Logo Search packages:      
Sourcecode: nmap version File versions

savefile.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.
 *
 * savefile.c - supports offline use of tcpdump
 *    Extraction/creation by Jeffrey Mogul, DECWRL
 *    Modified by Steve McCanne, LBL.
 *
 * Used to save the received packet headers, after filtering, to
 * a file, and then read them later.
 * The first record in the file contains saved values for the machine
 * dependent values so we can print the dump file on any architecture.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /CVS/nmap/libpcap-possiblymodified/savefile.c,v 1.4 2004/08/01 05:34:47 fyodor Exp $ (LBL)";
#endif

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

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

#include "pcap-int.h"

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

#define TCPDUMP_MAGIC 0xa1b2c3d4
#define PATCHED_TCPDUMP_MAGIC 0xa1b2cd34

/*
 * We use the "receiver-makes-right" approach to byte order,
 * because time is at a premium when we are writing the file.
 * In other words, the pcap_file_header and pcap_pkthdr,
 * records are written in host byte order.
 * Note that the bytes of packet data are written out in the order in
 * which they were received, so multi-byte fields in packets are not
 * written in host byte order, they're written in whatever order the
 * sending machine put them in.
 *
 * ntoh[ls] aren't sufficient because we might need to swap on a big-endian
 * machine (if the file was written in little-end order).
 */
#define     SWAPLONG(y) \
((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
#define     SWAPSHORT(y) \
      ( (((y)&0xff)<<8) | ((u_short)((y)&0xff00)>>8) )

#define SFERR_TRUNC           1
#define SFERR_BADVERSION      2
#define SFERR_BADF            3
#define SFERR_EOF       4 /* not really an error, just a status */

/*
 * We don't write DLT_* values to the capture file header, because
 * they're not the same on all platforms.
 *
 * Unfortunately, the various flavors of BSD have not always used the same
 * numerical values for the same data types, and various patches to
 * libpcap for non-BSD OSes have added their own DLT_* codes for link
 * layer encapsulation types seen on those OSes, and those codes have had,
 * in some cases, values that were also used, on other platforms, for other
 * link layer encapsulation types.
 *
 * This means that capture files of a type whose numerical DLT_* code
 * means different things on different BSDs, or with different versions
 * of libpcap, can't always be read on systems other than those like
 * the one running on the machine on which the capture was made.
 *
 * Instead, we define here a set of LINKTYPE_* codes, and map DLT_* codes
 * to LINKTYPE_* codes when writing a savefile header, and map LINKTYPE_*
 * codes to DLT_* codes when reading a savefile header.
 *
 * For those DLT_* codes that have, as far as we know, the same values on
 * all platforms (DLT_NULL through DLT_FDDI), we define LINKTYPE_xxx as
 * DLT_xxx; that way, captures of those types can still be read by
 * versions of libpcap that map LINKTYPE_* values to DLT_* values, and
 * captures of those types written by versions of libpcap that map DLT_
 * values to LINKTYPE_ values can still be read by older versions
 * of libpcap.
 *
 * The other LINKTYPE_* codes are given values starting at 100, in the
 * hopes that no DLT_* code will be given one of those values.
 *
 * In order to ensure that a given LINKTYPE_* code's value will refer to
 * the same encapsulation type on all platforms, you should not allocate
 * a new LINKTYPE_* value without consulting "tcpdump-workers@tcpdump.org".
 * The tcpdump developers will allocate a value for you, and will not
 * subsequently allocate it to anybody else; that value will be added to
 * the "pcap.h" in the tcpdump.org CVS repository, so that a future
 * libpcap release will include it.
 *
 * You should, if possible, also contribute patches to libpcap and tcpdump
 * to handle the new encapsulation type, so that they can also be checked
 * into the tcpdump.org CVS repository and so that they will appear in
 * future libpcap and tcpdump releases.
 *
 * Do *NOT* assume that any values after the largest value in this file
 * are available; you might not have the most up-to-date version of this
 * file, and new values after that one might have been assigned.  Also,
 * do *NOT* use any values below 100 - those might already have been
 * taken by one (or more!) organizations.
 */
#define LINKTYPE_NULL         DLT_NULL
#define LINKTYPE_ETHERNET     DLT_EN10MB  /* also for 100Mb and up */
#define LINKTYPE_EXP_ETHERNET DLT_EN3MB   /* 3Mb experimental Ethernet */
#define LINKTYPE_AX25         DLT_AX25
#define LINKTYPE_PRONET       DLT_PRONET
#define LINKTYPE_CHAOS        DLT_CHAOS
#define LINKTYPE_TOKEN_RING   DLT_IEEE802 /* DLT_IEEE802 is used for Token Ring */
#define LINKTYPE_ARCNET       DLT_ARCNET  /* BSD-style headers */
#define LINKTYPE_SLIP         DLT_SLIP
#define LINKTYPE_PPP          DLT_PPP
#define LINKTYPE_FDDI         DLT_FDDI

