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/* packet-isdn.c
* Routines for ISDN packet disassembly
*
* 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/prefs.h>
#include <wiretap/wtap.h>
#include <epan/conversation.h>
void proto_register_isdn(void);
void proto_reg_handoff_isdn(void);
static int proto_isdn = -1;
static int hf_isdn_direction = -1;
static int hf_isdn_channel = -1;
static gint ett_isdn = -1;
static dissector_handle_t isdn_handle;
/*
* Protocol used on the D channel.
*/
#define DCHANNEL_LAPD 0 /* LAPD */
#define DCHANNEL_DPNSS 1 /* DPNSS link layer */
static const enum_val_t dchannel_protocol_options[] = {
{ "lapd", "LAPD", DCHANNEL_LAPD },
{ "DPNSS", "DPNSS", DCHANNEL_DPNSS },
{ NULL, NULL, 0 }
};
static int dchannel_protocol = DCHANNEL_LAPD;
static dissector_handle_t lapd_phdr_handle;
static dissector_handle_t dpnss_link_handle;
static dissector_handle_t ppp_hdlc_handle;
static dissector_handle_t v120_handle;
static const true_false_string isdn_direction_tfs = {
"User->Network",
"Network->User"
};
static const value_string channel_vals[] = {
{ 0, "D" },
{ 1, "B1" },
{ 2, "B2" },
{ 3, "B3" },
{ 4, "B4" },
{ 5, "B5" },
{ 6, "B6" },
{ 7, "B7" },
{ 8, "B8" },
{ 9, "B9" },
{ 10, "B10" },
{ 11, "B11" },
{ 12, "B12" },
{ 13, "B13" },
{ 14, "B14" },
{ 15, "B15" },
{ 16, "B16" },
{ 17, "B17" },
{ 18, "B18" },
{ 19, "B19" },
{ 20, "B20" },
{ 21, "B21" },
{ 22, "B22" },
{ 23, "B23" },
{ 24, "B24" },
{ 25, "B25" },
{ 26, "B26" },
{ 27, "B27" },
{ 28, "B28" },
{ 29, "B29" },
{ 30, "B30" },
{ 0, NULL }
};
static int
dissect_isdn(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
struct isdn_phdr *isdn = (struct isdn_phdr *)data;
proto_tree *isdn_tree;
proto_item *ti;
static const guint8 v120_sabme[3] = { 0x08, 0x01, 0x7F };
static const guint8 ppp[2] = { 0xFF, 0x03 };
conversation_t *conv;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "ISDN");
if (isdn->uton) {
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "Network");
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "User");
pinfo->p2p_dir = P2P_DIR_SENT;
} else {
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "User");
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "Network");
pinfo->p2p_dir = P2P_DIR_RECV;
}
if (tree) {
ti = proto_tree_add_item(tree, proto_isdn, tvb, 0, 0, ENC_NA);
isdn_tree = proto_item_add_subtree(ti, ett_isdn);
proto_tree_add_boolean(isdn_tree, hf_isdn_direction, tvb, 0, 0,
isdn->uton);
proto_tree_add_uint(isdn_tree, hf_isdn_channel, tvb, 0, 0,
isdn->channel);
}
/*
* Set up a circuit for this channel, and assign it a dissector.
*/
conv = find_or_create_conversation_by_id(pinfo, CONVERSATION_ISDN,
isdn->channel);
if (conversation_get_dissector(conv, 0) == NULL) {
/*
* We don't yet know the type of traffic on the circuit.
*/
switch (isdn->channel) {
case 0:
/*
* D-channel. Dissect it with whatever protocol
* the user specified, or the default of LAPD if
* they didn't specify one.
*/
switch (dchannel_protocol) {
case DCHANNEL_LAPD:
conversation_set_dissector(conv, lapd_phdr_handle);
break;
case DCHANNEL_DPNSS:
conversation_set_dissector(conv,
dpnss_link_handle);
break;
}
break;
default:
/*
* B-channel.
*
* We don't know yet whether the datastream is
* V.120 or not; this heuristic tries to figure
* that out.
*
* We cannot glean this from the Q.931 SETUP message,
* because no commercial V.120 implementation I've
* seen actually sets the V.120 protocol discriminator
* (that, or I'm misreading the spec badly).
*
* TODO: close the circuit after a close on the B
* channel is detected.
*
* -Bert Driehuis (from the i4btrace reader;
* this heuristic was moved from there to
* here)
*
* XXX - I don't know that one can guarantee that
* the SABME will appear in the first frame on
* the channels, so we probably can't just say
* "it must be PPP" if we don't immediately see
* the V.120 SABME frame, so we do so only if
* we see the 0xFF 0x03. Unfortunately, that
* won't do the right thing if the PPP-over-HDLC
* headers aren't being used....
*/
if (tvb_memeql(tvb, 0, v120_sabme, 3) == 0) {
/*
* We assume this is V.120.
*/
conversation_set_dissector(conv, v120_handle);
} else if (tvb_memeql(tvb, 0, ppp, 2) == 0) {
/*
* We assume this is PPP.
*/
conversation_set_dissector(conv, ppp_hdlc_handle);
}
break;
}
}
if (!try_conversation_dissector_by_id(CONVERSATION_ISDN, isdn->channel,
tvb, pinfo, tree, data))
call_data_dissector(tvb, pinfo, tree);
return tvb_captured_length(tvb);
}
void
proto_register_isdn(void)
{
static hf_register_info hf[] = {
{ &hf_isdn_direction,
{ "Direction", "isdn.direction", FT_BOOLEAN, BASE_NONE,
TFS(&isdn_direction_tfs), 0x0, NULL, HFILL }},
{ &hf_isdn_channel,
{ "Channel", "isdn.channel", FT_UINT8, BASE_DEC,
VALS(channel_vals), 0x0, NULL, HFILL }},
};
static gint *ett[] = {
&ett_isdn,
};
module_t *isdn_module;
proto_isdn = proto_register_protocol("ISDN", "ISDN", "isdn");
proto_register_field_array(proto_isdn, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
isdn_module = prefs_register_protocol(proto_isdn, NULL);
prefs_register_enum_preference(isdn_module, "dchannel_protocol",
"D-channel protocol",
"The protocol running on the D channel",
&dchannel_protocol, dchannel_protocol_options, FALSE);
isdn_handle = register_dissector("isdn", dissect_isdn, proto_isdn);
}
void
proto_reg_handoff_isdn(void)
{
/*
* Get handles for the LAPD-with-pseudoheader, DPNSS link-layer,
* PPP, and V.120 dissectors.
*/
lapd_phdr_handle = find_dissector("lapd-phdr");
dpnss_link_handle = find_dissector("dpnss_link");
ppp_hdlc_handle = find_dissector("ppp_hdlc");
v120_handle = find_dissector("v120");
dissector_add_uint("wtap_encap", WTAP_ENCAP_ISDN, isdn_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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