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wireshark/epan/dissectors/packet-srp.c

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/* packet-srp.c
* Routines for H.324/SRP dissection
* 2004 Richard van der Hoff <richardv@mxtelecom.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/crc16-tvb.h>
void proto_register_srp(void);
void proto_register_ccsrl(void);
void proto_reg_handoff_srp(void);
/* Wireshark ID of the protocols */
static int proto_srp = -1;
static int proto_ccsrl = -1;
/* The following hf_* variables are used to hold the Wireshark IDs of
* our header fields; they are filled out when we call
* proto_register_field_array() in proto_register_srp()
*/
static int hf_srp_header = -1;
static int hf_srp_seqno = -1;
static int hf_srp_crc = -1;
static int hf_srp_crc_bad = -1;
static int hf_ccsrl_ls = -1;
/* These are the ids of the subtrees that we may be creating */
static gint ett_srp = -1;
static gint ett_ccsrl = -1;
static dissector_handle_t ccsrl_handle;
static dissector_handle_t h245dg_handle;
/*****************************************************************************/
#define SRP_SRP_COMMAND 249
#define SRP_SRP_RESPONSE 251
#define SRP_NSRP_RESPONSE 247
/* WNSRP definitions */
#define WNSRP_COMMAND_HEADER 241
#define WNSRP_RESPONSE_HEADER 243
static const value_string srp_frame_types[] = {
{SRP_SRP_COMMAND, "SRP command"},
{SRP_SRP_RESPONSE, "SRP response"},
{SRP_NSRP_RESPONSE, "NSRP response"},
{WNSRP_COMMAND_HEADER, "WNSRP command"},
{WNSRP_RESPONSE_HEADER, "WNSRP response"},
{0,NULL}
};
static const value_string ccsrl_ls_vals[] = {
{0xFF, "Yes"},
{0x00, "No"},
{0,NULL}
};
/*****************************************************************************/
static int dissect_ccsrl(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_)
{
proto_item *ccsrl_item;
proto_tree *ccsrl_tree=NULL;
guint8 lastseg = tvb_get_guint8(tvb,0);
tvbuff_t *next_tvb;
/* add the 'ccsrl' tree to the main tree */
if (tree) {
ccsrl_item = proto_tree_add_item (tree, proto_ccsrl, tvb, 0, -1, ENC_NA);
ccsrl_tree = proto_item_add_subtree (ccsrl_item, ett_ccsrl);
proto_tree_add_uint(ccsrl_tree,hf_ccsrl_ls,tvb,0,1,lastseg);
}
/* XXX add support for reassembly of fragments */
/* XXX currently, we always dissect as H245. It's not necessarily
that though.
*/
next_tvb = tvb_new_subset_remaining(tvb, 1);
call_dissector( h245dg_handle, next_tvb, pinfo, ccsrl_tree );
return tvb_captured_length(tvb);
}
static void dissect_srp_command(tvbuff_t * tvb, packet_info * pinfo, proto_tree * srp_tree)
{
tvbuff_t *next_tvb;
guint payload_len;
if( srp_tree )
proto_tree_add_item(srp_tree,hf_srp_seqno,tvb,1,1,ENC_BIG_ENDIAN);
payload_len = tvb_reported_length_remaining(tvb,4);
next_tvb = tvb_new_subset_length(tvb, 2, payload_len);
/* XXX currently, we always dissect as CCSRL. It's only that in
* H324/Annex C though.
*/
call_dissector(ccsrl_handle, next_tvb, pinfo, srp_tree );
}
static int dissect_srp (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_)
{
proto_item *srp_item = NULL;
proto_tree *srp_tree = NULL;
proto_item *hidden_item;
guint8 header = tvb_get_guint8(tvb,0);
/* add the 'srp' tree to the main tree */
if (tree) {
srp_item = proto_tree_add_item (tree, proto_srp, tvb, 0, -1, ENC_NA);
srp_tree = proto_item_add_subtree (srp_item, ett_srp);
proto_tree_add_uint(srp_tree,hf_srp_header,tvb,0,1,header);
}
switch( header ) {
case SRP_SRP_COMMAND:
case WNSRP_COMMAND_HEADER:
dissect_srp_command(tvb,pinfo,srp_tree);
break;
case SRP_SRP_RESPONSE:
break;
case SRP_NSRP_RESPONSE:
case WNSRP_RESPONSE_HEADER:
if( srp_tree )
proto_tree_add_item(srp_tree,hf_srp_seqno,tvb,1,1,ENC_BIG_ENDIAN);
break;
default:
break;
}
if( srp_tree ) {
guint16 crc, calc_crc;
guint crc_offset = tvb_reported_length(tvb)-2;
crc = tvb_get_letohs(tvb,-2);
/* crc includes the header */
calc_crc = crc16_ccitt_tvb(tvb,crc_offset);
if( crc == calc_crc ) {
proto_tree_add_uint_format_value(srp_tree, hf_srp_crc, tvb,
crc_offset, 2, crc,
"0x%04x (correct)", crc);
} else {
hidden_item = proto_tree_add_boolean(srp_tree, hf_srp_crc_bad, tvb,
crc_offset, 2, TRUE);
proto_item_set_hidden(hidden_item);
proto_tree_add_uint_format_value(srp_tree, hf_srp_crc, tvb,
crc_offset, 2, crc,
"0x%04x (incorrect, should be 0x%04x)",
crc,
calc_crc);
}
}
return tvb_captured_length(tvb);
}
void proto_register_ccsrl (void)
{
static hf_register_info hf[] = {
{ &hf_ccsrl_ls,
{ "Last Segment","ccsrl.ls",FT_UINT8, BASE_HEX, VALS(ccsrl_ls_vals), 0x0,
"Last segment indicator", HFILL}},
};
static gint *ett[] = {
&ett_ccsrl,
};
proto_ccsrl = proto_register_protocol ("H.324/CCSRL", "CCSRL", "ccsrl");
proto_register_field_array (proto_ccsrl, hf, array_length (hf));
proto_register_subtree_array (ett, array_length (ett));
register_dissector("ccsrl", dissect_ccsrl, proto_ccsrl);
}
void proto_register_srp (void)
{
static hf_register_info hf[] = {
{&hf_srp_header,
{ "Header", "srp.header", FT_UINT8, BASE_DEC, VALS(srp_frame_types), 0x0,
"SRP header octet", HFILL }},
{&hf_srp_seqno,
{ "Sequence Number", "srp.seqno", FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{&hf_srp_crc,
{ "CRC", "srp.crc", FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_srp_crc_bad,
{ "Bad CRC","srp.crc_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
};
static gint *ett[] = {
&ett_srp,
};
proto_srp = proto_register_protocol ("H.324/SRP", "SRP", "srp");
proto_register_field_array (proto_srp, hf, array_length (hf));
proto_register_subtree_array (ett, array_length (ett));
register_dissector("srp", dissect_srp, proto_srp);
/* register our init routine to be called at the start of a capture,
to clear out our hash tables etc */
/* register_init_routine(&srp_init_protocol); */
}
void proto_reg_handoff_srp(void) {
ccsrl_handle = find_dissector_add_dependency("ccsrl", proto_srp);
h245dg_handle = find_dissector_add_dependency("h245dg", proto_srp);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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