wiretap/i4btrace.c

   1 /* i4btrace.c
   2  *
   3  * $Id: i4btrace.c,v 1.12 2000/11/17 21:00:40 gram 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, int *data_offset);
  36 static int i4btrace_seek_read(wtap *wth, int seek_off,
  37     union wtap_pseudo_header *pseudo_header, u_char *pd, int length);
  38 static int i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err);
  39 static void i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr);
  40 static int i4b_read_rec_data(FILE_T fh, u_char *pd, int length, int *err);
  41 static void i4b_set_pseudo_header(wtap *wth, i4b_trace_hdr_t *hdr,
  42     union wtap_pseudo_header *pseudo_header);
  43
  44 /*
  45  * Test some fields in the header to see if they make sense.
  46  */
  47 #define I4B_HDR_IS_OK(hdr) \
  48         (!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
  49             (unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
  50             (unsigned)hdr.trunc > 2048))
  51
  52 int i4btrace_open(wtap *wth, int *err)
  53 {
  54         int bytes_read;
  55         i4b_trace_hdr_t hdr;
  56         gboolean byte_swapped = FALSE;
  57
  58         /* I4B trace files have no magic in the header... Sigh */
  59         file_seek(wth->fh, 0, SEEK_SET);
  60         errno = WTAP_ERR_CANT_READ;
  61         bytes_read = file_read(&hdr, 1, sizeof(hdr), wth->fh);
  62         if (bytes_read != sizeof(hdr)) {
  63                 *err = file_error(wth->fh);
  64                 if (*err != 0)
  65                         return -1;
  66                 return 0;
  67         }
  68
  69         /* Silly heuristic... */
  70         if (!I4B_HDR_IS_OK(hdr)) {
  71                 /*
  72                  * OK, try byte-swapping the header fields.
  73                  */
  74                 hdr.length = BSWAP32(hdr.length);
  75                 hdr.unit = BSWAP32(hdr.unit);
  76                 hdr.type = BSWAP32(hdr.type);
  77                 hdr.dir = BSWAP32(hdr.dir);
  78                 hdr.trunc = BSWAP32(hdr.trunc);
  79                 if (!I4B_HDR_IS_OK(hdr)) {
  80                         /*
  81                          * It doesn't look valid in either byte order.
  82                          */
  83                         return 0;
  84                 }
  85
  86                 /*
  87                  * It looks valid byte-swapped, so assume it's a
  88                  * trace written in the opposite byte order.
  89                  */
  90                 byte_swapped = TRUE;
  91         }
  92
  93         file_seek(wth->fh, 0, SEEK_SET);
  94         wth->data_offset = 0;
  95
  96         /* Get capture start time */
  97
  98         wth->file_type = WTAP_FILE_I4BTRACE;
  99         wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
 100         wth->subtype_read = i4btrace_read;
 101         wth->subtype_seek_read = i4btrace_seek_read;
 102         wth->snapshot_length = 2048;    /* actual length set per packet */
 103
 104         wth->capture.i4btrace->bchannel_prot[0] = -1;
 105         wth->capture.i4btrace->bchannel_prot[1] = -1;
 106         wth->capture.i4btrace->byte_swapped = byte_swapped;
 107
 108         wth->file_encap = WTAP_ENCAP_PER_PACKET;
 109
 110         return 1;
 111 }
 112
 113 #define V120SABME       "\010\001\177"
 114
 115 /* Read the next packet */
 116 static gboolean i4btrace_read(wtap *wth, int *err, int *data_offset)
 117 {
 118         int     ret;
 119         i4b_trace_hdr_t hdr;
 120         guint16 length;
 121         void *bufp;
 122         int channel;
 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         length = hdr.length - sizeof(hdr);
 134         if (length == 0)
 135                 return FALSE;
 136
 137         wth->phdr.len = length;
 138         wth->phdr.caplen = length;
 139
 140         wth->phdr.ts.tv_sec = hdr.time.tv_sec;
 141         wth->phdr.ts.tv_usec = hdr.time.tv_usec;
 142
 143         /*
 144          * Read the packet data.
 145          */
 146         buffer_assure_space(wth->frame_buffer, length);
 147         bufp = buffer_start_ptr(wth->frame_buffer);
 148         if (i4b_read_rec_data(wth->fh, bufp, length, err) < 0)
 149                 return FALSE;   /* Read error */
 150         wth->data_offset += length;
 151
 152         switch (hdr.type) {
 153
 154         case TRC_CH_I:
 155                 /*
 156                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 157                  * as that means it has a 4-byte AF_ type as the
 158                  * encapsulation header.
 159                  */
 160                 wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 161                 break;
 162
 163         case TRC_CH_D:
 164                 /*
 165                  * D channel, so it's LAPD.
 166                  */
 167                 wth->phdr.pkt_encap = WTAP_ENCAP_LAPD;
 168                 break;
 169
 170         case TRC_CH_B1:
 171         case TRC_CH_B2:
 172                 /*
 173                  * B channel, so it could be any of a number of things.
 174                  */
 175                 channel = hdr.type - TRC_CH_B1;
 176
 177                 if (wth->capture.i4btrace->bchannel_prot[channel] == -1) {
 178                         /*
 179                          * We don't know yet whether the datastream is
 180                          * V.120 or not; this heuristic tries to figure
 181                          * that out.
 182                          *
 183                          * We cannot glean this from the Q.931 SETUP message,
 184                          * because no commercial V.120 implementation I've
 185                          * seen actually sets the V.120 protocol discriminator
 186                          * (that, or I'm misreading the spec badly).
