wiretap/i4btrace.c

   1 /* i4btrace.c
   2  *
   3  * $Id$
   4  *
   5  * Wiretap Library
   6  * Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
   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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include <stdlib.h>
  28 #include <errno.h>
  29 #include <string.h>
  30 #include "wtap-int.h"
  31 #include "file_wrappers.h"
  32 #include "buffer.h"
  33 #include "i4b_trace.h"
  34 #include "i4btrace.h"
  35
  36 typedef struct {
  37         gboolean byte_swapped;
  38 } i4btrace_t;
  39
  40 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
  41     gint64 *data_offset);
  42 static gboolean i4btrace_seek_read(wtap *wth, gint64 seek_off,
  43     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
  44     int *err, gchar **err_info);
  45 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err,
  46     gchar **err_info);
  47 static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
  48 static gboolean i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err,
  49     gchar **err_info);
  50 static void i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
  51     union wtap_pseudo_header *pseudo_header);
  52
  53 /*
  54  * Test some fields in the header to see if they make sense.
  55  */
  56 #define I4B_HDR_IS_OK(hdr) \
  57         (!((unsigned)hdr.length < 3 || (unsigned)hdr.length > 16384 || \
  58             (unsigned)hdr.unit > 4 || (unsigned)hdr.type > 4 || \
  59             (unsigned)hdr.dir > 2 || (unsigned)hdr.trunc > 2048))
  60
  61 int i4btrace_open(wtap *wth, int *err, gchar **err_info)
  62 {
  63         int bytes_read;
  64         i4b_trace_hdr_t hdr;
  65         gboolean byte_swapped = FALSE;
  66         i4btrace_t *i4btrace;
  67
  68         /* I4B trace files have no magic in the header... Sigh */
  69         errno = WTAP_ERR_CANT_READ;
  70         bytes_read = file_read(&hdr, sizeof(hdr), wth->fh);
  71         if (bytes_read != sizeof(hdr)) {
  72                 *err = file_error(wth->fh, err_info);
  73                 if (*err != 0)
  74                         return -1;
  75                 return 0;
  76         }
  77
  78         /* Silly heuristic... */
  79         if (!I4B_HDR_IS_OK(hdr)) {
  80                 /*
  81                  * OK, try byte-swapping the header fields.
  82                  */
  83                 hdr.length = BSWAP32(hdr.length);
  84                 hdr.unit = BSWAP32(hdr.unit);
  85                 hdr.type = BSWAP32(hdr.type);
  86                 hdr.dir = BSWAP32(hdr.dir);
  87                 hdr.trunc = BSWAP32(hdr.trunc);
  88                 if (!I4B_HDR_IS_OK(hdr)) {
  89                         /*
  90                          * It doesn't look valid in either byte order.
  91                          */
  92                         return 0;
  93                 }
  94
  95                 /*
  96                  * It looks valid byte-swapped, so assume it's a
  97                  * trace written in the opposite byte order.
  98                  */
  99                 byte_swapped = TRUE;
 100         }
 101
 102         if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 103                 return -1;
 104         wth->data_offset = 0;
 105
 106         /* Get capture start time */
 107
 108         wth->file_type = WTAP_FILE_I4BTRACE;
 109         i4btrace = (i4btrace_t *)g_malloc(sizeof(i4btrace_t));
 110         wth->priv = (void *)i4btrace;
 111         wth->subtype_read = i4btrace_read;
 112         wth->subtype_seek_read = i4btrace_seek_read;
 113         wth->snapshot_length = 0;       /* not known */
 114
 115         i4btrace->byte_swapped = byte_swapped;
 116
 117         wth->file_encap = WTAP_ENCAP_ISDN;
 118         wth->tsprecision = WTAP_FILE_TSPREC_USEC;
 119
 120         return 1;
 121 }
 122
 123 /* Read the next packet */
 124 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 125     gint64 *data_offset)
 126 {
 127         int     ret;
 128         i4b_trace_hdr_t hdr;
 129         guint32 length;
 130         void *bufp;
 131
 132         /* Read record header. */
 133         *data_offset = wth->data_offset;
 134         ret = i4b_read_rec_header(wth->fh, &hdr, err, err_info);
 135         if (ret <= 0) {
 136                 /* Read error or EOF */
 137                 return FALSE;
 138         }
 139         wth->data_offset += sizeof hdr;
 140         i4b_byte_swap_header(wth, &hdr);
 141         if (hdr.length < sizeof(hdr)) {
 142                 *err = WTAP_ERR_BAD_RECORD;     /* record length < header! */
 143                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %lu",
 144                     hdr.length, (unsigned long)sizeof(hdr));
 145                 return FALSE;
 146         }
 147         length = hdr.length - (guint32)sizeof(hdr);
 148
 149         wth->phdr.len = length;
 150         wth->phdr.caplen = length;
 151
 152         wth->phdr.ts.secs = hdr.ts_sec;
 153         wth->phdr.ts.nsecs = hdr.ts_usec * 1000;
 154
 155         /*
 156          * Read the packet data.
