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wireshark/plugins/mgcp/packet-mgcp.c

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/* packet-mgcp.c
* Routines for mgcp packet disassembly
* RFC 2705
*
* $Id: packet-mgcp.c,v 1.27 2001/10/31 10:40:58 guy Exp $
*
* Copyright (c) 2000 by Ed Warnicke <hagbard@physics.rutgers.edu>
*
* Ethereal - Network traffic analyzer
* By Gerald Combs
* Copyright 1999 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 "plugins/plugin_api.h"
#include "moduleinfo.h"
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <gmodule.h>
#include <ctype.h>
#include <time.h>
#include <string.h>
#include "packet.h"
#include "resolv.h"
#include "prefs.h"
#include "strutil.h"
#include "plugins/plugin_api_defs.h"
#ifndef __ETHEREAL_STATIC__
G_MODULE_EXPORT const gchar version[] = VERSION;
#endif
#define TCP_PORT_MGCP_GATEWAY 2427
#define UDP_PORT_MGCP_GATEWAY 2427
#define TCP_PORT_MGCP_CALLAGENT 2727
#define UDP_PORT_MGCP_CALLAGENT 2727
void proto_reg_handoff_mgcp(void);
/* Define the mgcp proto */
static int proto_mgcp = -1;
/* Define many many headers for mgcp */
static int hf_mgcp_req = -1;
static int hf_mgcp_req_verb = -1;
static int hf_mgcp_req_endpoint = -1;
static int hf_mgcp_rsp = -1;
static int hf_mgcp_transid = -1;
static int hf_mgcp_version = -1;
static int hf_mgcp_rsp_rspcode = -1;
static int hf_mgcp_rsp_rspstring = -1;
static int hf_mgcp_param_rspack = -1;
static int hf_mgcp_param_bearerinfo = -1;
static int hf_mgcp_param_callid = -1;
static int hf_mgcp_param_connectionid = -1;
static int hf_mgcp_param_secondconnectionid = -1;
static int hf_mgcp_param_notifiedentity = -1;
static int hf_mgcp_param_requestid = -1;
static int hf_mgcp_param_localconnoptions = -1;
static int hf_mgcp_param_connectionmode = -1;
static int hf_mgcp_param_reqevents = -1;
static int hf_mgcp_param_restartmethod = -1;
static int hf_mgcp_param_restartdelay = -1;
static int hf_mgcp_param_signalreq = -1;
static int hf_mgcp_param_digitmap = -1;
static int hf_mgcp_param_observedevent = -1;
static int hf_mgcp_param_connectionparam = -1;
static int hf_mgcp_param_reasoncode = -1;
static int hf_mgcp_param_eventstates = -1;
static int hf_mgcp_param_specificendpoint = -1;
static int hf_mgcp_param_secondendpointid = -1;
static int hf_mgcp_param_reqinfo = -1;
static int hf_mgcp_param_quarantinehandling = -1;
static int hf_mgcp_param_detectedevents = -1;
static int hf_mgcp_param_capabilities = -1;
static int hf_mgcp_param_extention = -1;
static int hf_mgcp_param_invalid = -1;
static int hf_mgcp_messagecount = -1;
/*
* Define the trees for mgcp
* We need one for MGCP itself and one for the MGCP paramters
*/
static int ett_mgcp = -1;
static int ett_mgcp_param = -1;
/*
* Here are the global variables associated with
* the various user definable characteristics of the dissection
*
* MGCP has two kinds of "agents", gateways and callagents. Callagents
* control gateways in a master/slave sort of arrangement. Since gateways
* and callagents have different well known ports and could both
* operate under either udp or tcp we have rather a lot of port info to
* specify.
*
* global_mgcp_raw_text determines whether we are going to display
* the raw text of the mgcp message, much like the HTTP dissector does.
*
* global_mgcp_dissect_tree determines whether we are going to display
* a detailed tree that expresses a somewhat more semantically meaningful
* decode.
*/
static int global_mgcp_gateway_tcp_port = TCP_PORT_MGCP_GATEWAY;
static int global_mgcp_gateway_udp_port = UDP_PORT_MGCP_GATEWAY;
static int global_mgcp_callagent_tcp_port = TCP_PORT_MGCP_CALLAGENT;
static int global_mgcp_callagent_udp_port = UDP_PORT_MGCP_CALLAGENT;
static gboolean global_mgcp_raw_text = FALSE;
static gboolean global_mgcp_dissect_tree = TRUE;
static gboolean global_mgcp_message_count = FALSE;
/*
* Variables to allow for proper deletion of dissector registration when
* the user changes port from the gui.
*/
static int gateway_tcp_port = 0;
static int gateway_udp_port = 0;
static int callagent_tcp_port = 0;
static int callagent_udp_port = 0;
/* A simple MGCP type that is occasionally handy */
typedef enum _mgcp_type {
MGCP_REQUEST,
MGCP_RESPONSE,
MGCP_OTHERS
} mgcp_type_t;
/* Some basic utility functions that are specific to this dissector */
static gboolean is_mgcp_verb(tvbuff_t *tvb, gint offset, gint maxlength);
static gboolean is_mgcp_rspcode(tvbuff_t *tvb, gint offset, gint maxlength);
static gint tvb_parse_param(tvbuff_t *tvb, gint offset, gint maxlength,
int** hf);
/*
* The various functions that either dissect some
* subpart of MGCP. These aren't really proto dissectors but they
* are written in the same style.
