2012-02-26 17:30:38 +00:00
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/* packet-ehdlc.c
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* Routines for packet dissection of Ericsson HDLC as used in A-bis over IP
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* Copyright 2010-2012 by Harald Welte <laforge@gnumonks.org>
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*
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* $Id$
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*
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* This code is based on pure educational guesses while looking at protocol
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* traces, as there is no publicly available protocol description by Ericsson.
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* Even the name is a guess, since it looks quite a bit like HDLC and is used
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* by Ericsson, I called it EHDLC.
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/ipproto.h>
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#include <epan/xdlc.h>
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/* Initialize the protocol and registered fields */
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static int proto_ehdlc = -1;
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static int hf_ehdlc_data_len = -1;
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static int hf_ehdlc_protocol = -1;
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static int hf_ehdlc_sapi = -1;
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static int hf_ehdlc_c_r = -1;
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static int hf_ehdlc_xid_payload = -1;
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static int hf_ehdlc_control = -1;
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static int hf_ehdlc_p = -1;
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static int hf_ehdlc_f = -1;
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static int hf_ehdlc_u_modifier_cmd = -1;
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static int hf_ehdlc_u_modifier_resp = -1;
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static int hf_ehdlc_ftype_s_u = -1;
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static int hf_ehdlc_n_r = -1;
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static int hf_ehdlc_n_s = -1;
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static int hf_ehdlc_p_ext = -1;
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static int hf_ehdlc_f_ext = -1;
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static int hf_ehdlc_s_ftype = -1;
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static int hf_ehdlc_ftype_i = -1;
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static int hf_ehdlc_ftype_s_u_ext = -1;
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/* Used only for U frames */
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static const xdlc_cf_items ehdlc_cf_items = {
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NULL,
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NULL,
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&hf_ehdlc_p,
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&hf_ehdlc_f,
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NULL,
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&hf_ehdlc_u_modifier_cmd,
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&hf_ehdlc_u_modifier_resp,
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NULL,
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&hf_ehdlc_ftype_s_u
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};
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/* Used only for I and S frames */
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static const xdlc_cf_items ehdlc_cf_items_ext = {
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&hf_ehdlc_n_r,
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&hf_ehdlc_n_s,
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&hf_ehdlc_p_ext,
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&hf_ehdlc_f_ext,
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&hf_ehdlc_s_ftype,
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NULL,
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NULL,
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&hf_ehdlc_ftype_i,
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&hf_ehdlc_ftype_s_u_ext,
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};
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/* Initialize the subtree pointers */
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static gint ett_ehdlc = -1;
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static gint ett_ehdlc_control = -1;
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static const value_string ehdlc_protocol_vals[] = {
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{ 0x20, "RSL" },
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{ 0xa0, "ACK" },
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{ 0xc0, "OML" },
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{ 0, NULL }
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};
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enum {
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SUB_RSL,
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SUB_OML,
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SUB_DATA,
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SUB_MAX
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};
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static dissector_handle_t sub_handles[SUB_MAX];
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/* Code to actually dissect the packets */
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static void
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dissect_ehdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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2012-03-01 21:04:04 +00:00
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int offset = 4;
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2012-02-26 17:30:38 +00:00
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "EHDLC");
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col_clear(pinfo->cinfo, COL_INFO);
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2012-03-01 21:04:04 +00:00
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while (tvb_reported_length_remaining(tvb, offset) > 0) {
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proto_item *ti = NULL;
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proto_tree *ehdlc_tree = NULL;
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guint16 len, msg_type;
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tvbuff_t *next_tvb;
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guint16 control;
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gboolean is_response = FALSE, is_extended = TRUE;
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gint header_length = 2; /* Address + Length field */
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2012-02-26 17:30:38 +00:00
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2012-03-01 21:04:04 +00:00
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msg_type = tvb_get_guint8(tvb, offset);
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len = tvb_get_guint8(tvb, offset+1);
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2012-02-26 17:30:38 +00:00
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#if 0
