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/window_update_queue.go

@@ -0,0 +1,71 @@
+package quic
+
+import (
+	"sync"
+
+	"github.com/lucas-clemente/quic-go/internal/flowcontrol"
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+)
+
+type windowUpdateQueue struct {
+	mutex sync.Mutex
+
+	queue      map[protocol.StreamID]struct{} // used as a set
+	queuedConn bool                           // connection-level window update
+
+	streamGetter       streamGetter
+	connFlowController flowcontrol.ConnectionFlowController
+	callback           func(wire.Frame)
+}
+
+func newWindowUpdateQueue(
+	streamGetter streamGetter,
+	connFC flowcontrol.ConnectionFlowController,
+	cb func(wire.Frame),
+) *windowUpdateQueue {
+	return &windowUpdateQueue{
+		queue:              make(map[protocol.StreamID]struct{}),
+		streamGetter:       streamGetter,
+		connFlowController: connFC,
+		callback:           cb,
+	}
+}
+
+func (q *windowUpdateQueue) AddStream(id protocol.StreamID) {
+	q.mutex.Lock()
+	q.queue[id] = struct{}{}
+	q.mutex.Unlock()
+}
+
+func (q *windowUpdateQueue) AddConnection() {
+	q.mutex.Lock()
+	q.queuedConn = true
+	q.mutex.Unlock()
+}
+
+func (q *windowUpdateQueue) QueueAll() {
+	q.mutex.Lock()
+	// queue a connection-level window update
+	if q.queuedConn {
+		q.callback(&wire.MaxDataFrame{MaximumData: q.connFlowController.GetWindowUpdate()})
+		q.queuedConn = false
+	}
+	// queue all stream-level window updates
+	for id := range q.queue {
+		delete(q.queue, id)
+		str, err := q.streamGetter.GetOrOpenReceiveStream(id)
+		if err != nil || str == nil { // the stream can be nil if it was completed before dequeing the window update
+			continue
+		}
+		offset := str.getWindowUpdate()
+		if offset == 0 { // can happen if we received a final offset, right after queueing the window update
+			continue
+		}
+		q.callback(&wire.MaxStreamDataFrame{
+			StreamID:          id,
+			MaximumStreamData: offset,
+		})
+	}
+	q.mutex.Unlock()
+}