/*
 * LINKTYPE_PPP is for use when there might, or might not, be an RFC 1662
 * PPP in HDLC-like framing header (with 0xff 0x03 before the PPP protocol
 * field) at the beginning of the packet.
 *
 * This is for use when there is always such a header; the address field
 * might be 0xff, for regular PPP, or it might be an address field for Cisco
 * point-to-point with HDLC framing as per section 4.3.1 of RFC 1547 ("Cisco
 * HDLC").  This is, for example, what you get with NetBSD's DLT_PPP_SERIAL.
 *
 * We give it the same value as NetBSD's DLT_PPP_SERIAL, in the hopes that
 * nobody else will choose a DLT_ value of 50, and so that DLT_PPP_SERIAL
 * captures will be written out with a link type that NetBSD's tcpdump
 * can read.
 */
#define LINKTYPE_PPP_HDLC     50          /* PPP in HDLC-like framing */

#define LINKTYPE_PPP_ETHER    51          /* NetBSD PPP-over-Ethernet */

/*
 * This isn't supported in libpcap 0.8[.x], but is supported in the
 * current CVS version; we include it here to note that it's not available
 * for anybody else to use.
 */
#define LINKTYPE_SYMANTEC_FIREWALL 99           /* Symantec Enterprise Firewall */

#define LINKTYPE_ATM_RFC1483  100         /* LLC/SNAP-encapsulated ATM */
#define LINKTYPE_RAW          101         /* raw IP */
#define LINKTYPE_SLIP_BSDOS   102         /* BSD/OS SLIP BPF header */
#define LINKTYPE_PPP_BSDOS    103         /* BSD/OS PPP BPF header */
#define LINKTYPE_C_HDLC       104         /* Cisco HDLC */
#define LINKTYPE_IEEE802_11   105         /* IEEE 802.11 (wireless) */
#define LINKTYPE_ATM_CLIP     106         /* Linux Classical IP over ATM */
#define LINKTYPE_FRELAY       107         /* Frame Relay */
#define LINKTYPE_LOOP         108         /* OpenBSD loopback */
#define LINKTYPE_ENC          109         /* OpenBSD IPSEC enc */

/*
 * These three types are reserved for future use.
 */
#define LINKTYPE_LANE8023     110         /* ATM LANE + 802.3 */
#define LINKTYPE_HIPPI        111         /* NetBSD HIPPI */
#define LINKTYPE_HDLC         112         /* NetBSD HDLC framing */

#define LINKTYPE_LINUX_SLL    113         /* Linux cooked socket capture */
#define LINKTYPE_LTALK        114         /* Apple LocalTalk hardware */
#define LINKTYPE_ECONET       115         /* Acorn Econet */

/*
 * Reserved for use with OpenBSD ipfilter.
 */
#define LINKTYPE_IPFILTER     116

#define LINKTYPE_PFLOG        117         /* OpenBSD DLT_PFLOG */
#define LINKTYPE_CISCO_IOS    118         /* For Cisco-internal use */
#define LINKTYPE_PRISM_HEADER 119         /* 802.11+Prism II monitor mode */
#define LINKTYPE_AIRONET_HEADER     120         /* FreeBSD Aironet driver stuff */

/*
 * Reserved for Siemens HiPath HDLC.
 */
#define LINKTYPE_HHDLC        121

#define LINKTYPE_IP_OVER_FC   122         /* RFC 2625 IP-over-Fibre Channel */
#define LINKTYPE_SUNATM       123         /* Solaris+SunATM */

/*
 * Reserved as per request from Kent Dahlgren <kent@praesum.com>
 * for private use.
 */
#define LINKTYPE_RIO          124         /* RapidIO */
#define LINKTYPE_PCI_EXP      125         /* PCI Express */
#define LINKTYPE_AURORA       126         /* Xilinx Aurora link layer */

#define LINKTYPE_IEEE802_11_RADIO 127           /* 802.11 plus BSD radio header */

