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https://code.semirocket.science/wrapsix
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Full processing of UDP packets
This commit is contained in:
Michal Zima
parent
0157236357
commit
d6f93792cd
@ -9,4 +9,5 @@ wrapsix_wrapper_SOURCES = \
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nat.c nat.h \
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radixtree.c radixtree.h \
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transmitter.c transmitter.h \
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udp.c udp.h \
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wrapper.c wrapper.h
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@ -22,6 +22,7 @@
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#include "icmp.h"
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#include "ipv4.h"
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#include "udp.h"
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#include "wrapper.h"
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int ipv4(struct s_ethernet *eth, char *packet)
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@ -54,7 +55,7 @@ int ipv4(struct s_ethernet *eth, char *packet)
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break;
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case IPPROTO_UDP:
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printf("[Debug] IPv4 Protocol: UDP\n");
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/*ipv4_udp(eth, ip, payload, data_size);*/
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udp_ipv4(eth, ip, payload, data_size);
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break;
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case IPPROTO_ICMP:
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printf("[Debug] IPv4 Protocol: ICMP\n");
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@ -22,6 +22,7 @@
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#include "icmp.h"
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#include "ipv6.h"
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#include "udp.h"
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#include "wrapper.h"
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int ipv6(struct s_ethernet *eth, char *packet)
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@ -47,7 +48,7 @@ int ipv6(struct s_ethernet *eth, char *packet)
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break;
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case IPPROTO_UDP:
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printf("[Debug] IPv6 Protocol: UDP\n");
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/*ipv6_udp(eth, ip, payload);*/
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udp_ipv6(eth, ip, payload);
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break;
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case IPPROTO_ICMPV6:
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printf("[Debug] IPv6 Protocol: ICMP\n");
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207
src/udp.c
Normal file
207
src/udp.c
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@ -0,0 +1,207 @@
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/*
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* WrapSix
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* Copyright (C) 2008-2012 Michal Zima <xhire@mujmalysvet.cz>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <net/ethernet.h> /* ETHERTYPE_* */
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#include <netinet/in.h> /* htons */
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#include <stdio.h>
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#include <stdlib.h> /* malloc */
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#include <string.h> /* memcpy */
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#include "checksum.h"
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#include "ethernet.h"
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#include "ipv4.h"
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#include "ipv6.h"
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#include "nat.h"
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#include "transmitter.h"
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#include "udp.h"
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#include "wrapper.h"
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/**
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* Processing of incoming UDPv4 packets. Directly sends translated UDPv6
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* packets.
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*
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* @param eth4 Ethernet header
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* @param ip4 IPv4 header
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* @param payload UDPv4 data
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* @param payload_size Size of payload; needed because IPv4 header has
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* dynamic length
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*
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* @return 0 for success
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* @return 1 for failure
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*/
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int udp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
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unsigned short payload_size)
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{
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struct s_udp *udp;
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struct s_nat *connection;
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unsigned short orig_checksum;
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unsigned char *packet;
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struct s_ethernet *eth6;
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struct s_ipv6 *ip6;
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/* parse UDP header */
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udp = (struct s_udp *) payload;
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/* TODO: checksum recheck */
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/* find connection in NAT */
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connection = nat_in(nat4_udp, ip4->ip_src, udp->port_src, udp->port_dest);
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if (connection == NULL) {
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printf("[Debug] Incoming connection wasn't found in NAT\n");
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return 1;
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}
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/* allocate memory for translated packet */
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if ((packet = (unsigned char *) malloc(sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6) +
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payload_size)) == NULL) {
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fprintf(stderr, "[Error] Lack of free memory\n");
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return 1;
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}
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eth6 = (struct s_ethernet *) packet;
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ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet));
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/* build ethernet header */
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eth6->dest = connection->mac;
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eth6->src = mac;
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eth6->type = htons(ETHERTYPE_IPV6);
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/* build IPv6 packet */
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ip6->ver = 0x60;
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ip6->traffic_class = 0x0;
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ip6->flow_label = 0x0;
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ip6->len = htons(payload_size);
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ip6->next_header = IPPROTO_UDP;
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ip6->hop_limit = ip4->ttl;
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ipv4_to_ipv6(&ip4->ip_src, &ip6->ip_src);
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memcpy(&ip6->ip_dest, &connection->ipv6, sizeof(struct s_ipv6_addr));
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/* set incoming source port */
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udp->port_dest = connection->ipv6_port_src;
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/* compute UDP checksum */
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udp->checksum = 0x0;
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udp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, payload_size,
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IPPROTO_UDP, (unsigned char *) udp);
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/* copy the payload data (with new checksum) */
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memcpy(packet + sizeof(struct s_ethernet) + sizeof(struct s_ipv6),
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payload, payload_size);
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/* send translated packet */
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transmit_raw(packet, sizeof(struct s_ethernet) + sizeof(struct s_ipv6) +
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payload_size);
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/* clean-up */
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free(packet);
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return 0;
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}
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/**
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* Processing of outgoing UDPv6 packets. Directly sends translated UDPv4
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* packets.