*/
static void dissect_mgcp_message(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree,proto_tree *mgcp_tree, proto_tree *ti);
static void dissect_mgcp_firstline(tvbuff_t *tvb,
packet_info* pinfo,
proto_tree *tree);
static void dissect_mgcp_params(tvbuff_t *tvb,
packet_info* pinfo,
proto_tree *tree);
static void mgcp_raw_text_add(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree);
/*
* Some functions which should be moved to a library
* as I think that people may find them of general usefulness.
*/
static gint tvb_skip_wsp(tvbuff_t* tvb, gint offset, gint maxlength);
static gint tvb_find_null_line(tvbuff_t* tvb, gint offset, gint len,
gint* next_offset);
static gint tvb_find_dot_line(tvbuff_t* tvb, gint offset,
gint len, gint* next_offset);
static gboolean is_rfc2234_alpha(guint8 c);
static dissector_handle_t sdp_handle;
/*
* dissect_mgcp - The dissector for the Media Gateway Control Protocol
*/
static void
dissect_mgcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
gint sectionlen;
guint32 num_messages;
gint tvb_sectionend,tvb_sectionbegin, tvb_len, tvb_current_len;
proto_tree *mgcp_tree, *ti;
/* Initialize variables */
tvb_sectionend = 0;
tvb_sectionbegin = tvb_sectionend;
sectionlen = 0;
tvb_len = tvb_length(tvb);
tvb_current_len = tvb_len;
num_messages = 0;
mgcp_tree = NULL;
ti = NULL;
/*
* Set the columns now, so that they'll be set correctly if we throw
* an exception. We can set them later as well....
*/
if (check_col(pinfo->fd, COL_PROTOCOL))
col_add_str(pinfo->fd, COL_PROTOCOL, "MGCP");
if (check_col(pinfo->fd, COL_INFO))
col_clear(pinfo->fd, COL_INFO);
/*
* Check to see whether we're really dealing with MGCP by looking
* for a valid MGCP verb or response code. This isn't infallible,
* but its cheap and its better than nothing.
*/
if(is_mgcp_verb(tvb,0,tvb_len) || is_mgcp_rspcode(tvb,0,tvb_len)){
/* Build the info tree if we've been given a root */
if (tree || global_mgcp_message_count == TRUE) {
/*
* Loop through however many mgcp messages may be stuck in
* this packet using piggybacking
*/
do{
num_messages++;
if(tree){
/* Create out mgcp subtree */
ti = proto_tree_add_item(tree,proto_mgcp,tvb,0,0, FALSE);
mgcp_tree = proto_item_add_subtree(ti, ett_mgcp);
}
sectionlen = tvb_find_dot_line(tvb, tvb_sectionbegin, -1,
&tvb_sectionend);
if( sectionlen != -1){
dissect_mgcp_message(tvb_new_subset(tvb, tvb_sectionbegin,
sectionlen, -1),
pinfo, tree, mgcp_tree,ti);
tvb_sectionbegin = tvb_sectionend;
}
else {
break;
}
} while(tvb_sectionend < tvb_len );
if(mgcp_tree){
proto_tree_add_uint_hidden(mgcp_tree, hf_mgcp_messagecount, tvb,
0 ,0 , num_messages);
}
}
/*
* Add our column information we do this after dissecting SDP
* in order to prevent the column info changing to reflect the SDP.
*/
tvb_sectionbegin = 0;
if (check_col(pinfo->fd, COL_PROTOCOL)){
if( global_mgcp_message_count == TRUE ){
if(num_messages > 1){
col_add_fstr(pinfo->fd, COL_PROTOCOL, "MGCP (%i messages)",num_messages);
}
else {
col_add_fstr(pinfo->fd, COL_PROTOCOL, "MGCP (%i message)",num_messages);
}
}
else {
col_add_str(pinfo->fd, COL_PROTOCOL, "MGCP");
}
}
if (check_col(pinfo->fd, COL_INFO) ){
sectionlen = tvb_find_line_end(tvb, tvb_sectionbegin,-1,
&tvb_sectionend);
col_add_fstr(pinfo->fd,COL_INFO, "%s",
tvb_format_text(tvb,tvb_sectionbegin,sectionlen));
}
}
}
static void
dissect_mgcp_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
proto_tree *mgcp_tree, proto_tree *ti){
/* Declare variables */
gint sectionlen;
gint tvb_sectionend,tvb_sectionbegin, tvb_len, tvb_current_len;
tvbuff_t *next_tvb;
/* Initialize variables */
tvb_sectionend = 0;
tvb_sectionbegin = tvb_sectionend;
sectionlen = 0;
tvb_len = tvb_length(tvb);
tvb_current_len = tvb_len;
/*
* Check to see whether we're really dealing with MGCP by looking
* for a valid MGCP verb or response code. This isn't infallible,
* but its cheap and its better than nothing.
