- Original Message -
From: Matthias Andree matthias.and...@gmx.de
I'm adding back in -java as based on you comments it may well be
something in the jdk passing invalid values down to the kernel
syscall.
The socket bind works fine and the packets sent to the server arrive
and are processed by the app but when it tries to reply using
send the result is:-
java.io.IOException: Invalid argument
at java.net.PlainDatagramSocketImpl.send(Native Method)
at java.net.DatagramSocket.send(DatagramSocket.java:629)
using truss we see the following:-
socket(PF_INET6,SOCK_DGRAM,0)= 20 (0x14)
setsockopt(0x14,0x29,0x1b,0x7edf0318,0x4,0x0) = 0 (0x0)
setsockopt(0x14,0x,0x20,0x7edf031c,0x4,0x0) = 0 (0x0)
bind(20,{ AF_INET6 [3800::10:0:0:0]:20736 },28) = 0 (0x0)
..
sendto(20,\M^?\M^?\M^?\M^?I\aMultiplay :: ...,82,0x0,{ AF_INET6
[3800::10:0:0:0]:20736 },0x1c) ERR#22 'Invalid argument'
You're trying to send to your own address, but you're likely not using
the loopback interface for that. Is that permitted by your firewall
configuration and routing?
No I'm not its replying to the sender. In the java code we have:-
socket.send( new DatagramPacket( data, data.length, src.getSocketAddress() ) );
Where src is the src packet. This works fine on IPv4 only machines and
when the jdk is told to use only IPv4 stack. So its not a problem with
the java code itself but could well be an issue with the
sockstat shows it binding correctly
root java 894 21 tcp4 85.236.109.212:25675 *:*
This is unrelated, as it has fd #21 not #20 as in the socket/bind/sendto
calls. You've quoted the wrong line from sockstat output.
Oops sorry cut and paste error (wrong line) heres the correct line.
root java 894 20 udp4 85.236.109.212:25675 *:*
21 is the tcp port created in the same manor (ipv6 socket) which works
fine.
Note: net.inet6.ip6.v6only was set to the default 1 but changing
it to 0 has no effect on the issue.
You aren't using IPv4 mapped addresses, and you haven't stated whether
you're using wildcard listeners. Only in that case would it matter.
I'm not, its a bound port, as shown above now I have the correct line ;-)
inet6(4) reads:
IPV6CTL_V6ONLY(ip6.v6only) Boolean: enable/disable the prohib-
ited use of IPv4 mapped address on AF_INET6 sock-
ets. Defaults to on.
The jvm automatically sets this on all sockets for compatibility for
this exact reason. I'm not rulling out an issue with the IPv6 - v4
routing in the kernel though.
Are you sure that's what you seeing? It's not a match for what you give
above, but anyways it's an implementation artifact because the tcp code
for v4 and v6 used to be shared and the udp code separate.
Thats not how the jdk works, its ment to be 100% transparent but isn't.
See the following for some interesting details:-
http://diario.beerensalat.info/2008/10/12/java_and_ipv6_on_bsd.html
It is best to set up one IPv4 and one IPv6 listening socket.
I don't believe there is any way to do this in java it either uses the
IPv4 stack only or the IPv6 stack only hence relies on the kernel
routing IPv4 packets through the IPv6 stack.
Thats the reason the jdk explicitly enables this for all the ports it
creates, which was added as a back port of the jdk7 fixes which can
be seen here:-
http://www.freebsd.org/cgi/cvsweb.cgi/ports/java/openjdk6/files/patch-set
Check the URL above, perhaps that helps your understanding a bit. I
presume 3800::10:0:0:0 is your server?
Not that I'm aware of, here's the output from ifconfig if anyone can
tell me different, as I'm new to IPv6 and don't follow how its mapped
yet.
ifconfig
igb0: flags=8843UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST metric 0 mtu 1500
options=1bbRXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4
ether 00:25:90:2c:3c:b0
inet 85.236.109.212 netmask 0xff00 broadcast 85.236.109.255
inet6 fe80::225:90ff:fe2c:3cb0%igb0 prefixlen 64 scopeid 0x1
inet6 2001:4db0:20:2::1337 prefixlen 64
nd6 options=3PERFORMNUD,ACCEPT_RTADV
media: Ethernet autoselect (1000baseSX full-duplex)
status: active
igb1: flags=8802BROADCAST,SIMPLEX,MULTICAST metric 0 mtu 1500
options=1bbRXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4
ether 00:25:90:2c:3c:b1
media: Ethernet autoselect (1000baseSX full-duplex)
status: active
lo0: flags=8049UP,LOOPBACK,RUNNING,MULTICAST metric 0 mtu 16384
options=3RXCSUM,TXCSUM
inet 127.0.0.1 netmask 0xff00
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
nd6 options=3PERFORMNUD,ACCEPT_RTADV
This is currently running on 8.2-RELEASE with openjdk6-b22_5
Regards
Steve
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