https://bugs.winehq.org/show_bug.cgi?id=51097
Bug ID: 51097 Summary: Listening on the same port on two different IPs does not work Product: Wine Version: unspecified Hardware: x86-64 OS: Linux Status: NEW Severity: normal Priority: P2 Component: winsock Assignee: wine-bugs@winehq.org Reporter: stefan@codeweavers.com Distribution: ---
Creating two UDP sockets and binding them to the same port on different IP addresses does not work. Only the last bound socket receives its packets while the other's are silently discarded.
Description in pseudo code:
sock1 = socket(AF_INET, SOCK_DGRAM, 0); sock2 = socket(AF_INET, SOCK_DGRAM, 0);
addr.sin_family = AF_INET; addr.sin_addr.s_addr = inet_addr("192.168.1.100"); addr.sin_port = htons(22222); res = bind(sock1, &addr, sizeof(addr));
addr.sin_addr.s_addr = inet_addr("192.168.250.100"); res = bind(sock2, &addr, sizeof(addr));
Now put them into non-blocking mode and select() on them. Only sock1 will receive something.
The cause is the custom BPF filter written to solve bug 7929. It binds both ports to 0.0.0.0:22222 and sets up a custom filter to filter for 192.168.250.100 + 192.168.250.255 and 192.168.1.100 + 192.168.1.255 respectively. Packets received on 192.168.250.100 are evaluated by the filter rule for sock1, found not matching and discarded without being evaluated for a possible match on sock 2.
Disabling the custom filter rules and passing the actual IP addresses to Unix bind() solves the problem but brings back the non-matching broadcast rules that are at the heart of bug 7929.