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wireshark/packet-osi.c

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/* packet-osi.c
* Routines for ISO/OSI network and transport protocol packet disassembly
* Main entrance point and common functions
*
* $Id: packet-osi.c,v 1.63 2003/09/20 03:31:25 guy Exp $
* Laurent Deniel <laurent.deniel@free.fr>
* Ralf Schneider <Ralf.Schneider@t-online.de>
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* 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 <stdio.h>
#include <string.h>
#include <ctype.h>
#include <glib.h>
#include <epan/packet.h>
#include "llcsaps.h"
#include "aftypes.h"
#include "nlpid.h"
#include "ppptypes.h"
#include "chdlctypes.h"
#include "packet-osi.h"
#include "packet-isis.h"
#include "packet-esis.h"
cksum_status_t
calc_checksum( tvbuff_t *tvb, int offset, guint len, guint checksum) {
const gchar *buffer;
guint available_len;
const guint8 *p;
guint32 c0, c1;
guint seglen;
guint i;
if ( 0 == checksum )
return( NO_CKSUM );
available_len = tvb_length_remaining( tvb, offset );
if ( available_len < len )
return( DATA_MISSING );
buffer = tvb_get_ptr( tvb, offset, len );
/*
* The maximum values of c0 and c1 will occur if all bytes have the
* value 255; if so, then c0 will be len*255 and c1 will be
* (len*255 + (len-1)*255 + ... + 255), which is
* (len + (len - 1) + ... + 1)*255, or 255*(len*(len + 1))/2.
* This means it can overflow if "len" is 5804 or greater.
*
* (A+B) mod 255 = ((A mod 255) + (B mod 255) mod 255, so
* we can solve this by taking c0 and c1 mod 255 every
* 5803 bytes.
*/
p = buffer;
c0 = 0;
c1 = 0;
while (len != 0) {
seglen = len;
if (seglen > 5803)
seglen = 5803;
for (i = 0; i < seglen; i++) {
c0 = c0 + *(p++);
c1 += c0;
}
c0 = c0 % 255;
c1 = c1 % 255;
len -= seglen;
}
if (c0 != 0 || c1 != 0)
return( CKSUM_NOT_OK ); /* XXX - what should the checksum field be? */
else
return( CKSUM_OK );
}
cksum_status_t
check_and_get_checksum( tvbuff_t *tvb, int offset, guint len, guint checksum, int offset_check, guint16* result) {
const gchar *buffer;
guint available_len;
const guint8 *p;
guint8 discard = 0;
guint32 c0, c1, factor;
guint seglen, initlen = len;
guint i;
int block, x, y;
if ( 0 == checksum )
return( NO_CKSUM );
available_len = tvb_length_remaining( tvb, offset );
offset_check -= offset;
if ( ( available_len < len ) || ( offset_check < 0 ) || ( (guint)(offset_check+2) > len ) )
return( DATA_MISSING );
buffer = tvb_get_ptr( tvb, offset, len );
block = offset_check / 5803;
/*
* The maximum values of c0 and c1 will occur if all bytes have the
* value 255; if so, then c0 will be len*255 and c1 will be
* (len*255 + (len-1)*255 + ... + 255), which is
* (len + (len - 1) + ... + 1)*255, or 255*(len*(len + 1))/2.
* This means it can overflow if "len" is 5804 or greater.
*
* (A+B) mod 255 = ((A mod 255) + (B mod 255) mod 255, so
* we can solve this by taking c0 and c1 mod 255 every
* 5803 bytes.
*/
p = buffer;
c0 = 0;
c1 = 0;
while (len != 0) {
seglen = len;
if ( block-- == 0 ) {
seglen = offset_check % 5803;
discard = 1;
} else if ( seglen > 5803 )
seglen = 5803;
for (i = 0; i < seglen; i++) {
c0 = c0 + *(p++);
c1 += c0;
}
if ( discard ) {
/*
* This works even if (offset_check % 5803) == 5802
*/
p += 2;
c1 += 2*c0;
len -= 2;
discard = 0;
}
c0 = c0 % 255;
c1 = c1 % 255;
len -= seglen;
}
factor = ( initlen - offset_check ) * c0;
x = factor - c0 - c1;
y = c1 - factor - 1;
/*
* This algorithm uses the 8 bits one's complement arithmetic.
