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wireshark/packet-sndcp.c

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/* packet-sndcp.c
* Routines for Subnetwork Dependent Convergence Protocol (SNDCP) dissection
* Copyright 2000, Christian Falckenberg <christian.falckenberg@nortelnetworks.com>
*
* $Id: packet-sndcp.c,v 1.4 2004/05/04 09:12:26 guy Exp $
*
* 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 <stdlib.h>
#include <string.h>
#include <glib.h>
#ifdef NEED_SNPRINTF_H
# include "snprintf.h"
#endif
#include <epan/packet.h>
#include "reassemble.h"
/* Bitmasks for the bits in the address field
*/
#define MASK_X 0x80
#define MASK_F 0x40
#define MASK_T 0x20
#define MASK_M 0x10
/* Initialize the protocol and registered fields
*/
static int proto_sndcp = -1;
static int hf_sndcp_x = -1;
static int hf_sndcp_f = -1;
static int hf_sndcp_t = -1;
static int hf_sndcp_m = -1;
static int hf_sndcp_nsapi = -1;
static int hf_sndcp_nsapib = -1;
static int hf_sndcp_dcomp = -1;
static int hf_sndcp_pcomp = -1;
static int hf_sndcp_segment = -1;
static int hf_sndcp_npdu1 = -1;
static int hf_sndcp_npdu2 = -1;
/* These fields are used when reassembling N-PDU fragments
*/
static int hf_npdu_fragments = -1;
static int hf_npdu_fragment = -1;
static int hf_npdu_fragment_overlap = -1;
static int hf_npdu_fragment_overlap_conflict = -1;
static int hf_npdu_fragment_multiple_tails = -1;
static int hf_npdu_fragment_too_long_fragment = -1;
static int hf_npdu_fragment_error = -1;
static int hf_npdu_reassembled_in = -1;
/* Initialize the subtree pointers
*/
static gint ett_sndcp = -1;
static gint ett_sndcp_address_field = -1;
static gint ett_sndcp_compression_field = -1;
static gint ett_sndcp_npdu_field = -1;
static gint ett_npdu_fragment = -1;
static gint ett_npdu_fragments = -1;
/* Structure needed for the fragmentation routines in reassemble.c
*/
static const fragment_items npdu_frag_items = {
&ett_npdu_fragment,
&ett_npdu_fragments,
&hf_npdu_fragments,
&hf_npdu_fragment,
&hf_npdu_fragment_overlap,
&hf_npdu_fragment_overlap_conflict,
&hf_npdu_fragment_multiple_tails,
&hf_npdu_fragment_too_long_fragment,
&hf_npdu_fragment_error,
&hf_npdu_reassembled_in,
"fragments"
};
/* dissectors for the data portion of this protocol
*/
static dissector_handle_t data_handle;
static dissector_handle_t ip_handle;
/* reassembly of N-PDU
*/
static GHashTable *npdu_fragment_table = NULL;
static void
sndcp_defragment_init(void)
{
fragment_table_init(&npdu_fragment_table);
}
/* value strings
*/
static const value_string nsapi_t[] = {
{ 0, "Escape mechanism for future extensions"},
{ 1, "Point-to-Multipoint (PTM-M) Information" },
{ 2, "Reserved for future use" },
{ 3, "Reserved for future use" },
{ 4, "Reserved for future use" },
{ 5, "Dynamically allocated"},
{ 6, "Dynamically allocated"},
{ 7, "Dynamically allocated"},
{ 8, "Dynamically allocated"},
{ 9, "Dynamically allocated"},
{ 10, "Dynamically allocated"},
{ 11, "Dynamically allocated"},
{ 12, "Dynamically allocated"},
{ 13, "Dynamically allocated"},
{ 14, "Dynamically allocated"},
{ 15, "Dynamically allocated"},
{ 0, NULL },
};
static const value_string nsapi_abrv[] = {
{ 0, "0"},
{ 1, "PTM-M" },
{ 2, "2" },
{ 3, "3"},
{ 4, "4" },
{ 5, "DYN5" },
{ 6, "DYN6" },
{ 7, "DYN7" },
{ 8, "DYN8" },
{ 9, "DYN9" },
{ 10, "DYN10" },
{ 11, "DYN11" },
{ 12, "DYN12" },
{ 13, "DYN13" },
{ 14, "DYN14" },
{ 15, "DYN15" },
{ 0, NULL },
};
static const value_string compression_vals[] = {
{ 0, "No compression"},
{ 1, "Pointer to selected protocol/data compression mechanism" },
{ 2, "Pointer to selected protocol/data compression mechanism" },
