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pcap-snoop.c

/*
 * Copyright (c) 1993, 1994, 1995, 1996, 1997
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University 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 WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */
#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/libpcap/pcap-snoop.c,v 1.55.2.3 2008-04-14 20:41:52 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <net/raw.h>
#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

static int
pcap_read_snoop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
      int cc;
      register struct snoopheader *sh;
      register u_int datalen;
      register u_int caplen;
      register u_char *cp;

again:
      /*
       * Has "pcap_breakloop()" been called?
       */
      if (p->break_loop) {
            /*
             * Yes - clear the flag that indicates that it
             * has, and return -2 to indicate that we were
             * told to break out of the loop.
             */
            p->break_loop = 0;
            return (-2);
      }
      cc = read(p->fd, (char *)p->buffer, p->bufsize);
      if (cc < 0) {
            /* Don't choke when we get ptraced */
            switch (errno) {

            case EINTR:
                  goto again;

            case EWOULDBLOCK:
                  return (0);             /* XXX */
            }
            snprintf(p->errbuf, sizeof(p->errbuf),
                "read: %s", pcap_strerror(errno));
            return (-1);
      }
      sh = (struct snoopheader *)p->buffer;
      datalen = sh->snoop_packetlen;

      /*
       * XXX - Sigh, snoop_packetlen is a 16 bit quantity.  If we
       * got a short length, but read a full sized snoop pakcet,
       * assume we overflowed and add back the 64K...
       */
      if (cc == (p->snapshot + sizeof(struct snoopheader)) &&
          (datalen < p->snapshot))
            datalen += (64 * 1024);

      caplen = (datalen < p->snapshot) ? datalen : p->snapshot;
      cp = (u_char *)(sh + 1) + p->offset;            /* XXX */

      /* 
       * XXX unfortunately snoop loopback isn't exactly like
       * BSD's.  The address family is encoded in the first 2
       * bytes rather than the first 4 bytes!  Luckily the last
       * two snoop loopback bytes are zeroed.
       */
      if (p->linktype == DLT_NULL && *((short *)(cp + 2)) == 0) {
            u_int *uip = (u_int *)cp;
            *uip >>= 16;
      }

      if (p->fcode.bf_insns == NULL ||
          bpf_filter(p->fcode.bf_insns, cp, datalen, caplen)) {
            struct pcap_pkthdr h;
            ++p->md.stat.ps_recv;
            h.ts.tv_sec = sh->snoop_timestamp.tv_sec;
            h.ts.tv_usec = sh->snoop_timestamp.tv_usec;
            h.len = datalen;
            h.caplen = caplen;
            (*callback)(user, &h, cp);
            return (1);
      }
      return (0);
}

static int
pcap_inject_snoop(pcap_t *p, const void *buf, size_t size)
{
      int ret;

      /*
       * XXX - libnet overwrites the source address with what I
       * presume is the interface's address; is that required?
       */
      ret = write(p->fd, buf, size);
      if (ret == -1) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
                pcap_strerror(errno));
            return (-1);
      }
      return (ret);
}                           

static int
pcap_stats_snoop(pcap_t *p, struct pcap_stat *ps)
{
      register struct rawstats *rs;
      struct rawstats rawstats;

      rs = &rawstats;
      memset(rs, 0, sizeof(*rs));
      if (ioctl(p->fd, SIOCRAWSTATS, (char *)rs) < 0) {
            snprintf(p->errbuf, sizeof(p->errbuf),
                "SIOCRAWSTATS: %s", pcap_strerror(errno));
            return (-1);
      }

      /*
       * "ifdrops" are those dropped by the network interface
       * due to resource shortages or hardware errors.
       *
       * "sbdrops" are those dropped due to socket buffer limits.
       *
       * As filter is done in userland, "sbdrops" counts packets
       * regardless of whether they would've passed the filter.
       *
       * XXX - does this count *all* Snoop or Drain sockets,
       * rather than just this socket?  If not, why does it have
       * both Snoop and Drain statistics?
       */
      p->md.stat.ps_drop =
          rs->rs_snoop.ss_ifdrops + rs->rs_snoop.ss_sbdrops +
          rs->rs_drain.ds_ifdrops + rs->rs_drain.ds_sbdrops;

      /*
       * "ps_recv" counts only packets that passed the filter.
       * As filtering is done in userland, this does not include
       * packets dropped because we ran out of buffer space.
       */
      *ps = p->md.stat;
      return (0);
}