/*
 * Reserved for the TZSP encapsulation, as per request from
 * Chris Waters <chris.waters@networkchemistry.com>
 * TZSP is a generic encapsulation for any other link type,
 * which includes a means to include meta-information
 * with the packet, e.g. signal strength and channel
 * for 802.11 packets.
 */
#define LINKTYPE_TZSP         128         /* Tazmen Sniffer Protocol */

#define LINKTYPE_ARCNET_LINUX 129         /* Linux-style headers */

/*
 * Juniper-private data link types, as per request from
 * Hannes Gredler <hannes@juniper.net>.  The corresponding
 * DLT_s are used for passing on chassis-internal
 * metainformation such as QOS profiles, etc..
 */
#define LINKTYPE_JUNIPER_MLPPP  130
#define LINKTYPE_JUNIPER_MLFR   131
#define LINKTYPE_JUNIPER_ES     132
#define LINKTYPE_JUNIPER_GGSN   133
#define LINKTYPE_JUNIPER_MFR    134
#define LINKTYPE_JUNIPER_ATM2   135
#define LINKTYPE_JUNIPER_SERVICES 136
#define LINKTYPE_JUNIPER_ATM1   137

#define LINKTYPE_APPLE_IP_OVER_IEEE1394 138     /* Apple IP-over-IEEE 1394 cooked header */

#define LINKTYPE_RAWSS7         139             /* see rawss7.h for */
#define LINKTYPE_RAWSS7_MTP2    140         /* information  on these */
#define LINKTYPE_RAWSS7_MTP3    141             /* definitions */
#define LINKTYPE_RAWSS7_SCCP    142

/*
 * This isn't supported in libpcap 0.8[.x], but is supported in the
 * current CVS version; we include it here to note that it's not available
 * for anybody else to use.
 */
#define LINKTYPE_DOCSIS       143         /* DOCSIS MAC frames */

#define LINKTYPE_LINUX_IRDA   144         /* Linux-IrDA */

/*
 * Reserved for IBM SP switch and IBM Next Federation switch.
 */
#define LINKTYPE_IBM_SP       145
#define LINKTYPE_IBM_SN       146

/*
 * Reserved for private use.  If you have some link-layer header type
 * that you want to use within your organization, with the capture files
 * using that link-layer header type not ever be sent outside your
 * organization, you can use these values.
 *
 * No libpcap release will use these for any purpose, nor will any
 * tcpdump release use them, either.
 *
 * Do *NOT* use these in capture files that you expect anybody not using
 * your private versions of capture-file-reading tools to read; in
 * particular, do *NOT* use them in products, otherwise you may find that
 * people won't be able to use tcpdump, or snort, or Ethereal, or... to
 * read capture files from your firewall/intrusion detection/traffic
 * monitoring/etc. appliance, or whatever product uses that LINKTYPE_ value,
 * and you may also find that the developers of those applications will
 * not accept patches to let them read those files.
 *
 * Also, do not use them if somebody might send you a capture using them
 * for *their* private type and tools using them for *your* private type
 * would have to read them.
 *
 * Instead, in those cases, ask "tcpdump-workers@tcpdump.org" for a new DLT_
 * and LINKTYPE_ value, as per the comment in pcap-bpf.h, and use the type
 * you're given.
 */
#define LINKTYPE_USER0        147
#define LINKTYPE_USER1        148
#define LINKTYPE_USER2        149
#define LINKTYPE_USER3        150
#define LINKTYPE_USER4        151
#define LINKTYPE_USER5        152
#define LINKTYPE_USER6        153
#define LINKTYPE_USER7        154
#define LINKTYPE_USER8        155
#define LINKTYPE_USER9        156
#define LINKTYPE_USER10       157
#define LINKTYPE_USER11       158
#define LINKTYPE_USER12       159
#define LINKTYPE_USER13       160
#define LINKTYPE_USER14       161
#define LINKTYPE_USER15       162

/*
 * For future use with 802.11 captures - defined by AbsoluteValue
 * Systems to store a number of bits of link-layer information
 * including radio information:
 *
 *    http://www.shaftnet.org/~pizza/software/capturefrm.txt
 *
 * but could and arguably should also be used by non-AVS Linux
 * 802.11 drivers; that may happen in the future.
 */
#define LINKTYPE_IEEE802_11_RADIO_AVS 163 /* 802.11 plus AVS radio header */

