/* packet-isdn.c * Routines for ISDN packet disassembly * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include #include #include void proto_register_isdn(void); void proto_reg_handoff_isdn(void); static int proto_isdn; static int hf_isdn_direction; static int hf_isdn_channel; static gint ett_isdn; 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: */