*/
if(is_mgcp_verb(tvb,0,tvb_len) || is_mgcp_rspcode(tvb,0,tvb_len)){
/* Build the info tree if we've been given a root */
if (tree && mgcp_tree) {
/* dissect first line */
tvb_sectionbegin = 0;
tvb_current_len = tvb_len;
tvb_sectionend = tvb_sectionbegin;
sectionlen = tvb_find_line_end(tvb,0,-1,&tvb_sectionend);
if( sectionlen > 0){
dissect_mgcp_firstline(tvb_new_subset(tvb, tvb_sectionbegin,
sectionlen,-1),
pinfo, mgcp_tree);
}
tvb_sectionbegin = tvb_sectionend;
/* dissect params */
if(tvb_sectionbegin < tvb_len){
sectionlen = tvb_find_null_line(tvb, tvb_sectionbegin, -1,
&tvb_sectionend);
dissect_mgcp_params(tvb_new_subset(tvb, tvb_sectionbegin,
sectionlen, -1),
pinfo, mgcp_tree);
tvb_sectionbegin = tvb_sectionend;
}
/* set the mgcp payload length correctly so we don't include the
* encapsulated SDP
*/
sectionlen = tvb_sectionend;
proto_item_set_len(ti,sectionlen);
/* Display the raw text of the mgcp message if desired */
/* Do we want to display the raw text of our MGCP packet? */
if(global_mgcp_raw_text){
mgcp_raw_text_add(tvb_new_subset(tvb,0,tvb_len,-1),pinfo,
mgcp_tree);
}
/* dissect sdp payload */
if( tvb_sectionend < tvb_len && global_mgcp_dissect_tree == TRUE){
next_tvb = tvb_new_subset(tvb, tvb_sectionend, -1, -1);
call_dissector(sdp_handle, next_tvb, pinfo, tree);
}
}
}
}
/*
* Add the raw text of the message to the dissect tree if appropriate
* preferences are specified. The args and returns follow the general
* convention for proto dissectors (although this is NOT a proto dissector).
*/
static void mgcp_raw_text_add(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree){
gint tvb_linebegin,tvb_lineend,tvb_len,linelen;
tvb_linebegin = 0;
tvb_len = tvb_length(tvb);
do {
tvb_find_line_end(tvb,tvb_linebegin,-1,&tvb_lineend);
linelen = tvb_lineend - tvb_linebegin;
proto_tree_add_text(tree, tvb, tvb_linebegin, linelen,
"%s", tvb_format_text(tvb,tvb_linebegin,
linelen));
tvb_linebegin = tvb_lineend;
} while ( tvb_lineend < tvb_len );
}
/* Register all the bits needed with the filtering engine */
void
proto_register_mgcp(void)
{
static hf_register_info hf[] = {
{ &hf_mgcp_req,
{ "Request", "mgcp.req", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"True if MGCP request", HFILL }},
{ &hf_mgcp_rsp,
{ "Response", "mgcp.rsp", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"TRUE if MGCP response", HFILL }},
{ &hf_mgcp_req_verb,
{ "Verb", "mgcp.req.verb", FT_STRING, BASE_DEC, NULL, 0x0,
"Name of the verb", HFILL }},
{ &hf_mgcp_req_endpoint,
{ "Endpoint", "mgcp.req.endpoint", FT_STRING, BASE_DEC, NULL, 0x0,
"Endpoint referenced by the message", HFILL }},
{ &hf_mgcp_transid,
{ "Transaction ID", "mgcp.transid", FT_STRING, BASE_DEC, NULL, 0x0,
"Transaction ID of this message", HFILL }},
{ &hf_mgcp_version,
{ "Version", "mgcp.version", FT_STRING, BASE_DEC, NULL, 0x0,
"MGCP Version", HFILL }},
{ &hf_mgcp_rsp_rspcode,
{ "Response Code", "mgcp.rsp.rspcode", FT_STRING, BASE_DEC, NULL, 0x0,
"Response Code", HFILL }},
{ &hf_mgcp_rsp_rspstring,
{ "Response String", "mgcp.rsp.rspstring", FT_STRING, BASE_DEC, NULL,
0x0, "Response String", HFILL }},
{ &hf_mgcp_param_rspack,
{ "ResponseAck (K)", "mgcp.param.rspack", FT_STRING, BASE_DEC, NULL,
0x0, "Response Ack", HFILL }},
{ &hf_mgcp_param_bearerinfo,
{ "BearerInformation (B)", "mgcp.param.bearerinfo", FT_STRING, BASE_DEC,
NULL, 0x0, "Bearer Information", HFILL }},
{ &hf_mgcp_param_callid,
{ "CallId (C)", "mgcp.param.callid", FT_STRING, BASE_DEC, NULL, 0x0,
"Call Id", HFILL }},
{ &hf_mgcp_param_connectionid,
{"ConnectionIdentifier (I)", "mgcp.param.connectionid", FT_STRING,
BASE_DEC, NULL, 0x0, "Connection Identifier", HFILL }},
{ &hf_mgcp_param_secondconnectionid,
{ "SecondConnectionID (I2)", "mgcp.param.secondconnectionid", FT_STRING,
BASE_DEC, NULL, 0x0, "Second Connection Identifier", HFILL }},
{ &hf_mgcp_param_notifiedentity,
{ "NotifiedEntity (N)", "mgcp.param.notifiedentity", FT_STRING, BASE_DEC,
NULL, 0x0, "Notified Entity", HFILL }},
{ &hf_mgcp_param_requestid,
{ "RequestIdentifier (X)", "mgcp.param.requestid", FT_STRING, BASE_DEC,
NULL, 0x0, "Request Identifier", HFILL }},
{ &hf_mgcp_param_localconnoptions,
{ "LocalConnectionOptions (L)", "mgcp.param.localconnectionoptions",
FT_STRING, BASE_DEC, NULL, 0x0, "Local Connection Options", HFILL }},
{ &hf_mgcp_param_connectionmode,
{ "ConnectionMode (M)", "mgcp.param.connectionmode", FT_STRING, BASE_DEC,
NULL, 0x0, "Connection Mode", HFILL }},
{ &hf_mgcp_param_reqevents,
{ "RequestedEvents (R)", "mgcp.param.reqevents", FT_STRING, BASE_DEC,
NULL, 0x0, "Requested Events", HFILL }},
