forked from osmocom/wireshark
206 lines
5.4 KiB
C
206 lines
5.4 KiB
C
/* i4btrace.c
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*
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* $Id: i4btrace.c,v 1.3 2000/01/13 07:09:16 guy Exp $
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*
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* Wiretap Library
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* Copyright (c) 1999 by Bert Driehuis <driehuis@playbeing.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <errno.h>
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#include <time.h>
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#include "wtap.h"
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#include "file_wrappers.h"
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#include "buffer.h"
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#include "i4b_trace.h"
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static int i4btrace_read(wtap *wth, int *err);
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/*
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* Test some fields in the header to see if they make sense.
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*/
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#define I4B_HDR_IS_OK(hdr) \
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(!((unsigned)hdr.length < 3 || (unsigned)hdr.unit > 4 || \
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(unsigned)hdr.type > 4 || (unsigned)hdr.dir > 2 || \
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(unsigned)hdr.trunc > 2048))
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int i4btrace_open(wtap *wth, int *err)
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{
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int bytes_read;
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i4b_trace_hdr_t hdr;
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gboolean byte_swapped = FALSE;
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/* I4B trace files have no magic in the header... Sigh */
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file_seek(wth->fh, 0, SEEK_SET);
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errno = WTAP_ERR_CANT_READ;
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bytes_read = file_read(&hdr, 1, sizeof(hdr), wth->fh);
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if (bytes_read != sizeof(hdr)) {
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*err = file_error(wth->fh);
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if (*err != 0)
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return -1;
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return 0;
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}
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/* Silly heuristic... */
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if (!I4B_HDR_IS_OK(hdr)) {
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/*
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* OK, try byte-swapping the header fields.
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*/
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hdr.length = BSWAP32(hdr.length);
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hdr.unit = BSWAP32(hdr.unit);
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hdr.type = BSWAP32(hdr.type);
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hdr.dir = BSWAP32(hdr.dir);
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hdr.trunc = BSWAP32(hdr.trunc);
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if (!I4B_HDR_IS_OK(hdr)) {
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/*
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* It doesn't look valid in either byte order.
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*/
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return 0;
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}
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/*
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* It looks valid byte-swapped, so assume it's a
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* trace written in the opposite byte order.
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*/
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byte_swapped = TRUE;
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}
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file_seek(wth->fh, 0, SEEK_SET);
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wth->data_offset = 0;
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/* Get capture start time */
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wth->file_type = WTAP_FILE_I4BTRACE;
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wth->capture.i4btrace = g_malloc(sizeof(i4btrace_t));
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wth->subtype_read = i4btrace_read;
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wth->snapshot_length = 2048; /* actual length set per packet */
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wth->capture.i4btrace->start = hdr.time.tv_sec;
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wth->capture.i4btrace->bchannel_prot[0] = -1;
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wth->capture.i4btrace->bchannel_prot[1] = -1;
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wth->capture.i4btrace->byte_swapped = byte_swapped;
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wth->file_encap = WTAP_ENCAP_PER_PACKET;
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return 1;
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}
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#define V120SABME "\010\001\177"
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/* Read the next packet */
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static int i4btrace_read(wtap *wth, int *err)
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{
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int bytes_read;
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i4b_trace_hdr_t hdr;
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guint16 length;
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int data_offset;
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void *bufp;
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/* Read record header. */
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errno = WTAP_ERR_CANT_READ;
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bytes_read = file_read(&hdr, 1, sizeof hdr, wth->fh);
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if (bytes_read != sizeof hdr) {
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*err = file_error(wth->fh);
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if (*err != 0)
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return -1;
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if (bytes_read != 0) {
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*err = WTAP_ERR_SHORT_READ;
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return -1;
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}
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return 0;
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}
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wth->data_offset += sizeof hdr;
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if (wth->capture.i4btrace->byte_swapped) {
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/*
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* Byte-swap the header.
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*/
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hdr.length = BSWAP32(hdr.length);
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hdr.unit = BSWAP32(hdr.unit);
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hdr.type = BSWAP32(hdr.type);
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hdr.dir = BSWAP32(hdr.dir);
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hdr.trunc = BSWAP32(hdr.trunc);
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hdr.count = BSWAP32(hdr.count);
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hdr.time.tv_sec = BSWAP32(hdr.time.tv_sec);
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hdr.time.tv_usec = BSWAP32(hdr.time.tv_usec);
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}
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length = hdr.length - sizeof(hdr);
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if (length == 0)
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return 0;
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wth->phdr.len = length;
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wth->phdr.caplen = length;
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wth->phdr.ts.tv_sec = hdr.time.tv_sec;
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wth->phdr.ts.tv_usec = hdr.time.tv_usec;
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wth->phdr.pseudo_header.x25.flags = (hdr.dir == FROM_TE) ? 0x00 : 0x80;
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/*
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* Read the packet data.
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*/
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buffer_assure_space(wth->frame_buffer, length);
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data_offset = wth->data_offset;
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errno = WTAP_ERR_CANT_READ;
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bufp = buffer_start_ptr(wth->frame_buffer);
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bytes_read = file_read(bufp, 1, length, wth->fh);
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if (bytes_read != length) {
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*err = file_error(wth->fh);
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if (*err == 0)
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*err = WTAP_ERR_SHORT_READ;
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return -1;
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}
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wth->data_offset += length;
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/*
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* This heuristic tries to figure out whether the datastream is
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* V.120 or not. We cannot glean this from the Q.931 SETUP message,
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* because no commercial V.120 implementation I've seen actually
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* sets the V.120 protocol discriminator (that, or I'm misreading
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* the spec badly).
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* TODO: reset the flag to -1 (unknown) after a close on the B
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* channel is detected.
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*/
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if (hdr.type == TRC_CH_B1 || hdr.type == TRC_CH_B2) {
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int channel = hdr.type - TRC_CH_B1;
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if (wth->capture.i4btrace->bchannel_prot[channel] == -1) {
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if (memcmp(bufp, V120SABME, 3) == 0)
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wth->capture.i4btrace->bchannel_prot[channel] = 1;
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else
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wth->capture.i4btrace->bchannel_prot[channel] = 0;
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}
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}
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if (hdr.type == TRC_CH_I) {
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wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
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} else if (hdr.type == TRC_CH_D) {
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wth->phdr.pkt_encap = WTAP_ENCAP_LAPD;
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} else {
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int channel = hdr.type - TRC_CH_B1;
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if (wth->capture.i4btrace->bchannel_prot[channel] == 1)
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wth->phdr.pkt_encap = WTAP_ENCAP_V120;
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else
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wth->phdr.pkt_encap = WTAP_ENCAP_NULL;
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}
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return data_offset;
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}
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