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 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
  37     long *data_offset);
  38 static gboolean i4btrace_seek_read(wtap *wth, long seek_off,
  39     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
  40     int *err, gchar **err_info);
  41 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err);
  42 static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
  43 static gboolean i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err);
  44 static void i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
  45     union wtap_pseudo_header *pseudo_header);
  46 static void i4btrace_close(wtap *wth);
  47
  48 /*
  49  * Test some fields in the header to see if they make sense.
  50  */
  51 #define I4B_HDR_IS_OK(hdr) \
  52         (!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
  53             (unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
  54             (unsigned)hdr.trunc > 2048))
  55
  56 int i4btrace_open(wtap *wth, int *err, gchar **err_info _U_)
  57 {
  58         int bytes_read;
  59         i4b_trace_hdr_t hdr;
  60         gboolean byte_swapped = FALSE;
  61
  62         /* I4B trace files have no magic in the header... Sigh */
  63         errno = WTAP_ERR_CANT_READ;
  64         bytes_read = file_read(&hdr, 1, sizeof(hdr), wth->fh);
  65         if (bytes_read != sizeof(hdr)) {
  66                 *err = file_error(wth->fh);
  67                 if (*err != 0)
  68                         return -1;
  69                 return 0;
  70         }
  71
  72         /* Silly heuristic... */
  73         if (!I4B_HDR_IS_OK(hdr)) {
  74                 /*
  75                  * OK, try byte-swapping the header fields.
  76                  */
  77                 hdr.length = BSWAP32(hdr.length);
  78                 hdr.unit = BSWAP32(hdr.unit);
  79                 hdr.type = BSWAP32(hdr.type);
  80                 hdr.dir = BSWAP32(hdr.dir);
  81                 hdr.trunc = BSWAP32(hdr.trunc);
  82                 if (!I4B_HDR_IS_OK(hdr)) {
  83                         /*
  84                          * It doesn't look valid in either byte order.
  85                          */
  86                         return 0;
  87                 }
  88
  89                 /*
  90                  * It looks valid byte-swapped, so assume it's a
  91                  * trace written in the opposite byte order.
  92                  */
  93                 byte_swapped = TRUE;
  94         }
  95
  96         if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
  97                 return -1;
  98         wth->data_offset = 0;
  99
 100         /* Get capture start time */
 101
 102         wth->file_type = WTAP_FILE_I4BTRACE;
 103         wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
 104         wth->subtype_read = i4btrace_read;
 105         wth->subtype_seek_read = i4btrace_seek_read;
 106         wth->subtype_close = i4btrace_close;
 107         wth->snapshot_length = 0;       /* not known */
 108
 109         wth->capture.i4btrace->byte_swapped = byte_swapped;
 110
 111         wth->file_encap = WTAP_ENCAP_ISDN;
 112         wth->tsprecision = WTAP_FILE_TSPREC_USEC;
 113
 114         return 1;
 115 }
 116
 117 /* Read the next packet */
 118 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 119     long *data_offset)
 120 {
 121         int     ret;
 122         i4b_trace_hdr_t hdr;
 123         guint16 length;
 124         void *bufp;
 125
 126         /* Read record header. */
 127         *data_offset = wth->data_offset;
 128         ret = i4b_read_rec_header(wth->fh, &hdr, err);
 129         if (ret <= 0) {
 130                 /* Read error or EOF */
 131                 return FALSE;
 132         }
 133         wth->data_offset += sizeof hdr;
 134         i4b_byte_swap_header(wth, &hdr);
 135         if (hdr.length < sizeof(hdr)) {
 136                 *err = WTAP_ERR_BAD_RECORD;     /* record length < header! */
 137                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %lu",
 138                     hdr.length, (unsigned long)sizeof(hdr));
 139                 return FALSE;
 140         }
 141         length = hdr.length - sizeof(hdr);
 142
 143         wth->phdr.len = length;
 144         wth->phdr.caplen = length;
 145
 146         wth->phdr.ts.secs = hdr.ts_sec;
 147         wth->phdr.ts.nsecs = hdr.ts_usec * 1000;
 148
 149         /*
 150          * Read the packet data.
 151          */
 152         buffer_assure_space(wth->frame_buffer, length);
 153         bufp = buffer_start_ptr(wth->frame_buffer);
 154         if (!i4b_read_rec_data(wth->fh, bufp, length, err))
 155                 return FALSE;   /* Read error */
 156         wth->data_offset += length;
 157
 158         switch (hdr.type) {
 159
 160         case TRC_CH_I:
 161                 /*
 162                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 163                  * as that means it has a 4-byte AF_ type as the
 164                  * encapsulation header.
