *recvBufferReader) Read(p []byte) (n int, err error) {
+func (r *recvBufferReader) ReadMessageHeader(header []byte) (n int, err error) {
 	if r.err != nil {
 		return 0, r.err
 	}
 	if r.last != nil {
-		// Read remaining data left in last call.
-		copied, _ := r.last.Read(p)
-		if r.last.Len() == 0 {
-			r.freeBuffer(r.last)
-			r.last = nil
-		}
-		return copied, nil
+		n, r.last = mem.ReadUnsafe(header, r.last)
+		return n, nil
 	}
 	if r.closeStream != nil {
-		n, r.err = r.readClient(p)
+		n, r.err = r.readMessageHeaderClient(header)
 	} else {
-		n, r.err = r.read(p)
+		n, r.err = r.readMessageHeader(header)
 	}
 	return n, r.err
 }
 
-func (r *recvBufferReader) read(p []byte) (n int, err error) {
+// Read reads the next n bytes from last. If last is drained, it tries to read
+// additional data from recv. It blocks if there no additional data available in
+// recv. If Read returns any non-nil error, it will continue to return that
+// error.
+func (r *recvBufferReader) Read(n int) (buf mem.Buffer, err error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	if r.last != nil {
+		buf = r.last
+		if r.last.Len() > n {
+			buf, r.last = mem.SplitUnsafe(buf, n)
+		} else {
+			r.last = nil
+		}
+		return buf, nil
+	}
+	if r.closeStream != nil {
+		buf, r.err = r.readClient(n)
+	} else {
+		buf, r.err = r.read(n)
+	}
+	return buf, r.err
+}
+
+func (r *recvBufferReader) readMessageHeader(header []byte) (n int, err error) {
 	select {
 	case <-r.ctxDone:
 		return 0, ContextErr(r.ctx.Err())
 	case m := <-r.recv.get():
-		return r.readAdditional(m, p)
+		return r.readMessageHeaderAdditional(m, header)
 	}
 }
 
-func (r *recvBufferReader) readClient(p []byte) (n int, err error) {
+func (r *recvBufferReader) read(n int) (buf mem.Buffer, err error) {
+	select {
+	case <-r.ctxDone:
+		return nil, ContextErr(r.ctx.Err())
+	case m := <-r.recv.get():
+		return r.readAdditional(m, n)
+	}
+}
+
+func (r *recvBufferReader) readMessageHeaderClient(header []byte) (n int, err error) {
 	// If the context is canceled, then closes the stream with nil metadata.
 	// closeStream writes its error parameter to r.recv as a recvMsg.
 	// r.readAdditional acts on that message and returns the necessary error.
@@ -207,25 +211,67 @@ func (r *recvBufferReader) readClient(p []byte) (n int, err error) {
 		// faster.
 		r.closeStream(ContextErr(r.ctx.Err()))
 		m := <-r.recv.get()
-		return r.readAdditional(m, p)
+		return r.readMessageHeaderAdditional(m, header)
 	case m := <-r.recv.get():
-		return r.readAdditional(m, p)
+		return r.readMessageHeaderAdditional(m, header)
 	}
 }
 