/*
 * Juniper-private data link type, as per request from
 * Hannes Gredler <hannes@juniper.net>.  The corresponding
 * DLT_s are used for passing on chassis-internal
 * metainformation such as QOS profiles, etc..
 */
#define LINKTYPE_JUNIPER_MONITOR 164

static struct linktype_map {
      int   dlt;
      int   linktype;
} map[] = {
      /*
       * These DLT_* codes have LINKTYPE_* codes with values identical
       * to the values of the corresponding DLT_* code.
       */
      { DLT_NULL,       LINKTYPE_NULL },
      { DLT_EN10MB,           LINKTYPE_ETHERNET },
      { DLT_EN3MB,            LINKTYPE_EXP_ETHERNET },
      { DLT_AX25,       LINKTYPE_AX25 },
      { DLT_PRONET,           LINKTYPE_PRONET },
      { DLT_CHAOS,            LINKTYPE_CHAOS },
      { DLT_IEEE802,          LINKTYPE_TOKEN_RING },
      { DLT_ARCNET,           LINKTYPE_ARCNET },
      { DLT_SLIP,       LINKTYPE_SLIP },
      { DLT_PPP,        LINKTYPE_PPP },
      { DLT_FDDI,       LINKTYPE_FDDI },

      /*
       * These DLT_* codes have different values on different
       * platforms; we map them to LINKTYPE_* codes that
       * have values that should never be equal to any DLT_*
       * code.
       */
#ifdef DLT_FR
      /* BSD/OS Frame Relay */
      { DLT_FR,         LINKTYPE_FRELAY },
#endif

      { DLT_SYMANTEC_FIREWALL, LINKTYPE_SYMANTEC_FIREWALL },
      { DLT_ATM_RFC1483,      LINKTYPE_ATM_RFC1483 },
      { DLT_RAW,        LINKTYPE_RAW },
      { DLT_SLIP_BSDOS, LINKTYPE_SLIP_BSDOS },
      { DLT_PPP_BSDOS,  LINKTYPE_PPP_BSDOS },

      /* BSD/OS Cisco HDLC */
      { DLT_C_HDLC,           LINKTYPE_C_HDLC },

      /*
       * These DLT_* codes are not on all platforms, but, so far,
       * there don't appear to be any platforms that define
       * other codes with those values; we map them to
       * different LINKTYPE_* values anyway, just in case.
       */

      /* Linux ATM Classical IP */
      { DLT_ATM_CLIP,         LINKTYPE_ATM_CLIP },

      /* NetBSD sync/async serial PPP (or Cisco HDLC) */
      { DLT_PPP_SERIAL, LINKTYPE_PPP_HDLC },

      /* NetBSD PPP over Ethernet */
      { DLT_PPP_ETHER,  LINKTYPE_PPP_ETHER },

      /* IEEE 802.11 wireless */
      { DLT_IEEE802_11, LINKTYPE_IEEE802_11 },

      /* Frame Relay */
      { DLT_FRELAY,           LINKTYPE_FRELAY },

      /* OpenBSD loopback */
      { DLT_LOOP,       LINKTYPE_LOOP },

      /* Linux cooked socket capture */
      { DLT_LINUX_SLL,  LINKTYPE_LINUX_SLL },

      /* Apple LocalTalk hardware */
      { DLT_LTALK,            LINKTYPE_LTALK },

      /* Acorn Econet */
      { DLT_ECONET,           LINKTYPE_ECONET },

      /* OpenBSD DLT_PFLOG */
      { DLT_PFLOG,            LINKTYPE_PFLOG },

      /* For Cisco-internal use */
      { DLT_CISCO_IOS,  LINKTYPE_CISCO_IOS },

      /* Prism II monitor-mode header plus 802.11 header */
      { DLT_PRISM_HEADER,     LINKTYPE_PRISM_HEADER },

      /* FreeBSD Aironet driver stuff */
      { DLT_AIRONET_HEADER,   LINKTYPE_AIRONET_HEADER },

      /* Siemens HiPath HDLC */
      { DLT_HHDLC,            LINKTYPE_HHDLC },

      /* RFC 2625 IP-over-Fibre Channel */
      { DLT_IP_OVER_FC, LINKTYPE_IP_OVER_FC },

      /* Solaris+SunATM */
      { DLT_SUNATM,           LINKTYPE_SUNATM },

      /* RapidIO */
      { DLT_RIO,        LINKTYPE_RIO },

      /* PCI Express */
      { DLT_PCI_EXP,          LINKTYPE_PCI_EXP },

      /* Xilinx Aurora link layer */
      { DLT_AURORA,           LINKTYPE_AURORA },

      /* 802.11 plus BSD radio header */
      { DLT_IEEE802_11_RADIO, LINKTYPE_IEEE802_11_RADIO },