 165                  */
 166                 wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 167                 break;
 168
 169         case TRC_CH_D:
 170         case TRC_CH_B1:
 171         case TRC_CH_B2:
 172                 /*
 173                  * D or B channel.
 174                  */
 175                 wth->phdr.pkt_encap = WTAP_ENCAP_ISDN;
 176                 break;
 177         }
 178
 179         i4b_set_pseudo_header(&hdr, &wth->pseudo_header);
 180
 181         return TRUE;
 182 }
 183
 184 static gboolean
 185 i4btrace_seek_read(wtap *wth, long seek_off,
 186     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
 187     int *err, gchar **err_info _U_)
 188 {
 189         int     ret;
 190         i4b_trace_hdr_t hdr;
 191
 192         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 193                 return FALSE;
 194
 195         /* Read record header. */
 196         ret = i4b_read_rec_header(wth->random_fh, &hdr, err);
 197         if (ret <= 0) {
 198                 /* Read error or EOF */
 199                 if (ret == 0) {
 200                         /* EOF means "short read" in random-access mode */
 201                         *err = WTAP_ERR_SHORT_READ;
 202                 }
 203                 return FALSE;
 204         }
 205         i4b_byte_swap_header(wth, &hdr);
 206
 207         i4b_set_pseudo_header(&hdr, pseudo_header);
 208
 209         /*
 210          * Read the packet data.
 211          */
 212         return i4b_read_rec_data(wth->random_fh, pd, length, err);
 213 }
 214
 215 static int
 216 i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err)
 217 {
 218         int     bytes_read;
 219
 220         errno = WTAP_ERR_CANT_READ;
 221         bytes_read = file_read(hdr, 1, sizeof *hdr, fh);
 222         if (bytes_read != sizeof *hdr) {
 223                 *err = file_error(fh);
 224                 if (*err != 0)
 225                         return -1;
 226                 if (bytes_read != 0) {
 227                         *err = WTAP_ERR_SHORT_READ;
 228                         return -1;
 229                 }
 230                 return 0;
 231         }
 232         return 1;
 233 }
 234
 235 static void
 236 i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
 237 {
 238         if (wth->capture.i4btrace->byte_swapped) {
 239                 /*
 240                  * Byte-swap the header.
 241                  */
 242                 hdr->length = BSWAP32(hdr->length);
 243                 hdr->unit = BSWAP32(hdr->unit);
 244                 hdr->type = BSWAP32(hdr->type);
 245                 hdr->dir = BSWAP32(hdr->dir);
 246                 hdr->trunc = BSWAP32(hdr->trunc);
 247                 hdr->count = BSWAP32(hdr->count);
 248                 hdr->ts_sec = BSWAP32(hdr->ts_sec);
 249                 hdr->ts_usec = BSWAP32(hdr->ts_usec);
 250         }
 251 }
 252
 253 static gboolean
 254 i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err)
 255 {
 256         int     bytes_read;
 257
 258         errno = WTAP_ERR_CANT_READ;
 259         bytes_read = file_read(pd, 1, length, fh);
 260
 261         if (bytes_read != length) {
 262                 *err = file_error(fh);
 263                 if (*err == 0)
 264                         *err = WTAP_ERR_SHORT_READ;
 265                 return FALSE;
 266         }
 267         return TRUE;
 268 }
 269
 270 static void
 271 i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
 272     union wtap_pseudo_header *pseudo_header)
 273 {
 274         pseudo_header->isdn.uton = (hdr->dir == FROM_TE);
 275         switch (hdr->type) {
 276
 277         case TRC_CH_D:
 278                 /*
 279                  * D channel, so it's LAPD; set "p2p.sent".
 280                  */
 281                 pseudo_header->isdn.channel = 0;
 282                 break;
 283
 284         case TRC_CH_B1:
 285                 /*
 286                  * B channel 1.
 287                  */
 288                 pseudo_header->isdn.channel = 1;
 289                 break;
 290
 291         case TRC_CH_B2:
 292                 /*
 293                  * B channel 2.
 294                  */
 295                 pseudo_header->isdn.channel = 2;
 296                 break;
 297         }
 298 }
 299
 300 static void
 301 i4btrace_close(wtap *wth)
 302 {
 303         g_free(wth->capture.i4btrace);
 304 }