{ 3, "Pointer to selected protocol/data compression mechanism" },
{ 4, "Pointer to selected protocol/data compression mechanism" },
{ 5, "Pointer to selected protocol/data compression mechanism" },
{ 6, "Pointer to selected protocol/data compression mechanism" },
{ 7, "Pointer to selected protocol/data compression mechanism" },
{ 8, "Pointer to selected protocol/data compression mechanism" },
{ 9, "Pointer to selected protocol/data compression mechanism" },
{ 10, "Pointer to selected protocol/data compression mechanism" },
{ 11, "Pointer to selected protocol/data compression mechanism" },
{ 12, "Pointer to selected protocol/data compression mechanism" },
{ 13, "Pointer to selected protocol/data compression mechanism" },
{ 14, "Pointer to selected protocol/data compression mechanism" },
{ 15, "Pointer to selected protocol/data compression mechanism" },
{ 0, NULL },
};
static const true_false_string x_bit = {
"Invalid",
"Set to 0 by transmitting SNDCP entity (ignored by receiver)"
};
static const true_false_string f_bit = {
"This SN-PDU is the first segment of an N-PDU",
"This SN-PDU is not the first segment of an N-PDU"
};
static const true_false_string t_bit = {
"SN-UNITDATA PDU",
"SN-DATA PDU"
};
static const true_false_string m_bit = {
"Not the last segment of N-PDU, more segments to follow",
"Last segment of N-PDU"
};
/* Code to actually dissect the packets
*/
static void
dissect_sndcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint8 addr_field, comp_field, npdu_field1, nsapi, dcomp=0, pcomp=0;
guint16 offset=0, npdu=0, segment=0, npdu_field2;
tvbuff_t *next_tvb, *npdu_tvb;
guint32 len;
gboolean first, more_frags, unack;
/* Set up structures needed to add the protocol subtree and manage it
*/
proto_item *ti, *address_field_item, *compression_field_item, *npdu_field_item;
proto_tree *sndcp_tree = NULL, *address_field_tree, *compression_field_tree, *npdu_field_tree;
/* Make entries in Protocol column and clear Info column on summary display
*/
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "SNDCP");
if (check_col(pinfo->cinfo, COL_INFO))
col_clear(pinfo->cinfo, COL_INFO);
/* create display subtree for the protocol
*/
if (tree) {
ti = proto_tree_add_item(tree, proto_sndcp, tvb, 0, -1, FALSE);
sndcp_tree = proto_item_add_subtree(ti, ett_sndcp);
}
/* get address field from next byte
*/
addr_field = tvb_get_guint8(tvb,offset);
nsapi = addr_field & 0xF;
first = addr_field & MASK_F;
more_frags = addr_field & MASK_M;
unack = addr_field & MASK_T;
/* add subtree for the address field
*/
if (tree) {
address_field_item = proto_tree_add_uint_format(sndcp_tree,hf_sndcp_nsapi,
tvb, offset,1, nsapi,
"Address field NSAPI: %d", nsapi );
address_field_tree = proto_item_add_subtree(address_field_item, ett_sndcp_address_field);
proto_tree_add_boolean(address_field_tree, hf_sndcp_x, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_f, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_t, tvb,offset,1, addr_field );
proto_tree_add_boolean(address_field_tree, hf_sndcp_m, tvb,offset,1, addr_field );
proto_tree_add_uint(address_field_tree, hf_sndcp_nsapib, tvb, offset, 1, addr_field );
}
offset++;
/* get compression pointers from next byte if this is the first segment
*/
if (first) {
comp_field = tvb_get_guint8(tvb,offset);
dcomp = comp_field & 0xF0;
pcomp = comp_field & 0x0F;
/* add subtree for the compression field
*/
if (tree) {
if (!pcomp) {
if (!dcomp) {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "No compression");
}
else {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Data compression");
}
}
else {
if (!dcomp) {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Protocol compression");
}