      /* Tazmen Sniffer Protocol */
      { DLT_TZSP,       LINKTYPE_TZSP },

      /* Arcnet with Linux-style link-layer headers */
      { DLT_ARCNET_LINUX,     LINKTYPE_ARCNET_LINUX },

        /* Juniper-internal chassis encapsulation */
        { DLT_JUNIPER_MLPPP,    LINKTYPE_JUNIPER_MLPPP },
        { DLT_JUNIPER_MLFR,     LINKTYPE_JUNIPER_MLFR },
        { DLT_JUNIPER_ES,       LINKTYPE_JUNIPER_ES },
        { DLT_JUNIPER_GGSN,     LINKTYPE_JUNIPER_GGSN },
        { DLT_JUNIPER_MFR,      LINKTYPE_JUNIPER_MFR },
        { DLT_JUNIPER_ATM2,     LINKTYPE_JUNIPER_ATM2 },
        { DLT_JUNIPER_SERVICES, LINKTYPE_JUNIPER_SERVICES },
        { DLT_JUNIPER_ATM1,     LINKTYPE_JUNIPER_ATM1 },

      /* Apple IP-over-IEEE 1394 cooked header */
      { DLT_APPLE_IP_OVER_IEEE1394, LINKTYPE_APPLE_IP_OVER_IEEE1394 },

      /* DOCSIS MAC frames */
      { DLT_DOCSIS,           LINKTYPE_DOCSIS },

      /* IrDA IrLAP packets + Linux-cooked header */
      { DLT_LINUX_IRDA, LINKTYPE_LINUX_IRDA },

      /* IBM SP and Next Federation switches */
      { DLT_IBM_SP,           LINKTYPE_IBM_SP },
      { DLT_IBM_SN,           LINKTYPE_IBM_SN },

      /* 802.11 plus AVS radio header */
      { DLT_IEEE802_11_RADIO_AVS, LINKTYPE_IEEE802_11_RADIO_AVS },

      /*
       * Any platform that defines additional DLT_* codes should:
       *
       *    request a LINKTYPE_* code and value from tcpdump.org,
       *    as per the above;
       *
       *    add, in their version of libpcap, an entry to map
       *    those DLT_* codes to the corresponding LINKTYPE_*
       *    code;
       *
       *    redefine, in their "net/bpf.h", any DLT_* values
       *    that collide with the values used by their additional
       *    DLT_* codes, to remove those collisions (but without
       *    making them collide with any of the LINKTYPE_*
       *    values equal to 50 or above; they should also avoid
       *    defining DLT_* values that collide with those
       *    LINKTYPE_* values, either).
       */

        /* Juniper-internal chassis encapsulation */
        { DLT_JUNIPER_MONITOR,     LINKTYPE_JUNIPER_MONITOR },

      { -1,             -1 }
};

static int
dlt_to_linktype(int dlt)
{
      int i;

      for (i = 0; map[i].dlt != -1; i++) {
            if (map[i].dlt == dlt)
                  return (map[i].linktype);
      }

      /*
       * If we don't have a mapping for this DLT_ code, return an
       * error; that means that the table above needs to have an
       * entry added.
       */
      return (-1);
}

static int
linktype_to_dlt(int linktype)
{
      int i;

      for (i = 0; map[i].linktype != -1; i++) {
            if (map[i].linktype == linktype)
                  return (map[i].dlt);
      }

      /*
       * If we don't have an entry for this link type, return
       * the link type value; it may be a DLT_ value from an
       * older version of libpcap.
       */
      return linktype;
}

static int
sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen)
{
      struct pcap_file_header hdr;

      hdr.magic = TCPDUMP_MAGIC;
      hdr.version_major = PCAP_VERSION_MAJOR;
      hdr.version_minor = PCAP_VERSION_MINOR;

      hdr.thiszone = thiszone;
      hdr.snaplen = snaplen;
      hdr.sigfigs = 0;
      hdr.linktype = linktype;

      if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
            return (-1);

      return (0);
}

static void
swap_hdr(struct pcap_file_header *hp)
{
      hp->version_major = SWAPSHORT(hp->version_major);
      hp->version_minor = SWAPSHORT(hp->version_minor);
      hp->thiszone = SWAPLONG(hp->thiszone);
      hp->sigfigs = SWAPLONG(hp->sigfigs);
      hp->snaplen = SWAPLONG(hp->snaplen);
      hp->linktype = SWAPLONG(hp->linktype);
}