-func (r *recvBufferReader) readAdditional(m recvMsg, p []byte) (n int, err error) {
+func (r *recvBufferReader) readClient(n int) (buf mem.Buffer, err error) {
+	// If the context is canceled, then closes the stream with nil metadata.
+	// closeStream writes its error parameter to r.recv as a recvMsg.
+	// r.readAdditional acts on that message and returns the necessary error.
+	select {
+	case <-r.ctxDone:
+		// Note that this adds the ctx error to the end of recv buffer, and
+		// reads from the head. This will delay the error until recv buffer is
+		// empty, thus will delay ctx cancellation in Recv().
+		//
+		// It's done this way to fix a race between ctx cancel and trailer. The
+		// race was, stream.Recv() may return ctx error if ctxDone wins the
+		// race, but stream.Trailer() may return a non-nil md because the stream
+		// was not marked as done when trailer is received. This closeStream
+		// call will mark stream as done, thus fix the race.
+		//
+		// TODO: delaying ctx error seems like a unnecessary side effect. What
+		// we really want is to mark the stream as done, and return ctx error
+		// faster.
+		r.closeStream(ContextErr(r.ctx.Err()))
+		m := <-r.recv.get()
+		return r.readAdditional(m, n)
+	case m := <-r.recv.get():
+		return r.readAdditional(m, n)
+	}
+}
+
+func (r *recvBufferReader) readMessageHeaderAdditional(m recvMsg, header []byte) (n int, err error) {
 	r.recv.load()
 	if m.err != nil {
+		if m.buffer != nil {
+			m.buffer.Free()
+		}
 		return 0, m.err
 	}
-	copied, _ := m.buffer.Read(p)
-	if m.buffer.Len() == 0 {
-		r.freeBuffer(m.buffer)
-		r.last = nil
-	} else {
-		r.last = m.buffer
+
+	n, r.last = mem.ReadUnsafe(header, m.buffer)
+
+	return n, nil
+}
+
+func (r *recvBufferReader) readAdditional(m recvMsg, n int) (b mem.Buffer, err error) {
+	r.recv.load()
+	if m.err != nil {
+		if m.buffer != nil {
+			m.buffer.Free()
+		}
+		return nil, m.err
 	}
-	return copied, nil
+
+	if m.buffer.Len() > n {
+		m.buffer, r.last = mem.SplitUnsafe(m.buffer, n)
+	}
+
+	return m.buffer, nil
 }
 
 type streamState uint32
@@ -240,73 +286,26 @@ const (
 // Stream represents an RPC in the transport layer.
 type Stream struct {
 	id           uint32
-	st           ServerTransport    // nil for client side Stream
-	ct           *http2Client       // nil for server side Stream
-	ctx          context.Context    // the associated context of the stream
-	cancel       context.CancelFunc // always nil for client side Stream
-	done         chan struct{}      // closed at the end of stream to unblock writers. On the client side.
-	doneFunc     func()             // invoked at the end of stream on client side.
-	ctxDone      <-chan struct{}    // same as done chan but for server side. Cache of ctx.Done() (for performance)
-	method       string             // the associated RPC method of the stream
+	ctx          context.Context // the associated context of the stream
+	method       string          // the associated RPC method of the stream
 	recvCompress string
 	sendCompress string
 	buf          *recvBuffer
-	trReader     io.Reader
+	trReader     *transportReader
 	fc           *inFlow
 	wq           *writeQuota
 
-	// Holds compressor names passed in grpc-accept-encoding metadata from the
-	// client. This is empty for the client side stream.
-	clientAdvertisedCompressors string
 	// Callback to state application's intentions to read data. This
 	// is used to adjust flow control, if needed.
 	requestRead func(int)
 
-	headerChan       chan struct{} // closed to indicate the end of header metadata.
-	headerChanClosed uint32        // set when headerChan is closed. Used to avoid closing headerChan multiple times.
-	// headerValid indicates whether a valid header was received.  Only
-	// meaningful after headerChan is closed (always call waitOnHeader() before
-	// reading its value).  Not valid on server side.
-	headerValid      bool
-	headerWireLength int // Only set on server side.
-
-	// hdrMu protects header and trailer metadata on the server-side.
-	hdrMu sync.Mutex
-	// On client side, header keeps the received header metadata.
-	//
-	// On server side, header keeps the header set by SetHeader(). The complete
-	// header will merged into this after t.WriteHeader() is called.
-	header  metadata.MD
-	trailer metadata.MD // the key-value map of trailer metadata.
-
-	noHeaders bool // set if the client never received headers (set only after the stream is done).
-
-	// On the server-side, headerSent is atomically set to 1 when the headers are sent out.
-	headerSent uint32
-
 	state streamState
 
