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/internal/ackhandler/interfaces.go

@@ -0,0 +1,68 @@
+package ackhandler
+
+import (
+	"time"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+)
+
+// A Packet is a packet
+type Packet struct {
+	PacketNumber    protocol.PacketNumber
+	Frames          []Frame
+	LargestAcked    protocol.PacketNumber // InvalidPacketNumber if the packet doesn't contain an ACK
+	Length          protocol.ByteCount
+	EncryptionLevel protocol.EncryptionLevel
+	SendTime        time.Time
+
+	IsPathMTUProbePacket bool // We don't report the loss of Path MTU probe packets to the congestion controller.
+
+	includedInBytesInFlight bool
+	declaredLost            bool
+	skippedPacket           bool
+}
+
+// SentPacketHandler handles ACKs received for outgoing packets
+type SentPacketHandler interface {
+	// SentPacket may modify the packet
+	SentPacket(packet *Packet)
+	ReceivedAck(ackFrame *wire.AckFrame, encLevel protocol.EncryptionLevel, recvTime time.Time) (bool /* 1-RTT packet acked */, error)
+	ReceivedBytes(protocol.ByteCount)
+	DropPackets(protocol.EncryptionLevel)
+	ResetForRetry() error
+	SetHandshakeConfirmed()
+
+	// The SendMode determines if and what kind of packets can be sent.
+	SendMode() SendMode
+	// TimeUntilSend is the time when the next packet should be sent.
+	// It is used for pacing packets.
+	TimeUntilSend() time.Time
+	// HasPacingBudget says if the pacer allows sending of a (full size) packet at this moment.
+	HasPacingBudget() bool
+	SetMaxDatagramSize(count protocol.ByteCount)
+
+	// only to be called once the handshake is complete
+	QueueProbePacket(protocol.EncryptionLevel) bool /* was a packet queued */
+
+	PeekPacketNumber(protocol.EncryptionLevel) (protocol.PacketNumber, protocol.PacketNumberLen)
+	PopPacketNumber(protocol.EncryptionLevel) protocol.PacketNumber
+
+	GetLossDetectionTimeout() time.Time
+	OnLossDetectionTimeout() error
+}
+
+type sentPacketTracker interface {
+	GetLowestPacketNotConfirmedAcked() protocol.PacketNumber
+	ReceivedPacket(protocol.EncryptionLevel)
+}
+
+// ReceivedPacketHandler handles ACKs needed to send for incoming packets
+type ReceivedPacketHandler interface {
+	IsPotentiallyDuplicate(protocol.PacketNumber, protocol.EncryptionLevel) bool
+	ReceivedPacket(pn protocol.PacketNumber, ecn protocol.ECN, encLevel protocol.EncryptionLevel, rcvTime time.Time, shouldInstigateAck bool) error
+	DropPackets(protocol.EncryptionLevel)
+
+	GetAlarmTimeout() time.Time
+	GetAckFrame(encLevel protocol.EncryptionLevel, onlyIfQueued bool) *wire.AckFrame
+}