[sctp] multiple incoming udp connections not handled

[ashkitten]

sctp Association::server does not track multiple connections. DisconnectedPacketConn simply sends to the last address it received from, pretending that it's a 1:1 connection instead of 1:many, and Association doesn't know about remote addresses at all.

[lamafab]

Based on the pong example, it looks like each Arc<Stream> is just an independent entity and you cannot distinguish between connections. I guess it would be possible for Arc<Stream> to expose the SocketAddr type or change the API in such a way to you first have to call accept_connection before you can accept_stream.

EDIT: So an "Association" is always one-to-one, but the way it's implemented here is that it assumes that each Association is running on an individual port. Afaik the verification_tag is supposed to distinguish connections, but based on the source code it looks like it does not make use of the association_tag at all, and does not even check the verification_tag of an incoming Packet against the expected peer_verification_tag (?).