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- /* $Id: bridge.c 1242 2005-04-09 22:48:33Z aturner $ */
- /*
- * Copyright (c) 2001-2005 Aaron Turner.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the names of the copyright owners nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
- * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
- * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
- * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
- #include "config.h"
- #include "defines.h"
- #include "common.h"
- #include <sys/time.h>
- #include <signal.h>
- #include <string.h>
- #include <netinet/in.h>
- #include <time.h>
- #include "tcpbridge.h"
- #include "edit_packet.h"
- #include "bridge.h"
- #include "send_packets.h"
- #include "rewrite_l2.h"
- extern tcpbridge_opt_t options;
- extern struct timeval begin, end;
- extern COUNTER bytes_sent, failed, pkts_sent;
- extern volatile int didsig;
- #ifdef DEBUG
- extern int debug;
- #endif
- static int live_callback(struct live_data_t *,
- struct pcap_pkthdr *, const u_char *);
- /*
- * First, prep our RB Tree which tracks where each (source)
- * MAC really lives so we don't create really nasty network
- * storms.
- */
- static struct macsrc_t *new_node(void);
- RB_HEAD(macsrc_tree, macsrc_t) macsrc_root;
- static int
- rbmacsrc_comp(struct macsrc_t *a, struct macsrc_t *b)
- {
- return (memcmp(a->key, b->key, ETHER_ADDR_LEN));
- }
- RB_PROTOTYPE(macsrc_tree, macsrc_t, node, rbmacsrc_comp)
- RB_GENERATE(macsrc_tree, macsrc_t, node, rbmacsrc_comp)
- void
- rbinit(void)
- {
- RB_INIT(&macsrc_root);
- }
- struct macsrc_t *
- new_node(void)
- {
- struct macsrc_t *node;
- node = (struct macsrc_t *)safe_malloc(sizeof(struct macsrc_t));
-
- memset(node, '\0', sizeof(struct macsrc_t));
- return (node);
- }
- /*
- * main loop for bridging mode
- */
- void
- do_bridge(pcap_t * pcap1, pcap_t * pcap2)
- {
- struct pollfd polls[2]; /* one for left & right pcap */
- int pollresult = 0;
- u_char source1 = PCAP_INT1;
- u_char source2 = PCAP_INT2;
- struct live_data_t livedata;
- /* define polls */
- polls[PCAP_INT1].fd = pcap_fileno(pcap1);
- polls[PCAP_INT2].fd = pcap_fileno(pcap2);
- polls[PCAP_INT1].events = POLLIN | POLLPRI;
- polls[PCAP_INT2].events = POLLIN | POLLPRI;
- polls[PCAP_INT1].revents = 0;
- polls[PCAP_INT2].revents = 0;
- /* register signals */
- didsig = 0;
- (void)signal(SIGINT, catcher);
- /*
- * loop until ctrl-C or we've sent enough packets
- * note that if -L wasn't specified, limit_send is
- * set to 0 so this will loop infinately
- */
- while ((options.limit_send == 0) || (options.limit_send != pkts_sent)) {
- if (didsig) {
- packet_stats(&begin, &end, bytes_sent, pkts_sent, failed);
- exit(1);
- }
- dbg(1, "limit_send: " COUNTER_SPEC " \t pkts_sent: " COUNTER_SPEC,
- options.limit_send, pkts_sent);
- /* poll for a packet on the two interfaces */
- pollresult = poll(polls, 2, options.poll_timeout);
- /* poll has returned, process the result */
- if (pollresult > 0) {
- /* success, got one or more packets */
- if (polls[PCAP_INT1].revents > 0) {
- dbg(2, "Processing first interface");
- livedata.source = source1;
- livedata.pcap = pcap1;
- pcap_dispatch(pcap1, -1, (pcap_handler) live_callback,
- (u_char *) & livedata);
- }
- /* check the other interface */
- if (polls[PCAP_INT2].revents > 0) {
- dbg(2, "Processing second interface");
- livedata.source = source2;
- livedata.pcap = pcap2;
- pcap_dispatch(pcap2, -1, (pcap_handler) live_callback,
- (u_char *) & livedata);
- }
- }
- else if (pollresult == 0) {
- dbg(3, "poll timeout exceeded...");
- /* do something here? */
- }
- else {
- /* poll error, probably a Ctrl-C */
- warnx("poll() error: %s", strerror(errno));
- }
- /* reset the result codes */
- polls[PCAP_INT1].revents = 0;
- polls[PCAP_INT2].revents = 0;
- /* go back to the top of the loop */
- }
- } /* do_bridge() */
- /*
- * This is the callback we use with pcap_dispatch to process
- * each packet recieved by libpcap on the two interfaces.
