pppd: Accept IPCP ConfAck packets containing MS-WINS options
authorBertram Felgenhauer <bertram.felgenhauer@googlemail.com>
Thu, 2 Jan 2014 04:20:35 +0000 (15:20 +1100)
committerPaul Mackerras <paulus@samba.org>
Thu, 2 Jan 2014 04:20:35 +0000 (15:20 +1100)
commita243f217f1c6ac1aa7793806bc88590d077f490a
tree0bfde69413026bd2b7666b3888dc45b8970fe256
parent906814431bddeb2061825fa1ebad1a967b6d87a9
pppd: Accept IPCP ConfAck packets containing MS-WINS options

Since last week I'm seeing IPCP negotiations going like this (and
eventually failing) when connecting to my ISP:

Jul 11 20:03:25 * pppd[4833]: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1
0.0.0.0> <ms-dns2 0.0.0.0>]
Jul 11 20:03:26 * pppd[4833]: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1
0.0.0.0> <ms-dns2 0.0.0.0>]
Jul 11 20:03:26 * pppd[4833]: rcvd [IPCP ConfNak id=0x2 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:26 * pppd[4833]: sent [IPCP ConfReq id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:26 * pppd[4833]: rcvd [IPCP ConfAck id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:27 * pppd[4833]: sent [IPCP ConfReq id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
...

with the last two lines repeating until the IPCP error limit is
reached. As you can see, the peer added two extra fields in the
ConfNak reply. This is allowed, and indeed the following sent
ConfReq packet reflects this. However, when the ConfAck packet
is received, pppd discards it as invalid, because of the ms-wins
fields.

This fixes it.

Signed-off-by: Paul Mackerras <paulus@samba.org>
pppd/ipcp.c