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, Buffer *buf, int length,
  42     int *err, gchar **err_info);
  43 static int i4b_read_rec(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
  44     Buffer *buf, int *err, gchar **err_info);
  45
  46 /*
  47  * Test some fields in the header to see if they make sense.
  48  */
  49 #define I4B_HDR_IS_OK(hdr) \
  50         (!((unsigned)hdr.length < 3 || (unsigned)hdr.length > 16384 || \
  51             (unsigned)hdr.unit > 4 || (unsigned)hdr.type > 4 || \
  52             (unsigned)hdr.dir > 2 || (unsigned)hdr.trunc > 2048))
  53
  54 int i4btrace_open(wtap *wth, int *err, gchar **err_info)
  55 {
  56         int bytes_read;
  57         i4b_trace_hdr_t hdr;
  58         gboolean byte_swapped = FALSE;
  59         i4btrace_t *i4btrace;
  60
  61         /* I4B trace files have no magic in the header... Sigh */
  62         errno = WTAP_ERR_CANT_READ;
  63         bytes_read = file_read(&hdr, sizeof(hdr), wth->fh);
  64         if (bytes_read != sizeof(hdr)) {
  65                 *err = file_error(wth->fh, err_info);
  66                 if (*err != 0 && *err != WTAP_ERR_SHORT_READ)
  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 = GUINT32_SWAP_LE_BE(hdr.length);
  77                 hdr.unit = GUINT32_SWAP_LE_BE(hdr.unit);
  78                 hdr.type = GUINT32_SWAP_LE_BE(hdr.type);
  79                 hdr.dir = GUINT32_SWAP_LE_BE(hdr.dir);
  80                 hdr.trunc = GUINT32_SWAP_LE_BE(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
  98         /* Get capture start time */
  99
 100         wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_I4BTRACE;
 101         i4btrace = (i4btrace_t *)g_malloc(sizeof(i4btrace_t));
 102         wth->priv = (void *)i4btrace;
 103         wth->subtype_read = i4btrace_read;
 104         wth->subtype_seek_read = i4btrace_seek_read;
 105         wth->snapshot_length = 0;       /* not known */
 106
 107         i4btrace->byte_swapped = byte_swapped;
 108
 109         wth->file_encap = WTAP_ENCAP_ISDN;
 110         wth->tsprecision = WTAP_FILE_TSPREC_USEC;
 111
 112         return 1;
 113 }
 114
 115 /* Read the next packet */
 116 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 117     gint64 *data_offset)
 118 {
 119         *data_offset = file_tell(wth->fh);
 120
 121         return i4b_read_rec(wth, wth->fh, &wth->phdr, wth->frame_buffer,
 122             err, err_info);
 123 }
 124
 125 static gboolean
 126 i4btrace_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr,
 127     Buffer *buf, int length _U_, int *err, gchar **err_info)
 128 {
 129         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 130                 return FALSE;
 131
 132         if (!i4b_read_rec(wth, wth->random_fh, phdr, buf, err, err_info)) {
 133                 /* Read error or EOF */
 134                 if (*err == 0) {
 135                         /* EOF means "short read" in random-access mode */
 136                         *err = WTAP_ERR_SHORT_READ;
 137                 }
 138                 return FALSE;
 139         }
 140         return TRUE;
 141 }
 142
 143 static int
 144 i4b_read_rec(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
 145     int *err, gchar **err_info)
 146 {
 147         i4btrace_t *i4btrace = (i4btrace_t *)wth->priv;
 148         i4b_trace_hdr_t hdr;
 149         int     bytes_read;
 150         guint32 length;
 151
 152         errno = WTAP_ERR_CANT_READ;
 153         bytes_read = file_read(&hdr, sizeof hdr, fh);
 154         if (bytes_read != sizeof hdr) {
 155                 *err = file_error(fh, err_info);
 156                 if (*err == 0 && bytes_read != 0) {
 157                         /* Read something, but not enough */
 158                         *err = WTAP_ERR_SHORT_READ;
 159                 }
 160                 return FALSE;
 161         }
 162
 163         if (i4btrace->byte_swapped) {
 164                 /*
 165                  * Byte-swap the header.
 166                  */
 167                 hdr.length = GUINT32_SWAP_LE_BE(hdr.length);
 168                 hdr.unit = GUINT32_SWAP_LE_BE(hdr.unit);
 169                 hdr.type = GUINT32_SWAP_LE_BE(hdr.type);
 170                 hdr.dir = GUINT32_SWAP_LE_BE(hdr.dir);
 171                 hdr.trunc = GUINT32_SWAP_LE_BE(hdr.trunc);
 172                 hdr.count = GUINT32_SWAP_LE_BE(hdr.count);
 173                 hdr.ts_sec = GUINT32_SWAP_LE_BE(hdr.ts_sec);
 174                 hdr.ts_usec = GUINT32_SWAP_LE_BE(hdr.ts_usec);
 175         }
 176
 177         if (hdr.length < sizeof(hdr)) {
 178                 *err = WTAP_ERR_BAD_FILE;       /* record length < header! */
 179                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %lu",
 180                     hdr.length, (unsigned long)sizeof(hdr));
 181                 return FALSE;
 182         }
 183         length = hdr.length - (guint32)sizeof(hdr);
 184         if (length > WTAP_MAX_PACKET_SIZE) {
 185                 /*
 186                  * Probably a corrupt capture file; don't blow up trying
 187                  * to allocate space for an immensely-large packet.
 188                  */
 189                 *err = WTAP_ERR_BAD_FILE;
 190                 *err_info = g_strdup_printf("i4btrace: File has %u-byte packet, bigger than maximum of %u",
 191                     length, WTAP_MAX_PACKET_SIZE);
 192                 return FALSE;
 193         }
 194
 195         phdr->presence_flags = WTAP_HAS_TS;
 196
 197         phdr->len = length;
 198         phdr->caplen = length;
 199
 200         phdr->ts.secs = hdr.ts_sec;
 201         phdr->ts.nsecs = hdr.ts_usec * 1000;
 202
 203         switch (hdr.type) {
 204
 205         case TRC_CH_I:
 206                 /*
 207                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 208                  * as that means it has a 4-byte AF_ type as the
 209                  * encapsulation header.
 210                  */
 211                 phdr->pkt_encap = WTAP_ENCAP_NULL;
 212                 break;
 213
 214         case TRC_CH_D:
 215                 /*
 216                  * D channel, so it's LAPD; set "p2p.sent".
 217                  */
 218                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 219                 phdr->pseudo_header.isdn.channel = 0;
 220                 break;
 221
 222         case TRC_CH_B1:
 223                 /*
 224                  * B channel 1.
 225                  */
 226                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 227                 phdr->pseudo_header.isdn.channel = 1;
 228                 break;
 229
 230         case TRC_CH_B2:
 231                 /*
 232                  * B channel 2.
 233                  */
 234                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 235                 phdr->pseudo_header.isdn.channel = 2;
 236                 break;
 237         }
 238
 239         phdr->pseudo_header.isdn.uton = (hdr.dir == FROM_TE);
 240
 241         /*
 242          * Read the packet data.
 243          */
 244         return wtap_read_packet_bytes(fh, buf, length, err, err_info);
 245 }