wiretap/csids.c

   1 /* csids.c
   2  *
   3  * $Id$
   4  *
   5  * Copyright (c) 2000 by Mike Hall <mlh@io.com>
   6  * Copyright (c) 2000 by Cisco Systems
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 #include "config.h"
  24 #include "wtap-int.h"
  25 #include "buffer.h"
  26 #include "csids.h"
  27 #include "file_wrappers.h"
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 /*
  34  * This module reads the output from the Cisco Secure Intrusion Detection
  35  * System iplogging facility. The term iplogging is misleading since this
  36  * logger will only output TCP. There is no link layer information.
  37  * Packet format is 4 byte timestamp (seconds since epoch), and a 4 byte size
  38  * of data following for that packet.
  39  *
  40  * For a time there was an error in iplogging and the ip length, flags, and id
  41  * were byteswapped. We will check for this and handle it before handing to
  42  * wireshark.
  43  */
  44
  45 typedef struct {
  46         gboolean byteswapped;
  47 } csids_t;
  48
  49 static gboolean csids_read(wtap *wth, int *err, gchar **err_info,
  50         gint64 *data_offset);
  51 static gboolean csids_seek_read(wtap *wth, gint64 seek_off,
  52         struct wtap_pkthdr *phdr, Buffer *buf, int len,
  53         int *err, gchar **err_info);
  54 static gboolean csids_read_packet(FILE_T fh, csids_t *csids,
  55         struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info);
  56
  57 struct csids_header {
  58   guint32 seconds; /* seconds since epoch */
  59   guint16 zeropad; /* 2 byte zero'ed pads */
  60   guint16 caplen;  /* the capture length  */
  61 };
  62
  63 /* XXX - return -1 on I/O error and actually do something with 'err'. */
  64 int csids_open(wtap *wth, int *err, gchar **err_info)
  65 {
  66   /* There is no file header. There is only a header for each packet
  67    * so we read a packet header and compare the caplen with iplen. They
  68    * should always be equal except with the weird byteswap version.
  69    *
  70    * THIS IS BROKEN-- anytime the caplen is 0x0101 or 0x0202 up to 0x0505
  71    * this will byteswap it. I need to fix this. XXX --mlh
  72    */
  73
  74   int tmp,iplen,bytesRead;
  75
  76   gboolean byteswap = FALSE;
  77   struct csids_header hdr;
  78   csids_t *csids;
  79
  80   /* check the file to make sure it is a csids file. */
  81   bytesRead = file_read( &hdr, sizeof( struct csids_header), wth->fh );
  82   if( bytesRead != sizeof( struct csids_header) ) {
  83     *err = file_error( wth->fh, err_info );
  84     if( *err != 0 && *err != WTAP_ERR_SHORT_READ ) {
  85       return -1;
  86     }
  87     return 0;
  88   }
  89   if( hdr.zeropad != 0 || hdr.caplen == 0 ) {
  90         return 0;
  91   }
  92   hdr.seconds = pntohl( &hdr.seconds );
  93   hdr.caplen = pntohs( &hdr.caplen );
  94   bytesRead = file_read( &tmp, 2, wth->fh );
  95   if( bytesRead != 2 ) {
  96     *err = file_error( wth->fh, err_info );
  97     if( *err != 0 && *err != WTAP_ERR_SHORT_READ ) {
  98       return -1;
  99     }
 100     return 0;
 101   }
 102   bytesRead = file_read( &iplen, 2, wth->fh );
 103   if( bytesRead != 2 ) {
 104     *err = file_error( wth->fh, err_info );
 105     if( *err != 0 && *err != WTAP_ERR_SHORT_READ ) {
 106       return -1;
 107     }
 108     return 0;
 109   }
 110   iplen = pntohs(&iplen);
 111
 112   if ( iplen == 0 )
 113     return 0;
 114
 115   /* if iplen and hdr.caplen are equal, default to no byteswap. */
 116   if( iplen > hdr.caplen ) {
