TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/github.com/lucas-clemente/quic-go/retransmission_queue.go

@@ -0,0 +1,131 @@
+package quic
+
+import (
+	"fmt"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+)
+
+type retransmissionQueue struct {
+	initial           []wire.Frame
+	initialCryptoData []*wire.CryptoFrame
+
+	handshake           []wire.Frame
+	handshakeCryptoData []*wire.CryptoFrame
+
+	appData []wire.Frame
+
+	version protocol.VersionNumber
+}
+
+func newRetransmissionQueue(ver protocol.VersionNumber) *retransmissionQueue {
+	return &retransmissionQueue{version: ver}
+}
+
+func (q *retransmissionQueue) AddInitial(f wire.Frame) {
+	if cf, ok := f.(*wire.CryptoFrame); ok {
+		q.initialCryptoData = append(q.initialCryptoData, cf)
+		return
+	}
+	q.initial = append(q.initial, f)
+}
+
+func (q *retransmissionQueue) AddHandshake(f wire.Frame) {
+	if cf, ok := f.(*wire.CryptoFrame); ok {
+		q.handshakeCryptoData = append(q.handshakeCryptoData, cf)
+		return
+	}
+	q.handshake = append(q.handshake, f)
+}
+
+func (q *retransmissionQueue) HasInitialData() bool {
+	return len(q.initialCryptoData) > 0 || len(q.initial) > 0
+}
+
+func (q *retransmissionQueue) HasHandshakeData() bool {
+	return len(q.handshakeCryptoData) > 0 || len(q.handshake) > 0
+}
+
+func (q *retransmissionQueue) HasAppData() bool {
+	return len(q.appData) > 0
+}
+
+func (q *retransmissionQueue) AddAppData(f wire.Frame) {
+	if _, ok := f.(*wire.StreamFrame); ok {
+		panic("STREAM frames are handled with their respective streams.")
+	}
+	q.appData = append(q.appData, f)
+}
+
+func (q *retransmissionQueue) GetInitialFrame(maxLen protocol.ByteCount) wire.Frame {
+	if len(q.initialCryptoData) > 0 {
+		f := q.initialCryptoData[0]
+		newFrame, needsSplit := f.MaybeSplitOffFrame(maxLen, q.version)
+		if newFrame == nil && !needsSplit { // the whole frame fits
+			q.initialCryptoData = q.initialCryptoData[1:]
+			return f
+		}
+		if newFrame != nil { // frame was split. Leave the original frame in the queue.
+			return newFrame
+		}
+	}
+	if len(q.initial) == 0 {
+		return nil
+	}
+	f := q.initial[0]
+	if f.Length(q.version) > maxLen {
+		return nil
+	}
+	q.initial = q.initial[1:]
+	return f
+}
+
+func (q *retransmissionQueue) GetHandshakeFrame(maxLen protocol.ByteCount) wire.Frame {
+	if len(q.handshakeCryptoData) > 0 {
+		f := q.handshakeCryptoData[0]
+		newFrame, needsSplit := f.MaybeSplitOffFrame(maxLen, q.version)
+		if newFrame == nil && !needsSplit { // the whole frame fits
+			q.handshakeCryptoData = q.handshakeCryptoData[1:]
+			return f
+		}
+		if newFrame != nil { // frame was split. Leave the original frame in the queue.
+			return newFrame
+		}
+	}
+	if len(q.handshake) == 0 {
+		return nil
+	}
+	f := q.handshake[0]
+	if f.Length(q.version) > maxLen {
+		return nil
+	}
+	q.handshake = q.handshake[1:]
+	return f
+}
+
+func (q *retransmissionQueue) GetAppDataFrame(maxLen protocol.ByteCount) wire.Frame {
+	if len(q.appData) == 0 {
+		return nil
+	}
+	f := q.appData[0]
+	if f.Length(q.version) > maxLen {
+		return nil
+	}
+	q.appData = q.appData[1:]
+	return f
+}
+
+func (q *retransmissionQueue) DropPackets(encLevel protocol.EncryptionLevel) {
+	//nolint:exhaustive // Can only drop Initial and Handshake packet number space.
+	switch encLevel {
+	case protocol.EncryptionInitial:
+		q.initial = nil
+		q.initialCryptoData = nil
+	case protocol.EncryptionHandshake:
+		q.handshake = nil
+		q.handshakeCryptoData = nil
+	default:
+		panic(fmt.Sprintf("unexpected encryption level: %s", encLevel))
+	}
+}