Clamp MSS to miminum MTU in both directions.

[tinc] / src / route.c

diff --git a/src/route.c b/src/route.c
index 77bec04..6c381cc 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -1,7 +1,7 @@
 /*
     route.c -- routing
     Copyright (C) 2000-2005 Ivo Timmermans,
-                  2000-2009 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2010 Guus Sliepen <guus@tinc-vpn.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -94,9 +94,13 @@ static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
 }
 
 static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
-       if(!via || via == myself)
+       if(!source || !via || !(via->options & OPTION_CLAMP_MSS))
                return;
 
+       uint16_t mtu = source->mtu;
+       if(via != myself && via->mtu < mtu)
+               mtu = via->mtu;
+
        /* Find TCP header */
        int start = 0;
        uint16_t type = packet->data[12] << 8 | packet->data[13];
@@ -112,6 +116,9 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
        /* Use data offset field to calculate length of options field */
        int len = ((packet->data[start + 12] >> 4) - 5) * 4;
 
+       if(packet->len < start + 20 + len)
+               return;
+
        /* Search for MSS option header */
        for(int i = 0; i < len;) {
                if(packet->data[start + 20 + i] == 0)
@@ -137,7 +144,7 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
 
                /* Found it */
                uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
-               uint16_t newmss = via->mtu - start - 20;
+               uint16_t newmss = mtu - start - 20;
                uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
 
                if(oldmss <= newmss)
@@ -185,6 +192,7 @@ static void learn_mac(mac_t *address) {
                subnet->net.mac.address = *address;
                subnet->weight = 10;
                subnet_add(myself, subnet);
+               subnet_update(myself, subnet, true);
 
                /* And tell all other tinc daemons it's our MAC */
 
@@ -220,6 +228,7 @@ void age_subnets(void) {
                                        send_del_subnet(c, s);
                        }
 
+                       subnet_update(myself, s, false);
                        subnet_del(myself, s);
                }
        }