------- Comment #2 from BenGardiner at nanometrics dot ca 2007-10-29 20:43 ------- Created an attachment (id=14436) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14436&action=view) a patch for libjava/gnu/java/net/natPlainDatagramSocketImplPosix.cc to use the given NetworkInterface* in the IP_ADD_MEMBERSHIP sockopt call.
Created for gcc 4.0.1's libjava; noticed that the file in trunk still has the FIXME. The change affects how multicast join/leave is implemented: if the NetworkInterface* passed in the arguments is null, then the behaviour is the same as the previous. That is, put the INADDR_ANY value into the ip_mreq structure and pass it to the kernel (on linux 2.4.24 this ends up always referring to the default gateway interface); otherwise, create a ip_mreq structure for each address owned by the NetworkInterface and pass it to the kernel. For linux it is a little overkill to do an IP_ADD_MEMBERSHIP call for each address owned by the network interface, since they will each get mapped back into the interface inside the kernel. It seemed that since the ip_mreq (mostly standard) structure contained no field for a specific interface, the mostly standard thing to do would be to do an _ADD_ for each address. If this is not needed to accomodate all unices (something Im not qualified to decide) the method could always do what is done in the openJDK: do an _ADD_ for the first interface address owned by the NetworkInterface. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13288