/* XXX can't disable promiscuous */
static int
pcap_activate_snoop(pcap_t *p)
{
      int fd;
      struct sockaddr_raw sr;
      struct snoopfilter sf;
      u_int v;
      int ll_hdrlen;
      int snooplen;
      struct ifreq ifr;

      fd = socket(PF_RAW, SOCK_RAW, RAWPROTO_SNOOP);
      if (fd < 0) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "snoop socket: %s",
                pcap_strerror(errno));
            goto bad;
      }
      p->fd = fd;
      memset(&sr, 0, sizeof(sr));
      sr.sr_family = AF_RAW;
      (void)strncpy(sr.sr_ifname, p->opt.source, sizeof(sr.sr_ifname));
      if (bind(fd, (struct sockaddr *)&sr, sizeof(sr))) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "snoop bind: %s",
                pcap_strerror(errno));
            goto bad;
      }
      memset(&sf, 0, sizeof(sf));
      if (ioctl(fd, SIOCADDSNOOP, &sf) < 0) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "SIOCADDSNOOP: %s",
                pcap_strerror(errno));
            goto bad;
      }
      if (handle->opt.buffer_size != 0)
            v = handle->opt.buffer_size;
      else
            v = 64 * 1024;    /* default to 64K buffer size */
      (void)setsockopt(fd, SOL_SOCKET, SO_RCVBUF, (char *)&v, sizeof(v));
      /*
       * XXX hack - map device name to link layer type
       */
      if (strncmp("et", p->opt.source, 2) == 0 ||     /* Challenge 10 Mbit */
          strncmp("ec", p->opt.source, 2) == 0 ||     /* Indigo/Indy 10 Mbit,
                                             O2 10/100 */
          strncmp("ef", p->opt.source, 2) == 0 ||     /* O200/2000 10/100 Mbit */
          strncmp("eg", p->opt.source, 2) == 0 ||     /* Octane/O2xxx/O3xxx Gigabit */
          strncmp("gfe", p->opt.source, 3) == 0 ||    /* GIO 100 Mbit */
          strncmp("fxp", p->opt.source, 3) == 0 ||    /* Challenge VME Enet */
          strncmp("ep", p->opt.source, 2) == 0 ||     /* Challenge 8x10 Mbit EPLEX */
          strncmp("vfe", p->opt.source, 3) == 0 ||    /* Challenge VME 100Mbit */
          strncmp("fa", p->opt.source, 2) == 0 ||
          strncmp("qaa", p->opt.source, 3) == 0 ||
          strncmp("cip", p->opt.source, 3) == 0 ||
          strncmp("el", p->opt.source, 2) == 0) {
            p->linktype = DLT_EN10MB;
            p->offset = RAW_HDRPAD(sizeof(struct ether_header));
            ll_hdrlen = sizeof(struct ether_header);
            /*
             * This is (presumably) a real Ethernet capture; give it a
             * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
             * that an application can let you choose it, in case you're
             * capturing DOCSIS traffic that a Cisco Cable Modem
             * Termination System is putting out onto an Ethernet (it
             * doesn't put an Ethernet header onto the wire, it puts raw
             * DOCSIS frames out on the wire inside the low-level
             * Ethernet framing).
             *
             * XXX - are there any sorts of "fake Ethernet" that have
             * Ethernet link-layer headers but that *shouldn't offer
             * DLT_DOCSIS as a Cisco CMTS won't put traffic onto it
             * or get traffic bridged onto it?  "el" is for ATM LANE
             * Ethernet devices, so that might be the case for them;
             * the same applies for "qaa" classical IP devices.  If
             * "fa" devices are for FORE SPANS, that'd apply to them
             * as well; what are "cip" devices - some other ATM
             * Classical IP devices?
             */
            p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
            /*
             * If that fails, just leave the list empty.
             */
            if (p->dlt_list != NULL) {
                  p->dlt_list[0] = DLT_EN10MB;
                  p->dlt_list[1] = DLT_DOCSIS;
                  p->dlt_count = 2;
            }
      } else if (strncmp("ipg", p->opt.source, 3) == 0 ||
               strncmp("rns", p->opt.source, 3) == 0 ||     /* O2/200/2000 FDDI */
               strncmp("xpi", p->opt.source, 3) == 0) {
            p->linktype = DLT_FDDI;
            p->offset = 3;                      /* XXX yeah? */
            ll_hdrlen = 13;
      } else if (strncmp("ppp", p->opt.source, 3) == 0) {
            p->linktype = DLT_RAW;
            ll_hdrlen = 0;    /* DLT_RAW meaning "no PPP header, just the IP packet"? */
      } else if (strncmp("qfa", p->opt.source, 3) == 0) {
            p->linktype = DLT_IP_OVER_FC;
            ll_hdrlen = 24;
      } else if (strncmp("pl", p->opt.source, 2) == 0) {
            p->linktype = DLT_RAW;
            ll_hdrlen = 0;    /* Cray UNICOS/mp pseudo link */
      } else if (strncmp("lo", p->opt.source, 2) == 0) {
            p->linktype = DLT_NULL;
            ll_hdrlen = 4;
      } else {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                "snoop: unknown physical layer type");
            goto bad;
      }

