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

connection/quic.go

@@ -0,0 +1,84 @@
+package connection
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+
+	"github.com/lucas-clemente/quic-go"
+	"github.com/pkg/errors"
+	"github.com/rs/zerolog"
+
+	quicpogs "github.com/cloudflare/cloudflared/quic"
+)
+
+// QUICConnection represents the type that facilitates Proxying via QUIC streams.
+type QUICConnection struct {
+	session quic.Session
+	logger  zerolog.Logger
+}
+
+// NewQUICConnection returns a new instance of QUICConnection.
+func NewQUICConnection(
+	ctx context.Context,
+	quicConfig *quic.Config,
+	edgeAddr net.Addr,
+	tlsConfig *tls.Config,
+	logger zerolog.Logger,
+) (*QUICConnection, error) {
+	session, err := quic.DialAddr(edgeAddr.String(), tlsConfig, quicConfig)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to dial to edge")
+	}
+
+	//TODO: RegisterConnectionRPC here.
+
+	return &QUICConnection{
+		session: session,
+		logger:  logger,
+	}, nil
+}
+
+// Serve starts a QUIC session that begins accepting streams.
+func (q *QUICConnection) Serve(ctx context.Context) error {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	for {
+		stream, err := q.session.AcceptStream(ctx)
+		if err != nil {
+			return errors.Wrap(err, "failed to accept QUIC stream")
+		}
+		go func() {
+			defer stream.Close()
+			if err = q.handleStream(stream); err != nil {
+				q.logger.Err(err).Msg("Failed to handle QUIC stream")
+			}
+		}()
+	}
+}
+
+// Close calls this to close the QuicConnection stream.
+func (q *QUICConnection) Close() {
+	q.session.CloseWithError(0, "")
+}
+
+func (q *QUICConnection) handleStream(stream quic.Stream) error {
+	connectRequest, err := quicpogs.ReadConnectRequestData(stream)
+	if err != nil {
+		return err
+	}
+
+	switch connectRequest.Type {
+	case quicpogs.ConnectionTypeHTTP, quicpogs.ConnectionTypeWebsocket:
+		// Temporary dummy code for the unit test.
+		if err := quicpogs.WriteConnectResponseData(stream, nil, quicpogs.Metadata{Key: "HTTPStatus", Val: "200"}); err != nil {
+			return err
+		}
+
+		stream.Write([]byte("OK"))
+	case quicpogs.ConnectionTypeTCP:
+
+	}
+	return nil
+}