Conversation
Correctly set the IPV6_MULTICAST_IF option on the IP6 socket. This option affects outgoing multicast packets. Those are used by the client when searching for IPv6 LAN servers. The old code setting IPV6_MULTICAST_IF was useless because it was in NET_JoinMulticast6() which is only called when starting a server.
Avoid leaking socket fd's into gamelogic subprocesses, which causes a 'bind: address already in use' error upon /net_restart. The same bug was fixed for Windows in f70cf74.
Internet sources say you are supposed to bind to the all-zeroes address if you want to receive multicast packets, not the multicast address. Indeed, when tested on Windows the attempt to bind to a multicast address produced an error.
DolceTriade
approved these changes
Oct 2, 2026
DolceTriade
reviewed
Oct 2, 2026
| else | ||
| { | ||
| if ( ( multicast6_socket = NET_IP6Socket( net_mcast6addr->string, ntohs( boundto.sin6_port ), nullptr, &err ) ) == INVALID_SOCKET ) | ||
| if ( ( multicast6_socket = NET_IP6Socket( nullptr, ntohs( boundto.sin6_port ), false, nullptr, &err ) ) == INVALID_SOCKET ) |
Member
Author
There was a problem hiding this comment.
Don't try to bind to IPv6 multicast address
Internet sources say you are supposed to bind to the all-zeroes address
if you want to receive multicast packets, not the multicast address.
Indeed, when tested on Windows the attempt to bind to a multicast
address produced an error.
And null is treated as the all-zeroes address.
DolceTriade
reviewed
Oct 2, 2026
| for ( i = ( port6 == PORT_ANY ? 1 : MAX_TRY_PORTS ); i; i-- ) | ||
| { | ||
| ip6_socket = NET_IP6Socket( net_ip6->string, port6, &boundto, &err ); | ||
| bool sendingMulticast = !serverMode && !( net_enabled->integer & NET_DISABLEMCAST ); |
Member
Author
There was a problem hiding this comment.
Only the client can send multicast packets. This is supposed to be the equivalent of the IPv4 broadcast, to search for servers in a LAN. The server responds with a normal packet.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
net_restartcommand on *nix. It has the same issue with leaking sockets into the NaCl process that Windows did.