wiretap/i4btrace.c

   1 /* i4btrace.c
   2  *
   3  * $Id: i4btrace.c,v 1.24 2004/01/25 21:55:15 guy Exp $
   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
  35 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
  36     long *data_offset);
  37 static gboolean i4btrace_seek_read(wtap *wth, long seek_off,
  38     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
  39     int *err, gchar **err_info);
  40 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err);
  41 static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
  42 static gboolean i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err);
  43 static void i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
  44     union wtap_pseudo_header *pseudo_header);
  45 static void i4btrace_close(wtap *wth);
  46
  47 /*
  48  * Test some fields in the header to see if they make sense.
  49  */
  50 #define I4B_HDR_IS_OK(hdr) \
  51         (!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
  52             (unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
  53             (unsigned)hdr.trunc > 2048))
  54
  55 int i4btrace_open(wtap *wth, int *err, gchar **err_info _U_)
  56 {
  57         int bytes_read;
  58         i4b_trace_hdr_t hdr;
  59         gboolean byte_swapped = FALSE;
  60
  61         /* I4B trace files have no magic in the header... Sigh */
  62         errno = WTAP_ERR_CANT_READ;
  63         bytes_read = file_read(&hdr, 1, sizeof(hdr), wth->fh);
  64         if (bytes_read != sizeof(hdr)) {
  65                 *err = file_error(wth->fh);
  66                 if (*err != 0)
  67                         return -1;
  68                 return 0;
  69         }
  70
  71         /* Silly heuristic... */
  72         if (!I4B_HDR_IS_OK(hdr)) {
  73                 /*
  74                  * OK, try byte-swapping the header fields.
  75                  */
  76                 hdr.length = BSWAP32(hdr.length);
  77                 hdr.unit = BSWAP32(hdr.unit);
  78                 hdr.type = BSWAP32(hdr.type);
  79                 hdr.dir = BSWAP32(hdr.dir);
  80                 hdr.trunc = BSWAP32(hdr.trunc);
  81                 if (!I4B_HDR_IS_OK(hdr)) {
  82                         /*
  83                          * It doesn't look valid in either byte order.
  84                          */
  85                         return 0;
  86                 }
  87
  88                 /*
  89                  * It looks valid byte-swapped, so assume it's a
  90                  * trace written in the opposite byte order.
  91                  */
  92                 byte_swapped = TRUE;
  93         }
  94
  95         if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
  96                 return -1;
  97         wth->data_offset = 0;
  98
  99         /* Get capture start time */
 100
 101         wth->file_type = WTAP_FILE_I4BTRACE;
 102         wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
 103         wth->subtype_read = i4btrace_read;
 104         wth->subtype_seek_read = i4btrace_seek_read;
 105         wth->subtype_close = i4btrace_close;
 106         wth->snapshot_length = 0;       /* not known */
 107
 108         wth->capture.i4btrace->byte_swapped = byte_swapped;
 109
 110         wth->file_encap = WTAP_ENCAP_ISDN;
 111
 112         return 1;
 113 }
 114
 115 /* Read the next packet */
 116 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 117     long *data_offset)
 118 {
 119         int     ret;
 120         i4b_trace_hdr_t hdr;
 121         guint16 length;
 122         void *bufp;
 123
 124         /* Read record header. */
 125         *data_offset = wth->data_offset;
 126         ret = i4b_read_rec_header(wth->fh, &hdr, err);
 127         if (ret <= 0) {
 128                 /* Read error or EOF */
 129                 return FALSE;
 130         }
 131         wth->data_offset += sizeof hdr;
 132         i4b_byte_swap_header(wth, &hdr);
 133         if (hdr.length < sizeof(hdr)) {
 134                 *err = WTAP_ERR_BAD_RECORD;     /* record length < header! */
 135                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %u",
 136                     hdr.length, sizeof(hdr));
 137                 return FALSE;
 138         }
 139         length = hdr.length - sizeof(hdr);
 140
 141         wth->phdr.len = length;
 142         wth->phdr.caplen = length;
 143
 144         wth->phdr.ts.tv_sec = hdr.time.tv_sec;
 145         wth->phdr.ts.tv_usec = hdr.time.tv_usec;
 146
 147         /*
 148          * Read the packet data.
 149          */
 150         buffer_assure_space(wth->frame_buffer, length);
 151         bufp = buffer_start_ptr(wth->frame_buffer);
 152         if (!i4b_read_rec_data(wth->fh, bufp, length, err))
 153                 return FALSE;   /* Read error */
 154         wth->data_offset += length;
 155
 156         switch (hdr.type) {
 157
 158         case TRC_CH_I:
 159                 /*
 160                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 161                  * as that means it has a 4-byte AF_ type as the
 162                  * encapsulation header.