 157          */
 158         buffer_assure_space(wth->frame_buffer, length);
 159         bufp = buffer_start_ptr(wth->frame_buffer);
 160         if (!i4b_read_rec_data(wth->fh, bufp, length, err, err_info))
 161                 return FALSE;   /* Read error */
 162         wth->data_offset += length;
 163
 164         switch (hdr.type) {
 165
 166         case TRC_CH_I:
 167                 /*
 168                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 169                  * as that means it has a 4-byte AF_ type as the
 170                  * encapsulation header.
 171                  */
 172                 wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 173                 break;
 174
 175         case TRC_CH_D:
 176         case TRC_CH_B1:
 177         case TRC_CH_B2:
 178                 /*
 179                  * D or B channel.
 180                  */
 181                 wth->phdr.pkt_encap = WTAP_ENCAP_ISDN;
 182                 break;
 183         }
 184
 185         i4b_set_pseudo_header(&hdr, &wth->pseudo_header);
 186
 187         return TRUE;
 188 }
 189
 190 static gboolean
 191 i4btrace_seek_read(wtap *wth, gint64 seek_off,
 192     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
 193     int *err, gchar **err_info)
 194 {
 195         int     ret;
 196         i4b_trace_hdr_t hdr;
 197
 198         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 199                 return FALSE;
 200
 201         /* Read record header. */
 202         ret = i4b_read_rec_header(wth->random_fh, &hdr, err, err_info);
 203         if (ret <= 0) {
 204                 /* Read error or EOF */
 205                 if (ret == 0) {
 206                         /* EOF means "short read" in random-access mode */
 207                         *err = WTAP_ERR_SHORT_READ;
 208                 }
 209                 return FALSE;
 210         }
 211         i4b_byte_swap_header(wth, &hdr);
 212
 213         i4b_set_pseudo_header(&hdr, pseudo_header);
 214
 215         /*
 216          * Read the packet data.
 217          */
 218         return i4b_read_rec_data(wth->random_fh, pd, length, err, err_info);
 219 }
 220
 221 static int
 222 i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err, gchar **err_info)
 223 {
 224         int     bytes_read;
 225
 226         errno = WTAP_ERR_CANT_READ;
 227         bytes_read = file_read(hdr, sizeof *hdr, fh);
 228         if (bytes_read != sizeof *hdr) {
 229                 *err = file_error(fh, err_info);
 230                 if (*err != 0)
 231                         return -1;
 232                 if (bytes_read != 0) {
 233                         *err = WTAP_ERR_SHORT_READ;
 234                         return -1;
 235                 }
 236                 return 0;
 237         }
 238         return 1;
 239 }
 240
 241 static void
 242 i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
 243 {
 244         i4btrace_t *i4btrace = (i4btrace_t *)wth->priv;
 245
 246         if (i4btrace->byte_swapped) {
 247                 /*
 248                  * Byte-swap the header.
 249                  */
 250                 hdr->length = BSWAP32(hdr->length);
 251                 hdr->unit = BSWAP32(hdr->unit);
 252                 hdr->type = BSWAP32(hdr->type);
 253                 hdr->dir = BSWAP32(hdr->dir);
 254                 hdr->trunc = BSWAP32(hdr->trunc);
 255                 hdr->count = BSWAP32(hdr->count);
 256                 hdr->ts_sec = BSWAP32(hdr->ts_sec);
 257                 hdr->ts_usec = BSWAP32(hdr->ts_usec);
 258         }
 259 }
 260
 261 static gboolean
 262 i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err, gchar **err_info)
 263 {
 264         int     bytes_read;
 265
 266         errno = WTAP_ERR_CANT_READ;
 267         bytes_read = file_read(pd, length, fh);
 268
 269         if (bytes_read != length) {
 270                 *err = file_error(fh, err_info);
 271                 if (*err == 0)
 272                         *err = WTAP_ERR_SHORT_READ;
 273                 return FALSE;
 274         }
 275         return TRUE;
 276 }
 277
 278 static void
 279 i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
 280     union wtap_pseudo_header *pseudo_header)
 281 {
 282         pseudo_header->isdn.uton = (hdr->dir == FROM_TE);
 283         switch (hdr->type) {
 284
 285         case TRC_CH_D:
 286                 /*
 287                  * D channel, so it's LAPD; set "p2p.sent".
 288                  */
 289                 pseudo_header->isdn.channel = 0;
 290                 break;
 291
 292         case TRC_CH_B1:
 293                 /*
 294                  * B channel 1.
 295                  */
 296                 pseudo_header->isdn.channel = 1;
 297                 break;
 298
 299         case TRC_CH_B2:
 300                 /*
 301                  * B channel 2.
 302                  */
 303                 pseudo_header->isdn.channel = 2;
 304                 break;
 305         }
 306 }