* Therefore, we must correct an effect produced
* by the "standard" arithmetic (two's complement)
*/
if (x < 0 ) x--;
if (y > 0 ) y++;
x %= 255;
y %= 255;
if (x == 0) x = 0xFF;
if (y == 0) y = 0x01;
*result = ( x << 8 ) | ( y & 0xFF );
if (*result != checksum)
return( CKSUM_NOT_OK ); /* XXX - what should the checksum field be? */
else
return( CKSUM_OK );
}
/* main entry point */
/*
* These assume the NLPID is a secondary protocol identifier, not an
* initial protocol identifier.
*
* This is an issue only if, in any packet where an NLPID appears, it's
* an initial protocol identifier *AND* it can have the value 1, which
* means T.70 for an IPI and X.29 for an SPI.
*/
const value_string nlpid_vals[] = {
{ NLPID_NULL, "NULL" },
{ NLPID_SPI_X_29, "X.29" },
{ NLPID_X_633, "X.633" },
{ NLPID_Q_931, "Q.931" },
{ NLPID_Q_2931, "Q.2931" },
{ NLPID_Q_2119, "Q.2119" },
{ NLPID_SNAP, "SNAP" },
{ NLPID_ISO8473_CLNP, "CLNP" },
{ NLPID_ISO9542_ESIS, "ESIS" },
{ NLPID_ISO10589_ISIS, "ISIS" },
{ NLPID_ISO10747_IDRP, "IDRP" },
{ NLPID_ISO9542X25_ESIS, "ESIS (X.25)" },
{ NLPID_ISO10030, "ISO 10030" },
{ NLPID_ISO11577, "ISO 11577" },
{ NLPID_COMPRESSED, "Data compression protocol" },
{ NLPID_IP, "IP" },
{ NLPID_SNDCF, "SubNetwork Dependent Convergence Function"},
{ NLPID_IP6, "IPv6" },
{ NLPID_PPP, "PPP" },
{ 0, NULL },
};
static dissector_table_t osinl_subdissector_table;
static dissector_handle_t data_handle, ppp_handle;
static void dissect_osi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint8 nlpid;
tvbuff_t *new_tvb;
pinfo->current_proto = "OSI";
nlpid = tvb_get_guint8(tvb, 0);
/* do lookup with the subdissector table */
if (dissector_try_port(osinl_subdissector_table, nlpid, tvb, pinfo, tree))
return;
switch (nlpid) {
/* ESIS (X.25) is not currently decoded */
case NLPID_ISO9542X25_ESIS:
if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
col_set_str(pinfo->cinfo, COL_PROTOCOL, "ESIS (X.25)");
}
call_dissector(data_handle,tvb, pinfo, tree);
break;
case NLPID_ISO10747_IDRP:
if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
col_set_str(pinfo->cinfo, COL_PROTOCOL, "IDRP");
}
call_dissector(data_handle,tvb, pinfo, tree);
break;
case NLPID_PPP:
/* XXX - we should put the NLPID into the protocol tree.
We should also probably have a subdissector table for
those protocols whose PDUs *aren't* defined to begin
with an NLPID. */
new_tvb = tvb_new_subset(tvb, 1, -1, -1);
call_dissector(ppp_handle, new_tvb, pinfo, tree);
break;
default:
if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
col_set_str(pinfo->cinfo, COL_PROTOCOL, "ISO");
}
if (check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown ISO protocol (%02x)", nlpid);
}
call_dissector(data_handle,tvb, pinfo, tree);
break;
}
} /* dissect_osi */
void
proto_register_osi(void)
{
/* There's no "OSI" protocol *per se*, but we do register a
dissector table so various protocols running at the
network layer can register themselves. */
osinl_subdissector_table = register_dissector_table("osinl",
"OSI NLPID", FT_UINT8, BASE_HEX);
}
void
proto_reg_handoff_osi(void)
{
dissector_handle_t osi_handle;
osi_handle = create_dissector_handle(dissect_osi, -1);
dissector_add("llc.dsap", SAP_OSINL1, osi_handle);
dissector_add("llc.dsap", SAP_OSINL2, osi_handle);
dissector_add("llc.dsap", SAP_OSINL3, osi_handle);
dissector_add("llc.dsap", SAP_OSINL4, osi_handle);
dissector_add("llc.dsap", SAP_OSINL5, osi_handle);
dissector_add("ppp.protocol", PPP_OSI, osi_handle);
dissector_add("chdlctype", CHDLCTYPE_OSI, osi_handle);
dissector_add("null.type", BSD_AF_ISO, osi_handle);
dissector_add("gre.proto", SAP_OSINL5, osi_handle);
data_handle = find_dissector("data");
ppp_handle = find_dissector("ppp");
}
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