 163                  */
 164                 wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 165                 break;
 166
 167         case TRC_CH_D:
 168         case TRC_CH_B1:
 169         case TRC_CH_B2:
 170                 /*
 171                  * D or B channel.
 172                  */
 173                 wth->phdr.pkt_encap = WTAP_ENCAP_ISDN;
 174                 break;
 175         }
 176
 177         i4b_set_pseudo_header(&hdr, &wth->pseudo_header);
 178
 179         return TRUE;
 180 }
 181
 182 static gboolean
 183 i4btrace_seek_read(wtap *wth, long seek_off,
 184     union wtap_pseudo_header *pseudo_header, guchar *pd, int length,
 185     int *err, gchar **err_info _U_)
 186 {
 187         int     ret;
 188         i4b_trace_hdr_t hdr;
 189
 190         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 191                 return FALSE;
 192
 193         /* Read record header. */
 194         ret = i4b_read_rec_header(wth->random_fh, &hdr, err);
 195         if (ret <= 0) {
 196                 /* Read error or EOF */
 197                 if (ret == 0) {
 198                         /* EOF means "short read" in random-access mode */
 199                         *err = WTAP_ERR_SHORT_READ;
 200                 }
 201                 return FALSE;
 202         }
 203         i4b_byte_swap_header(wth, &hdr);
 204
 205         i4b_set_pseudo_header(&hdr, pseudo_header);
 206
 207         /*
 208          * Read the packet data.
 209          */
 210         return i4b_read_rec_data(wth->random_fh, pd, length, err);
 211 }
 212
 213 static int
 214 i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err)
 215 {
 216         int     bytes_read;
 217
 218         errno = WTAP_ERR_CANT_READ;
 219         bytes_read = file_read(hdr, 1, sizeof *hdr, fh);
 220         if (bytes_read != sizeof *hdr) {
 221                 *err = file_error(fh);
 222                 if (*err != 0)
 223                         return -1;
 224                 if (bytes_read != 0) {
 225                         *err = WTAP_ERR_SHORT_READ;
 226                         return -1;
 227                 }
 228                 return 0;
 229         }
 230         return 1;
 231 }
 232
 233 static void
 234 i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
 235 {
 236         if (wth->capture.i4btrace->byte_swapped) {
 237                 /*
 238                  * Byte-swap the header.
 239                  */
 240                 hdr->length = BSWAP32(hdr->length);
 241                 hdr->unit = BSWAP32(hdr->unit);
 242                 hdr->type = BSWAP32(hdr->type);
 243                 hdr->dir = BSWAP32(hdr->dir);
 244                 hdr->trunc = BSWAP32(hdr->trunc);
 245                 hdr->count = BSWAP32(hdr->count);
 246                 hdr->time.tv_sec = BSWAP32(hdr->time.tv_sec);
 247                 hdr->time.tv_usec = BSWAP32(hdr->time.tv_usec);
 248         }
 249 }
 250
 251 static gboolean
 252 i4b_read_rec_data(FILE_T fh, guchar *pd, int length, int *err)
 253 {
 254         int     bytes_read;
 255
 256         errno = WTAP_ERR_CANT_READ;
 257         bytes_read = file_read(pd, 1, length, fh);
 258
 259         if (bytes_read != length) {
 260                 *err = file_error(fh);
 261                 if (*err == 0)
 262                         *err = WTAP_ERR_SHORT_READ;
 263                 return FALSE;
 264         }
 265         return TRUE;
 266 }
 267
 268 static void
 269 i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
 270     union wtap_pseudo_header *pseudo_header)
 271 {
 272         pseudo_header->isdn.uton = (hdr->dir == FROM_TE);
 273         switch (hdr->type) {
 274
 275         case TRC_CH_D:
 276                 /*
 277                  * D channel, so it's LAPD; set "p2p.sent".
 278                  */
 279                 pseudo_header->isdn.channel = 0;
 280                 break;
 281
 282         case TRC_CH_B1:
 283                 /*
 284                  * B channel 1.
 285                  */
 286                 pseudo_header->isdn.channel = 1;
 287                 break;
 288
 289         case TRC_CH_B2:
 290                 /*
 291                  * B channel 2.
 292                  */
 293                 pseudo_header->isdn.channel = 2;
 294                 break;
 295         }
 296 }
 297
 298 static void
 299 i4btrace_close(wtap *wth)
 300 {
 301         g_free(wth->capture.i4btrace);
 302 }