/* packet-ehdlc.c * Routines for packet dissection of Ericsson HDLC as used in A-bis over IP * Copyright 2010-2012 by Harald Welte * * This code is based on pure educational guesses while looking at protocol * traces, as there is no publicly available protocol description by Ericsson. * Even the name is a guess, since it looks quite a bit like HDLC and is used * by Ericsson, I called it EHDLC. * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "config.h" #include #include #include "packet-l2tp.h" void proto_register_ehdlc(void); void proto_reg_handoff_ehdlc(void); /* Initialize the protocol and registered fields */ static int proto_ehdlc = -1; static int hf_ehdlc_data_len = -1; static int hf_ehdlc_protocol = -1; /* static int hf_ehdlc_sapi = -1; */ /* static int hf_ehdlc_c_r = -1; */ static int hf_ehdlc_xid_payload = -1; static int hf_ehdlc_control = -1; static int hf_ehdlc_p = -1; static int hf_ehdlc_f = -1; static int hf_ehdlc_u_modifier_cmd = -1; static int hf_ehdlc_u_modifier_resp = -1; static int hf_ehdlc_ftype_s_u = -1; static int hf_ehdlc_n_r = -1; static int hf_ehdlc_n_s = -1; static int hf_ehdlc_p_ext = -1; static int hf_ehdlc_f_ext = -1; static int hf_ehdlc_s_ftype = -1; static int hf_ehdlc_ftype_i = -1; static int hf_ehdlc_ftype_s_u_ext = -1; static dissector_handle_t ehdlc_handle; /* Used only for U frames */ static const xdlc_cf_items ehdlc_cf_items = { NULL, NULL, &hf_ehdlc_p, &hf_ehdlc_f, NULL, &hf_ehdlc_u_modifier_cmd, &hf_ehdlc_u_modifier_resp, NULL, &hf_ehdlc_ftype_s_u }; /* Used only for I and S frames */ static const xdlc_cf_items ehdlc_cf_items_ext = { &hf_ehdlc_n_r, &hf_ehdlc_n_s, &hf_ehdlc_p_ext, &hf_ehdlc_f_ext, &hf_ehdlc_s_ftype, NULL, NULL, &hf_ehdlc_ftype_i, &hf_ehdlc_ftype_s_u_ext, }; /* Initialize the subtree pointers */ static gint ett_ehdlc = -1; static gint ett_ehdlc_control = -1; static const value_string ehdlc_protocol_vals[] = { { 0x20, "RSL" }, { 0xa0, "ACK" }, { 0xc0, "OML" }, { 0, NULL } }; enum { SUB_RSL, SUB_OML, SUB_DATA, SUB_MAX }; static dissector_handle_t sub_handles[SUB_MAX]; /* Code to actually dissect the packets */ static int dissect_ehdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) { int offset = 4; col_set_str(pinfo->cinfo, COL_PROTOCOL, "EHDLC"); col_clear(pinfo->cinfo, COL_INFO); while (tvb_reported_length_remaining(tvb, offset) > 0) { proto_item *ti = NULL; proto_tree *ehdlc_tree = NULL; guint16 len, msg_type; tvbuff_t *next_tvb; guint16 control; gboolean is_response = FALSE, is_extended = TRUE; gint header_length = 2; /* Address + Length field */ msg_type = tvb_get_guint8(tvb, offset); len = tvb_get_guint8(tvb, offset+1); #if 0 col_append_fstr(pinfo->cinfo, COL_INFO, "%s ", val_to_str(msg_type, ehdlc_protocol_vals, "unknown 0x%02x")); #endif if (tree) { /* Use MIN(...,...) in the following to prevent a premature */ /* exception before we try to dissect whatever is available. */ ti = proto_tree_add_protocol_format(tree, proto_ehdlc, tvb, offset, MIN(len, tvb_captured_length_remaining(tvb,offset)), "Ericsson HDLC protocol, type: %s", val_to_str(msg_type, ehdlc_protocol_vals, "unknown 0x%02x")); ehdlc_tree = proto_item_add_subtree(ti, ett_ehdlc); proto_tree_add_item(ehdlc_tree, hf_ehdlc_protocol, tvb, offset, 1, ENC_BIG_ENDIAN); #if 0 proto_tree_add_item(ehdlc_tree, hf_ehdlc_sapi, tvb, offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(ehdlc_tree, hf_ehdlc_c_r, tvb, offset, 1, ENC_BIG_ENDIAN); #endif proto_tree_add_item(ehdlc_tree, hf_ehdlc_data_len, tvb, offset+1, 1, ENC_BIG_ENDIAN); } control = dissect_xdlc_control(tvb, offset+2, pinfo, ehdlc_tree, hf_ehdlc_control, ett_ehdlc_control, &ehdlc_cf_items, &ehdlc_cf_items_ext, NULL, NULL, is_response, is_extended, FALSE); header_length += XDLC_CONTROL_LEN(control, is_extended); if (XDLC_IS_INFORMATION(control)) { next_tvb = tvb_new_subset_length(tvb, offset+header_length, len-header_length); switch (msg_type) { case 0x20: /* len == 4 seems to be some kind of ACK */ if (len <= 4) break; call_dissector(sub_handles[SUB_RSL], next_tvb, pinfo, tree); break; case 0xbc: case 0xdc: case 0xa0: case 0xc0: /* len == 4 seems to be some kind of ACK */ if (len <= 4) break; call_dissector(sub_handles[SUB_OML], next_tvb, pinfo, tree); break; default: call_dissector(sub_handles[SUB_DATA], next_tvb, pinfo, tree); break; } } else if (control == (XDLC_U | XDLC_XID)) { /* XID is formatted like ISO 8885, typically we see * something like * 82 format identifier * 80 group identifier * 00 09 length * 07 01 05 Window Size Tx * 09 01 04 Ack Timer (msec) * 08 01 05 Window Size Rx */ proto_tree_add_item(ehdlc_tree, hf_ehdlc_xid_payload, tvb, offset+header_length, len-header_length, ENC_NA); } if (len == 0) len = 1; offset += len; } return tvb_captured_length(tvb); } void proto_register_ehdlc(void) { static hf_register_info hf[] = { { &hf_ehdlc_data_len, { "DataLen", "ehdlc.data_len", FT_UINT8, BASE_DEC, NULL, 0x0, "The length of the data (in bytes)", HFILL } }, { &hf_ehdlc_protocol, { "Protocol", "ehdlc.protocol", FT_UINT8, BASE_HEX, VALS(ehdlc_protocol_vals), 0x0, "The HDLC Sub-Protocol", HFILL } }, #if 0 { &hf_ehdlc_sapi, { "SAPI", "ehdlc.sapi", FT_UINT8, BASE_DEC, NULL, 0x1f, NULL, HFILL } }, { &hf_ehdlc_c_r, { "C/R", "ehdlc.c_r", FT_UINT8, BASE_HEX, NULL, 0x20, NULL, HFILL } }, #endif { &hf_ehdlc_xid_payload, { "XID Payload", "ehdlc.xid_payload", FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_ehdlc_control, { "Control Field", "ehdlc.control", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_ehdlc_n_r, { "N(R)", "ehdlc.control.n_r", FT_UINT16, BASE_DEC, NULL, XDLC_N_R_EXT_MASK, NULL, HFILL } }, { &hf_ehdlc_n_s, { "N(S)", "ehdlc.control.n_s", FT_UINT16, BASE_DEC, NULL, XDLC_N_S_EXT_MASK, NULL, HFILL } }, { &hf_ehdlc_p, { "Poll", "ehdlc.control.p", FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL } }, { &hf_ehdlc_p_ext, { "Poll", "ehdlc.control.p", FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL } }, { &hf_ehdlc_f, { "Final", "ehdlc.control.f", FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL } }, { &hf_ehdlc_f_ext, { "Final", "ehdlc.control.f", FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT, NULL, HFILL } }, { &hf_ehdlc_s_ftype, { "Supervisory frame type", "ehdlc.control.s_ftype", FT_UINT16, BASE_HEX, VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL } }, { &hf_ehdlc_u_modifier_cmd, { "Command", "ehdlc.control.u_modifier_cmd", FT_UINT8, BASE_HEX, VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL } }, { &hf_ehdlc_u_modifier_resp, { "Response", "ehdlc.control.u_modifier_resp", FT_UINT8, BASE_HEX, VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL } }, { &hf_ehdlc_ftype_i, { "Frame Type", "ehdlc.control.ftype", FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL } }, { &hf_ehdlc_ftype_s_u, { "Frame Type", "ehdlc.control.ftype", FT_UINT8, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL } }, { &hf_ehdlc_ftype_s_u_ext, { "Frame Type", "ehdlc.control.ftype", FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL } }, }; static gint *ett[] = { &ett_ehdlc, &ett_ehdlc_control, }; proto_ehdlc = proto_register_protocol("Ericsson HDLC", "Ericsson HDLC as used in A-bis over IP", "ehdlc"); proto_register_field_array(proto_ehdlc, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); ehdlc_handle = register_dissector("ehdlc", dissect_ehdlc, proto_ehdlc); } void proto_reg_handoff_ehdlc(void) { sub_handles[SUB_RSL] = find_dissector_add_dependency("gsm_abis_rsl", proto_ehdlc); sub_handles[SUB_OML] = find_dissector_add_dependency("gsm_abis_oml", proto_ehdlc); sub_handles[SUB_DATA] = find_dissector("data"); dissector_add_uint("l2tp.pw_type", L2TPv3_PROTOCOL_ERICSSON, ehdlc_handle); } /* * Editor modelines - http://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: */