wiretap/csids.c

   1 /* csids.c
   2  *
   3  * Copyright (c) 2000 by Mike Hall <mlh@io.com>
   4  * Copyright (c) 2000 by Cisco Systems
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-or-later
   7  */
   8
   9 #include "config.h"
  10 #include "csids.h"
  11 #include "wtap-int.h"
  12 #include "file_wrappers.h"
  13
  14 #include <stdlib.h>
  15 #include <string.h>
  16
  17 /*
  18  * This module reads the output from the Cisco Secure Intrusion Detection
  19  * System iplogging facility. The term iplogging is misleading since this
  20  * logger will only output TCP. There is no link layer information.
  21  * Packet format is 4 byte timestamp (seconds since epoch), and a 4 byte size
  22  * of data following for that packet.
  23  *
  24  * For a time there was an error in iplogging and the ip length, flags, and id
  25  * were byteswapped. We will check for this and handle it before handing to
  26  * wireshark.
  27  */
  28
  29 typedef struct {
  30   bool byteswapped;
  31 } csids_t;
  32
  33 static bool csids_read(wtap *wth, wtap_rec *rec, Buffer *buf,
  34         int *err, char **err_info, int64_t *data_offset);
  35 static bool csids_seek_read(wtap *wth, int64_t seek_off,
  36         wtap_rec *rec, Buffer *buf, int *err, char **err_info);
  37 static bool csids_read_packet(FILE_T fh, csids_t *csids,
  38         wtap_rec *rec, Buffer *buf, int *err, char **err_info);
  39
  40 struct csids_header {
  41   uint32_t seconds; /* seconds since epoch */
  42   uint16_t zeropad; /* 2 byte zero'ed pads */
  43   uint16_t caplen;  /* the capture length  */
  44 };
  45
  46 static int csids_file_type_subtype = -1;
  47
  48 void register_csids(void);
  49
  50 wtap_open_return_val csids_open(wtap *wth, int *err, char **err_info)
  51 {
  52   /* There is no file header. There is only a header for each packet
  53    * so we read a packet header and compare the caplen with iplen. They
  54    * should always be equal except with the weird byteswap version.
  55    *
  56    * THIS IS BROKEN-- anytime the caplen is 0x0101 or 0x0202 up to 0x0505
  57    * this will byteswap it. I need to fix this. XXX --mlh
  58    */
  59
  60   int tmp,iplen;
  61
  62   bool byteswap = false;
  63   struct csids_header hdr;
  64   csids_t *csids;
  65
  66   /* check the file to make sure it is a csids file. */
  67   if( !wtap_read_bytes( wth->fh, &hdr, sizeof( struct csids_header), err, err_info ) ) {
  68     if( *err != WTAP_ERR_SHORT_READ ) {
  69       return WTAP_OPEN_ERROR;
  70     }
  71     return WTAP_OPEN_NOT_MINE;
  72   }
  73   if( hdr.zeropad != 0 || hdr.caplen == 0 ) {
  74     return WTAP_OPEN_NOT_MINE;
  75   }
  76   hdr.seconds = pntoh32( &hdr.seconds );
  77   hdr.caplen = pntoh16( &hdr.caplen );
  78   if( !wtap_read_bytes( wth->fh, &tmp, 2, err, err_info ) ) {
  79     if( *err != WTAP_ERR_SHORT_READ ) {
  80       return WTAP_OPEN_ERROR;
  81     }
  82     return WTAP_OPEN_NOT_MINE;
  83   }
  84   if( !wtap_read_bytes(wth->fh, &iplen, 2, err, err_info ) ) {
  85     if( *err != WTAP_ERR_SHORT_READ ) {
  86       return WTAP_OPEN_ERROR;
  87     }
  88     return WTAP_OPEN_NOT_MINE;
  89   }
  90   iplen = pntoh16(&iplen);
  91
  92   if ( iplen == 0 )
  93     return WTAP_OPEN_NOT_MINE;
  94
  95   /* if iplen and hdr.caplen are equal, default to no byteswap. */
  96   if( iplen > hdr.caplen ) {
  97     /* maybe this is just a byteswapped version. the iplen ipflags */
  98     /* and ipid are swapped. We cannot use the normal swaps because */
  99     /* we don't know the host */
 100     iplen = GUINT16_SWAP_LE_BE(iplen);
 101     if( iplen <= hdr.caplen ) {
 102       /* we know this format */
 103       byteswap = true;
 104     } else {
 105       /* don't know this one */
 106       return WTAP_OPEN_NOT_MINE;
 107     }
 108   } else {
 109     byteswap = false;
 110   }
 111
 112   /* no file header. So reset the fh to 0 so we can read the first packet */
 113   if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 114     return WTAP_OPEN_ERROR;
 115
 116   csids = g_new(csids_t, 1);
 117   wth->priv = (void *)csids;
 118   csids->byteswapped = byteswap;
 119   wth->file_encap = WTAP_ENCAP_RAW_IP;
 120   wth->file_type_subtype = csids_file_type_subtype;
 121   wth->snapshot_length = 0; /* not known */
 122   wth->subtype_read = csids_read;
 123   wth->subtype_seek_read = csids_seek_read;
 124   wth->file_tsprec = WTAP_TSPREC_SEC;
 125
 126   /*
 127    * Add an IDB; we don't know how many interfaces were
 128    * involved, so we just say one interface, about which
 129    * we only know the link-layer type, snapshot length,
 130    * and time stamp resolution.
