RSDK-6917: Have ClientConn objects expose access to underlying PeerCo…

…nnection, if applicable. (#261)

rpc/dialer.go

@@ -12,6 +12,7 @@ import (
 	"github.com/edaniels/golog"
 	grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
 	grpc_zap "github.com/grpc-ecosystem/go-grpc-middleware/logging/zap"
+	"github.com/pion/webrtc/v3"
 	"github.com/pkg/errors"
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
@@ -59,6 +60,10 @@ type Dialer interface {
 // there is a way to close the connection.
 type ClientConn interface {
 	grpc.ClientConnInterface
+
+	// PeerConn returns the backing PeerConnection object, or nil if the underlying transport is not
+	// a PeerConnection.
+	PeerConn() *webrtc.PeerConnection
 	Close() error
 }
 
@@ -68,6 +73,16 @@ type ClientConnAuthenticator interface {
 	Authenticate(ctx context.Context) (string, error)
 }
 
+// A GrpcOverHTTPClientConn is grpc connection that is not backed by a `webrtc.PeerConnection`.
+type GrpcOverHTTPClientConn struct {
+	*grpc.ClientConn
+}
+
+// PeerConn returns nil as this is a native gRPC connection.
+func (cc GrpcOverHTTPClientConn) PeerConn() *webrtc.PeerConnection {
+	return nil
+}
+
 type cachedDialer struct {
 	mu    sync.Mutex // Note(erd): not suitable for highly concurrent usage
 	conns map[string]*refCountedConnWrapper
@@ -92,7 +107,7 @@ func (cd *cachedDialer) DialDirect(
 		if err != nil {
 			return nil, nil, err
 		}
-		return conn, onClose, nil
+		return GrpcOverHTTPClientConn{conn}, onClose, nil
 	})
 }
 
@@ -328,7 +343,11 @@ func dialDirectGRPC(ctx context.Context, address string, dOpts dialOptions, logg
 	if ctxDialer := contextDialer(ctx); ctxDialer != nil {
 		conn, cached, err = ctxDialer.DialDirect(ctx, address, dOpts.cacheKey(), closeCredsFunc, dialOpts...)
 	} else {
-		conn, err = grpc.DialContext(ctx, address, dialOpts...)
+		var grpcConn *grpc.ClientConn
+		grpcConn, err = grpc.DialContext(ctx, address, dialOpts...)
+		if err == nil {
+			conn = GrpcOverHTTPClientConn{grpcConn}
+		}
 		if err == nil && closeCredsFunc != nil {
 			conn = wrapClientConnWithCloseFunc(conn, closeCredsFunc)
 		}

rpc/server_test.go

@@ -369,8 +369,9 @@ func TestServerWithExternalListenerAddress(t *testing.T) {
 		WithInsecure(),
 		WithDialDebug(),
 	)
+
 	test.That(t, err, test.ShouldBeNil)
-	test.That(t, conn.(*grpc.ClientConn).Target(), test.ShouldEqual, listener.Addr().String())
+	test.That(t, conn.(GrpcOverHTTPClientConn).Target(), test.ShouldEqual, listener.Addr().String())
 	test.That(t, conn.Close(), test.ShouldBeNil)
 
 	test.That(t, rpcServer.Stop(), test.ShouldBeNil)

rpc/wrtc_client_channel.go

@@ -70,6 +70,10 @@ func newWebRTCClientChannel(
 	return ch
 }
 
+func (ch *webrtcClientChannel) PeerConn() *webrtc.PeerConnection {
+	return ch.webrtcBaseChannel.peerConn
+}
+
 // Close closes all streams and the underlying channel.
 func (ch *webrtcClientChannel) Close() error {
 	ch.mu.Lock()