{ &hf_mgcp_param_signalreq,
{ "SignalRequests (S)", "mgcp.param.signalreq", FT_STRING, BASE_DEC,
NULL, 0x0, "Signal Request", HFILL }},
{ &hf_mgcp_param_restartmethod,
{ "RestartMethod (RM)", "mgcp.param.restartmethod", FT_STRING, BASE_DEC,
NULL, 0x0, "Restart Method", HFILL }},
{ &hf_mgcp_param_restartdelay,
{ "RestartDelay (RD)", "mgcp.param.restartdelay", FT_STRING, BASE_DEC,
NULL, 0x0, "Restart Delay", HFILL }},
{ &hf_mgcp_param_digitmap,
{ "DigitMap (D)", "mgcp.param.digitmap", FT_STRING, BASE_DEC, NULL, 0x0,
"Digit Map", HFILL }},
{ &hf_mgcp_param_observedevent,
{ "ObservedEvents (O)", "mgcp.param.observedevents", FT_STRING,
BASE_DEC, NULL, 0x0, "Observed Events", HFILL }},
{ &hf_mgcp_param_connectionparam,
{ "ConnectionParameters (P)", "mgcp.param.connectionparam", FT_STRING,
BASE_DEC, NULL, 0x0, "Connection Parameters", HFILL }},
{ &hf_mgcp_param_reasoncode,
{ "ReasonCode (E)", "mgcp.param.reasoncode", FT_STRING, BASE_DEC,
NULL, 0x0, "Reason Code", HFILL }},
{ &hf_mgcp_param_eventstates,
{ "EventStates (ES)", "mgcp.param.eventstates", FT_STRING, BASE_DEC,
NULL, 0x0, "Event States", HFILL }},
{ &hf_mgcp_param_specificendpoint,
{ "SpecificEndpointID (Z)", "mgcp.param.specificendpointid", FT_STRING,
BASE_DEC, NULL, 0x0, "Specific Endpoint ID", HFILL }},
{ &hf_mgcp_param_secondendpointid,
{ "SecondEndpointID (Z2)", "mgcp.param.secondendpointid", FT_STRING,
BASE_DEC, NULL, 0x0, "Second Endpoing ID", HFILL }},
{ &hf_mgcp_param_reqinfo,
{ "RequestedInfo (F)", "mgcp.param.reqinfo", FT_STRING, BASE_DEC,
NULL, 0x0,"Requested Info", HFILL }},
{ &hf_mgcp_param_quarantinehandling,
{ "QuarantineHandling (Q)", "mgcp.param.quarantinehandling", FT_STRING,
BASE_DEC, NULL, 0x0, "Quarantine Handling", HFILL }},
{ &hf_mgcp_param_detectedevents,
{ "DetectedEvents (T)", "mgcp.param.detectedevents", FT_STRING, BASE_DEC,
NULL, 0x0, "Detected Events", HFILL }},
{ &hf_mgcp_param_capabilities,
{ "Capabilities (A)", "mgcp.param.capabilities", FT_STRING, BASE_DEC,
NULL, 0x0, "Capabilities", HFILL }},
{ &hf_mgcp_param_extention,
{ "Extention Parameter (X-*)", "mgcp.param.extention", FT_STRING,
BASE_DEC, NULL, 0x0, "Extension Parameter", HFILL }},
{ &hf_mgcp_param_invalid,
{ "Invalid Parameter", "mgcp.param.invalid", FT_STRING,
BASE_DEC, NULL, 0x0, "Invalid Parameter", HFILL }},
{ &hf_mgcp_messagecount,
{ "MGCP Message Count", "mgcp.messagecount", FT_UINT32,
BASE_DEC, NULL, 0x0, "Number of MGCP message in a packet", HFILL }},
/* Add more fields here */
};
static gint *ett[] = {
&ett_mgcp,
&ett_mgcp_param,
};
module_t *mgcp_module;
proto_mgcp = proto_register_protocol("Media Gateway Control Protocol",
"MGCP", "mgcp");
proto_register_field_array(proto_mgcp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
/* Register our configuration options for , particularly our ports */
mgcp_module = prefs_register_protocol(proto_mgcp, proto_reg_handoff_mgcp);
prefs_register_uint_preference(mgcp_module, "tcp.gateway_port",
"MGCP Gateway TCP Port",
"Set the UDP port for gateway messages "
"(if other than the default of 2427)",
10, &global_mgcp_gateway_tcp_port);
prefs_register_uint_preference(mgcp_module, "udp.gateway_port",
"MGCP Gateway UDP Port",
"Set the TCP port for gateway messages "
"(if other than the default of 2427)",
10, &global_mgcp_gateway_udp_port);
prefs_register_uint_preference(mgcp_module, "tcp.callagent_port",
"MGCP Callagent TCP Port",
"Set the TCP port for callagent messages "
"(if other than the default of 2727)",
10, &global_mgcp_callagent_tcp_port);
prefs_register_uint_preference(mgcp_module, "udp.callagent_port",
"MGCP Callagent UDP Port",
"Set the UDP port for callagent messages "
"(if other than the default of 2727)",
10, &global_mgcp_callagent_udp_port);
prefs_register_bool_preference(mgcp_module, "display_raw_text",
"Display raw text for MGCP message",
"Specifies that the raw text of the "
"MGCP message should be displayed "
"instead of (or in addition to) the "
"dissection tree",
&global_mgcp_raw_text);
prefs_register_bool_preference(mgcp_module, "display_dissect_tree",
"Display tree dissection for MGCP message",
"Specifies that the dissection tree of the "
"MGCP message should be displayed "
"instead of (or in addition to) the "
"raw text",
&global_mgcp_dissect_tree);
prefs_register_bool_preference(mgcp_module, "display_mgcp_message_count",
"Display the number of MGCP messages",
"found in a packet in the protocol column.",
&global_mgcp_message_count);
}
/* The registration hand-off routine */
void
proto_reg_handoff_mgcp(void)
{
static int mgcp_prefs_initialized = FALSE;
/*
* Get a handle for the SDP dissector.
