Now this check is necessary because IPv6 source routing might use
control data bigger than MLEN. (e.g. 16bytes IPv6 addr x 23 hops)
Actually mbuf cluster should be used in uipc_socket.c:sbcreatecontrol()
and uipc_syscalls.c:sockargs() when data size is bigger then MLEN,
and such patches were already in KAME environment and have been
confirmed to work well. I just forgot to merge them into 4.0, sorry.
For safety, I'll postpone such patches until after 4.0 release.
The effect of postponement is followings.
-Ping6 source routing hops are limitted to around 6 or so.
-If some apps do setsockopt IPV6_RTHDR and try to receive
incoming IPv6 source routing info, it can't receive more
than 6 hops source routing info.
(But currently, no apps seems to be doing it.)
Approved by: jkh
0b97e97cd2