From: Guus Sliepen Date: Sat, 12 Sep 2009 12:19:36 +0000 (+0200) Subject: Handle unicast packets larger than PMTU in switch mode. X-Git-Tag: release-1.0.10~34 X-Git-Url: https://git.tinc-vpn.org/git/browse?a=commitdiff_plain;h=9915f2abbedb7f1aa2b9e2f81d52ddcfca60e82d;p=tinc Handle unicast packets larger than PMTU in switch mode. If PMTUDiscovery is enabled, and we see a unicast packet that is larger than the path MTU in switch mode, treat it just like we would do in router mode. --- diff --git a/src/route.c b/src/route.c index e79fae51..d748db16 100644 --- a/src/route.c +++ b/src/route.c @@ -94,6 +94,13 @@ static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) { } else return true; } + +static void swap_mac_addresses(vpn_packet_t *packet) { + mac_t tmp; + memcpy(&tmp, &packet->data[0], sizeof tmp); + memcpy(&packet->data[0], &packet->data[6], sizeof tmp); + memcpy(&packet->data[6], &tmp, sizeof tmp); +} static void learn_mac(mac_t *address) { @@ -160,40 +167,6 @@ void age_subnets(void) } } -static void route_mac(node_t *source, vpn_packet_t *packet) -{ - subnet_t *subnet; - mac_t dest; - - cp(); - - - /* Learn source address */ - - if(source == myself) { - mac_t src; - memcpy(&src, &packet->data[6], sizeof src); - learn_mac(&src); - } - - /* Lookup destination address */ - - memcpy(&dest, &packet->data[0], sizeof dest); - subnet = lookup_subnet_mac(&dest); - - if(!subnet) { - broadcast_packet(source, packet); - return; - } - - if(subnet->owner == source) { - ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname); - return; - } - - send_packet(subnet->owner, packet); -} - /* RFC 792 */ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code) @@ -210,6 +183,10 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t cp(); + /* Swap Ethernet source and destination addresses */ + + swap_mac_addresses(packet); + /* Copy headers from packet into properly aligned structs on the stack */ memcpy(&ip, packet->data + ether_size, ip_size); @@ -406,6 +383,10 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t cp(); + /* Swap Ethernet source and destination addresses */ + + swap_mac_addresses(packet); + /* Copy headers from packet to structs on the stack */ memcpy(&ip6, packet->data + ether_size, ip6_size); @@ -743,6 +724,64 @@ static void route_arp(node_t *source, vpn_packet_t *packet) send_packet(source, packet); } +static void route_mac(node_t *source, vpn_packet_t *packet) +{ + subnet_t *subnet; + mac_t dest; + + cp(); + + + /* Learn source address */ + + if(source == myself) { + mac_t src; + memcpy(&src, &packet->data[6], sizeof src); + learn_mac(&src); + } + + /* Lookup destination address */ + + memcpy(&dest, &packet->data[0], sizeof dest); + subnet = lookup_subnet_mac(&dest); + + if(!subnet) { + broadcast_packet(source, packet); + return; + } + + if(subnet->owner == source) { + ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname); + return; + } + + // Handle packets larger than PMTU + + node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via; + + 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(packet->data[20] & 0x40) { + packet->len = via->mtu; + route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED); + } else { + fragment_ipv4_packet(via, packet); + } + } else if(type == ETH_P_IPV6) { + packet->len = via->mtu; + route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0); + } else + ifdebug(TRAFFIC) logger(LOG_INFO, _("Large packet of unhandled type %hx dropped"), type); + + return; + } + + send_packet(subnet->owner, packet); +} + + void route(node_t *source, vpn_packet_t *packet) { cp(); @@ -753,9 +792,8 @@ void route(node_t *source, vpn_packet_t *packet) switch (routing_mode) { case RMODE_ROUTER: { - uint16_t type; + uint16_t type = packet->data[12] << 8 | packet->data[13]; - type = ntohs(*((uint16_t *)(&packet->data[12]))); switch (type) { case ETH_P_ARP: route_arp(source, packet);