*/
sdp_handle = find_dissector("sdp");
if (mgcp_prefs_initialized) {
dissector_delete("tcp.port", gateway_tcp_port, dissect_mgcp);
dissector_delete("udp.port", gateway_udp_port, dissect_mgcp);
dissector_delete("tcp.port", callagent_tcp_port, dissect_mgcp);
dissector_delete("udp.port", callagent_udp_port, dissect_mgcp);
}
else {
mgcp_prefs_initialized = TRUE;
}
/* Set our port number for future use */
gateway_tcp_port = global_mgcp_gateway_tcp_port;
gateway_udp_port = global_mgcp_gateway_udp_port;
callagent_tcp_port = global_mgcp_callagent_tcp_port;
callagent_udp_port = global_mgcp_callagent_udp_port;
dissector_add("tcp.port", global_mgcp_gateway_tcp_port, dissect_mgcp,
proto_mgcp);
dissector_add("udp.port", global_mgcp_gateway_udp_port, dissect_mgcp,
proto_mgcp);
dissector_add("tcp.port", global_mgcp_callagent_tcp_port, dissect_mgcp,
proto_mgcp);
dissector_add("udp.port", global_mgcp_callagent_udp_port, dissect_mgcp,
proto_mgcp);
}
/*
* is_mgcp_verb - A function for determining whether there is a
* MGCP verb at offset in tvb
*
* Parameter:
* tvb - The tvbuff in which we are looking for an MGCP verb
* offset - The offset in tvb at which we are looking for a MGCP verb
* maxlength - The maximum distance from offset we may look for the
* characters that make up a MGCP verb.
*
* Return: TRUE if there is an MGCP verb at offset in tvb, otherwise FALSE
*/
static gboolean is_mgcp_verb(tvbuff_t *tvb, gint offset, gint maxlength){
int returnvalue = FALSE;
guint8 word[5];
if(( maxlength >= 4) && tvb_get_nstringz0(tvb,offset,4,word)){
if (strncasecmp(word, "EPCF", 4) == 0 ||
strncasecmp(word, "CRCX", 4) == 0 ||
strncasecmp(word, "MDCX", 4) == 0 ||
strncasecmp(word, "DLCX", 4) == 0 ||
strncasecmp(word, "RQNT", 4) == 0 ||
strncasecmp(word, "NTFY", 4) == 0 ||
strncasecmp(word, "AUEP", 4) == 0 ||
strncasecmp(word, "AUCX", 4) == 0 ||
strncasecmp(word, "RSIP", 4) == 0 ||
(word[0] == 'X' && is_rfc2234_alpha(word[1]) && is_rfc2234_alpha(word[2]) &&
is_rfc2234_alpha(word[3]))
){
returnvalue = TRUE;
}
}
if( returnvalue && maxlength >= 5 &&
(word[0] = tvb_get_guint8(tvb,4)) != ' ' && word[0] != '\t'){
returnvalue = FALSE;
}
return returnvalue;
}
/*
* is_mgcp_rspcode - A function for determining whether something which
* looks roughly like a MGCP response code is at
* offset in tvb
*
* Parameters:
* tvb - The tvbuff in which we are looking for an MGCP response code
* offset - The offset in tvb at which we are looking for a MGCP response code
* maxlength - The maximum distance from offset we may look for the
* characters that make up a MGCP response code.
*
* Return: TRUE if there is an MGCP response code at offset in tvb,
* otherwise FALSE
*/
static gboolean is_mgcp_rspcode(tvbuff_t *tvb, gint offset, gint maxlength){
int returnvalue = FALSE;
guint8 word[4];
if(maxlength >= 3){
tvb_get_nstringz0(tvb,offset,3,word);
if( isdigit(word[0]) &&
isdigit(word[1]) &&
isdigit(word[2])){
returnvalue = TRUE;
}
}
if( returnvalue && maxlength >= 4 &&
(word[0] = tvb_get_guint8(tvb,3)) != ' ' && word[0] != '\t'){
returnvalue = FALSE;
}
return returnvalue;
}
/*
* is_rfc2234_alpha - Indicates whether the character c is an alphabetical
* character. This function is used instead of
* isalpha because isalpha may deviate from the rfc2234
* definition of ALPHA in some locales.
*
* Parameter:
* c - The character being checked for being an alphabetical character.
*
* Return: TRUE if c is an upper or lower case alphabetical character,
* FALSE otherwise.
*/
static gboolean is_rfc2234_alpha(guint8 c){
int returnvalue = FALSE;
if(( c <= 'Z' && c >= 'A' ) || (c <= 'z' && c >= 'a')){
returnvalue = TRUE;
}
return returnvalue;
}
/*
* tvb_parse_param - Parse the MGCP param into a type and a value.
*
* Parameters:
* tvb - The tvbuff containing the MGCP param we are to parse.
* offset - The offset in tvb at which we will begin looking for a
* MGCP parameter to parse.
* len - The maximum distance from offset in tvb that we can look for
* an MGCP parameter to parse.
* hf - The place to write a pointer to the integer representing the
* header field associated with the MGCP parameter parsed.
*
* Returns: The offset in tvb where the value of the MGCP parameter
* begins.
