[jboss-jira] [JBoss JIRA] Commented: (JGRP-777) Revisit multicast socket creation code

Revisit multicast socket creation code -------------------------------------- Key: JGRP-777 URL: https://jira.jboss.org/jira/browse/JGRP-777 Project: JGroups Issue Type: Task Reporter: Bela Ban Assignee: Bela Ban Fix For: 2.7 [Dieter Cailliau] I looked into the UDP class (trunk) and found out that the MulticastSocket(port) constructor is used. This doesn't work well on many linux systems: http://forum.java.sun.com/thread.jspa?threadID=5216130&messageID=9875372 It's not entirely clear who's 'fault' this is, but i have a workaround below. I experienced this problem in jgroups when i tried to set up 2 distinct processes on the same machine, that use a different stack with different UDP mcast_addr. Still the one process would complain about the other: discard msg from different group. java 1.5.0_10-b03, jgroups 2.5.0.GA. The code i use for making MulticastSockets is below. In combination with a default gateway and preferIPv4 this was the only way to make sure that my socket only received datagrams for the group it actually joined. Using the constructor with only a port results in a sokcet receiving ALL datagrams that are multicasted to that port (regardless of the group address it joined!). Can someone please give some feedback on this, and consider if this is a fix for UDP? public static MulticastSocket createMulticastSocket(int TIMEOUT_MS, InetAddress group, int port) { MulticastSocket socket = null; try { socket = new MulticastSocket(new InetSocketAddress(group, port)); } catch (BindException e1) { String warn = null == System.getProperty("java.net.preferIPv4Stack") ? "-Djava.net.preferIPv4Stack != true ??" : "java.net.preferIPv4Stack=true"; log.warn("Unable to create the multicast socket at address " + group + ":" + port + "; I'll fall back to the windows solution (create the socket with port only) " + warn,e1); // Windows fallback try { socket = new MulticastSocket(new InetSocketAddress(port)); } catch (IOException e) { throw new RuntimeException(e1); } } catch (Exception e1) { throw new RuntimeException(e1); } try { socket.setSoTimeout(TIMEOUT_MS); socket.joinGroup(group); } catch (Exception e1) { byte[] address = group.getAddress(); String ad = address[0] + "." + address[1] + "." + address[2] + "." + address[3] + ":" + port + " " + e1.toString(); try { socket.close(); } catch(Exception c){ log.warn("Ignore exception while closing bad multicast socket: " + c); } throw new RuntimeException(ad,e1); } return socket; }