 131    */
 132   wtap_add_generated_idb(wth);
 133
 134   return WTAP_OPEN_MINE;
 135 }
 136
 137 /* Find the next packet and parse it; called from wtap_read(). */
 138 static bool csids_read(wtap *wth, wtap_rec *rec, Buffer *buf,
 139     int *err, char **err_info, int64_t *data_offset)
 140 {
 141   csids_t *csids = (csids_t *)wth->priv;
 142
 143   *data_offset = file_tell(wth->fh);
 144
 145   return csids_read_packet( wth->fh, csids, rec, buf, err, err_info );
 146 }
 147
 148 /* Used to read packets in random-access fashion */
 149 static bool
 150 csids_seek_read(wtap *wth,
 151                 int64_t seek_off,
 152                 wtap_rec *rec,
 153                 Buffer *buf,
 154                 int *err,
 155                 char **err_info)
 156 {
 157   csids_t *csids = (csids_t *)wth->priv;
 158
 159   if( file_seek( wth->random_fh, seek_off, SEEK_SET, err ) == -1 )
 160     return false;
 161
 162   if( !csids_read_packet( wth->random_fh, csids, rec, buf, err, err_info ) ) {
 163     if( *err == 0 )
 164       *err = WTAP_ERR_SHORT_READ;
 165     return false;
 166   }
 167   return true;
 168 }
 169
 170 static bool
 171 csids_read_packet(FILE_T fh, csids_t *csids, wtap_rec *rec,
 172                   Buffer *buf, int *err, char **err_info)
 173 {
 174   struct csids_header hdr;
 175   uint8_t *pd;
 176
 177   if( !wtap_read_bytes_or_eof( fh, &hdr, sizeof( struct csids_header), err, err_info ) )
 178     return false;
 179   hdr.seconds = pntoh32(&hdr.seconds);
 180   hdr.caplen = pntoh16(&hdr.caplen);
 181   /*
 182    * The maximum value of hdr.caplen is 65535, which is less than
 183    * WTAP_MAX_PACKET_SIZE_STANDARD will ever be, so we don't need to check
 184    * it.
 185    */
 186
 187   rec->rec_type = REC_TYPE_PACKET;
 188   rec->block = wtap_block_create(WTAP_BLOCK_PACKET);
 189   rec->presence_flags = WTAP_HAS_TS;
 190   rec->rec_header.packet_header.len = hdr.caplen;
 191   rec->rec_header.packet_header.caplen = hdr.caplen;
 192   rec->ts.secs = hdr.seconds;
 193   rec->ts.nsecs = 0;
 194
 195   if( !wtap_read_packet_bytes( fh, buf, rec->rec_header.packet_header.caplen, err, err_info ) )
 196     return false;
 197
 198   pd = ws_buffer_start_ptr( buf );
 199   if( csids->byteswapped ) {
 200     if( rec->rec_header.packet_header.caplen >= 2 ) {
 201       PBSWAP16(pd);   /* the ip len */
 202       if( rec->rec_header.packet_header.caplen >= 4 ) {
 203         PBSWAP16(pd+2); /* ip id */
 204         if( rec->rec_header.packet_header.caplen >= 6 )
 205           PBSWAP16(pd+4); /* ip flags and fragoff */
 206       }
 207     }
 208   }
 209
 210   return true;
 211 }
 212
 213 static const struct supported_block_type csids_blocks_supported[] = {
 214   /*
 215    * We support packet blocks, with no comments or other options.
 216    */
 217   { WTAP_BLOCK_PACKET, MULTIPLE_BLOCKS_SUPPORTED, NO_OPTIONS_SUPPORTED }
 218 };
 219
 220 static const struct file_type_subtype_info csids_info = {
 221   "CSIDS IPLog", "csids", NULL, NULL,
 222   false, BLOCKS_SUPPORTED(csids_blocks_supported),
 223   NULL, NULL, NULL
 224 };
 225
 226 void register_csids(void)
 227 {
 228   csids_file_type_subtype = wtap_register_file_type_subtype(&csids_info);
 229
 230   /*
 231    * Register name for backwards compatibility with the
 232    * wtap_filetypes table in Lua.
 233    */
 234   wtap_register_backwards_compatibility_lua_name("CSIDS",
 235                                                  csids_file_type_subtype);
 236 }
 237
 238 /*
 239  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 240  *
 241  * Local Variables:
 242  * c-basic-offset: 2
 243  * tab-width: 8
 244  * indent-tabs-mode: nil
 245  * End:
 246  *
 247  * vi: set shiftwidth=2 tabstop=8 expandtab:
 248  * :indentSize=2:tabSize=8:noTabs=true:
 249  */