-	// On client-side it is the status error received from the server.
-	// On server-side it is unused.
-	status *status.Status
-
-	bytesReceived uint32 // indicates whether any bytes have been received on this stream
-	unprocessed   uint32 // set if the server sends a refused stream or GOAWAY including this stream
-
 	// contentSubtype is the content-subtype for requests.
 	// this must be lowercase or the behavior is undefined.
 	contentSubtype string
-}
 
-// isHeaderSent is only valid on the server-side.
-func (s *Stream) isHeaderSent() bool {
-	return atomic.LoadUint32(&s.headerSent) == 1
-}
-
-// updateHeaderSent updates headerSent and returns true
-// if it was alreay set. It is valid only on server-side.
-func (s *Stream) updateHeaderSent() bool {
-	return atomic.SwapUint32(&s.headerSent, 1) == 1
+	trailer metadata.MD // the key-value map of trailer metadata.
 }
 
 func (s *Stream) swapState(st streamState) streamState {
@@ -321,110 +320,12 @@ func (s *Stream) getState() streamState {
 	return streamState(atomic.LoadUint32((*uint32)(&s.state)))
 }
 
-func (s *Stream) waitOnHeader() {
-	if s.headerChan == nil {
-		// On the server headerChan is always nil since a stream originates
-		// only after having received headers.
-		return
-	}
-	select {
-	case <-s.ctx.Done():
-		// Close the stream to prevent headers/trailers from changing after
-		// this function returns.
-		s.ct.CloseStream(s, ContextErr(s.ctx.Err()))
-		// headerChan could possibly not be closed yet if closeStream raced
-		// with operateHeaders; wait until it is closed explicitly here.
-		<-s.headerChan
-	case <-s.headerChan:
-	}
-}
-
-// RecvCompress returns the compression algorithm applied to the inbound
-// message. It is empty string if there is no compression applied.
-func (s *Stream) RecvCompress() string {
-	s.waitOnHeader()
-	return s.recvCompress
-}
-
-// SetSendCompress sets the compression algorithm to the stream.
-func (s *Stream) SetSendCompress(name string) error {
-	if s.isHeaderSent() || s.getState() == streamDone {
-		return errors.New("transport: set send compressor called after headers sent or stream done")
-	}
-
-	s.sendCompress = name
-	return nil
-}
-
-// SendCompress returns the send compressor name.
-func (s *Stream) SendCompress() string {
-	return s.sendCompress
-}
-
-// ClientAdvertisedCompressors returns the compressor names advertised by the
-// client via grpc-accept-encoding header.
-func (s *Stream) ClientAdvertisedCompressors() []string {
-	values := strings.Split(s.clientAdvertisedCompressors, ",")
-	for i, v := range values {
-		values[i] = strings.TrimSpace(v)
-	}
-	return values
-}
-
-// Done returns a channel which is closed when it receives the final status
-// from the server.
-func (s *Stream) Done() <-chan struct{} {
-	return s.done
-}
-
-// Header returns the header metadata of the stream.
-//
-// On client side, it acquires the key-value pairs of header metadata once it is
-// available. It blocks until i) the metadata is ready or ii) there is no header
-// metadata or iii) the stream is canceled/expired.
-//
-// On server side, it returns the out header after t.WriteHeader is called.  It
-// does not block and must not be called until after WriteHeader.
-func (s *Stream) Header() (metadata.MD, error) {
-	if s.headerChan == nil {
-		// On server side, return the header in stream. It will be the out
-		// header after t.WriteHeader is called.
-		return s.header.Copy(), nil
-	}
-	s.waitOnHeader()
-
-	if !s.headerValid || s.noHeaders {
-		return nil, s.status.Err()
-	}
-
-	return s.header.Copy(), nil
-}
-
-// TrailersOnly blocks until a header or trailers-only frame is received and
-// then returns true if the stream was trailers-only.  If the stream ends
-// before headers are received, returns true, nil.  Client-side only.
-func (s *Stream) TrailersOnly() bool {
-	s.waitOnHeader()
-	return s.noHeaders
-}
-
-// Trailer returns the cached trailer metedata. Note that if it is not called
-// after the entire stream is done, it could return an empty MD. Client
-// side only.
+// Trailer returns the cached trailer metadata. Note that if it is not called
+// after the entire stream is done, it could return an empty MD.
 // It can be safely read only after stream has ended that is either read
 // or write have returned io.EOF.
 func (s *Stream) Trailer() metadata.MD {
-	c := s.trailer.Copy()
-	return c
-}
-
-// ContentSubtype returns the content-subtype for a request. For example, a
-// content-subtype of "proto" will result in a content-type of
-// "application/grpc+proto". This will always be lowercase.  See
-// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
-// more details.
-func (s *Stream) ContentSubtype() string {
-	return s.contentSubtype
+	return s.trailer.Copy()
 }
 
