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Diffstat (limited to 'epan/dissectors/packet-isdn.c')
-rw-r--r-- | epan/dissectors/packet-isdn.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/epan/dissectors/packet-isdn.c b/epan/dissectors/packet-isdn.c new file mode 100644 index 00000000..c1344929 --- /dev/null +++ b/epan/dissectors/packet-isdn.c @@ -0,0 +1,260 @@ +/* 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: + */ |