[jboss-jira] [JBoss JIRA] Commented: (JGRP-978) JGroups diagnostics uses hard-coded IPv4 multicast address

[Richard Achmatowicz (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12473963#action_12473963 ] 

Richard Achmatowicz commented on JGRP-978:
------------------------------------------

Bela

I've attached a preliminary version of the algorithm to check for version consistent addresses in the case of UDP. Some utilities are missing, but this will give you the idea.

The idea is that if any of bind_addr, mcast_addr, diagnostics_addr or bind_interface are non-null, then the user has specified them and these should be used in calculating the complete set of addresses, those specified as well as required defaults.

bind_addr posed a challenge, as it is set based on any value passed for bind_interface. It just introduces more cases which need to be checked. I had to move bind_addr processing from TP.setProperties() to UDP.init() - it was happening too early and can be influenced by values for mcast_addr and diagnostics_addr.

I'm stuck doing EAP stuff at the moment (again) so it may not be until next week before I get a chance to finish this and commit it. Any feedback welcomed..

> JGroups diagnostics uses hard-coded IPv4 multicast address 
> -----------------------------------------------------------
>
>                 Key: JGRP-978
>                 URL: https://jira.jboss.org/jira/browse/JGRP-978
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Richard Achmatowicz
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 2.8
>
>         Attachments: UDP.java
>
>
> When  running JGroups using IPv6 bind and multicast addresses, the following messages appear on the console:
> > 20:21:36,565 WARN [UDP] failed to join /224.0.75.75:7500 on vif0.0:
> > java.net.SocketException: No such device
> > 20:21:36,566 WARN [UDP] failed to join /224.0.75.75:7500 on peth0:
> > java.net.SocketException: No such device
> > 20:21:36,566 WARN [UDP] failed to join /224.0.75.75:7500 on xenbr0:
> > java.net.SocketException: No such device 
> The multicast address 224.0.75.75 is used by the JGroups diagnostics handler (in TP.java) to listen for incoming probe requests. Probe requests are issued from clients using Probe.java to find out which JGroups members are using UDP in a given network.
>  
> These messages expose two issues:
> (i) JGroups is trying to join a multicast group on certain Xen virtual interfaces (vif0, peth0, xenbr0) and this is failing
> (ii) JGroups is using a fixed IPv4 multicast address, despite the fact that IPv6 addresses are being used as bind_addresses and multicast addreses.
> Something similar to the first issue was addressed in https://jira.jboss.org/jira/browse/JGRP-167..
> As for the second issue, shouldn't JGroups use default IP addresses which correspond to the IP mode the JGroups instance has been started in (i.e. if JGroups instance bound to IPv4 bind address, use IPv4 diagnostics multicast address; if JGroups bound to IPv6 global address, use IPv6 global diagnostics multicast address, etc)
> This may very likely cause problems if JGroups is run in an IPv6 only environment, where IPv4 socket use is disallowed.
>  

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