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col_append_fstr(pinfo->cinfo, COL_INFO, "%s ",
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val_to_str(msg_type, ehdlc_protocol_vals,
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"unknown 0x%02x"));
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#endif
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if (tree) {
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2012-03-01 21:04:04 +00:00
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/* Use MIN(...,...) in the following to prevent a premature */
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/* exception before we try to dissect whatever is available. */
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2012-02-26 17:30:38 +00:00
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ti = proto_tree_add_protocol_format(tree, proto_ehdlc,
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2012-03-01 21:04:04 +00:00
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tvb, offset, MIN(len, tvb_length_remaining(tvb,offset)),
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2012-02-26 17:30:38 +00:00
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"Ericsson HDLC protocol, type: %s",
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val_to_str(msg_type, ehdlc_protocol_vals,
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"unknown 0x%02x"));
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ehdlc_tree = proto_item_add_subtree(ti, ett_ehdlc);
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proto_tree_add_item(ehdlc_tree, hf_ehdlc_protocol,
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2012-03-01 21:04:04 +00:00
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tvb, offset, 1, ENC_BIG_ENDIAN);
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2012-02-26 17:30:38 +00:00
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#if 0
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proto_tree_add_item(ehdlc_tree, hf_ehdlc_sapi,
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2012-03-01 21:04:04 +00:00
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tvb, offset, 1, ENC_BIG_ENDIAN);
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2012-02-26 17:30:38 +00:00
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proto_tree_add_item(ehdlc_tree, hf_ehdlc_c_r,
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2012-03-01 21:04:04 +00:00
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tvb, offset, 1, ENC_BIG_ENDIAN);
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2012-02-26 17:30:38 +00:00
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#endif
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proto_tree_add_item(ehdlc_tree, hf_ehdlc_data_len,
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2012-03-01 21:04:04 +00:00
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tvb, offset+1, 1, ENC_BIG_ENDIAN);
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2012-02-26 17:30:38 +00:00
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}
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control = dissect_xdlc_control(tvb, offset+2, pinfo, ehdlc_tree, hf_ehdlc_control,
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ett_ehdlc_control, &ehdlc_cf_items, &ehdlc_cf_items_ext,
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NULL, NULL, is_response, is_extended, FALSE);
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header_length += XDLC_CONTROL_LEN(control, is_extended);
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if (XDLC_IS_INFORMATION(control)) {
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next_tvb = tvb_new_subset(tvb, offset+header_length,
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2012-03-01 21:04:04 +00:00
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len-header_length, len-header_length);
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2012-02-26 17:30:38 +00:00
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switch (msg_type) {
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case 0x20:
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/* len == 4 seems to be some kind of ACK */
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if (len <= 4)
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break;
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call_dissector(sub_handles[SUB_RSL], next_tvb, pinfo, tree);
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break;
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case 0xbc:
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case 0xdc:
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case 0xa0:
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case 0xc0:
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/* len == 4 seems to be some kind of ACK */
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if (len <= 4)
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break;
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call_dissector(sub_handles[SUB_OML], next_tvb, pinfo, tree);
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break;
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default:
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call_dissector(sub_handles[SUB_DATA], next_tvb, pinfo, tree);
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break;
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}
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} else if (control == (XDLC_U | XDLC_XID)) {
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/* XID is formatted like ISO 8885, typically we see
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* something like
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* 82 format identifier
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* 80 group identifier
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* 00 09 length
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* 07 01 05 Window Size Tx
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* 09 01 04 Ack Timer (msec)
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* 08 01 05 Window Size Rx */
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proto_tree_add_item(ehdlc_tree, hf_ehdlc_xid_payload,
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tvb, offset+header_length,
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2012-03-01 21:04:04 +00:00
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len-header_length, ENC_NA);
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2012-02-26 17:30:38 +00:00
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}
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if (len == 0)
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len = 1;
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offset += len;
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}
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}
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2012-03-01 21:04:04 +00:00
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void
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proto_register_ehdlc(void)
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2012-02-26 17:30:38 +00:00
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{
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static hf_register_info hf[] = {
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{ &hf_ehdlc_data_len,
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{ "DataLen", "ehdlc.data_len",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"The length of the data (in bytes)", HFILL }