static int
sf_getnonblock(pcap_t *p, char *errbuf)
{
      /*
       * This is a savefile, not a live capture file, so never say
       * it's in non-blocking mode.
       */
      return (0);
}

static int
sf_setnonblock(pcap_t *p, int nonblock, char *errbuf)
{
      /*
       * This is a savefile, not a live capture file, so ignore
       * requests to put it in non-blocking mode.
       */
      return (0);
}

static int
sf_stats(pcap_t *p, struct pcap_stat *ps)
{
      snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
          "Statistics aren't available from savefiles");
      return (-1);
}

static void
sf_close(pcap_t *p)
{
      if (p->sf.rfile != stdin)
            (void)fclose(p->sf.rfile);
      if (p->sf.base != NULL)
            free(p->sf.base);
}

pcap_t *
pcap_open_offline(const char *fname, char *errbuf)
{
      register pcap_t *p;
      register FILE *fp;
      struct pcap_file_header hdr;
      bpf_u_int32 magic;
      int linklen;

      p = (pcap_t *)malloc(sizeof(*p));
      if (p == NULL) {
            strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
            return (NULL);
      }

      memset((char *)p, 0, sizeof(*p));

      if (fname[0] == '-' && fname[1] == '\0')
            fp = stdin;
      else {
#ifndef WIN32
            fp = fopen(fname, "r");
#else
            fp = fopen(fname, "rb");
#endif
            if (fp == NULL) {
                  snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname,
                      pcap_strerror(errno));
                  goto bad;
            }
      }
      if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
            snprintf(errbuf, PCAP_ERRBUF_SIZE, "fread: %s",
                pcap_strerror(errno));
            goto bad;
      }
      magic = hdr.magic;
      if (magic != TCPDUMP_MAGIC && magic != PATCHED_TCPDUMP_MAGIC) {
            magic = SWAPLONG(magic);
            if (magic != TCPDUMP_MAGIC && magic != PATCHED_TCPDUMP_MAGIC) {
                  snprintf(errbuf, PCAP_ERRBUF_SIZE,
                      "bad dump file format");
                  goto bad;
            }
            p->sf.swapped = 1;
            swap_hdr(&hdr);
      }
      if (magic == PATCHED_TCPDUMP_MAGIC) {
            /*
             * XXX - the patch that's in some versions of libpcap
             * changes the packet header but not the magic number;
             * we'd have to use some hacks^H^H^H^H^Hheuristics to
             * detect that.
             */
            p->sf.hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
      } else
            p->sf.hdrsize = sizeof(struct pcap_sf_pkthdr);
      if (hdr.version_major < PCAP_VERSION_MAJOR) {
            snprintf(errbuf, PCAP_ERRBUF_SIZE, "archaic file format");
            goto bad;
      }
      p->tzoff = hdr.thiszone;
      p->snapshot = hdr.snaplen;
      p->linktype = linktype_to_dlt(hdr.linktype);
      p->sf.rfile = fp;
#ifndef WIN32
      p->bufsize = hdr.snaplen;
#else
      /* Allocate the space for pcap_pkthdr as well. It will be used by pcap_read_ex */
      p->bufsize = hdr.snaplen+sizeof(struct pcap_pkthdr);
#endif

      /* Align link header as required for proper data alignment */
      /* XXX should handle all types */
      switch (p->linktype) {

      case DLT_EN10MB:
            linklen = 14;
            break;

      case DLT_FDDI:
            linklen = 13 + 8; /* fddi_header + llc */
            break;

      case DLT_NULL:
      default:
            linklen = 0;
            break;
      }

      if (p->bufsize < 0)
            p->bufsize = BPF_MAXBUFSIZE;
      p->sf.base = (u_char *)malloc(p->bufsize + BPF_ALIGNMENT);
      if (p->sf.base == NULL) {
            strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
            goto bad;
      }
      p->buffer = p->sf.base + BPF_ALIGNMENT - (linklen % BPF_ALIGNMENT);
      p->sf.version_major = hdr.version_major;
      p->sf.version_minor = hdr.version_minor;
#ifdef PCAP_FDDIPAD
      /* XXX padding only needed for kernel fcode */
      pcap_fddipad = 0;
#endif

