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/* i4btrace.c
*
* $Id: i4btrace.c,v 1.4 2000/04/15 21:12:37 guy Exp $
*
* Wiretap Library
* Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <errno.h>
#include <time.h>
#include "wtap.h"
#include "file_wrappers.h"
#include "buffer.h"
#include "i4b_trace.h"
static int i4btrace_read(wtap *wth, int *err);
/*
* Test some fields in the header to see if they make sense.
*/
#define I4B_HDR_IS_OK(hdr) \
(!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
(unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
(unsigned)hdr.trunc > 2048))
int i4btrace_open(wtap *wth, int *err)
{
int bytes_read;
i4b_trace_hdr_t hdr;
gboolean byte_swapped = FALSE;
/* I4B trace files have no magic in the header... Sigh */
file_seek(wth->fh, 0, SEEK_SET);
errno = WTAP_ERR_CANT_READ;
bytes_read = file_read(&hdr, 1, sizeof(hdr), wth->fh);
if (bytes_read != sizeof(hdr)) {
*err = file_error(wth->fh);
if (*err != 0)
return -1;
return 0;
}
/* Silly heuristic... */
if (!I4B_HDR_IS_OK(hdr)) {
/*
* OK, try byte-swapping the header fields.
*/
hdr.length = BSWAP32(hdr.length);
hdr.unit = BSWAP32(hdr.unit);
hdr.type = BSWAP32(hdr.type);
hdr.dir = BSWAP32(hdr.dir);
hdr.trunc = BSWAP32(hdr.trunc);
if (!I4B_HDR_IS_OK(hdr)) {
/*
* It doesn't look valid in either byte order.
*/
return 0;
}
/*
* It looks valid byte-swapped, so assume it's a
* trace written in the opposite byte order.
*/
byte_swapped = TRUE;
}
file_seek(wth->fh, 0, SEEK_SET);
wth->data_offset = 0;
/* Get capture start time */
wth->file_type = WTAP_FILE_I4BTRACE;
wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
wth->subtype_read = i4btrace_read;
wth->snapshot_length = 2048; /* actual length set per packet */
wth->capture.i4btrace->bchannel_prot[0] = -1;
wth->capture.i4btrace->bchannel_prot[1] = -1;
wth->capture.i4btrace->byte_swapped = byte_swapped;
wth->file_encap = WTAP_ENCAP_PER_PACKET;
return 1;
}
#define V120SABME "\010\001\177"
/* Read the next packet */
static int i4btrace_read(wtap *wth, int *err)
{
int bytes_read;
i4b_trace_hdr_t hdr;
guint16 length;
int data_offset;
void *bufp;
/* Read record header. */
errno = WTAP_ERR_CANT_READ;
bytes_read = file_read(&hdr, 1, sizeof hdr, wth->fh);
if (bytes_read != sizeof hdr) {
*err = file_error(wth->fh);
if (*err != 0)
return -1;
if (bytes_read != 0) {
*err = WTAP_ERR_SHORT_READ;
return -1;
}
return 0;
}
wth->data_offset += sizeof hdr;
if (wth->capture.i4btrace->byte_swapped) {
/*
* Byte-swap the header.
*/
hdr.length = BSWAP32(hdr.length);
hdr.unit = BSWAP32(hdr.unit);
hdr.type = BSWAP32(hdr.type);
hdr.dir = BSWAP32(hdr.dir);
hdr.trunc = BSWAP32(hdr.trunc);
hdr.count = BSWAP32(hdr.count);
hdr.time.tv_sec = BSWAP32(hdr.time.tv_sec);
hdr.time.tv_usec = BSWAP32(hdr.time.tv_usec);
}
length = hdr.length - sizeof(hdr);
if (length == 0)
return 0;
wth->phdr.len = length;
wth->phdr.caplen = length;
wth->phdr.ts.tv_sec = hdr.time.tv_sec;
wth->phdr.ts.tv_usec = hdr.time.tv_usec;
wth->phdr.pseudo_header.x25.flags = (hdr.dir == FROM_TE) ? 0x00 : 0x80;
/*
* Read the packet data.
*/
buffer_assure_space(wth->frame_buffer, length);
data_offset = wth->data_offset;
errno = WTAP_ERR_CANT_READ;
bufp = buffer_start_ptr(wth->frame_buffer);
bytes_read = file_read(bufp, 1, length, wth->fh);
if (bytes_read != length) {
*err = file_error(wth->fh);
if (*err == 0)
*err = WTAP_ERR_SHORT_READ;
return -1;
}
wth->data_offset += length;
/*
* This heuristic tries to figure out whether the datastream is
* V.120 or not. We cannot glean this from the Q.931 SETUP message,
* because no commercial V.120 implementation I've seen actually
* sets the V.120 protocol discriminator (that, or I'm misreading
* the spec badly).
* TODO: reset the flag to -1 (unknown) after a close on the B
* channel is detected.
*/
if (hdr.type == TRC_CH_B1 || hdr.type == TRC_CH_B2) {
int channel = hdr.type - TRC_CH_B1;
if (wth->capture.i4btrace->bchannel_prot[channel] == -1) {
if (memcmp(bufp, V120SABME, 3) == 0)
wth->capture.i4btrace->bchannel_prot[channel] = 1;
else
wth->capture.i4btrace->bchannel_prot[channel] = 0;
}
}
if (hdr.type == TRC_CH_I) {
wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
} else if (hdr.type == TRC_CH_D) {
wth->phdr.pkt_encap = WTAP_ENCAP_LAPD;
} else {
int channel = hdr.type - TRC_CH_B1;
if (wth->capture.i4btrace->bchannel_prot[channel] == 1)
wth->phdr.pkt_encap = WTAP_ENCAP_V120;
else
wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
}
return data_offset;
}
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