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

1 files changed, 5 insertions, 0 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 7010d1b68..825854148 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -68,6 +68,7 @@ func (e *Error) IgnoreStats() bool {
 var (
 	ErrUnknownProtocol       = &Error{msg: "unknown protocol"}
 	ErrUnknownNICID          = &Error{msg: "unknown nic id"}
+	ErrUnknownDevice         = &Error{msg: "unknown device"}
 	ErrUnknownProtocolOption = &Error{msg: "unknown option for protocol"}
 	ErrDuplicateNICID        = &Error{msg: "duplicate nic id"}
 	ErrDuplicateAddress      = &Error{msg: "duplicate address"}
@@ -477,6 +478,10 @@ type MulticastInterfaceOption struct {
 	InterfaceAddr Address
 }
 
+// MulticastLoopOption is used by SetSockOpt/GetSockOpt to specify whether
+// multicast packets sent over a non-loopback interface will be looped back.
+type MulticastLoopOption bool
+
 // MembershipOption is used by SetSockOpt/GetSockOpt as an argument to
 // AddMembershipOption and RemoveMembershipOption.
 type MembershipOption struct {