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},
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{ &hf_ehdlc_protocol,
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{ "Protocol", "ehdlc.protocol",
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FT_UINT8, BASE_HEX, VALS(ehdlc_protocol_vals), 0x0,
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"The HDLC Sub-Protocol", HFILL }
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},
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{ &hf_ehdlc_sapi,
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{ "SAPI", "ehdlc.sapi",
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FT_UINT8, BASE_DEC, NULL, 0x1f,
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NULL, HFILL }
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},
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{ &hf_ehdlc_c_r,
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{ "C/R", "ehdlc.c_r",
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FT_UINT8, BASE_HEX, NULL, 0x20,
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NULL, HFILL }
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},
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{ &hf_ehdlc_xid_payload,
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{ "XID Payload", "ehdlc.xid_payload",
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FT_BYTES, BASE_NONE, NULL, 0,
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NULL, HFILL }
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},
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{ &hf_ehdlc_control,
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{ "Control Field", "ehdlc.control",
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FT_UINT16, BASE_HEX, NULL, 0,
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NULL, HFILL }
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},
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{ &hf_ehdlc_n_r,
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{ "N(R)", "ehdlc.control.n_r",
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FT_UINT16, BASE_DEC, NULL, XDLC_N_R_EXT_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_n_s,
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{ "N(S)", "ehdlc.control.n_s",
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FT_UINT16, BASE_DEC, NULL, XDLC_N_S_EXT_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_p,
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{ "Poll", "ehdlc.control.p",
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FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F,
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NULL, HFILL }
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},
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{ &hf_ehdlc_p_ext,
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{ "Poll", "ehdlc.control.p",
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FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT,
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NULL, HFILL }
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},
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{ &hf_ehdlc_f,
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{ "Final", "ehdlc.control.f",
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FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F,
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NULL, HFILL }
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},
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{ &hf_ehdlc_f_ext,
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{ "Final", "ehdlc.control.f",
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FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT,
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NULL, HFILL }
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},
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{ &hf_ehdlc_s_ftype,
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{ "Supervisory frame type", "ehdlc.control.s_ftype",
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FT_UINT16, BASE_HEX, VALS(stype_vals), XDLC_S_FTYPE_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_u_modifier_cmd,
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{ "Command", "ehdlc.control.u_modifier_cmd",
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FT_UINT8, BASE_HEX, VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_u_modifier_resp,
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{ "Response", "ehdlc.control.u_modifier_resp",
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FT_UINT8, BASE_HEX, VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_ftype_i,
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{ "Frame Type", "ehdlc.control.ftype",
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FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_I_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_ftype_s_u,
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{ "Frame Type", "ehdlc.control.ftype",
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FT_UINT8, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK,
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NULL, HFILL }
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},
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{ &hf_ehdlc_ftype_s_u_ext,
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{ "Frame Type", "ehdlc.control.ftype",
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FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK,
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NULL, HFILL }
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},
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};
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static gint *ett[] = {
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&ett_ehdlc,
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&ett_ehdlc_control,
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};
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proto_ehdlc =
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proto_register_protocol("Ericsson HDLC",
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"Ericsson HDLC as used in A-bis over IP", "ehdlc");
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proto_register_field_array(proto_ehdlc, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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register_dissector("ehdlc", dissect_ehdlc, proto_ehdlc);
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}
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2012-03-01 21:04:04 +00:00
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void
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proto_reg_handoff_ehdlc(void)
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2012-02-26 17:30:38 +00:00
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{
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2012-03-01 21:04:04 +00:00
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sub_handles[SUB_RSL] = find_dissector("gsm_abis_rsl");
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sub_handles[SUB_OML] = find_dissector("gsm_abis_oml");
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2012-02-26 17:30:38 +00:00
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sub_handles[SUB_DATA] = find_dissector("data");
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|
|
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}
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