[Bug 7929] C&C 3 network does not work

Wine Bugs wine-bugs at winehq.org
Wed Jun 20 01:34:10 CDT 2007


------- Additional Comments From damjan.jov at gmail.com  2007-20-06 01:34 -------
An app asks to bind to A.B.C.D, and on Windows that means it sends only through
that NIC, receives unicasts from only that NIC, and still receives broadcasts
through that NIC. On Linux it means it also sends only through that NIC, also
receives unicasts only from that NIC, but *DOESN'T* receive any broadcasts from
that NIC or any other. It's not a wine-specific bug, it's a long standing bug in
Java too, see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4212324.

User-space filtering is unthinkably ugly - you would have to bind to so
you can receive broadcasts, but you would not only get broadcasts from other
NICs but also unicasts from other NICs (on the same port), as well as sending
broadcasts through other NICs you would not normally send to. It would be a
terrible hack - not only would bind/connect/recv/send have to be patched, but
functions like select as well (since it has to peek at incoming UDP datagrams
and chuck out the ones from the wrong NIC...) and getsockname (you have to lie
to the app and say you're bound to A.B.C.D) and probably numerous others. It
means you need radically different treatment of TCP and UDP sockets, and the
patch would not only span ws2_32 but wineserver as well.

The SO_BINDTODEVICE option needs root access - so I can think of 2 solutions
where wine doesn't run as root. You could pass the socket to a helper process
that runs as root and have it apply SO_BINDTODEVICE for us, and if the helper
process doesn't exist or have root access, fall back to what we have now. Or,
when a UDP socket binds to an address other than, call a helper process
and have it bind to and the same port, then when the helper process
receives a broadcast packet, filter it, and either use a raw socket to send it
to the wine app that wants broadcasts or send it from a well-known port and
somehow pass wine additional data that tells ws2_32 what to put into the address
field of recvfrom().

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