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TUN-6584: Define QUIC datagram v2 format to support proxying IP packets

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This commit is contained in:
cthuang
2022-08-01 13:48:33 +01:00
committed by Chung-Ting Huang
parent d3fd581b7b
commit 278df5478a
12 changed files with 548 additions and 352 deletions
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60
datagramsession/session.go
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@@ -4,6 +4,7 @@ import (
"context"
"fmt"
"io"
"net"
"time"
"github.com/google/uuid"
@@ -18,21 +19,20 @@ func SessionIdleErr(timeout time.Duration) error {
return fmt.Errorf("session idle for %v", timeout)
}
type transportSender func(sessionID uuid.UUID, payload []byte) error
// Session is a bidirectional pipe of datagrams between transport and dstConn
// Currently the only implementation of transport is quic DatagramMuxer
// Destination can be a connection with origin or with eyeball
// When the destination is origin:
// - Datagrams from edge are read by Manager from the transport. Manager finds the corresponding Session and calls the
// write method of the Session to send to origin
// - Datagrams from origin are read from conn and SentTo transport. Transport will return them to eyeball
// - Manager receives datagrams from receiveChan and calls the transportToDst method of the Session to send to origin
// - Datagrams from origin are read from conn and Send to transport using the transportSender callback. Transport will return them to eyeball
// When the destination is eyeball:
// - Datagrams from eyeball are read from conn and SentTo transport. Transport will send them to cloudflared
// - Datagrams from cloudflared are read by Manager from the transport. Manager finds the corresponding Session and calls the
// write method of the Session to send to eyeball
// - Datagrams from eyeball are read from conn and Send to transport. Transport will send them to cloudflared using the transportSender callback.
// - Manager receives datagrams from receiveChan and calls the transportToDst method of the Session to send to the eyeball
type Session struct {
ID uuid.UUID
transport transport
dstConn io.ReadWriteCloser
ID uuid.UUID
sendFunc transportSender
dstConn io.ReadWriteCloser
// activeAtChan is used to communicate the last read/write time
activeAtChan chan time.Time
closeChan chan error
@@ -46,9 +46,16 @@ func (s *Session) Serve(ctx context.Context, closeAfterIdle time.Duration) (clos
const maxPacketSize = 1500
readBuffer := make([]byte, maxPacketSize)
for {
if err := s.dstToTransport(readBuffer); err != nil {
s.closeChan <- err
return
if closeSession, err := s.dstToTransport(readBuffer); err != nil {
if err != net.ErrClosed {
s.log.Error().Err(err).Msg("Failed to send session payload from destination to transport")
} else {
s.log.Debug().Msg("Session cannot read from destination because the connection is closed")
}
if closeSession {
s.closeChan <- err
return
}
}
}
}()
@@ -89,32 +96,25 @@ func (s *Session) waitForCloseCondition(ctx context.Context, closeAfterIdle time
}
}
func (s *Session) dstToTransport(buffer []byte) error {
func (s *Session) dstToTransport(buffer []byte) (closeSession bool, err error) {
n, err := s.dstConn.Read(buffer)
s.markActive()
// https://pkg.go.dev/io#Reader suggests caller should always process n > 0 bytes
if n > 0 {
if n <= int(s.transport.MTU()) {
err = s.transport.SendTo(s.ID, buffer[:n])
} else {
// drop packet for now, eventually reply with ICMP for PMTUD
s.log.Debug().
Str("session", s.ID.String()).
Int("len", n).
Int("mtu", s.transport.MTU()).
Msg("dropped packet exceeding MTU")
if n > 0 || err == nil {
if sendErr := s.sendFunc(s.ID, buffer[:n]); sendErr != nil {
return false, sendErr
}
}
// Some UDP application might send 0-size payload.
if err == nil && n == 0 {
err = s.transport.SendTo(s.ID, []byte{})
}
return err
return err != nil, err
}
func (s *Session) transportToDst(payload []byte) (int, error) {
s.markActive()
return s.dstConn.Write(payload)
n, err := s.dstConn.Write(payload)
if err != nil {
s.log.Err(err).Msg("Failed to write payload to session")
}
return n, err
}
// Sends the last active time to the idle checker loop without blocking. activeAtChan will only be full when there