 187                          *
 188                          * TODO: reset the flag to -1 (unknown) after a close
 189                          * on the B channel is detected.
 190                          */
 191                         if (memcmp(bufp, V120SABME, 3) == 0)
 192                             wth->capture.i4btrace->bchannel_prot[channel] = 1;
 193                         else
 194                             wth->capture.i4btrace->bchannel_prot[channel] = 0;
 195                 }
 196                 if (wth->capture.i4btrace->bchannel_prot[channel] == 1) {
 197                         /*
 198                          * V.120.
 199                          */
 200                         wth->phdr.pkt_encap = WTAP_ENCAP_V120;
 201                 } else {
 202                         /*
 203                          * Not V.120.
 204                          *
 205                          * XXX - what is it?  It's probably not
 206                          * WTAP_ENCAP_NULL, as that means it has a
 207                          * 4-byte AF_ type as the encapsulation header.
 208                          * If it's PPP, we should use WTAP_ENCAP_PPP here.
 209                          */
 210                         wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
 211                 }
 212                 break;
 213         }
 214
 215         i4b_set_pseudo_header(wth, &hdr, &wth->pseudo_header);
 216
 217         return TRUE;
 218 }
 219
 220 static int
 221 i4btrace_seek_read(wtap *wth, int seek_off,
 222     union wtap_pseudo_header *pseudo_header, u_char *pd, int length)
 223 {
 224         int     ret;
 225         int     err;            /* XXX - return this */
 226         i4b_trace_hdr_t hdr;
 227
 228         file_seek(wth->random_fh, seek_off, SEEK_SET);
 229
 230         /* Read record header. */
 231         ret = i4b_read_rec_header(wth->random_fh, &hdr, &err);
 232         if (ret <= 0) {
 233                 /* Read error or EOF */
 234                 return ret;
 235         }
 236         i4b_byte_swap_header(wth, &hdr);
 237
 238         i4b_set_pseudo_header(wth, &hdr, pseudo_header);
 239
 240         /*
 241          * Read the packet data.
 242          */
 243         return i4b_read_rec_data(wth->random_fh, pd, length, &err);
 244 }
 245
 246 static int
 247 i4b_read_rec_header(FILE_T fh, i4b_trace_hdr_t *hdr, int *err)
 248 {
 249         int     bytes_read;
 250
 251         errno = WTAP_ERR_CANT_READ;
 252         bytes_read = file_read(hdr, 1, sizeof *hdr, fh);
 253         if (bytes_read != sizeof *hdr) {
 254                 *err = file_error(fh);
 255                 if (*err != 0)
 256                         return -1;
 257                 if (bytes_read != 0) {
 258                         *err = WTAP_ERR_SHORT_READ;
 259                         return -1;
 260                 }
 261                 return 0;
 262         }
 263         return 1;
 264 }
 265
 266 static void
 267 i4b_byte_swap_header(wtap *wth, i4b_trace_hdr_t *hdr)
 268 {
 269         if (wth->capture.i4btrace->byte_swapped) {
 270                 /*
 271                  * Byte-swap the header.
 272                  */
 273                 hdr->length = BSWAP32(hdr->length);
 274                 hdr->unit = BSWAP32(hdr->unit);
 275                 hdr->type = BSWAP32(hdr->type);
 276                 hdr->dir = BSWAP32(hdr->dir);
 277                 hdr->trunc = BSWAP32(hdr->trunc);
 278                 hdr->count = BSWAP32(hdr->count);
 279                 hdr->time.tv_sec = BSWAP32(hdr->time.tv_sec);
 280                 hdr->time.tv_usec = BSWAP32(hdr->time.tv_usec);
 281         }
 282 }
 283
 284 static int
 285 i4b_read_rec_data(FILE_T fh, u_char *pd, int length, int *err)
 286 {
 287         int     bytes_read;
 288
 289         errno = WTAP_ERR_CANT_READ;
 290         bytes_read = file_read(pd, 1, length, fh);
 291
 292         if (bytes_read != length) {
 293                 *err = file_error(fh);
 294                 if (*err == 0)
 295                         *err = WTAP_ERR_SHORT_READ;
 296                 return -1;
 297         }
 298         return 0;
 299 }
 300
 301 static void
 302 i4b_set_pseudo_header(wtap *wth, i4b_trace_hdr_t *hdr,
 303     union wtap_pseudo_header *pseudo_header)
 304 {
 305         int channel;
 306
 307         switch (hdr->type) {
 308
 309         case TRC_CH_D:
 310                 /*
 311                  * D channel, so it's LAPD; set "p2p.sent".
 312                  */
 313                 pseudo_header->p2p.sent = (hdr->dir == FROM_TE) ? TRUE : FALSE;
 314                 break;
 315
 316         case TRC_CH_B1:
 317         case TRC_CH_B2:
 318                 /*
 319                  * B channel, so it could be any of a number of things;
 320                  * if it's V.120, set "x25.flags".
 321                  */
 322                 channel = hdr->type - TRC_CH_B1;
 323
 324                 if (wth->capture.i4btrace->bchannel_prot[channel] == 1) {
 325                         /*
 326                          * V.120.
 327                          */
 328                         pseudo_header->x25.flags =
 329                             (hdr->dir == FROM_TE) ? 0x00 : 0x80;
 330                 }
 331                 break;
 332         }
 333 }