 // Context returns the context of the stream.
@@ -432,114 +333,104 @@ func (s *Stream) Context() context.Context {
 	return s.ctx
 }
 
-// SetContext sets the context of the stream. This will be deleted once the
-// stats handler callouts all move to gRPC layer.
-func (s *Stream) SetContext(ctx context.Context) {
-	s.ctx = ctx
-}
-
 // Method returns the method for the stream.
 func (s *Stream) Method() string {
 	return s.method
 }
 
-// Status returns the status received from the server.
-// Status can be read safely only after the stream has ended,
-// that is, after Done() is closed.
-func (s *Stream) Status() *status.Status {
-	return s.status
-}
-
-// HeaderWireLength returns the size of the headers of the stream as received
-// from the wire. Valid only on the server.
-func (s *Stream) HeaderWireLength() int {
-	return s.headerWireLength
-}
-
-// SetHeader sets the header metadata. This can be called multiple times.
-// Server side only.
-// This should not be called in parallel to other data writes.
-func (s *Stream) SetHeader(md metadata.MD) error {
-	if md.Len() == 0 {
-		return nil
-	}
-	if s.isHeaderSent() || s.getState() == streamDone {
-		return ErrIllegalHeaderWrite
-	}
-	s.hdrMu.Lock()
-	s.header = metadata.Join(s.header, md)
-	s.hdrMu.Unlock()
-	return nil
-}
-
-// SendHeader sends the given header metadata. The given metadata is
-// combined with any metadata set by previous calls to SetHeader and
-// then written to the transport stream.
-func (s *Stream) SendHeader(md metadata.MD) error {
-	return s.st.WriteHeader(s, md)
-}
-
-// SetTrailer sets the trailer metadata which will be sent with the RPC status
-// by the server. This can be called multiple times. Server side only.
-// This should not be called parallel to other data writes.
-func (s *Stream) SetTrailer(md metadata.MD) error {
-	if md.Len() == 0 {
-		return nil
-	}
-	if s.getState() == streamDone {
-		return ErrIllegalHeaderWrite
-	}
-	s.hdrMu.Lock()
-	s.trailer = metadata.Join(s.trailer, md)
-	s.hdrMu.Unlock()
-	return nil
-}
-
 func (s *Stream) write(m recvMsg) {
 	s.buf.put(m)
 }
 