*/
static gint tvb_parse_param(tvbuff_t* tvb, gint offset, gint len, int** hf){
gint returnvalue, tvb_current_offset,counter;
guint8 tempchar;
tvb_current_offset = offset;
returnvalue = -1;
*hf = NULL;
if(len > 0){
tempchar = tvb_get_guint8(tvb,tvb_current_offset);
switch(tempchar){
case 'K':
*hf = &hf_mgcp_param_rspack;
break;
case 'B':
*hf = &hf_mgcp_param_bearerinfo;
break;
case 'C':
*hf = &hf_mgcp_param_callid;
break;
case 'I':
tvb_current_offset++;
if(len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
*hf = &hf_mgcp_param_connectionid;
tvb_current_offset--;
}
else if ( tempchar == '2'){
*hf = &hf_mgcp_param_secondconnectionid;
}
break;
case 'N':
*hf = &hf_mgcp_param_notifiedentity;
break;
case 'X':
tvb_current_offset++;
if(len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
*hf = &hf_mgcp_param_requestid;
}
else if(len > (tvb_current_offset - offset) && (
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == '-' ||
tempchar == '+')){
tvb_current_offset++;
for(counter = 1;(counter <= 6) && (len > (counter + tvb_current_offset
- offset))
&& ( is_rfc2234_alpha(tempchar =
tvb_get_guint8(tvb,
tvb_current_offset+counter))
|| isdigit(tempchar));counter++);
if(tempchar == ':'){
tvb_current_offset += counter;
*hf = &hf_mgcp_param_extention;
}
}
tvb_current_offset--;
break;
case 'L':
*hf = &hf_mgcp_param_localconnoptions;
break;
case 'M':
*hf = &hf_mgcp_param_connectionmode;
break;
case 'R':
tvb_current_offset++;
if(len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
*hf = &hf_mgcp_param_reqevents;
tvb_current_offset--;
}
else if ( tempchar == 'M'){
*hf = &hf_mgcp_param_restartmethod;
}
else if ( tempchar == 'D'){
*hf = &hf_mgcp_param_restartdelay;
}
break;
case 'S':
*hf = &hf_mgcp_param_signalreq;
break;
case 'D':
*hf = &hf_mgcp_param_digitmap;
break;
case 'O':
*hf = &hf_mgcp_param_observedevent;
break;
case 'P':
*hf = &hf_mgcp_param_connectionparam;
break;
case 'E':
tvb_current_offset++;
if(len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
*hf = &hf_mgcp_param_reasoncode;
tvb_current_offset--;
}
else if ( tempchar == 'S'){
*hf = &hf_mgcp_param_eventstates;
}
break;
case 'Z':
tvb_current_offset++;
if(len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
*hf = &hf_mgcp_param_specificendpoint;
tvb_current_offset--;
}
else if ( tempchar == '2'){
*hf = &hf_mgcp_param_secondendpointid;
}
break;
case 'F':
*hf = &hf_mgcp_param_reqinfo;
break;
case 'Q':
*hf = &hf_mgcp_param_quarantinehandling;
break;
case 'T':
*hf = &hf_mgcp_param_detectedevents;
break;
case 'A':
*hf = &hf_mgcp_param_capabilities;
break;
default:
*hf = &hf_mgcp_param_invalid;
break;
}
tvb_current_offset++;
if(*hf != NULL && len > (tvb_current_offset - offset) &&
(tempchar = tvb_get_guint8(tvb,tvb_current_offset)) == ':'){
tvb_current_offset++;
tvb_current_offset = tvb_skip_wsp(tvb,tvb_current_offset,
(len - tvb_current_offset + offset));
returnvalue = tvb_current_offset;
}
else {
*hf = &hf_mgcp_param_invalid;
}
}
else{
*hf = &hf_mgcp_param_invalid;
}
if(*hf == &hf_mgcp_param_invalid){
returnvalue = offset;
}
return returnvalue;
}
/*
* dissect_mgcp_firstline - Dissects the firstline of an MGCP message.
* Adds the appropriate headers fields to
* tree for the dissection of the first line
* of an MGCP message.
*
* Parameters:
* tvb - The tvb containing the first line of an MGCP message. This
* tvb is presumed to ONLY contain the first line of the MGCP
* message.
* pinfo - The packet info for the packet. This is not really used
* by this function but is passed through so as to retain the
* style of a dissector.
* tree - The tree from which to hang the structured information parsed
* from the first line of the MGCP message.
