/* * WrapSix * Copyright (C) 2008-2012 Michal Zima * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . */ #include /* ETHERTYPE_* */ #include /* htons */ #include #include /* malloc */ #include /* memcpy */ #include "checksum.h" #include "ethernet.h" #include "ipv4.h" #include "ipv6.h" #include "nat.h" #include "transmitter.h" #include "udp.h" #include "wrapper.h" /** * Processing of incoming UDPv4 packets. Directly sends translated UDPv6 * packets. * * @param eth4 Ethernet header * @param ip4 IPv4 header * @param payload UDPv4 data * @param payload_size Size of payload; needed because IPv4 header has * dynamic length * * @return 0 for success * @return 1 for failure */ int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload, unsigned short payload_size) { struct s_udp *udp; struct s_nat *connection; unsigned short orig_checksum; unsigned char *packet; struct s_ethernet *eth6; struct s_ipv6 *ip6; /* parse UDP header */ udp = (struct s_udp *) payload; /* checksum recheck */ if (udp->checksum != 0x0000) { orig_checksum = udp->checksum; udp->checksum = 0; udp->checksum = checksum_ipv4(ip4->ip_src, ip4->ip_dest, payload_size, IPPROTO_UDP, (unsigned char *) udp); if (udp->checksum != orig_checksum) { /* packet is corrupted and shouldn't be processed */ printf("[Debug] Wrong checksum\n"); return 1; } } /* find connection in NAT */ connection = nat_in(nat4_udp, ip4->ip_src, udp->port_src, udp->port_dest); if (connection == NULL) { printf("[Debug] Incoming connection wasn't found in NAT\n"); return 1; } /* allocate memory for translated packet */ if ((packet = (unsigned char *) malloc(sizeof(struct s_ethernet) + sizeof(struct s_ipv6) + payload_size)) == NULL) { fprintf(stderr, "[Error] Lack of free memory\n"); return 1; } eth6 = (struct s_ethernet *) packet; ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet)); /* build ethernet header */ eth6->dest = connection->mac; eth6->src = mac; eth6->type = htons(ETHERTYPE_IPV6); /* build IPv6 packet */ ip6->ver = 0x60; ip6->traffic_class = 0x0; ip6->flow_label = 0x0; ip6->len = htons(payload_size); ip6->next_header = IPPROTO_UDP; ip6->hop_limit = ip4->ttl; ipv4_to_ipv6(&ip4->ip_src, &ip6->ip_src); memcpy(&ip6->ip_dest, &connection->ipv6, sizeof(struct s_ipv6_addr)); /* set incoming source port */ udp->port_dest = connection->ipv6_port_src; /* compute UDP checksum */ if (udp->checksum) { udp->checksum = checksum_ipv6_update(udp->checksum, ip4->ip_src, ip4->ip_dest, connection->ipv4_port_src, ip6->ip_src, ip6->ip_dest, connection->ipv6_port_src); } else { /* if original checksum was 0x0000, we need to compute it */ udp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, payload_size, IPPROTO_UDP, (unsigned char *) udp); } /* copy the payload data (with new checksum) */ memcpy(packet + sizeof(struct s_ethernet) + sizeof(struct s_ipv6), payload, payload_size); /* send translated packet */ transmit_raw(packet, sizeof(struct s_ethernet) + sizeof(struct s_ipv6) + payload_size); /* clean-up */ free(packet); return 0; } /** * Processing of outgoing UDPv6 packets. Directly sends translated UDPv4 * packets. * * @param eth6 Ethernet header * @param ip6 IPv6 header * @param payload UDPv6 data * * @return 0 for success * @return 1 for failure */ int udp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload) { struct s_udp *udp; struct s_nat *connection; unsigned short orig_checksum; struct s_ipv4 *ip4; unsigned char *packet; unsigned int packet_size; /* parse UDP header */ udp = (struct s_udp *) payload; /* checksum recheck */ orig_checksum = udp->checksum; udp->checksum = 0; udp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, htons(ip6->len), IPPROTO_UDP, (unsigned char *) payload); if (udp->checksum != orig_checksum) { /* packet is corrupted and shouldn't be processed */ printf("[Debug] Wrong checksum\n"); return 1; } /* find connection in NAT */ connection = nat_out(nat6_udp, nat4_udp, eth6->src, ip6->ip_src, ip6->ip_dest, udp->port_src, udp->port_dest); if (connection == NULL) { printf("[Debug] Error! Outgoing connection wasn't " "found/created in NAT!\n"); return 1; } /* allocate memory for translated packet */ packet_size = sizeof(struct s_ipv4) + htons(ip6->len); if ((packet = (unsigned char *) malloc(packet_size)) == NULL) { fprintf(stderr, "[Error] Lack of free memory\n"); return 1; } ip4 = (struct s_ipv4 *) packet; /* build IPv4 packet */ ip4->ver_hdrlen = 0x45; /* ver 4, header length 20 B */ ip4->tos = 0x0; ip4->len = htons(sizeof(struct s_ipv4) + htons(ip6->len)); ip4->id = 0x0; ip4->flags_offset = htons(IPV4_FLAG_DONT_FRAGMENT); ip4->ttl = ip6->hop_limit; ip4->proto = IPPROTO_UDP; ipv6_to_ipv4(&ip6->ip_dest, &ip4->ip_dest); memcpy(&ip4->ip_src, &wrapsix_ipv4_addr, sizeof(struct s_ipv4_addr)); /* set outgoing source port */ udp->port_src = connection->ipv4_port_src; /* compute UDP checksum */ udp->checksum = checksum_ipv4_update(udp->checksum, ip6->ip_src, ip6->ip_dest, connection->ipv6_port_src, ip4->ip_src, ip4->ip_dest, connection->ipv4_port_src); /* copy the payload data (with new checksum) */ memcpy(packet + sizeof(struct s_ipv4), payload, htons(ip6->len)); /* compute IPv4 checksum */ ip4->checksum = 0x0; ip4->checksum = checksum(ip4, sizeof(struct s_ipv4)); /* send translated packet */ transmit_ipv4(&ip4->ip_dest, packet, htons(ip4->len)); /* clean-up */ free(packet); return 0; }