      /*
       * We interchanged the caplen and len fields at version 2.3,
       * in order to match the bpf header layout.  But unfortunately
       * some files were written with version 2.3 in their headers
       * but without the interchanged fields.
       *
       * In addition, DG/UX tcpdump writes out files with a version
       * number of 543.0, and with the caplen and len fields in the
       * pre-2.3 order.
       */
      switch (hdr.version_major) {

      case 2:
            if (hdr.version_minor < 3)
                  p->sf.lengths_swapped = SWAPPED;
            else if (hdr.version_minor == 3)
                  p->sf.lengths_swapped = MAYBE_SWAPPED;
            else
                  p->sf.lengths_swapped = NOT_SWAPPED;
            break;

      case 543:
            p->sf.lengths_swapped = SWAPPED;
            break;

      default:
            p->sf.lengths_swapped = NOT_SWAPPED;
            break;
      }

#ifndef WIN32
      /*
       * You can do "select()" and "poll()" on plain files on most
       * platforms, and should be able to do so on pipes.
       *
       * You can't do "select()" on anything other than sockets in
       * Windows, so, on Win32 systems, we don't have "selectable_fd".
       */
      p->selectable_fd = fileno(fp);
#endif

      p->read_op = pcap_offline_read;
      p->setfilter_op = install_bpf_program;
      p->set_datalink_op = NULL;    /* we don't support munging link-layer headers */
      p->getnonblock_op = sf_getnonblock;
      p->setnonblock_op = sf_setnonblock;
      p->stats_op = sf_stats;
      p->close_op = sf_close;

      return (p);
 bad:
      if(fp)
            fclose(fp);
      free(p);
      return (NULL);
}

/*
 * Read sf_readfile and return the next packet.  Return the header in hdr
 * and the contents in buf.  Return 0 on success, SFERR_EOF if there were
 * no more packets, and SFERR_TRUNC if a partial packet was encountered.
 */
static int
sf_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char *buf, u_int buflen)
{
      struct pcap_sf_patched_pkthdr sf_hdr;
      FILE *fp = p->sf.rfile;
      size_t amt_read;
      bpf_u_int32 t;

      /*
       * Read the packet header; the structure we use as a buffer
       * is the longer structure for files generated by the patched
       * libpcap, but if the file has the magic number for an
       * unpatched libpcap we only read as many bytes as the regular
       * header has.
       */
      amt_read = fread(&sf_hdr, 1, p->sf.hdrsize, fp);
      if (amt_read != p->sf.hdrsize) {
            if (ferror(fp)) {
                  snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                      "error reading dump file: %s",
                      pcap_strerror(errno));
                  return (-1);
            } else {
                  if (amt_read != 0) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "truncated dump file; tried to read %d header bytes, only got %lu",
                            p->sf.hdrsize, (unsigned long)amt_read);
                        return (-1);
                  }
                  /* EOF */
                  return (1);
            }
      }

      if (p->sf.swapped) {
            /* these were written in opposite byte order */
            hdr->caplen = SWAPLONG(sf_hdr.caplen);
            hdr->len = SWAPLONG(sf_hdr.len);
            hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
            hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
      } else {
            hdr->caplen = sf_hdr.caplen;
            hdr->len = sf_hdr.len;
            hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
            hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
      }
      /* Swap the caplen and len fields, if necessary. */
      switch (p->sf.lengths_swapped) {

      case NOT_SWAPPED:
            break;

      case MAYBE_SWAPPED:
            if (hdr->caplen <= hdr->len) {
                  /*
                   * The captured length is <= the actual length,
                   * so presumably they weren't swapped.
                   */
                  break;
            }
            /* FALLTHROUGH */

      case SWAPPED:
            t = hdr->caplen;
            hdr->caplen = hdr->len;
            hdr->len = t;
            break;
      }

      if (hdr->caplen > buflen) {
            /*
             * This can happen due to Solaris 2.3 systems tripping
             * over the BUFMOD problem and not setting the snapshot
             * correctly in the savefile header.  If the caplen isn't
             * grossly wrong, try to salvage.
             */
            static u_char *tp = NULL;
            static size_t tsize = 0;

            if (hdr->caplen > 65535) {
                  snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                      "bogus savefile header");
                  return (-1);
            }

            if (tsize < hdr->caplen) {
                  tsize = ((hdr->caplen + 1023) / 1024) * 1024;
                  if (tp != NULL)
                        free((u_char *)tp);
                  tp = (u_char *)malloc(tsize);
                  if (tp == NULL) {
                        tsize = 0;
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "BUFMOD hack malloc");
                        return (-1);
                  }
            }
            amt_read = fread((char *)tp, 1, hdr->caplen, fp);
            if (amt_read != hdr->caplen) {
                  if (ferror(fp)) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "error reading dump file: %s",
                            pcap_strerror(errno));
                  } else {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "truncated dump file; tried to read %u captured bytes, only got %lu",
                            hdr->caplen, (unsigned long)amt_read);
                  }
                  return (-1);
            }
            /*
             * We can only keep up to buflen bytes.  Since caplen > buflen
             * is exactly how we got here, we know we can only keep the
             * first buflen bytes and must drop the remainder.  Adjust
             * caplen accordingly, so we don't get confused later as
             * to how many bytes we have to play with.
             */
            hdr->caplen = buflen;
            memcpy((char *)buf, (char *)tp, buflen);