-// Read reads all p bytes from the wire for this stream.
-func (s *Stream) Read(p []byte) (n int, err error) {
+// ReadMessageHeader reads data into the provided header slice from the stream.
+// It first checks if there was an error during a previous read operation and
+// returns it if present. It then requests a read operation for the length of
+// the header. It continues to read from the stream until the entire header
+// slice is filled or an error occurs. If an `io.EOF` error is encountered with
+// partially read data, it is converted to `io.ErrUnexpectedEOF` to indicate an
+// unexpected end of the stream. The method returns any error encountered during
+// the read process or nil if the header was successfully read.
+func (s *Stream) ReadMessageHeader(header []byte) (err error) {
 	// Don't request a read if there was an error earlier
-	if er := s.trReader.(*transportReader).er; er != nil {
-		return 0, er
+	if er := s.trReader.er; er != nil {
+		return er
 	}
-	s.requestRead(len(p))
-	return io.ReadFull(s.trReader, p)
+	s.requestRead(len(header))
+	for len(header) != 0 {
+		n, err := s.trReader.ReadMessageHeader(header)
+		header = header[n:]
+		if len(header) == 0 {
+			err = nil
+		}
+		if err != nil {
+			if n > 0 && err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			return err
+		}
+	}
+	return nil
 }
 
-// tranportReader reads all the data available for this Stream from the transport and
+// Read reads n bytes from the wire for this stream.
+func (s *Stream) read(n int) (data mem.BufferSlice, err error) {
+	// Don't request a read if there was an error earlier
+	if er := s.trReader.er; er != nil {
+		return nil, er
+	}
+	s.requestRead(n)
+	for n != 0 {
+		buf, err := s.trReader.Read(n)
+		var bufLen int
+		if buf != nil {
+			bufLen = buf.Len()
+		}
+		n -= bufLen
+		if n == 0 {
+			err = nil
+		}
+		if err != nil {
+			if bufLen > 0 && err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			data.Free()
+			return nil, err
+		}
+		data = append(data, buf)
+	}
+	return data, nil
+}
+
+// transportReader reads all the data available for this Stream from the transport and
 // passes them into the decoder, which converts them into a gRPC message stream.
 // The error is io.EOF when the stream is done or another non-nil error if
 // the stream broke.
 type transportReader struct {
-	reader io.Reader
+	reader *recvBufferReader
 	// The handler to control the window update procedure for both this
 	// particular stream and the associated transport.
 	windowHandler func(int)
 	er            error
 }
 
-func (t *transportReader) Read(p []byte) (n int, err error) {
-	n, err = t.reader.Read(p)
+func (t *transportReader) ReadMessageHeader(header []byte) (int, error) {
+	n, err := t.reader.ReadMessageHeader(header)
 	if err != nil {
 		t.er = err
-		return
+		return 0, err
 	}
 	t.windowHandler(n)
-	return
+	return n, nil
 }
 
-// BytesReceived indicates whether any bytes have been received on this stream.
-func (s *Stream) BytesReceived() bool {
-	return atomic.LoadUint32(&s.bytesReceived) == 1
-}
-
-// Unprocessed indicates whether the server did not process this stream --
-// i.e. it sent a refused stream or GOAWAY including this stream ID.
-func (s *Stream) Unprocessed() bool {
-	return atomic.LoadUint32(&s.unprocessed) == 1
+func (t *transportReader) Read(n int) (mem.Buffer, error) {
+	buf, err := t.reader.Read(n)
+	if err != nil {
+		t.er = err
+		return buf, err
+	}
+	t.windowHandler(buf.Len())
+	return buf, nil
 }
 
 // GoString is implemented by Stream so context.String() won't
@@ -574,6 +465,7 @@ type ServerConfig struct {
 	ChannelzParent        *channelz.Server
 	MaxHeaderListSize     *uint32
 	HeaderTableSize       *uint32
+	BufferPool            mem.BufferPool
 }
 
 // ConnectOptions covers all relevant options for communicating with the server.
@@ -610,19 +502,13 @@ type ConnectOptions struct {
 	ChannelzParent *channelz.SubChannel
 	// MaxHeaderListSize sets the max (uncompressed) size of header list that is prepared to be received.
 	MaxHeaderListSize *uint32
-	// UseProxy specifies if a proxy should be used.
-	UseProxy bool
+	// The mem.BufferPool to use when reading/writing to the wire.
+	BufferPool mem.BufferPool
 }
 
