wiretap/i4btrace.c

   1 /* i4btrace.c
   2  *
   3  * Wiretap Library
   4  * Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include "config.h"
  22
  23 #include <stdlib.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include "wtap-int.h"
  27 #include "file_wrappers.h"
  28 #include <wsutil/buffer.h>
  29 #include "i4b_trace.h"
  30 #include "i4btrace.h"
  31
  32 typedef struct {
  33         gboolean byte_swapped;
  34 } i4btrace_t;
  35
  36 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
  37     gint64 *data_offset);
  38 static gboolean i4btrace_seek_read(wtap *wth, gint64 seek_off,
  39     struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info);
  40 static int i4b_read_rec(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
  41     Buffer *buf, int *err, gchar **err_info);
  42
  43 /*
  44  * Test some fields in the header to see if they make sense.
  45  */
  46 #define I4B_HDR_IS_OK(hdr) \
  47         (!((unsigned int)hdr.length < 3 || (unsigned int)hdr.length > 16384 || \
  48             (unsigned int)hdr.unit > 4 || (unsigned int)hdr.type > 4 || \
  49             (unsigned int)hdr.dir > 2 || (unsigned int)hdr.trunc > 2048))
  50
  51 int i4btrace_open(wtap *wth, int *err, gchar **err_info)
  52 {
  53         i4b_trace_hdr_t hdr;
  54         gboolean byte_swapped = FALSE;
  55         i4btrace_t *i4btrace;
  56
  57         /* I4B trace files have no magic in the header... Sigh */
  58         errno = WTAP_ERR_CANT_READ;
  59         if (!wtap_read_bytes(wth->fh, &hdr, sizeof(hdr), err, err_info)) {
  60                 if (*err != WTAP_ERR_SHORT_READ)
  61                         return -1;
  62                 return 0;
  63         }
  64
  65         /* Silly heuristic... */
  66         if (!I4B_HDR_IS_OK(hdr)) {
  67                 /*
  68                  * OK, try byte-swapping the header fields.
  69                  */
  70                 hdr.length = GUINT32_SWAP_LE_BE(hdr.length);
  71                 hdr.unit = GUINT32_SWAP_LE_BE(hdr.unit);
  72                 hdr.type = GUINT32_SWAP_LE_BE(hdr.type);
  73                 hdr.dir = GUINT32_SWAP_LE_BE(hdr.dir);
  74                 hdr.trunc = GUINT32_SWAP_LE_BE(hdr.trunc);
  75                 if (!I4B_HDR_IS_OK(hdr)) {
  76                         /*
  77                          * It doesn't look valid in either byte order.
  78                          */
  79                         return 0;
  80                 }
  81
  82                 /*
  83                  * It looks valid byte-swapped, so assume it's a
  84                  * trace written in the opposite byte order.
  85                  */
  86                 byte_swapped = TRUE;
  87         }
  88
  89         if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
  90                 return -1;
  91
  92         /* Get capture start time */
  93
  94         wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_I4BTRACE;
  95         i4btrace = (i4btrace_t *)g_malloc(sizeof(i4btrace_t));
  96         wth->priv = (void *)i4btrace;
  97         wth->subtype_read = i4btrace_read;
  98         wth->subtype_seek_read = i4btrace_seek_read;
  99         wth->snapshot_length = 0;       /* not known */
 100
 101         i4btrace->byte_swapped = byte_swapped;
 102
 103         wth->file_encap = WTAP_ENCAP_ISDN;
 104         wth->file_tsprec = WTAP_TSPREC_USEC;
 105
 106         return 1;
 107 }
 108
 109 /* Read the next packet */
 110 static gboolean i4btrace_read(wtap *wth, int *err, gchar **err_info,
 111     gint64 *data_offset)
 112 {
 113         *data_offset = file_tell(wth->fh);
 114
 115         return i4b_read_rec(wth, wth->fh, &wth->phdr, wth->frame_buffer,
 116             err, err_info);
 117 }
 118
 119 static gboolean
 120 i4btrace_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr,
 121     Buffer *buf, int *err, gchar **err_info)
 122 {
 123         if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 124                 return FALSE;
 125
 126         if (!i4b_read_rec(wth, wth->random_fh, phdr, buf, err, err_info)) {
 127                 /* Read error or EOF */
 128                 if (*err == 0) {
 129                         /* EOF means "short read" in random-access mode */
 130                         *err = WTAP_ERR_SHORT_READ;
 131                 }
 132                 return FALSE;
 133         }
 134         return TRUE;
 135 }
 136
 137 static gboolean
 138 i4b_read_rec(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf,
 139     int *err, gchar **err_info)
 140 {
 141         i4btrace_t *i4btrace = (i4btrace_t *)wth->priv;
 142         i4b_trace_hdr_t hdr;
 143         guint32 length;
 144
 145         errno = WTAP_ERR_CANT_READ;
 146         if (!wtap_read_bytes_or_eof(fh, &hdr, sizeof hdr, err, err_info))
 147                 return FALSE;
 148
 149         if (i4btrace->byte_swapped) {
 150                 /*
 151                  * Byte-swap the header.
