The command "ip mroute show" will only show the first Oif.
mark@flappie:~$ ip mroute show
(192.168.1.1, 224.0.0.123) Iif: _rename Oifs: eth1
mark@flappie:~$ cat /proc/net/ip_mr_cache
Group Origin Iif Pkts Bytes Wrong Oifs
7B0000E0 0101A8C0 2 0 0 0 0:1 1:1
This shows 2 Oifs here. However, ipmroute.c, function read_mroute_list(), uses sscanf() with a %s mask for oiflist, which stops after the first whitespace (i.e. after Oif 0:1). The patch below fixes this to read until the newline (though I'm not sure whether this is the proper way to fix it).
After this patch:
mark@flappie:~/iproute-20090324/ip$ ./ip mroute show
(192.168.1.1, 224.0.0.123) Iif: _rename Oifs: eth1 eth0
This patch originally submitted as http://bugs.debian.org/550097
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
080b3ad428