else {
compression_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Data and Protocol compression");
}
}
compression_field_tree = proto_item_add_subtree(compression_field_item, ett_sndcp_compression_field);
proto_tree_add_uint(compression_field_tree, hf_sndcp_dcomp, tvb, offset, 1, comp_field );
proto_tree_add_uint(compression_field_tree, hf_sndcp_pcomp, tvb, offset, 1, comp_field );
}
offset++;
/* get N-PDU number from next byte for acknowledged mode (only for first segment)
*/
if (!unack) {
npdu = npdu_field1 = tvb_get_guint8(tvb,offset);
if (check_col(pinfo->cinfo, COL_INFO))
col_add_fstr(pinfo->cinfo, COL_INFO, "SN-DATA N-PDU %d", npdu_field1);
if (tree) {
npdu_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,1, "Acknowledged mode, N-PDU %d", npdu_field1 );
npdu_field_tree = proto_item_add_subtree(npdu_field_item, ett_sndcp_npdu_field);
proto_tree_add_uint(npdu_field_tree, hf_sndcp_npdu1, tvb, offset, 1, npdu_field1 );
offset++;
}
}
}
/* get segment and N-PDU number from next two bytes for unacknowledged mode
*/
if (unack) {
npdu_field2 = tvb_get_ntohs(tvb, offset);
segment = (npdu_field2 & 0xF000) >> 12;
npdu = (npdu_field2 & 0x0FFF);
if (check_col(pinfo->cinfo, COL_INFO))
col_add_fstr(pinfo->cinfo, COL_INFO, "SN-UNITDATA N-PDU %d (segment %d)", npdu, segment);
if (tree) {
npdu_field_item = proto_tree_add_text(sndcp_tree, tvb, offset,2, "Unacknowledged mode, N-PDU %d (segment %d)", npdu, segment );
npdu_field_tree = proto_item_add_subtree(npdu_field_item, ett_sndcp_npdu_field);
proto_tree_add_uint(npdu_field_tree, hf_sndcp_segment, tvb, offset, 2, npdu_field2 );
proto_tree_add_uint(npdu_field_tree, hf_sndcp_npdu2, tvb, offset, 2, npdu_field2 );
}
offset += 2;
}
/* handle N-PDU data, reassemble if necessary
*/
if (first && !more_frags) {
next_tvb = tvb_new_subset (tvb, offset, -1, -1);
if (!dcomp && !pcomp) {
call_dissector(ip_handle, next_tvb, pinfo, tree);
}
else {
call_dissector(data_handle, next_tvb, pinfo, tree);
}
}
else {
/* Try reassembling fragments
*/
fragment_data *fd_npdu = NULL;
guint32 reassembled_in = 0;
gboolean save_fragmented = pinfo->fragmented;
len = tvb_length_remaining(tvb, offset);
pinfo->fragmented = TRUE;
if (unack)
fd_npdu = fragment_add_seq(tvb, offset, pinfo, npdu,
npdu_fragment_table, segment, len, more_frags);
else
fd_npdu = fragment_add(tvb, offset, pinfo, npdu,
npdu_fragment_table, offset, len, more_frags);
npdu_tvb = process_reassembled_data(tvb, offset, pinfo,
"Reassembled N-PDU", fd_npdu, &npdu_frag_items,
NULL, sndcp_tree);
if (fd_npdu) {
/* Reassembled
*/
reassembled_in = fd_npdu->reassembled_in;
if (pinfo->fd->num == reassembled_in) {
/* Reassembled in this very packet:
* We can safely hand the tvb to the IP dissector
*/
call_dissector(ip_handle, npdu_tvb, pinfo, tree);
}
else {
/* Not reassembled in this packet
*/
if (check_col(pinfo->cinfo, COL_INFO)) {
col_append_fstr(pinfo->cinfo, COL_INFO,
" (N-PDU payload reassembled in packet %u)",
fd_npdu->reassembled_in);
}
if (tree) {
proto_tree_add_text(sndcp_tree, tvb, offset, -1, "Payload");
}
}
} else {
/* Not reassembled yet, or not reassembled at all
*/
if (check_col(pinfo->cinfo, COL_INFO)) {
if (unack)
col_append_fstr(pinfo->cinfo, COL_INFO, " (Unreassembled fragment %u)", segment);
else
col_append_str(pinfo->cinfo, COL_INFO, " (Unreassembled fragment)");
}
if (tree) {
proto_tree_add_text(sndcp_tree, tvb, offset, -1, "Payload");
}
}
/* Now reset fragmentation information in pinfo
*/
pinfo->fragmented = save_fragmented;
}
}
/* Register the protocol with Ethereal
this format is required because a script is used to build the C function
that calls all the protocol registration.
