Implement IP_MULTICAST_LOOP.

IP_MULTICAST_LOOP controls whether or not multicast packets sent on the default
route are looped back. In order to implement this switch, support for sending
and looping back multicast packets on the default route had to be implemented.

For now we only support IPv4 multicast.

PiperOrigin-RevId: 237534603
Change-Id: I490ac7ff8e8ebef417c7eb049a919c29d156ac1c

2 files changed, 3 insertions, 3 deletions

diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index 05c4b532a..d876005fe 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -277,7 +277,7 @@ func (e *endpoint) Write(p tcpip.Payload, opts tcpip.WriteOptions) (uintptr, <-c
 		}
 
 		// Find the enpoint.
-		r, err := e.stack.FindRoute(nicid, e.bindAddr, to.Addr, netProto)
+		r, err := e.stack.FindRoute(nicid, e.bindAddr, to.Addr, netProto, false /* multicastLoop */)
 		if err != nil {
 			return 0, nil, err
 		}
@@ -471,7 +471,7 @@ func (e *endpoint) Connect(addr tcpip.FullAddress) *tcpip.Error {
 	}
 
 	// Find a route to the desired destination.
-	r, err := e.stack.FindRoute(nicid, e.bindAddr, addr.Addr, netProto)
+	r, err := e.stack.FindRoute(nicid, e.bindAddr, addr.Addr, netProto, false /* multicastLoop */)
 	if err != nil {
 		return err
 	}
diff --git a/pkg/tcpip/transport/icmp/endpoint_state.go b/pkg/tcpip/transport/icmp/endpoint_state.go
index 21008d089..8a7909246 100644
--- a/pkg/tcpip/transport/icmp/endpoint_state.go
+++ b/pkg/tcpip/transport/icmp/endpoint_state.go
@@ -71,7 +71,7 @@ func (e *endpoint) afterLoad() {
 
 	var err *tcpip.Error
 	if e.state == stateConnected {
-		e.route, err = e.stack.FindRoute(e.regNICID, e.bindAddr, e.id.RemoteAddress, e.netProto)
+		e.route, err = e.stack.FindRoute(e.regNICID, e.bindAddr, e.id.RemoteAddress, e.netProto, false /* multicastLoop */)
 		if err != nil {
 			panic(*err)
 		}