Reduce the interface MTU by 2 when MPPE has been successfully negotiated.

This is necessary because MPPE will combine the protocol id with the
payload received on the tun interface, encrypt it, then prepend its
own protocol id, effectively increasing the payload by two bytes.

1 files changed, 7 insertions, 0 deletions

diff --git a/usr.sbin/ppp/mp.c b/usr.sbin/ppp/mp.c
index 2652d46..448b9e2 100644
--- a/usr.sbin/ppp/mp.c
+++ b/usr.sbin/ppp/mp.c
@@ -167,6 +167,8 @@ static void
 mp_LayerUp(void *v, struct fsm *fp)
 {
   /* The given fsm (ccp) is now up */
+
+  bundle_CalculateBandwidth(fp->bundle);	/* Against ccp_MTUOverhead */
 }
 
 static void
@@ -646,6 +648,11 @@ mp_Output(struct mp *mp, struct bundle *bundle, struct link *l,
                mp->out.seq, m_length(m), l->name);
   mp->out.seq = inc_seq(mp->peer_is12bit, mp->out.seq);
 
+  if (l->ccp.fsm.state != ST_OPENED && ccp_Required(&l->ccp)) {
+    log_Printf(LogPHASE, "%s: Not transmitting... waiting for CCP\n", l->name);
+    return;
+  }
+
   link_PushPacket(l, m, bundle, LINK_QUEUES(l) - 1, PROTO_MP);
 }