*/
void
proto_register_sndcp(void)
{
/* Setup list of header fields
*/
static hf_register_info hf[] = {
{ &hf_sndcp_nsapi,
{ "NSAPI",
"sndcp.nsapi",
FT_UINT8, BASE_DEC, VALS(nsapi_abrv), 0x0,
"Network Layer Service Access Point Identifier", HFILL
}
},
{ &hf_sndcp_x,
{ "Spare bit",
"sndcp.x",
FT_BOOLEAN,8, TFS(&x_bit), MASK_X,
"Spare bit (should be 0)", HFILL
}
},
{ &hf_sndcp_f,
{ "First segment indicator bit",
"sndcp.f",
FT_BOOLEAN,8, TFS(&f_bit), MASK_F,
"First segment indicator bit", HFILL
}
},
{ &hf_sndcp_t,
{ "Type",
"sndcp.t",
FT_BOOLEAN,8, TFS(&t_bit), MASK_T,
"SN-PDU Type", HFILL
}
},
{ &hf_sndcp_m,
{ "More bit",
"sndcp.m",
FT_BOOLEAN,8, TFS(&m_bit), MASK_M,
"More bit", HFILL
}
},
{ &hf_sndcp_dcomp,
{ "DCOMP",
"sndcp.dcomp",
FT_UINT8, BASE_DEC, VALS(compression_vals), 0xF0,
"Data compression coding", HFILL
}
},
{ &hf_sndcp_pcomp,
{ "PCOMP",
"sndcp.pcomp",
FT_UINT8, BASE_DEC, VALS(compression_vals), 0x0F,
"Protocol compression coding", HFILL
}
},
{ &hf_sndcp_nsapib,
{ "NSAPI",
"sndcp.nsapib",
FT_UINT8, BASE_DEC , VALS(nsapi_t), 0xf,
"Network Layer Service Access Point Identifier ",HFILL
}
},
{ &hf_sndcp_segment,
{ "Segment",
"sndcp.segment",
FT_UINT16, BASE_DEC, NULL, 0xF000,
"Segment number", HFILL
}
},
{ &hf_sndcp_npdu1,
{ "N-PDU",
"sndcp.npdu",
FT_UINT8, BASE_DEC, NULL, 0,
"N-PDU", HFILL
}
},
{ &hf_sndcp_npdu2,
{ "N-PDU",
"sndcp.npdu",
FT_UINT16, BASE_DEC, NULL, 0x0FFF,
"N-PDU", HFILL
}
},
/* Fragment fields
*/
{ &hf_npdu_fragment_overlap,
{ "Fragment overlap",
"npdu.fragment.overlap",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment overlaps with other fragments", HFILL
}
},
{ &hf_npdu_fragment_overlap_conflict,
{ "Conflicting data in fragment overlap",
"npdu.fragment.overlap.conflict",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Overlapping fragments contained conflicting data", HFILL
}
},
{ &hf_npdu_fragment_multiple_tails,
{ "Multiple tail fragments found",
"npdu.fragment.multipletails",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Several tails were found when defragmenting the packet", HFILL
}
},
{ &hf_npdu_fragment_too_long_fragment,
{ "Fragment too long",
"npdu.fragment.toolongfragment",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment contained data past end of packet", HFILL
}
},
{ &hf_npdu_fragment_error,
{ "Defragmentation error",
"npdu.fragment.error",
FT_FRAMENUM, BASE_NONE, NULL, 0x0,
"Defragmentation error due to illegal fragments", HFILL
}
},
{ &hf_npdu_reassembled_in,
{ "Reassembled in",
"npdu.reassembled.in",
FT_FRAMENUM, BASE_NONE, NULL, 0x0,
"N-PDU fragments are reassembled in the given packet", HFILL
}
},
{ &hf_npdu_fragment,
{ "N-PDU Fragment",
"npdu.fragment",
FT_FRAMENUM, BASE_NONE, NULL, 0x0,
"N-PDU Fragment", HFILL
}
},
{ &hf_npdu_fragments,
{ "N-PDU Fragments",
"npdu.fragments",
FT_NONE, BASE_NONE, NULL, 0x0,
"N-PDU Fragments", HFILL
}
}
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_sndcp ,
&ett_sndcp_address_field,
&ett_sndcp_compression_field,
&ett_sndcp_npdu_field,
&ett_npdu_fragment,
&ett_npdu_fragments,
};
/* Register the protocol name and description */
proto_sndcp = proto_register_protocol("Subnetwork Dependent Convergence Protocol",
"SNDCP", "sndcp");
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_sndcp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("sndcp", dissect_sndcp, proto_sndcp);
register_init_routine(sndcp_defragment_init);
}
/* If this dissector uses sub-dissector registration add a registration routine.
This format is required because a script is used to find these routines and
create the code that calls these routines.
*/
void
proto_reg_handoff_sndcp(void)
{
dissector_handle_t sndcp_handle;
sndcp_handle = create_dissector_handle(dissect_sndcp, proto_sndcp);
/* Register SNDCP dissector with LLC layer for SAPI 3,5,9 and 11
*/
dissector_add("llcgprs.sapi", 3, sndcp_handle);
dissector_add("llcgprs.sapi", 5, sndcp_handle);
dissector_add("llcgprs.sapi", 9, sndcp_handle);
dissector_add("llcgprs.sapi", 11, sndcp_handle);
/* Find IP and data handle for upper layer dissectors
*/
ip_handle = find_dissector("ip");
data_handle = find_dissector("data");
}
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