      if (p->opt.rfmon) {
            /*
             * No monitor mode on Irix (no Wi-Fi devices on
             * hardware supported by Irix).
             */
            return (PCAP_ERROR_RFMON_NOTSUP);
      }

#ifdef SIOCGIFMTU
      /*
       * XXX - IRIX appears to give you an error if you try to set the
       * capture length to be greater than the MTU, so let's try to get
       * the MTU first and, if that succeeds, trim the snap length
       * to be no greater than the MTU.
       */
      (void)strncpy(ifr.ifr_name, p->opt.source, sizeof(ifr.ifr_name));
      if (ioctl(fd, SIOCGIFMTU, (char *)&ifr) < 0) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "SIOCGIFMTU: %s",
                pcap_strerror(errno));
            goto bad;
      }
      /*
       * OK, we got it.
       *
       * XXX - some versions of IRIX 6.5 define "ifr_mtu" and have an
       * "ifru_metric" member of the "ifr_ifru" union in an "ifreq"
       * structure, others don't.
       *
       * I've no idea what's going on, so, if "ifr_mtu" isn't defined,
       * we define it as "ifr_metric", as using that field appears to
       * work on the versions that lack "ifr_mtu" (and, on those that
       * don't lack it, "ifru_metric" and "ifru_mtu" are both "int"
       * members of the "ifr_ifru" union, which suggests that they
       * may be interchangeable in this case).
       */
#ifndef ifr_mtu
#define ifr_mtu   ifr_metric
#endif
      if (p->snapshot > ifr.ifr_mtu + ll_hdrlen)
            p->snapshot = ifr.ifr_mtu + ll_hdrlen;
#endif

      /*
       * The argument to SIOCSNOOPLEN is the number of link-layer
       * payload bytes to capture - it doesn't count link-layer
       * header bytes.
       */
      snooplen = p->snapshot - ll_hdrlen;
      if (snooplen < 0)
            snooplen = 0;
      if (ioctl(fd, SIOCSNOOPLEN, &snooplen) < 0) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPLEN: %s",
                pcap_strerror(errno));
            goto bad;
      }
      v = 1;
      if (ioctl(fd, SIOCSNOOPING, &v) < 0) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPING: %s",
                pcap_strerror(errno));
            goto bad;
      }

      p->bufsize = 4096;                        /* XXX */
      p->buffer = (u_char *)malloc(p->bufsize);
      if (p->buffer == NULL) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "malloc: %s",
                pcap_strerror(errno));
            goto bad;
      }

      /*
       * "p->fd" is a socket, so "select()" should work on it.
       */
      p->selectable_fd = p->fd;

      p->read_op = pcap_read_snoop;
      p->inject_op = pcap_inject_snoop;
      p->setfilter_op = install_bpf_program;    /* no kernel filtering */
      p->setdirection_op = NULL;    /* Not implemented. */
      p->set_datalink_op = NULL;    /* can't change data link type */
      p->getnonblock_op = pcap_getnonblock_fd;
      p->setnonblock_op = pcap_setnonblock_fd;
      p->stats_op = pcap_stats_snoop;

      return (0);
 bad:
      return (PCAP_ERROR);
}

pcap_t *
pcap_create(const char *device, char *ebuf)
{
      pcap_t *p;

      p = pcap_create_common(device, ebuf);
      if (p == NULL)
            return (NULL);

      p->activate_op = pcap_activate_snoop;
      return (p);
}

int
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
{
      return (0);
}

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