-// NewClientTransport establishes the transport with the required ConnectOptions
-// and returns it to the caller.
-func NewClientTransport(connectCtx, ctx context.Context, addr resolver.Address, opts ConnectOptions, onClose func(GoAwayReason)) (ClientTransport, error) {
-	return newHTTP2Client(connectCtx, ctx, addr, opts, onClose)
-}
-
-// Options provides additional hints and information for message
+// WriteOptions provides additional hints and information for message
 // transmission.
-type Options struct {
+type WriteOptions struct {
 	// Last indicates whether this write is the last piece for
 	// this stream.
 	Last bool
@@ -671,18 +557,8 @@ type ClientTransport interface {
 	// It does not block.
 	GracefulClose()
 
-	// Write sends the data for the given stream. A nil stream indicates
-	// the write is to be performed on the transport as a whole.
-	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
-
 	// NewStream creates a Stream for an RPC.
-	NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
-
-	// CloseStream clears the footprint of a stream when the stream is
-	// not needed any more. The err indicates the error incurred when
-	// CloseStream is called. Must be called when a stream is finished
-	// unless the associated transport is closing.
-	CloseStream(stream *Stream, err error)
+	NewStream(ctx context.Context, callHdr *CallHdr) (*ClientStream, error)
 
 	// Error returns a channel that is closed when some I/O error
 	// happens. Typically the caller should have a goroutine to monitor
@@ -702,12 +578,6 @@ type ClientTransport interface {
 
 	// RemoteAddr returns the remote network address.
 	RemoteAddr() net.Addr
-
-	// IncrMsgSent increments the number of message sent through this transport.
-	IncrMsgSent()
-
-	// IncrMsgRecv increments the number of message received through this transport.
-	IncrMsgRecv()
 }
 
 // ServerTransport is the common interface for all gRPC server-side transport
@@ -717,19 +587,7 @@ type ClientTransport interface {
 // Write methods for a given Stream will be called serially.
 type ServerTransport interface {
 	// HandleStreams receives incoming streams using the given handler.
-	HandleStreams(context.Context, func(*Stream))
-
-	// WriteHeader sends the header metadata for the given stream.
-	// WriteHeader may not be called on all streams.
-	WriteHeader(s *Stream, md metadata.MD) error
-
-	// Write sends the data for the given stream.
-	// Write may not be called on all streams.
-	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
-
-	// WriteStatus sends the status of a stream to the client.  WriteStatus is
-	// the final call made on a stream and always occurs.
-	WriteStatus(s *Stream, st *status.Status) error
+	HandleStreams(context.Context, func(*ServerStream))
 
 	// Close tears down the transport. Once it is called, the transport
 	// should not be accessed any more. All the pending streams and their
@@ -741,12 +599,14 @@ type ServerTransport interface {
 
 	// Drain notifies the client this ServerTransport stops accepting new RPCs.
 	Drain(debugData string)
+}
 
-	// IncrMsgSent increments the number of message sent through this transport.
-	IncrMsgSent()
-
-	// IncrMsgRecv increments the number of message received through this transport.
-	IncrMsgRecv()
+type internalServerTransport interface {
+	ServerTransport
+	writeHeader(s *ServerStream, md metadata.MD) error
+	write(s *ServerStream, hdr []byte, data mem.BufferSlice, opts *WriteOptions) error
+	writeStatus(s *ServerStream, st *status.Status) error
+	incrMsgRecv()
 }
 
 // connectionErrorf creates an ConnectionError with the specified error description.
@@ -798,7 +658,7 @@ var (
 	// connection is draining. This could be caused by goaway or balancer
 	// removing the address.
 	errStreamDrain = status.Error(codes.Unavailable, "the connection is draining")
-	// errStreamDone is returned from write at the client side to indiacte application
+	// errStreamDone is returned from write at the client side to indicate application
 	// layer of an error.
 	errStreamDone = errors.New("the stream is done")
 	// StatusGoAway indicates that the server sent a GOAWAY that included this