static const size_t icmp6_size = sizeof(struct icmp6_hdr);
static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
static const size_t opt_size = sizeof(struct nd_opt_hdr);
+#define max(a, b) ((a) > (b) ? (a) : (b))
/* RFC 1071 */
return true;
}
+static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
+ if(!via || via == myself || !(via->options & OPTION_CLAMP_MSS))
+ return;
+
+ /* Find TCP header */
+ int start = 0;
+ uint16_t type = packet->data[12] << 8 | packet->data[13];
+
+ if(type == ETH_P_IP && packet->data[23] == 6)
+ start = 14 + (packet->data[14] & 0xf) * 4;
+ else if(type == ETH_P_IPV6 && packet->data[20] == 6)
+ start = 14 + 40;
+
+ if(!start || packet->len <= start + 20)
+ return;
+
+ /* 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)
+ break;
+
+ if(packet->data[start + 20 + i] == 1) {
+ i++;
+ continue;
+ }
+
+ if(i > len - 2 || i > len - packet->data[start + 21 + i])
+ break;
+
+ if(packet->data[start + 20 + i] != 2) {
+ if(packet->data[start + 21 + i] < 2)
+ break;
+ i += packet->data[start + 21 + i];
+ continue;
+ }
+
+ if(packet->data[start + 21] != 4)
+ break;
+
+ /* 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 csum = packet->data[start + 16] << 8 | packet->data[start + 17];
+
+ if(oldmss <= newmss)
+ break;
+
+ ifdebug(TRAFFIC) logger(LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
+
+ /* Update the MSS value and the checksum */
+ packet->data[start + 22 + i] = newmss >> 8;
+ packet->data[start + 23 + i] = newmss & 0xff;
+ csum ^= 0xffff;
+ csum -= oldmss;
+ csum += newmss;
+ csum ^= 0xffff;
+ packet->data[start + 16] = csum >> 8;
+ packet->data[start + 17] = csum & 0xff;
+ break;
+ }
+}
+
static void swap_mac_addresses(vpn_packet_t *packet) {
mac_t tmp;
memcpy(&tmp, &packet->data[0], sizeof tmp);
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 */
send_del_subnet(c, s);
}
+ subnet_update(myself, s, false);
subnet_del(myself, s);
}
}
via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
- if(via && packet->len > via->mtu && via != myself) {
+ if(via && packet->len > max(via->mtu, 590) && via != myself) {
ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
if(packet->data[20] & 0x40) {
- packet->len = via->mtu;
+ packet->len = max(via->mtu, 590);
route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
} else {
fragment_ipv4_packet(via, packet);
return;
}
+ clamp_mss(source, via, packet);
+
send_packet(subnet->owner, packet);
}
via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
- if(via && packet->len > via->mtu && via != myself) {
+ if(via && packet->len > max(via->mtu, 1294) && via != myself) {
ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
- packet->len = via->mtu;
+ packet->len = max(via->mtu, 1294);
route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
return;
}
+ clamp_mss(source, via, packet);
+
send_packet(subnet->owner, packet);
}
if(via && packet->len > via->mtu && via != myself) {
ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
uint16_t type = packet->data[12] << 8 | packet->data[13];
- if(type == ETH_P_IP) {
+ if(type == ETH_P_IP && packet->len > 590) {
if(packet->data[20] & 0x40) {
packet->len = via->mtu;
route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
fragment_ipv4_packet(via, packet);
}
return;
- } else if(type == ETH_P_IPV6) {
+ } else if(type == ETH_P_IPV6 && packet->len > 1294) {
packet->len = via->mtu;
route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
return;
}
}
+ clamp_mss(source, via, packet);
+
send_packet(subnet->owner, packet);
}