I can write a simple test server and client programs and I'll post it here,= in a few hours. Our existing code is just too large.
Thanks Oleg > > On Thu, Apr 11, 2013 at 02:19:25PM -0700, Oleg Moskalenko wrote: > >Hi All > > > >I found a non-standard behavior of UDP sockets in Cygwin. Normally, people = > do not experience it, but the communication pattern that I am going to desc= > ribe here is often used in DTLS (actually, this is virtually the only way t= > o make > OpenSSL working with DTLS on the server side), so I suppose that wit= h the > growing DTLS popularity people will experience the problem often. > > > >So this is how to reproduce the problem in "plain" UDP (without actually > >using > DTLS): > > > >1) Server application: open a UDP socket (socket A); > > > >2) Server application: bind socket A to a local server address (say, > 172.17.17.107:3478); > > > >3) Server application: wait for a packet from a client application; > > > >4) Client application: open a UDP socket (socket C); > > > >5) Client application: bind socket C it to a local client address (say, > 168.16.16.106:12345); > > > >6) Client application: send a UDP packet P1 from socket C to server > >socket A > (to 172.17.17.107:3478); > > > >7) Server application: socket A receives the packet P1 from socket C; > > > >8) Server application: create another UDP socket B; > > > >9) Server application: bind socket B TO THE SAME LOCAL ADDRESS as socket > A (172.17.17.107:3478); > > > >10) Server application: connect socket B to the remote address of socket C > (168.16.16.106:12345) by calling connect() on the datagram socket B. > > > >11) Server application: send packet P2 from socket B to socket C (to > 168.16.16.106:12345). > > > >12) Client application: on socket C, receive packet P2 from socket B (from > 172.17.17.107:3478). > > > >13) Client application: from socket C, send packet P3 to the server address > 172.17.17.107:3478. > > > >14) Server application: socket A receives the packet P3 from the client > >socket. > ERROR !!! > > > >Step 14 is wrong: the packet P3 must be delivered to socket B, because socket > B is "connected" > >to the remote address 168.16.16.106:12345, but socket A is "unconnected". > >Both sockets (A and B) are "bound" to the same server ad= dress > >(172.17.17.107:3478) but the connected one (socket B) must be obtaining > packets from the remote address that it is connected to. > > > >This is a very essential functionality for anybody who wants to implement the > server-side DTLS communications. > > > >This patterns works in any OS that I tried (all FreeBSD versions, all Linux > versions and Solaris) but Cygwin fails, unfortunately. > > > >I am trying to migrate (port) our server application to Cygwin, and it stops > >us > completely. It works everywhere else. > > > >Please take a look if this is something that can be fixed quickly. > > How about a simple test case? > > cgf > > -- > Problem reports: http://cygwin.com/problems.html > FAQ: http://cygwin.com/faq/ > Documentation: http://cygwin.com/docs.html > Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple