X-Git-Url: https://www.tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Froute.c;h=5c69671ad30a7d55602569defe55db43eb970f9d;hp=e9451c8c18acdcfec4947816bff1e39e1ac3e30b;hb=43a6e786648fb666a9b7be8f05c8a173031c9110;hpb=ed509312906625acee4007da6262de3898846888 diff --git a/src/route.c b/src/route.c index e9451c8c..5c69671a 100644 --- a/src/route.c +++ b/src/route.c @@ -1,7 +1,7 @@ /* route.c -- routing - Copyright (C) 2000-2002 Ivo Timmermans , - 2000-2002 Guus Sliepen + Copyright (C) 2000-2005 Ivo Timmermans, + 2000-2009 Guus Sliepen 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 @@ -13,302 +13,770 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - $Id: route.c,v 1.1.2.24 2002/02/20 16:04:59 guus Exp $ + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ -#include "config.h" - -#if defined(HAVE_FREEBSD) || defined(HAVE_OPENBSD) - #include -#endif -#include -#include -#if defined(HAVE_SOLARIS) || defined(HAVE_OPENBSD) - #include - #define ETHER_ADDR_LEN 6 -#else - #include -#endif -#include -#include -#include -#include -#include - -#include +#include "system.h" -#include "net.h" +#include "avl_tree.h" #include "connection.h" -#include "subnet.h" -#include "route.h" +#include "ethernet.h" +#include "ipv4.h" +#include "ipv6.h" +#include "logger.h" +#include "net.h" #include "protocol.h" -#include "device.h" +#include "route.h" +#include "subnet.h" +#include "utils.h" + +rmode_t routing_mode = RMODE_ROUTER; +bool priorityinheritance = false; +int macexpire = 600; +bool overwrite_mac = false; +mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}}; + +/* Sizes of various headers */ + +static const size_t ether_size = sizeof(struct ether_header); +static const size_t arp_size = sizeof(struct ether_arp); +static const size_t ip_size = sizeof(struct ip); +static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip); +static const size_t ip6_size = sizeof(struct ip6_hdr); +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); + +/* RFC 1071 */ + +static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) { + uint16_t *p = data; + uint32_t checksum = prevsum ^ 0xFFFF; + + while(len >= 2) { + checksum += *p++; + len -= 2; + } + + if(len) + checksum += *(uint8_t *)p; + + while(checksum >> 16) + checksum = (checksum & 0xFFFF) + (checksum >> 16); + + return ~checksum; +} -#include "system.h" +static bool ratelimit(int frequency) { + static time_t lasttime = 0; + static int count = 0; + + if(lasttime == now) { + if(++count > frequency) + return true; + } else { + lasttime = now; + count = 0; + } + + return false; +} -int routing_mode = RMODE_ROUTER; -subnet_t mymac; - -void learn_mac(mac_t *address) -{ - subnet_t *subnet; - avl_node_t *node; - connection_t *c; -cp - subnet = lookup_subnet_mac(address); - - /* If we don't know this MAC address yet, store it */ - - if(!subnet || subnet->owner!=myself) - { - if(debug_lvl >= DEBUG_TRAFFIC) - syslog(LOG_INFO, _("Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx"), - address->x[0], address->x[1], address->x[2], address->x[3], address->x[4], address->x[5]); - - subnet = new_subnet(); - subnet->type = SUBNET_MAC; - memcpy(&subnet->net.mac.address, address, sizeof(mac_t)); - subnet_add(myself, subnet); - - /* And tell all other tinc daemons it's our MAC */ - - for(node = connection_tree->head; node; node = node->next) - { - c = (connection_t *)node->data; - if(c->status.active) - send_add_subnet(c, subnet); - } - } +static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) { + if(packet->len < length) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Got too short packet from %s (%s)", source->name, source->hostname); + return false; + } else + return true; } -node_t *route_mac(vpn_packet_t *packet) -{ - subnet_t *subnet; -cp - /* Learn source address */ - - learn_mac((mac_t *)(&packet->data[6])); - - /* Lookup destination address */ - - subnet = lookup_subnet_mac((mac_t *)(&packet->data[0])); - - if(subnet) - return subnet->owner; - else - return NULL; +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) { + subnet_t *subnet; + avl_node_t *node; + connection_t *c; + + subnet = lookup_subnet_mac(address); + + /* If we don't know this MAC address yet, store it */ + + if(!subnet) { + ifdebug(TRAFFIC) logger(LOG_INFO, "Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx", + address->x[0], address->x[1], address->x[2], address->x[3], + address->x[4], address->x[5]); + + subnet = new_subnet(); + subnet->type = SUBNET_MAC; + subnet->expires = now + macexpire; + subnet->net.mac.address = *address; + subnet->weight = 10; + subnet_add(myself, subnet); + + /* And tell all other tinc daemons it's our MAC */ + + for(node = connection_tree->head; node; node = node->next) { + c = node->data; + if(c->status.active) + send_add_subnet(c, subnet); + } + } -node_t *route_ipv4(vpn_packet_t *packet) -{ - subnet_t *subnet; -cp - subnet = lookup_subnet_ipv4((ipv4_t *)&packet->data[30]); -cp - if(!subnet) - { - if(debug_lvl >= DEBUG_TRAFFIC) - { - syslog(LOG_WARNING, _("Cannot route packet: unknown IPv4 destination address %d.%d.%d.%d"), - packet->data[30], packet->data[31], packet->data[32], packet->data[33]); - } - - return NULL; - } -cp - return subnet->owner; + if(subnet->expires) + subnet->expires = now + macexpire; } -node_t *route_ipv6(vpn_packet_t *packet) -{ - subnet_t *subnet; -cp - subnet = lookup_subnet_ipv6((ipv6_t *)&packet->data[38]); -cp - if(!subnet) - { - if(debug_lvl >= DEBUG_TRAFFIC) - { - syslog(LOG_WARNING, _("Cannot route packet: unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"), - ntohs(*(short unsigned int *)&packet->data[38]), - ntohs(*(short unsigned int *)&packet->data[40]), - ntohs(*(short unsigned int *)&packet->data[42]), - ntohs(*(short unsigned int *)&packet->data[44]), - ntohs(*(short unsigned int *)&packet->data[46]), - ntohs(*(short unsigned int *)&packet->data[48]), - ntohs(*(short unsigned int *)&packet->data[50]), - ntohs(*(short unsigned int *)&packet->data[52])); - } - - return NULL; - } -cp - return subnet->owner; +void age_subnets(void) { + subnet_t *s; + connection_t *c; + avl_node_t *node, *next, *node2; + + for(node = myself->subnet_tree->head; node; node = next) { + next = node->next; + s = node->data; + if(s->expires && s->expires < now) { + ifdebug(TRAFFIC) { + char netstr[MAXNETSTR]; + if(net2str(netstr, sizeof netstr, s)) + logger(LOG_INFO, "Subnet %s expired", netstr); + } + + for(node2 = connection_tree->head; node2; node2 = node2->next) { + c = node2->data; + if(c->status.active) + send_del_subnet(c, s); + } + + subnet_del(myself, s); + } + } } -void route_arp(vpn_packet_t *packet) -{ - struct ether_arp *arp; - subnet_t *subnet; - unsigned char ipbuf[4]; -cp - /* First, snatch the source address from the ARP packet */ - - memcpy(mymac.net.mac.address.x, packet->data + 6, 6); - - /* This routine generates replies to ARP requests. - You don't need to set NOARP flag on the interface anymore (which is broken on FreeBSD). - Most of the code here is taken from choparp.c by Takamichi Tateoka (tree@mma.club.uec.ac.jp) - */ - - arp = (struct ether_arp *)(packet->data + 14); - - /* Check if this is a valid ARP request */ - - if(ntohs(arp->arp_hrd) != ARPHRD_ETHER || - ntohs(arp->arp_pro) != ETHERTYPE_IP || - (int) (arp->arp_hln) != ETHER_ADDR_LEN || - (int) (arp->arp_pln) != 4 || - ntohs(arp->arp_op) != ARPOP_REQUEST ) - { - if(debug_lvl > DEBUG_TRAFFIC) - { - syslog(LOG_WARNING, _("Cannot route packet: received unknown type ARP request")); - } - return; - } - - /* Check if the IP address exists on the VPN */ - - subnet = lookup_subnet_ipv4((ipv4_t *)arp->arp_tpa); - - if(!subnet) - { - if(debug_lvl >= DEBUG_TRAFFIC) - { - syslog(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"), - arp->arp_tpa[0], arp->arp_tpa[1], arp->arp_tpa[2], arp->arp_tpa[3]); - } - - return; - } - - /* Check if it is for our own subnet */ - - if(subnet->owner == myself) - return; /* silently ignore */ - - memcpy(packet->data, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN); /* copy destination address */ - packet->data[ETHER_ADDR_LEN*2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */ - - memcpy(ipbuf, arp->arp_tpa, 4); /* save protocol addr */ - memcpy(arp->arp_tpa, arp->arp_spa, 4); /* swap destination and source protocol address */ - memcpy(arp->arp_spa, ipbuf, 4); /* ... */ - - memcpy(arp->arp_tha, arp->arp_sha, 10); /* set target hard/proto addr */ - memcpy(arp->arp_sha, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN); /* add fake source hard addr */ - arp->arp_op = htons(ARPOP_REPLY); - - write_packet(packet); -cp +/* RFC 792 */ + +static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code) { + struct ip ip = {0}; + struct icmp icmp = {0}; + + struct in_addr ip_src; + struct in_addr ip_dst; + uint32_t oldlen; + + if(ratelimit(3)) + return; + + /* 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); + + /* Remember original source and destination */ + + ip_src = ip.ip_src; + ip_dst = ip.ip_dst; + + oldlen = packet->len - ether_size; + + if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) + icmp.icmp_nextmtu = htons(packet->len - ether_size); + + if(oldlen >= IP_MSS - ip_size - icmp_size) + oldlen = IP_MSS - ip_size - icmp_size; + + /* Copy first part of original contents to ICMP message */ + + memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen); + + /* Fill in IPv4 header */ + + ip.ip_v = 4; + ip.ip_hl = ip_size / 4; + ip.ip_tos = 0; + ip.ip_len = htons(ip_size + icmp_size + oldlen); + ip.ip_id = 0; + ip.ip_off = 0; + ip.ip_ttl = 255; + ip.ip_p = IPPROTO_ICMP; + ip.ip_sum = 0; + ip.ip_src = ip_dst; + ip.ip_dst = ip_src; + + ip.ip_sum = inet_checksum(&ip, ip_size, ~0); + + /* Fill in ICMP header */ + + icmp.icmp_type = type; + icmp.icmp_code = code; + icmp.icmp_cksum = 0; + + icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0); + icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum); + + /* Copy structs on stack back to packet */ + + memcpy(packet->data + ether_size, &ip, ip_size); + memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size); + + packet->len = ether_size + ip_size + icmp_size + oldlen; + + send_packet(source, packet); } -void route_outgoing(vpn_packet_t *packet) -{ - unsigned short int type; - node_t *n; -cp - /* FIXME: multicast? */ - - switch(routing_mode) - { - case RMODE_ROUTER: - type = ntohs(*((unsigned short*)(&packet->data[12]))); - switch(type) - { - case 0x0800: - n = route_ipv4(packet); - break; - case 0x86DD: - n = route_ipv6(packet); - break; - case 0x0806: - route_arp(packet); - return; - default: - if(debug_lvl >= DEBUG_TRAFFIC) - { - syslog(LOG_WARNING, _("Cannot route packet: unknown type %hx"), type); - } - return; - } - if(n) - send_packet(n, packet); - break; - - case RMODE_SWITCH: - n = route_mac(packet); - if(n) - send_packet(n, packet); - else - broadcast_packet(myself, packet); - break; - - case RMODE_HUB: - broadcast_packet(myself, packet); - break; - } +/* RFC 791 */ + +static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet) { + struct ip ip; + vpn_packet_t fragment; + int len, maxlen, todo; + uint8_t *offset; + uint16_t ip_off, origf; + + memcpy(&ip, packet->data + ether_size, ip_size); + fragment.priority = packet->priority; + + if(ip.ip_hl != ip_size / 4) + return; + + todo = ntohs(ip.ip_len) - ip_size; + + if(ether_size + ip_size + todo != packet->len) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Length of packet (%d) doesn't match length in IPv4 header (%zd)", packet->len, ether_size + ip_size + todo); + return; + } + + ifdebug(TRAFFIC) logger(LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname); + + offset = packet->data + ether_size + ip_size; + maxlen = (dest->mtu - ether_size - ip_size) & ~0x7; + ip_off = ntohs(ip.ip_off); + origf = ip_off & ~IP_OFFMASK; + ip_off &= IP_OFFMASK; + + while(todo) { + len = todo > maxlen ? maxlen : todo; + memcpy(fragment.data + ether_size + ip_size, offset, len); + todo -= len; + offset += len; + + ip.ip_len = htons(ip_size + len); + ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0)); + ip.ip_sum = 0; + ip.ip_sum = inet_checksum(&ip, ip_size, ~0); + memcpy(fragment.data, packet->data, ether_size); + memcpy(fragment.data + ether_size, &ip, ip_size); + fragment.len = ether_size + ip_size + len; + + send_packet(dest, &fragment); + + ip_off += len / 8; + } } -void route_incoming(node_t *source, vpn_packet_t *packet) -{ - switch(routing_mode) - { - case RMODE_ROUTER: - { - node_t *n; - - n = route_ipv4(packet); - - if(n) - { - if(n == myself) - { - memcpy(packet->data, mymac.net.mac.address.x, 6); - write_packet(packet); +static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) { + subnet_t *subnet; + node_t *via; + ipv4_t dest; + + memcpy(&dest, &packet->data[30], sizeof dest); + subnet = lookup_subnet_ipv4(&dest); + + if(!subnet) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d", + source->name, source->hostname, + dest.x[0], + dest.x[1], + dest.x[2], + dest.x[3]); + + route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN); + return; + } + + if(subnet->owner == source) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname); + return; + } + + if(!subnet->owner->status.reachable) + route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNREACH); + + if(priorityinheritance) + packet->priority = packet->data[15]; + + 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); + 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 - send_packet(n, packet); - } - } - break; - case RMODE_SWITCH: - { - subnet_t *subnet; - - subnet = lookup_subnet_mac((mac_t *)(&packet->data[0])); - - if(subnet) - { - if(subnet->owner == myself) - write_packet(packet); - else - send_packet(subnet->owner, packet); - } - else - { - broadcast_packet(source, packet); - write_packet(packet); - } - } - break; - case RMODE_HUB: - broadcast_packet(source, packet); /* Spread it on */ - write_packet(packet); - break; - } + + return; + } + + send_packet(subnet->owner, packet); +} + +static void route_ipv4(node_t *source, vpn_packet_t *packet) { + if(!checklength(source, packet, ether_size + ip_size)) + return; + + if(((packet->data[30] & 0xf0) == 0xe0) || ( + packet->data[30] == 255 && + packet->data[31] == 255 && + packet->data[32] == 255 && + packet->data[33] == 255)) + broadcast_packet(source, packet); + else + route_ipv4_unicast(source, packet); +} + +/* RFC 2463 */ + +static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code) { + struct ip6_hdr ip6; + struct icmp6_hdr icmp6 = {0}; + uint16_t checksum; + + struct { + struct in6_addr ip6_src; /* source address */ + struct in6_addr ip6_dst; /* destination address */ + uint32_t length; + uint32_t next; + } pseudo; + + if(ratelimit(3)) + return; + + /* 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); + + /* Remember original source and destination */ + + pseudo.ip6_src = ip6.ip6_dst; + pseudo.ip6_dst = ip6.ip6_src; + + pseudo.length = packet->len - ether_size; + + if(type == ICMP6_PACKET_TOO_BIG) + icmp6.icmp6_mtu = htonl(pseudo.length); + + if(pseudo.length >= IP_MSS - ip6_size - icmp6_size) + pseudo.length = IP_MSS - ip6_size - icmp6_size; + + /* Copy first part of original contents to ICMP message */ + + memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length); + + /* Fill in IPv6 header */ + + ip6.ip6_flow = htonl(0x60000000UL); + ip6.ip6_plen = htons(icmp6_size + pseudo.length); + ip6.ip6_nxt = IPPROTO_ICMPV6; + ip6.ip6_hlim = 255; + ip6.ip6_src = pseudo.ip6_src; + ip6.ip6_dst = pseudo.ip6_dst; + + /* Fill in ICMP header */ + + icmp6.icmp6_type = type; + icmp6.icmp6_code = code; + icmp6.icmp6_cksum = 0; + + /* Create pseudo header */ + + pseudo.length = htonl(icmp6_size + pseudo.length); + pseudo.next = htonl(IPPROTO_ICMPV6); + + /* Generate checksum */ + + checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); + checksum = inet_checksum(&icmp6, icmp6_size, checksum); + checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum); + + icmp6.icmp6_cksum = checksum; + + /* Copy structs on stack back to packet */ + + memcpy(packet->data + ether_size, &ip6, ip6_size); + memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size); + + packet->len = ether_size + ip6_size + ntohl(pseudo.length); + + send_packet(source, packet); +} + +static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) { + subnet_t *subnet; + node_t *via; + ipv6_t dest; + + memcpy(&dest, &packet->data[38], sizeof dest); + subnet = lookup_subnet_ipv6(&dest); + + if(!subnet) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx", + source->name, source->hostname, + ntohs(dest.x[0]), + ntohs(dest.x[1]), + ntohs(dest.x[2]), + ntohs(dest.x[3]), + ntohs(dest.x[4]), + ntohs(dest.x[5]), + ntohs(dest.x[6]), + ntohs(dest.x[7])); + + route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR); + return; + } + + if(subnet->owner == source) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname); + return; + } + + if(!subnet->owner->status.reachable) + route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE); + + 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); + packet->len = via->mtu; + route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0); + return; + } + + send_packet(subnet->owner, packet); +} + +/* RFC 2461 */ + +static void route_neighborsol(node_t *source, vpn_packet_t *packet) { + struct ip6_hdr ip6; + struct nd_neighbor_solicit ns; + struct nd_opt_hdr opt; + subnet_t *subnet; + uint16_t checksum; + bool has_opt; + + struct { + struct in6_addr ip6_src; /* source address */ + struct in6_addr ip6_dst; /* destination address */ + uint32_t length; + uint32_t next; + } pseudo; + + if(!checklength(source, packet, ether_size + ip6_size + ns_size)) + return; + + has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN; + + if(source != myself) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname); + return; + } + + /* Copy headers from packet to structs on the stack */ + + memcpy(&ip6, packet->data + ether_size, ip6_size); + memcpy(&ns, packet->data + ether_size + ip6_size, ns_size); + if(has_opt) + memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size); + + /* First, snatch the source address from the neighbor solicitation packet */ + + if(overwrite_mac) + memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN); + + /* Check if this is a valid neighbor solicitation request */ + + if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT || + (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request"); + return; + } + + /* Create pseudo header */ + + pseudo.ip6_src = ip6.ip6_src; + pseudo.ip6_dst = ip6.ip6_dst; + if(has_opt) + pseudo.length = htonl(ns_size + opt_size + ETH_ALEN); + else + pseudo.length = htonl(ns_size); + pseudo.next = htonl(IPPROTO_ICMPV6); + + /* Generate checksum */ + + checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); + checksum = inet_checksum(&ns, ns_size, checksum); + if(has_opt) { + checksum = inet_checksum(&opt, opt_size, checksum); + checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum); + } + + if(checksum) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request"); + return; + } + + /* Check if the IPv6 address exists on the VPN */ + + subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target); + + if(!subnet) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx", + ntohs(((uint16_t *) &ns.nd_ns_target)[0]), + ntohs(((uint16_t *) &ns.nd_ns_target)[1]), + ntohs(((uint16_t *) &ns.nd_ns_target)[2]), + ntohs(((uint16_t *) &ns.nd_ns_target)[3]), + ntohs(((uint16_t *) &ns.nd_ns_target)[4]), + ntohs(((uint16_t *) &ns.nd_ns_target)[5]), + ntohs(((uint16_t *) &ns.nd_ns_target)[6]), + ntohs(((uint16_t *) &ns.nd_ns_target)[7])); + + return; + } + + /* Check if it is for our own subnet */ + + if(subnet->owner == myself) + return; /* silently ignore */ + + /* Create neighbor advertation reply */ + + memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */ + packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */ + + ip6.ip6_dst = ip6.ip6_src; /* swap destination and source protocoll address */ + ip6.ip6_src = ns.nd_ns_target; + + if(has_opt) + memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */ + + ns.nd_ns_cksum = 0; + ns.nd_ns_type = ND_NEIGHBOR_ADVERT; + ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */ + opt.nd_opt_type = ND_OPT_TARGET_LINKADDR; + + /* Create pseudo header */ + + pseudo.ip6_src = ip6.ip6_src; + pseudo.ip6_dst = ip6.ip6_dst; + if(has_opt) + pseudo.length = htonl(ns_size + opt_size + ETH_ALEN); + else + pseudo.length = htonl(ns_size); + pseudo.next = htonl(IPPROTO_ICMPV6); + + /* Generate checksum */ + + checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); + checksum = inet_checksum(&ns, ns_size, checksum); + if(has_opt) { + checksum = inet_checksum(&opt, opt_size, checksum); + checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum); + } + + ns.nd_ns_hdr.icmp6_cksum = checksum; + + /* Copy structs on stack back to packet */ + + memcpy(packet->data + ether_size, &ip6, ip6_size); + memcpy(packet->data + ether_size + ip6_size, &ns, ns_size); + if(has_opt) + memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size); + + send_packet(source, packet); +} + +static void route_ipv6(node_t *source, vpn_packet_t *packet) { + if(!checklength(source, packet, ether_size + ip6_size)) + return; + + if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) { + route_neighborsol(source, packet); + return; + } + + if(packet->data[38] == 255) + broadcast_packet(source, packet); + else + route_ipv6_unicast(source, packet); +} + +/* RFC 826 */ + +static void route_arp(node_t *source, vpn_packet_t *packet) { + struct ether_arp arp; + subnet_t *subnet; + struct in_addr addr; + + if(!checklength(source, packet, ether_size + arp_size)) + return; + + if(source != myself) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname); + return; + } + + /* First, snatch the source address from the ARP packet */ + + if(overwrite_mac) + memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN); + + /* Copy headers from packet to structs on the stack */ + + memcpy(&arp, packet->data + ether_size, arp_size); + + /* Check if this is a valid ARP request */ + + if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP || + arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type ARP request"); + return; + } + + /* Check if the IPv4 address exists on the VPN */ + + subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa); + + if(!subnet) { + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d", + arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2], + arp.arp_tpa[3]); + return; + } + + /* Check if it is for our own subnet */ + + if(subnet->owner == myself) + return; /* silently ignore */ + + memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */ + packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */ + + memcpy(&addr, arp.arp_tpa, sizeof(addr)); /* save protocol addr */ + memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */ + memcpy(arp.arp_spa, &addr, sizeof(addr)); /* ... */ + + memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */ + memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */ + arp.arp_op = htons(ARPOP_REPLY); + + /* Copy structs on stack back to packet */ + + memcpy(packet->data + ether_size, &arp, arp_size); + + send_packet(source, packet); +} + +static void route_mac(node_t *source, vpn_packet_t *packet) { + subnet_t *subnet; + mac_t dest; + + /* 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); + } + return; + } else if(type == ETH_P_IPV6) { + packet->len = via->mtu; + route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0); + return; + } + } + + send_packet(subnet->owner, packet); +} + +void route(node_t *source, vpn_packet_t *packet) { + if(!checklength(source, packet, ether_size)) + return; + + switch (routing_mode) { + case RMODE_ROUTER: + { + uint16_t type = packet->data[12] << 8 | packet->data[13]; + + switch (type) { + case ETH_P_ARP: + route_arp(source, packet); + break; + + case ETH_P_IP: + route_ipv4(source, packet); + break; + + case ETH_P_IPV6: + route_ipv6(source, packet); + break; + + default: + ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type); + break; + } + } + break; + + case RMODE_SWITCH: + route_mac(source, packet); + break; + + case RMODE_HUB: + broadcast_packet(source, packet); + break; + } }