8195bdd340
A conversation in Wireshark might have two endpoints or might have no endpoints; few if any have one endpoint. Distinguish between conversations and endpoints.
261 lines
6.3 KiB
C
261 lines
6.3 KiB
C
/* packet-isdn.c
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* Routines for ISDN packet disassembly
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/prefs.h>
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#include <wiretap/wtap.h>
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#include <epan/conversation.h>
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void proto_register_isdn(void);
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void proto_reg_handoff_isdn(void);
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static int proto_isdn = -1;
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static int hf_isdn_direction = -1;
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static int hf_isdn_channel = -1;
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static gint ett_isdn = -1;
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static dissector_handle_t isdn_handle;
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/*
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* Protocol used on the D channel.
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*/
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#define DCHANNEL_LAPD 0 /* LAPD */
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#define DCHANNEL_DPNSS 1 /* DPNSS link layer */
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static const enum_val_t dchannel_protocol_options[] = {
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{ "lapd", "LAPD", DCHANNEL_LAPD },
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{ "DPNSS", "DPNSS", DCHANNEL_DPNSS },
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{ NULL, NULL, 0 }
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};
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static int dchannel_protocol = DCHANNEL_LAPD;
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static dissector_handle_t lapd_phdr_handle;
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static dissector_handle_t dpnss_link_handle;
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static dissector_handle_t ppp_hdlc_handle;
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static dissector_handle_t v120_handle;
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static const true_false_string isdn_direction_tfs = {
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"User->Network",
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"Network->User"
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};
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static const value_string channel_vals[] = {
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{ 0, "D" },
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{ 1, "B1" },
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{ 2, "B2" },
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{ 3, "B3" },
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{ 4, "B4" },
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{ 5, "B5" },
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{ 6, "B6" },
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{ 7, "B7" },
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{ 8, "B8" },
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{ 9, "B9" },
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{ 10, "B10" },
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{ 11, "B11" },
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{ 12, "B12" },
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{ 13, "B13" },
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{ 14, "B14" },
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{ 15, "B15" },
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{ 16, "B16" },
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{ 17, "B17" },
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{ 18, "B18" },
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{ 19, "B19" },
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{ 20, "B20" },
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{ 21, "B21" },
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{ 22, "B22" },
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{ 23, "B23" },
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{ 24, "B24" },
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{ 25, "B25" },
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{ 26, "B26" },
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{ 27, "B27" },
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{ 28, "B28" },
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{ 29, "B29" },
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{ 30, "B30" },
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{ 0, NULL }
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};
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static int
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dissect_isdn(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
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{
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struct isdn_phdr *isdn = (struct isdn_phdr *)data;
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proto_tree *isdn_tree;
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proto_item *ti;
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static const guint8 v120_sabme[3] = { 0x08, 0x01, 0x7F };
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static const guint8 ppp[2] = { 0xFF, 0x03 };
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conversation_t *conv;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "ISDN");
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if (isdn->uton) {
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "Network");
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "User");
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pinfo->p2p_dir = P2P_DIR_SENT;
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} else {
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "User");
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "Network");
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pinfo->p2p_dir = P2P_DIR_RECV;
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}
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if (tree) {
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ti = proto_tree_add_item(tree, proto_isdn, tvb, 0, 0, ENC_NA);
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isdn_tree = proto_item_add_subtree(ti, ett_isdn);
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proto_tree_add_boolean(isdn_tree, hf_isdn_direction, tvb, 0, 0,
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isdn->uton);
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proto_tree_add_uint(isdn_tree, hf_isdn_channel, tvb, 0, 0,
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isdn->channel);
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}
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/*
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* Set up a circuit for this channel, and assign it a dissector.
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*/
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conv = find_or_create_conversation_by_id(pinfo, CONVERSATION_ISDN,
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isdn->channel);
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if (conversation_get_dissector(conv, 0) == NULL) {
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/*
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* We don't yet know the type of traffic on the circuit.
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*/
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switch (isdn->channel) {
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case 0:
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/*
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* D-channel. Dissect it with whatever protocol
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* the user specified, or the default of LAPD if
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* they didn't specify one.
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*/
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switch (dchannel_protocol) {
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case DCHANNEL_LAPD:
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conversation_set_dissector(conv, lapd_phdr_handle);
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break;
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case DCHANNEL_DPNSS:
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conversation_set_dissector(conv,
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dpnss_link_handle);
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break;
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}
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break;
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default:
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/*
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* B-channel.
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*
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* We don't know yet whether the datastream is
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* V.120 or not; this heuristic tries to figure
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* that out.
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*
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* We cannot glean this from the Q.931 SETUP message,
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* because no commercial V.120 implementation I've
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* seen actually sets the V.120 protocol discriminator
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* (that, or I'm misreading the spec badly).
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*
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* TODO: close the circuit after a close on the B
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* channel is detected.
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*
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* -Bert Driehuis (from the i4btrace reader;
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* this heuristic was moved from there to
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* here)
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*
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* XXX - I don't know that one can guarantee that
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* the SABME will appear in the first frame on
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* the channels, so we probably can't just say
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* "it must be PPP" if we don't immediately see
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* the V.120 SABME frame, so we do so only if
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* we see the 0xFF 0x03. Unfortunately, that
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* won't do the right thing if the PPP-over-HDLC
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* headers aren't being used....
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*/
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if (tvb_memeql(tvb, 0, v120_sabme, 3) == 0) {
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/*
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* We assume this is V.120.
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*/
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conversation_set_dissector(conv, v120_handle);
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} else if (tvb_memeql(tvb, 0, ppp, 2) == 0) {
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/*
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* We assume this is PPP.
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*/
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conversation_set_dissector(conv, ppp_hdlc_handle);
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}
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break;
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}
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}
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if (!try_conversation_dissector_by_id(CONVERSATION_ISDN, isdn->channel,
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tvb, pinfo, tree, data))
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call_data_dissector(tvb, pinfo, tree);
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return tvb_captured_length(tvb);
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}
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void
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proto_register_isdn(void)
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{
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static hf_register_info hf[] = {
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{ &hf_isdn_direction,
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{ "Direction", "isdn.direction", FT_BOOLEAN, BASE_NONE,
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TFS(&isdn_direction_tfs), 0x0, NULL, HFILL }},
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{ &hf_isdn_channel,
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{ "Channel", "isdn.channel", FT_UINT8, BASE_DEC,
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VALS(channel_vals), 0x0, NULL, HFILL }},
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};
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static gint *ett[] = {
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&ett_isdn,
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};
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module_t *isdn_module;
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proto_isdn = proto_register_protocol("ISDN", "ISDN", "isdn");
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proto_register_field_array(proto_isdn, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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isdn_module = prefs_register_protocol(proto_isdn, NULL);
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prefs_register_enum_preference(isdn_module, "dchannel_protocol",
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"D-channel protocol",
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"The protocol running on the D channel",
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&dchannel_protocol, dchannel_protocol_options, FALSE);
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isdn_handle = register_dissector("isdn", dissect_isdn, proto_isdn);
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}
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void
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proto_reg_handoff_isdn(void)
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{
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/*
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* Get handles for the LAPD-with-pseudoheader, DPNSS link-layer,
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* PPP, and V.120 dissectors.
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*/
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lapd_phdr_handle = find_dissector("lapd-phdr");
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dpnss_link_handle = find_dissector("dpnss_link");
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ppp_hdlc_handle = find_dissector("ppp_hdlc");
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v120_handle = find_dissector("v120");
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dissector_add_uint("wtap_encap", WTAP_ENCAP_ISDN, isdn_handle);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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