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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 #include "config.h"
  24
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include <string.h>
  28 #include "wtap-int.h"
  29 #include "file_wrappers.h"
  30 #include "buffer.h"
  31 #include "i4b_trace.h"
  32 #include "i4btrace.h"
  33
  34 typedef struct {
  35         gboolean byte_swapped;
  36 } i4btrace_t;
  37
  38 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
  39     gint64 *data_offset);
  40 static gboolean i4btrace_seek_read(wtap *wth, gint64 seek_off,
  41     struct wtap_pkthdr *phdr, guint8 *pd, int length,
  42     int *err, gchar **err_info);
  43 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err,
  44     gchar **err_info);
  45 static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
  46 static gboolean i4b_read_rec_data(FILE_T fh, guint8 *pd, int length, int *err,
  47     gchar **err_info);
  48 static void i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
  49     union wtap_pseudo_header *pseudo_header);
  50
  51 /*
  52  * Test some fields in the header to see if they make sense.
  53  */
  54 #define I4B_HDR_IS_OK(hdr) \
  55         (!((unsigned)hdr.length < 3 || (unsigned)hdr.length > 16384 || \
  56             (unsigned)hdr.unit > 4 || (unsigned)hdr.type > 4 || \
  57             (unsigned)hdr.dir > 2 || (unsigned)hdr.trunc > 2048))
  58
  59 int i4btrace_open(wtap *wth, int *err, gchar **err_info)
  60 {
  61         int bytes_read;
  62         i4b_trace_hdr_t hdr;
  63         gboolean byte_swapped = FALSE;
  64         i4btrace_t *i4btrace;
  65
  66         /* I4B trace files have no magic in the header... Sigh */
  67         errno = WTAP_ERR_CANT_READ;
  68         bytes_read = file_read(&hdr, sizeof(hdr), wth->fh);
  69         if (bytes_read != sizeof(hdr)) {
  70                 *err = file_error(wth->fh, err_info);
  71                 if (*err != 0 && *err != WTAP_ERR_SHORT_READ)
  72                         return -1;
  73                 return 0;
  74         }
  75
  76         /* Silly heuristic... */
  77         if (!I4B_HDR_IS_OK(hdr)) {
  78                 /*
  79                  * OK, try byte-swapping the header fields.
  80                  */
  81                 hdr.length = BSWAP32(hdr.length);
  82                 hdr.unit = BSWAP32(hdr.unit);
  83                 hdr.type = BSWAP32(hdr.type);
  84                 hdr.dir = BSWAP32(hdr.dir);
  85                 hdr.trunc = BSWAP32(hdr.trunc);
  86                 if (!I4B_HDR_IS_OK(hdr)) {
  87                         /*
  88                          * It doesn't look valid in either byte order.
  89                          */
  90                         return 0;
  91                 }
  92
  93                 /*
  94                  * It looks valid byte-swapped, so assume it's a
  95                  * trace written in the opposite byte order.
  96                  */
  97                 byte_swapped = TRUE;
  98         }
  99
 100         if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 101                 return -1;
 102
 103         /* Get capture start time */
 104
 105         wth->file_type = WTAP_FILE_I4BTRACE;
 106         i4btrace = (i4btrace_t *)g_malloc(sizeof(i4btrace_t));
 107         wth->priv = (void *)i4btrace;
 108         wth->subtype_read = i4btrace_read;
 109         wth->subtype_seek_read = i4btrace_seek_read;
 110         wth->snapshot_length = 0;       /* not known */
 111
 112         i4btrace->byte_swapped = byte_swapped;
 113
 114         wth->file_encap = WTAP_ENCAP_ISDN;
 115         wth->tsprecision = WTAP_FILE_TSPREC_USEC;
 116
 117         return 1;
 118 }
 119
 120 /* Read the next packet */
 121 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 122     gint64 *data_offset)
 123 {
 124         int     ret;
 125         i4b_trace_hdr_t hdr;
 126         guint32 length;
 127         void *bufp;
 128
 129         /* Read record header. */
 130         *data_offset = file_tell(wth->fh);
 131         ret = i4b_read_rec_header(wth->fh, &hdr, err, err_info);
 132         if (ret <= 0) {
 133                 /* Read error or EOF */
 134                 return FALSE;
 135         }
 136         i4b_byte_swap_header(wth, &hdr);
 137         if (hdr.length < sizeof(hdr)) {
 138                 *err = WTAP_ERR_BAD_FILE;       /* record length < header! */
 139                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %lu",
 140                     hdr.length, (unsigned long)sizeof(hdr));
 141                 return FALSE;
 142         }
 143         length = hdr.length - (guint32)sizeof(hdr);
 144         if (length > WTAP_MAX_PACKET_SIZE) {
 145                 /*
 146                  * Probably a corrupt capture file; don't blow up trying
 147                  * to allocate space for an immensely-large packet.
 148                  */
 149                 *err = WTAP_ERR_BAD_FILE;
 150                 *err_info = g_strdup_printf("i4btrace: File has %u-byte packet, bigger than maximum of %u",
 151                     length, WTAP_MAX_PACKET_SIZE);
 152                 return FALSE;
 153         }
 154
 155         wth->phdr.presence_flags = WTAP_HAS_TS;
 156
 157         wth->phdr.len = length;
 158         wth->phdr.caplen = length;
 159
 160         wth->phdr.ts.secs = hdr.ts_sec;
 161         wth->phdr.ts.nsecs = hdr.ts_usec * 1000;
 162
 163         /*
 164          * Read the packet data.