 152                  */
 153                 hdr.length = GUINT32_SWAP_LE_BE(hdr.length);
 154                 hdr.unit = GUINT32_SWAP_LE_BE(hdr.unit);
 155                 hdr.type = GUINT32_SWAP_LE_BE(hdr.type);
 156                 hdr.dir = GUINT32_SWAP_LE_BE(hdr.dir);
 157                 hdr.trunc = GUINT32_SWAP_LE_BE(hdr.trunc);
 158                 hdr.count = GUINT32_SWAP_LE_BE(hdr.count);
 159                 hdr.ts_sec = GUINT32_SWAP_LE_BE(hdr.ts_sec);
 160                 hdr.ts_usec = GUINT32_SWAP_LE_BE(hdr.ts_usec);
 161         }
 162
 163         if (hdr.length < sizeof(hdr)) {
 164                 *err = WTAP_ERR_BAD_FILE;       /* record length < header! */
 165                 *err_info = g_strdup_printf("i4btrace: record length %u < header length %lu",
 166                     hdr.length, (unsigned long)sizeof(hdr));
 167                 return FALSE;
 168         }
 169         length = hdr.length - (guint32)sizeof(hdr);
 170         if (length > WTAP_MAX_PACKET_SIZE) {
 171                 /*
 172                  * Probably a corrupt capture file; don't blow up trying
 173                  * to allocate space for an immensely-large packet.
 174                  */
 175                 *err = WTAP_ERR_BAD_FILE;
 176                 *err_info = g_strdup_printf("i4btrace: File has %u-byte packet, bigger than maximum of %u",
 177                     length, WTAP_MAX_PACKET_SIZE);
 178                 return FALSE;
 179         }
 180
 181         phdr->rec_type = REC_TYPE_PACKET;
 182         phdr->presence_flags = WTAP_HAS_TS;
 183
 184         phdr->len = length;
 185         phdr->caplen = length;
 186
 187         phdr->ts.secs = hdr.ts_sec;
 188         phdr->ts.nsecs = hdr.ts_usec * 1000;
 189
 190         switch (hdr.type) {
 191
 192         case TRC_CH_I:
 193                 /*
 194                  * XXX - what is it?  It's probably not WTAP_ENCAP_NULL,
 195                  * as that means it has a 4-byte AF_ type as the
 196                  * encapsulation header.
 197                  */
 198                 phdr->pkt_encap = WTAP_ENCAP_NULL;
 199                 break;
 200
 201         case TRC_CH_D:
 202                 /*
 203                  * D channel, so it's LAPD; set "p2p.sent".
 204                  */
 205                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 206                 phdr->pseudo_header.isdn.channel = 0;
 207                 break;
 208
 209         case TRC_CH_B1:
 210                 /*
 211                  * B channel 1.
 212                  */
 213                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 214                 phdr->pseudo_header.isdn.channel = 1;
 215                 break;
 216
 217         case TRC_CH_B2:
 218                 /*
 219                  * B channel 2.
 220                  */
 221                 phdr->pkt_encap = WTAP_ENCAP_ISDN;
 222                 phdr->pseudo_header.isdn.channel = 2;
 223                 break;
 224         }
 225
 226         phdr->pseudo_header.isdn.uton = (hdr.dir == FROM_TE);
 227
 228         /*
 229          * Read the packet data.
 230          */
 231         return wtap_read_packet_bytes(fh, buf, length, err, err_info);
 232 }