*/
static void dissect_mgcp_firstline(tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree){
gint tvb_current_offset,tvb_previous_offset,tvb_len,tvb_current_len;
gint tokennum, tokenlen;
mgcp_type_t mgcp_type = MGCP_OTHERS;
proto_item* (*my_proto_tree_add_string)(proto_tree*, int, tvbuff_t*, gint,
gint, const char*);
tvb_previous_offset = 0;
tvb_len = tvb_length(tvb);
tvb_current_len = tvb_len;
tvb_current_offset = tvb_previous_offset;
if(tree){
tokennum = 0;
if(global_mgcp_dissect_tree){
my_proto_tree_add_string = proto_tree_add_string;
}
else{
my_proto_tree_add_string = proto_tree_add_string_hidden;
}
do {
tvb_current_len = tvb_length_remaining(tvb,tvb_previous_offset);
tvb_current_offset = tvb_find_guint8(tvb, tvb_previous_offset,
tvb_current_len, ' ');
if(tvb_current_offset == -1){
tvb_current_offset = tvb_len;
tokenlen = tvb_current_len;
}
else{
tokenlen = tvb_current_offset - tvb_previous_offset;
}
if(tokennum == 0){
if(is_mgcp_verb(tvb,tvb_previous_offset,tvb_current_len)){
mgcp_type = MGCP_REQUEST;
my_proto_tree_add_string(tree,hf_mgcp_req_verb, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb,tvb_previous_offset
,tokenlen));
}
else if (is_mgcp_rspcode(tvb,tvb_previous_offset,tvb_current_len)){
mgcp_type = MGCP_RESPONSE;
my_proto_tree_add_string(tree,hf_mgcp_rsp_rspcode, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb,tvb_previous_offset
,tokenlen));
}
else {
break;
}
}
if(tokennum == 1){
my_proto_tree_add_string(tree,hf_mgcp_transid, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb,tvb_previous_offset,
tokenlen));
}
if(tokennum == 2){
if(mgcp_type == MGCP_REQUEST){
my_proto_tree_add_string(tree,hf_mgcp_req_endpoint, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb, tvb_previous_offset,
tokenlen));
}
else if(mgcp_type == MGCP_RESPONSE){
if(tvb_current_offset < tvb_len){
tokenlen = tvb_find_line_end(tvb, tvb_previous_offset,
-1,&tvb_current_offset);
}
else{
tokenlen = tvb_current_len;
}
my_proto_tree_add_string(tree, hf_mgcp_rsp_rspstring, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb, tvb_previous_offset,
tokenlen));
break;
}
}
if( (tokennum == 3 && mgcp_type == MGCP_REQUEST) ){
if(tvb_current_offset < tvb_len ){
tokenlen = tvb_find_line_end(tvb, tvb_previous_offset,
-1,&tvb_current_offset);
}
else{
tokenlen = tvb_current_len;
}
my_proto_tree_add_string(tree,hf_mgcp_version, tvb,
tvb_previous_offset, tokenlen,
tvb_format_text(tvb,tvb_previous_offset,
tokenlen));
break;
}
if(tvb_current_offset < tvb_len){
tvb_previous_offset = tvb_skip_wsp(tvb, tvb_current_offset,
tvb_current_len);
}
tokennum++;
} while( tvb_current_offset < tvb_len && tvb_previous_offset < tvb_len
&& tokennum <= 3);
switch (mgcp_type){
case MGCP_RESPONSE:
proto_tree_add_boolean_hidden(tree, hf_mgcp_rsp, tvb, 0, 0, TRUE);
break;
case MGCP_REQUEST:
proto_tree_add_boolean_hidden(tree, hf_mgcp_req, tvb, 0, 0, TRUE);
break;
default:
break;
}
}
}
/*
* dissect_mgcp_params - Dissects the parameters of an MGCP message.
* Adds the appropriate headers fields to
* tree for the dissection of the parameters
* of an MGCP message.
*
* Parameters:
* tvb - The tvb containing the parameters of an MGCP message. This
* tvb is presumed to ONLY contain the part of the MGCP
* message which contains the MGCP parameters.
* pinfo - The packet info for the packet. This is not really used
* by this function but is passed through so as to retain the
* style of a dissector.
* tree - The tree from which to hang the structured information parsed
* from the parameters of the MGCP message.
*/
static void dissect_mgcp_params(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree){
int linelen, tokenlen, *my_param;
gint tvb_lineend,tvb_current_len, tvb_linebegin,tvb_len;
gint tvb_tokenbegin;
proto_tree *mgcp_param_ti, *mgcp_param_tree;
proto_item* (*my_proto_tree_add_string)(proto_tree*, int, tvbuff_t*, gint,
gint, const char*);
tvb_len = tvb_length(tvb);
tvb_linebegin = 0;
tvb_current_len = tvb_length_remaining(tvb,tvb_linebegin);
tvb_lineend = tvb_linebegin;
if(tree){
if(global_mgcp_dissect_tree){
my_proto_tree_add_string = proto_tree_add_string;
mgcp_param_ti = proto_tree_add_item(tree, proto_mgcp, tvb,
tvb_linebegin, tvb_len, FALSE);
proto_item_set_text(mgcp_param_ti, "Parameters");
mgcp_param_tree = proto_item_add_subtree(mgcp_param_ti, ett_mgcp_param);
}
else{
my_proto_tree_add_string = proto_tree_add_string_hidden;
mgcp_param_tree = tree;
mgcp_param_ti = NULL;
}
/* Parse the parameters */
while(tvb_lineend < tvb_len){
linelen = tvb_find_line_end(tvb, tvb_linebegin, -1,&tvb_lineend);
tvb_tokenbegin = tvb_parse_param(tvb, tvb_linebegin, linelen,
&my_param);
if( my_param != NULL ){
tokenlen = tvb_find_line_end(tvb,tvb_tokenbegin,-1,&tvb_lineend);
my_proto_tree_add_string(mgcp_param_tree,*my_param, tvb,
tvb_linebegin, linelen,
tvb_format_text(tvb,tvb_tokenbegin,
tokenlen));
}
tvb_linebegin = tvb_lineend;
}
}
}
/*
* tvb_skip_wsp - Returns the position in tvb of the first non-whitespace
* character following offset or offset + maxlength -1 whichever
* is smaller.
*
* Parameters:
* tvb - The tvbuff in which we are skipping whitespace.
* offset - The offset in tvb from which we begin trying to skip whitespace.
* maxlength - The maximum distance from offset that we may try to skip
* whitespace.
*
* Returns: The position in tvb of the first non-whitespace
* character following offset or offset + maxlength -1 whichever
* is smaller.
*/
static gint tvb_skip_wsp(tvbuff_t* tvb, gint offset, gint maxlength){
gint counter = offset;
gint end = offset + maxlength,tvb_len;
guint8 tempchar;
tvb_len = tvb_length(tvb);
end = offset + maxlength;
if(end >= tvb_len){
end = tvb_len;
}
for(counter = offset; counter < end &&
((tempchar = tvb_get_guint8(tvb,counter)) == ' ' ||
tempchar == '\t');counter++);
return (counter);
}
/*
* tvb_find_null_line - Returns the length from offset to the first null
* line found (a null line is a line that begins
* with a CR or LF. The offset to the first character
* after the null line is written into the gint pointed
* to by next_offset.