 165          */
 166         buffer_assure_space(wth->frame_buffer, length);
 167         bufp = buffer_start_ptr(wth->frame_buffer);
 168         if (!i4b_read_rec_data(wth->fh, (guint8 *)bufp, length, err, err_info))
 169                 return FALSE;   /* Read error */
 170
 171         switch (hdr.type) {
 172
 173         case TRC_CH_I:
 174                 /*
 175                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 176                  * as that means it has a 4-byte AF_ type as the
 177                  * encapsulation header.
 178                  */
 179                 wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 180                 break;
 181
 182         case TRC_CH_D:
 183         case TRC_CH_B1:
 184         case TRC_CH_B2:
 185                 /*
 186                  * D or B channel.
 187                  */
 188                 wth->phdr.pkt_encap = WTAP_ENCAP_ISDN;
 189                 break;
 190         }
 191
 192         i4b_set_pseudo_header(&hdr, &wth->phdr.pseudo_header);
 193
 194         return TRUE;
 195 }
 196
 197 static gboolean
 198 i4btrace_seek_read(wtap *wth, gint64 seek_off,
 199     struct wtap_pkthdr *phdr, guint8 *pd, int length,
 200     int *err, gchar **err_info)
 201 {
 202         union wtap_pseudo_header *pseudo_header = &phdr->pseudo_header;
 203         int     ret;
 204         i4b_trace_hdr_t hdr;
 205
 206         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 207                 return FALSE;
 208
 209         /* Read record header. */
 210         ret = i4b_read_rec_header(wth->random_fh, &hdr, err, err_info);
 211         if (ret <= 0) {
 212                 /* Read error or EOF */
 213                 if (ret == 0) {
 214                         /* EOF means "short read" in random-access mode */
 215                         *err = WTAP_ERR_SHORT_READ;
 216                 }
 217                 return FALSE;
 218         }
 219         i4b_byte_swap_header(wth, &hdr);
 220
 221         i4b_set_pseudo_header(&hdr, pseudo_header);
 222
 223         /*
 224          * Read the packet data.
 225          */
 226         return i4b_read_rec_data(wth->random_fh, pd, length, err, err_info);
 227 }
 228
 229 static int
 230 i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err, gchar **err_info)
 231 {
 232         int     bytes_read;
 233
 234         errno = WTAP_ERR_CANT_READ;
 235         bytes_read = file_read(hdr, sizeof *hdr, fh);
 236         if (bytes_read != sizeof *hdr) {
 237                 *err = file_error(fh, err_info);
 238                 if (*err != 0)
 239                         return -1;
 240                 if (bytes_read != 0) {
 241                         *err = WTAP_ERR_SHORT_READ;
 242                         return -1;
 243                 }
 244                 return 0;
 245         }
 246         return 1;
 247 }
 248
 249 static void
 250 i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
 251 {
 252         i4btrace_t *i4btrace = (i4btrace_t *)wth->priv;
 253
 254         if (i4btrace->byte_swapped) {
 255                 /*
 256                  * Byte-swap the header.
 257                  */
 258                 hdr->length = BSWAP32(hdr->length);
 259                 hdr->unit = BSWAP32(hdr->unit);
 260                 hdr->type = BSWAP32(hdr->type);
 261                 hdr->dir = BSWAP32(hdr->dir);
 262                 hdr->trunc = BSWAP32(hdr->trunc);
 263                 hdr->count = BSWAP32(hdr->count);
 264                 hdr->ts_sec = BSWAP32(hdr->ts_sec);
 265                 hdr->ts_usec = BSWAP32(hdr->ts_usec);
 266         }
 267 }
 268
 269 static gboolean
 270 i4b_read_rec_data(FILE_T fh, guint8 *pd, int length, int *err, gchar **err_info)
 271 {
 272         int     bytes_read;
 273
 274         errno = WTAP_ERR_CANT_READ;
 275         bytes_read = file_read(pd, length, fh);
 276
 277         if (bytes_read != length) {
 278                 *err = file_error(fh, err_info);
 279                 if (*err == 0)
 280                         *err = WTAP_ERR_SHORT_READ;
 281                 return FALSE;
 282         }
 283         return TRUE;
 284 }
 285
 286 static void
 287 i4b_set_pseudo_header(i4b_trace_hdr_t *hdr,
 288     union wtap_pseudo_header *pseudo_header)
 289 {
 290         pseudo_header->isdn.uton = (hdr->dir == FROM_TE);
 291         switch (hdr->type) {
 292
 293         case TRC_CH_D:
 294                 /*
 295                  * D channel, so it's LAPD; set "p2p.sent".
 296                  */
 297                 pseudo_header->isdn.channel = 0;
 298                 break;
 299
 300         case TRC_CH_B1:
 301                 /*
 302                  * B channel 1.
 303                  */
 304                 pseudo_header->isdn.channel = 1;
 305                 break;
 306
 307         case TRC_CH_B2:
 308                 /*
 309                  * B channel 2.
 310                  */
 311                 pseudo_header->isdn.channel = 2;
 312                 break;
 313         }
 314 }