 117     /* maybe this is just a byteswapped version. the iplen ipflags */
 118     /* and ipid are swapped. We cannot use the normal swaps because */
 119     /* we don't know the host */
 120     iplen = BSWAP16(iplen);
 121     if( iplen <= hdr.caplen ) {
 122       /* we know this format */
 123       byteswap = TRUE;
 124     } else {
 125       /* don't know this one */
 126       return 0;
 127     }
 128   } else {
 129     byteswap = FALSE;
 130   }
 131
 132   /* no file header. So reset the fh to 0 so we can read the first packet */
 133   if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 134     return -1;
 135
 136   csids = (csids_t *)g_malloc(sizeof(csids_t));
 137   wth->priv = (void *)csids;
 138   csids->byteswapped = byteswap;
 139   wth->file_encap = WTAP_ENCAP_RAW_IP;
 140   wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_CSIDS;
 141   wth->snapshot_length = 0; /* not known */
 142   wth->subtype_read = csids_read;
 143   wth->subtype_seek_read = csids_seek_read;
 144   wth->tsprecision = WTAP_FILE_TSPREC_SEC;
 145
 146   return 1;
 147 }
 148
 149 /* Find the next packet and parse it; called from wtap_read(). */
 150 static gboolean csids_read(wtap *wth, int *err, gchar **err_info,
 151     gint64 *data_offset)
 152 {
 153   csids_t *csids = (csids_t *)wth->priv;
 154
 155   *data_offset = file_tell(wth->fh);
 156
 157   return csids_read_packet( wth->fh, csids, &wth->phdr, wth->frame_buffer,
 158                             err, err_info );
 159 }
 160
 161 /* Used to read packets in random-access fashion */
 162 static gboolean
 163 csids_seek_read(wtap *wth,
 164                  gint64 seek_off,
 165                  struct wtap_pkthdr *phdr,
 166                  Buffer *buf,
 167                  int len _U_,
 168                  int *err,
 169                  gchar **err_info)
 170 {
 171   csids_t *csids = (csids_t *)wth->priv;
 172
 173   if( file_seek( wth->random_fh, seek_off, SEEK_SET, err ) == -1 )
 174     return FALSE;
 175
 176   if( !csids_read_packet( wth->random_fh, csids, phdr, buf, err, err_info ) ) {
 177     if( *err == 0 )
 178       *err = WTAP_ERR_SHORT_READ;
 179     return FALSE;
 180   }
 181   return TRUE;
 182 }
 183
 184 static gboolean
 185 csids_read_packet(FILE_T fh, csids_t *csids, struct wtap_pkthdr *phdr,
 186                   Buffer *buf, int *err, gchar **err_info)
 187 {
 188   struct csids_header hdr;
 189   int bytesRead = 0;
 190   guint8 *pd;
 191
 192   bytesRead = file_read( &hdr, sizeof( struct csids_header), fh );
 193   if( bytesRead != sizeof( struct csids_header) ) {
 194     *err = file_error( fh, err_info );
 195     if (*err == 0 && bytesRead != 0)
 196       *err = WTAP_ERR_SHORT_READ;
 197     return FALSE;
 198   }
 199   hdr.seconds = pntohl(&hdr.seconds);
 200   hdr.caplen = pntohs(&hdr.caplen);
 201
 202   phdr->presence_flags = WTAP_HAS_TS;
 203   phdr->len = hdr.caplen;
 204   phdr->caplen = hdr.caplen;
 205   phdr->ts.secs = hdr.seconds;
 206   phdr->ts.nsecs = 0;
 207
 208   if( !wtap_read_packet_bytes( fh, buf, phdr->caplen, err, err_info ) )
 209     return FALSE;
 210
 211   pd = buffer_start_ptr( buf );
 212   if( csids->byteswapped ) {
 213     if( phdr->caplen >= 2 ) {
 214       PBSWAP16(pd);   /* the ip len */
 215       if( phdr->caplen >= 4 ) {
 216         PBSWAP16(pd+2); /* ip id */
 217         if( phdr->caplen >= 6 )
 218           PBSWAP16(pd+4); /* ip flags and fragoff */
 219       }
 220     }
 221   }
 222
 223   return TRUE;
 224 }