Code: static gboolean netscreen_read(wtap *wth, int *err, gchar **err_info,
     gint64 *data_offset)
 {
 	gint64		offset;
	int		pkt_len;
 	char		line[NETSCREEN_LINE_LENGTH];
	char		cap_int[NETSCREEN_MAX_INT_NAME_LENGTH];
	gboolean	cap_dir;
	char		cap_dst[13];
 
 	/* Find the next packet */
 	offset = netscreen_seek_next_packet(wth, err, err_info, line);
 	if (offset < 0)
 		return FALSE;
 
	/* Parse the header */
	pkt_len = parse_netscreen_rec_hdr(&wth->phdr, line, cap_int, &cap_dir,
	    cap_dst, err, err_info);
	if (pkt_len == -1)
		return FALSE;
	/* Convert the ASCII hex dump to binary data, and fill in some
	   struct wtap_pkthdr fields */
	if (!parse_netscreen_hex_dump(wth->fh, pkt_len, cap_int,
	    cap_dst, &wth->phdr, wth->frame_buffer, err, err_info))
 		return FALSE;
 
 	/*
	 * If the per-file encapsulation isn't known, set it to this
	 * packet's encapsulation.
	 *
	 * If it *is* known, and it isn't this packet's encapsulation,
	 * set it to WTAP_ENCAP_PER_PACKET, as this file doesn't
	 * have a single encapsulation for all packets in the file.
	 */
	if (wth->file_encap == WTAP_ENCAP_UNKNOWN)
		wth->file_encap = wth->phdr.pkt_encap;
	else {
		if (wth->file_encap != wth->phdr.pkt_encap)
			wth->file_encap = WTAP_ENCAP_PER_PACKET;
	}

	*data_offset = offset;
	return TRUE;
}

Commit Message: Fix packet length handling.

Treat the packet length as unsigned - it shouldn't be negative in the
file.  If it is, that'll probably cause the sscanf to fail, so we'll
report the file as bad.

Check it against WTAP_MAX_PACKET_SIZE to make sure we don't try to
allocate a huge amount of memory, just as we do in other file readers.

Use the now-validated packet size as the length in
ws_buffer_assure_space(), so we are certain to have enough space, and
don't allocate too much space.

Merge the header and packet data parsing routines while we're at it.

Bug: 12396
Change-Id: I7f981f9cdcbea7ecdeb88bfff2f12d875de2244f
Reviewed-on: https://code.wireshark.org/review/15176
Reviewed-by: Guy Harris <guy@alum.mit.edu>
CWE ID: CWE-20
static gboolean netscreen_read(wtap *wth, int *err, gchar **err_info,
     gint64 *data_offset)
 {
 	gint64		offset;
 	char		line[NETSCREEN_LINE_LENGTH];
 
 	/* Find the next packet */
 	offset = netscreen_seek_next_packet(wth, err, err_info, line);
 	if (offset < 0)
 		return FALSE;
 
	/* Parse the header and convert the ASCII hex dump to binary data */
	if (!parse_netscreen_packet(wth->fh, &wth->phdr,
	    wth->frame_buffer, line, err, err_info))
 		return FALSE;
 
 	/*
	 * If the per-file encapsulation isn't known, set it to this
	 * packet's encapsulation.
	 *
	 * If it *is* known, and it isn't this packet's encapsulation,
	 * set it to WTAP_ENCAP_PER_PACKET, as this file doesn't
	 * have a single encapsulation for all packets in the file.
	 */
	if (wth->file_encap == WTAP_ENCAP_UNKNOWN)
		wth->file_encap = wth->phdr.pkt_encap;
	else {
		if (wth->file_encap != wth->phdr.pkt_encap)
			wth->file_encap = WTAP_ENCAP_PER_PACKET;
	}

	*data_offset = offset;
	return TRUE;
}