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*
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* @param eth6 Ethernet header
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* @param ip6 IPv6 header
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* @param payload UDPv6 data
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*
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* @return 0 for success
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* @return 1 for failure
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*/
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int udp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload)
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{
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struct s_udp *udp;
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struct s_nat *connection;
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unsigned short orig_checksum;
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struct s_ipv4 *ip4;
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unsigned char *packet;
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unsigned int packet_size;
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/* parse UDP header */
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udp = (struct s_udp *) payload;
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/* checksum recheck */
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orig_checksum = udp->checksum;
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udp->checksum = 0;
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udp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest,
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htons(ip6->len), IPPROTO_UDP,
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(unsigned char *) payload);
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if (udp->checksum != orig_checksum) {
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/* packet is corrupted and shouldn't be processed */
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printf("[Debug] Wrong checksum\n");
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return 1;
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}
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/* find connection in NAT */
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connection = nat_out(nat6_udp, nat4_udp, eth->src,
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ip6->ip_src, ip6->ip_dest,
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udp->port_src, udp->port_dest);
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if (connection == NULL) {
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printf("[Debug] Error! Outgoing connection wasn't "
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"found/created in NAT!\n");
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return 1;
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}
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/* allocate memory for translated packet */
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packet_size = sizeof(struct s_ipv4) + ip6->len;
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if ((packet = (unsigned char *) malloc(packet_size)) == NULL) {
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fprintf(stderr, "[Error] Lack of free memory\n");
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return 1;
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}
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ip4 = (struct s_ipv4 *) packet;
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/* build IPv4 packet */
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ip4->ver_hdrlen = 0x45; /* ver 4, header length 20 B */
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ip4->tos = 0x0;
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ip4->len = htons(sizeof(struct s_ipv4) + htons(ip6->len));
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ip4->id = 0x0;
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ip4->flags_offset = htons(IPV4_FLAG_DONT_FRAGMENT);
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ip4->ttl = ip6->hop_limit;
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ip4->proto = IPPROTO_UDP;
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ipv6_to_ipv4(&ip6->ip_dest, &ip4->ip_dest);
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memcpy(&ip4->ip_src, &wrapsix_ipv4_addr, sizeof(struct s_ipv4_addr));
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/* set outgoing source port */
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udp->port_src = connection->ipv4_port_src;
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/* compute UDP checksum */
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udp->checksum = 0;
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/* TODO: checksum computation; in IPv4 it's optional in UDP */
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/* copy the payload data (with new checksum) */
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memcpy(packet + sizeof(struct s_ipv4), payload, htons(ip6->len));
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/* compute IPv4 checksum */
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ip4->checksum = checksum_ipv4(ip4->ip_src, ip4->ip_dest,
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htons(ip4->len), IPPROTO_UDP,
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(unsigned char *) udp);
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/* send translated packet */
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printf("[Debug] transmitting\n");
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transmit_ipv4(&ip4->ip_dest, packet, htons(ip4->len));
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/* clean-up */
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free(packet);
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return 0;
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}
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34
src/udp.h
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34
src/udp.h
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@ -0,0 +1,34 @@
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/*
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* WrapSix
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* Copyright (C) 2008-2012 Michal Zima <xhire@mujmalysvet.cz>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef UDP_H
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#define UDP_H
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/* UDP header structure */
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struct s_udp {
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unsigned short port_src; /* 16 b; source port */
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unsigned short port_dest; /* 16 b; destination port */
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unsigned short len; /* 16 b; header + data length */
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unsigned short checksum; /* 16 b; optional checksum */
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} __attribute__ ((__packed__));
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int udp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
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unsigned short payload_size);
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int udp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload);
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#endif /* UDP_H */
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