r0 = socket$inet6_udp(0xa, 0x2, 0x0)
setsockopt$inet6_group_source_req(r0, 0x29, 0x0, &(0x7f000000a180)={0x0, {{0xa, 0x0, 0x0, @mcast2}}, {{0xa, 0x0, 0x0, @mcast1}}}, 0x108)