- */
- static int
- live_callback(struct live_data_t *livedata, struct pcap_pkthdr *pkthdr,
- const u_char * nextpkt)
- {
- ip_hdr_t *ip_hdr = NULL;
- libnet_t *l = NULL;
- u_char *pktdata = NULL; /* full packet buffer */
- #ifdef FORCE_ALIGN
- u_char *ipbuff = NULL; /* IP header and above buffer */
- #endif
- static int first_time = 1;
- int ret, newl2len, cache_mode;
- static unsigned long packetnum = 0;
- struct macsrc_t *node, finder; /* rb tree nodes */
- #ifdef DEBUG
- u_char dstmac[ETHER_ADDR_LEN];
- #endif
- packetnum++;
- dbg(2, "packet %d caplen %d", packetnum, pkthdr->caplen);
- /* only malloc the first time */
- if (first_time) {
- /* create packet buffers */
- pktdata = (u_char *)safe_malloc(MAXPACKET);
- #ifdef FORCE_ALIGN
- ipbuff = (u_char *)safe_malloc(MAXPACKET);
- #endif
- first_time = 0;
- } else {
- /* zero out the old packet info */
- memset(pktdata, '\0', MAXPACKET);
- #ifdef FORCE_ALIGN
- memset(ipbuff, '\0', MAXPACKET);
- #endif
- }
- /* lookup our source MAC in the tree */
- memcpy(&finder.key, &pktdata[ETHER_ADDR_LEN], ETHER_ADDR_LEN);
- #ifdef DEBUG
- memcpy(&dstmac, pktdata, ETHER_ADDR_LEN);
- dbg(1, "Source MAC: " MAC_FORMAT "\tDestin MAC: " MAC_FORMAT,
- MAC_STR(finder.key), MAC_STR(dstmac));
- #endif
- /* first, is this a packet sent locally? If so, ignore it */
- if ((memcmp(libnet_get_hwaddr(options.send1), &finder.key,
- ETHER_ADDR_LEN)) == 0) {
- dbg(1, "Packet matches the MAC of %s, skipping.", options.intf1);
- return (1);
- }
- else if ((memcmp(libnet_get_hwaddr(options.send2), &finder.key,
- ETHER_ADDR_LEN)) == 0) {
- dbg(1, "Packet matches the MAC of %s, skipping.", options.intf2);
- return (1);
- }
- node = RB_FIND(macsrc_tree, &macsrc_root, &finder);
- /* if we can't find the node, build a new one */
- if (node == NULL) {
- dbg(1, "Unable to find MAC in the tree");
- node = new_node();
- node->source = livedata->source;
- memcpy(&node->key, &finder.key, ETHER_ADDR_LEN);
- RB_INSERT(macsrc_tree, &macsrc_root, node);
- } /* otherwise compare sources */
- else if (node->source != livedata->source) {
- dbg(1,
- "Found the MAC and we had a source missmatch... skipping packet");
- /*
- * IMPORTANT!!!
- * Never send a packet out the same interface we sourced it on!
- */
- return (1);
- }
- /* what is our cache mode? */
- cache_mode = livedata->source == PCAP_INT1 ? CACHE_PRIMARY : CACHE_SECONDARY;
- /* Rewrite any Layer 2 data and copy the data to our local buffer */
- if ((newl2len = rewrite_l2(livedata->pcap, &pkthdr, pktdata, cache_mode))
- == 0) {
- warnx("Error rewriting layer 2 data... skipping packet %d", packetnum);
- return (1);
- }
- /*
- * send packets out the OTHER interface
- * and update the dst mac if necessary
- */
- if (node->source == PCAP_INT1) {
- dbg(2, "Packet source was %s... sending out on %s", options.intf1,
- options.intf2);
- l = options.send2;
- }
- else if (node->source == PCAP_INT2) {
- dbg(2, "Packet source was %s... sending out on %s", options.intf2,
- options.intf1);
- l = options.send1;
- } else {
- errx(1, "wtf? our node->source != PCAP_INT1 and != PCAP_INT2: %c",
- node->source);
- }
- if (get_l2protocol(nextpkt, pkthdr->caplen, livedata->linktype)
- == ETHERTYPE_IP) {
- dbg(3, "Packet is IP");
- #ifdef FORCE_ALIGN
- /*
- * copy layer 3 and up to our temp packet buffer
- * for now on, we have to edit the packetbuff because
- * just before we send the packet, we copy the packetbuff
- * back onto the pkt.data + newl2len buffer
- * we do all this work to prevent byte alignment issues
- */
- ip_hdr = (ip_hdr_t *) ipbuff;
- memcpy(ip_hdr, (&pktdata[newl2len]), pkthdr->caplen - newl2len);
- #else
- /*
- * on non-strict byte align systems, don't need to memcpy(),
- * just point to 14 bytes into the existing buffer
- */
- ip_hdr = (ip_hdr_t *) (&pktdata[newl2len]);
- #endif
- /* look for include or exclude CIDR match */
- if (options.xX.cidr != NULL) {
- if (!process_xX_by_cidr(options.xX.mode, options.xX.cidr, ip_hdr)) {
- return (1);
- }
- }
- }
- else {
- dbg(3, "Packet is not IP");
- /* non-IP packets have a NULL ip_hdr struct */
- ip_hdr = NULL;
- }
- #ifdef STRICT_ALIGN
- /*
- * put back the layer 3 and above back in the pkt.data buffer
- * we can't edit the packet at layer 3 or above beyond this point
- */
- memcpy(&pktdata[newl2len], ip_hdr, pkthdr->caplen - newl2len);
- #endif
- /*
- * write packet out on the network
- */
- do {
- ret = libnet_adv_write_link(l, pktdata, pkthdr->caplen);
- if (ret == -1) {
- /* Make note of failed writes due to full buffers */
- if (errno == ENOBUFS) {
- failed++;
- }
- else {
- errx(1, "libnet_adv_write_link(): %s", strerror(errno));
- }
- }
- } while (ret == -1 && !didsig);
- bytes_sent += pkthdr->caplen;
- pkts_sent++;
- dbg(1, "Sent packet " COUNTER_SPEC, pkts_sent);
- return (1);
- } /* live_callback() */
- /*
- Local Variables:
- mode:c
- indent-tabs-mode:nil
- c-basic-offset:4
- End:
- */
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