*
* Parameters:
* tvb - The tvbuff in which we are looking for a null line.
* offset - The offset in tvb at which we will begin looking for
* a null line.
* len - The maximum distance from offset in tvb that we will look for
* a null line. If it is -1 we will look to the end of the buffer.
*
* next_offset - The location to write the offset of first character
* FOLLOWING the null line.
*
* Returns: The length from offset to the first character BEFORE
* the null line..
*/
static gint tvb_find_null_line(tvbuff_t* tvb, gint offset,
gint len, gint* next_offset){
gint tvb_lineend,tvb_current_len,tvb_linebegin,maxoffset;
guint tempchar;
tvb_linebegin = offset;
tvb_lineend = tvb_linebegin;
/* Simple setup to allow for the traditional -1 search to the end
* of the tvbuff
*/
if(len != -1){
tvb_current_len = len;
}
else{
tvb_current_len = tvb_length_remaining(tvb,offset);
}
maxoffset = (tvb_current_len - 1) + offset;
/*
* Loop around until we either find a line begining with a carriage return
* or newline character or until we hit the end of the tvbuff.
*/
do {
tvb_linebegin = tvb_lineend;
tvb_current_len = tvb_length_remaining(tvb,tvb_linebegin);
tvb_find_line_end(tvb, tvb_linebegin, tvb_current_len, &tvb_lineend);
tempchar = tvb_get_guint8(tvb,tvb_linebegin);
}
while( tempchar != '\r' && tempchar != '\n' &&
tvb_lineend <= maxoffset);
*next_offset = tvb_lineend;
if( tvb_lineend <= maxoffset ) {
tvb_current_len = tvb_linebegin - offset;
}
else {
tvb_current_len = tvb_length_remaining(tvb,offset);
}
return (tvb_current_len);
}
/*
* tvb_find_dot_line - Returns the length from offset to the first line
* containing only a dot (.) character. A line
* containing only a dot is used to indicate a
* separation between multiple MGCP messages
* piggybacked in the same UDP packet.
*
* Parameters:
* tvb - The tvbuff in which we are looking for a dot line.
* offset - The offset in tvb at which we will begin looking for
* a dot line.
* len - The maximum distance from offset in tvb that we will look for
* a dot line. If it is -1 we will look to the end of the buffer.
*
* next_offset - The location to write the offset of first character
* FOLLOWING the dot line.
*
* Returns: The length from offset to the first character BEFORE
* the dot line or -1 if the character at offset is a .
* followed by a newline or a carriage return.
*/
static gint tvb_find_dot_line(tvbuff_t* tvb, gint offset,
gint len, gint* next_offset){
gint tvb_current_offset, tvb_current_len, maxoffset,tvb_len;
guint8 tempchar;
tvb_current_offset = offset;
tvb_current_len = len;
tvb_len = tvb_length(tvb);
if(len == -1){
maxoffset = ( tvb_len - 1 );
}
else {
maxoffset = (len - 1 ) + offset;
}
tvb_current_offset = offset -1;
do {
tvb_current_offset = tvb_find_guint8(tvb, tvb_current_offset+1,
tvb_current_len, '.');
tvb_current_len = maxoffset - tvb_current_offset + 1;
/*
* if we didn't find a . then break out of the loop
*/
if(tvb_current_offset == -1){
break;
}
/* do we have and characters following the . ? */
if( tvb_current_offset < maxoffset ) {
tempchar = tvb_get_guint8(tvb,tvb_current_offset+1);
/*
* are the characters that follow the dot a newline or carriage return ?
*/
if(tempchar == '\r' || tempchar == '\n'){
/*
* do we have any charaters that proceed the . ?
*/
if( tvb_current_offset == 0 ){
break;
}
else {
tempchar = tvb_get_guint8(tvb,tvb_current_offset-1);
/*
* are the characters that follow the dot a newline or a carriage
* return ?
*/
if(tempchar == '\r' || tempchar == '\n'){
break;
}
}
}
}
else if ( tvb_current_offset == maxoffset ) {
if( tvb_current_offset == 0 ){
break;
}
else {
tempchar = tvb_get_guint8(tvb,tvb_current_offset-1);
if(tempchar == '\r' || tempchar == '\n'){
break;
}
}
}
} while (tvb_current_offset < maxoffset);
/*
* so now we either have the tvb_current_offset of a . in a dot line
* or a tvb_current_offset of -1
*/
if(tvb_current_offset == -1){
tvb_current_offset = maxoffset +1;
*next_offset = maxoffset + 1;
}
else {
tvb_find_line_end(tvb,tvb_current_offset,tvb_current_len,next_offset);
}
if( tvb_current_offset == offset ){
tvb_current_len = -1;
}
else {
tvb_current_len = tvb_current_offset - offset;
}
return tvb_current_len;
}
/* Start the functions we need for the plugin stuff */
#ifndef __ETHEREAL_STATIC__
G_MODULE_EXPORT void
plugin_reg_handoff(void){
proto_reg_handoff_mgcp();
}
G_MODULE_EXPORT void
plugin_init(plugin_address_table_t *pat){
/* initialise the table of pointers needed in Win32 DLLs */
plugin_address_table_init(pat);
/* register the new protocol, protocol fields, and subtrees */
if (proto_mgcp == -1) { /* execute protocol initialization only once */
proto_register_mgcp();
}
}
#endif
/* End the functions we need for plugin stuff */
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