      } else {
            /* read the packet itself */
            amt_read = fread((char *)buf, 1, hdr->caplen, fp);
            if (amt_read != hdr->caplen) {
                  if (ferror(fp)) {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "error reading dump file: %s",
                            pcap_strerror(errno));
                  } else {
                        snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                            "truncated dump file; tried to read %u captured bytes, only got %lu",
                            hdr->caplen, (unsigned long)amt_read);
                  }
                  return (-1);
            }
      }
      return (0);
}

/*
 * Print out packets stored in the file initialized by sf_read_init().
 * If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
 */
int
pcap_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
      struct bpf_insn *fcode = p->fcode.bf_insns;
      int status = 0;
      int n = 0;

      while (status == 0) {
            struct pcap_pkthdr h;

            /*
             * Has "pcap_breakloop()" been called?
             * If so, return immediately - if we haven't read any
             * packets, clear the flag and return -2 to indicate
             * that we were told to break out of the loop, otherwise
             * leave the flag set, so that the *next* call will break
             * out of the loop without having read any packets, and
             * return the number of packets we've processed so far.
             */
            if (p->break_loop) {
                  if (n == 0) {
                        p->break_loop = 0;
                        return (-2);
                  } else
                        return (n);
            }

            status = sf_next_packet(p, &h, p->buffer, p->bufsize);
            if (status) {
                  if (status == 1)
                        return (0);
                  return (status);
            }

            if (fcode == NULL ||
                bpf_filter(fcode, p->buffer, h.len, h.caplen)) {
                  (*callback)(user, &h, p->buffer);
                  if (++n >= cnt && cnt > 0)
                        break;
            }
      }
      /*XXX this breaks semantics tcpslice expects */
      return (n);
}

/*
 * Output a packet to the initialized dump file.
 */
void
pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
      register FILE *f;
      struct pcap_sf_pkthdr sf_hdr;

      f = (FILE *)user;
      sf_hdr.ts.tv_sec  = h->ts.tv_sec;
      sf_hdr.ts.tv_usec = h->ts.tv_usec;
      sf_hdr.caplen     = h->caplen;
      sf_hdr.len        = h->len;
      /* XXX we should check the return status */
      (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
      (void)fwrite((char *)sp, h->caplen, 1, f);
}

/*
 * Initialize so that sf_write() will output to the file named 'fname'.
 */
pcap_dumper_t *
pcap_dump_open(pcap_t *p, const char *fname)
{
      FILE *f;
      int linktype;

      linktype = dlt_to_linktype(p->linktype);
      if (linktype == -1) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
                "%s: link-layer type %d isn't supported in savefiles",
                fname, linktype);
            return (NULL);
      }

      if (fname[0] == '-' && fname[1] == '\0') {
            f = stdout;
#ifdef WIN32
            _setmode(_fileno(f), _O_BINARY);
#endif
      } else {
#ifndef WIN32
            f = fopen(fname, "w");
#else
            f = fopen(fname, "wb");
            setbuf(f, NULL);  /* XXX - why? */
#endif
            if (f == NULL) {
                  snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
                      fname, pcap_strerror(errno));
                  return (NULL);
            }
      }
      (void)sf_write_header(f, linktype, p->tzoff, p->snapshot);
      return ((pcap_dumper_t *)f);
}

FILE *
pcap_dump_file(pcap_dumper_t *p)
{
      return ((FILE *)p);
}

int
pcap_dump_flush(pcap_dumper_t *p)
{

      if (fflush((FILE *)p) == EOF)
            return (-1);
      else
            return (0);
}

void
pcap_dump_close(pcap_dumper_t *p)
{

#ifdef notyet
      if (ferror((FILE *)p))
            return-an-error;
      /* XXX should check return from fclose() too */
#endif
      (void)fclose((FILE *)p);
}

Generated by  Doxygen 1.6.0   Back to index