forked from osmocom/wireshark
223 lines
6.2 KiB
C
223 lines
6.2 KiB
C
/* packet-sdlc.c
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* Routines for SDLC frame disassembly
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*
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* $Id: packet-sdlc.c,v 1.4 2004/01/18 08:32:46 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998
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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 <stdio.h>
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#include <glib.h>
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#include <string.h>
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#include <epan/packet.h>
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#include "xdlc.h"
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/*
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* See
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*
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* http://www.protocols.com/pbook/sna.htm
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*/
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static int proto_sdlc = -1;
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static int hf_sdlc_address = -1;
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static int hf_sdlc_control = -1;
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static int hf_sdlc_n_r = -1;
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static int hf_sdlc_n_s = -1;
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static int hf_sdlc_p = -1;
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static int hf_sdlc_f = -1;
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static int hf_sdlc_s_ftype = -1;
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static int hf_sdlc_u_modifier_cmd = -1;
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static int hf_sdlc_u_modifier_resp = -1;
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static int hf_sdlc_ftype_i = -1;
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static int hf_sdlc_ftype_s_u = -1;
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static gint ett_sdlc = -1;
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static gint ett_sdlc_control = -1;
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static dissector_handle_t sna_handle;
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static dissector_handle_t data_handle;
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static const xdlc_cf_items sdlc_cf_items = {
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&hf_sdlc_n_r,
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&hf_sdlc_n_s,
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&hf_sdlc_p,
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&hf_sdlc_f,
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&hf_sdlc_s_ftype,
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&hf_sdlc_u_modifier_cmd,
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&hf_sdlc_u_modifier_resp,
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&hf_sdlc_ftype_i,
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&hf_sdlc_ftype_s_u
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};
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static void
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dissect_sdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_tree *sdlc_tree;
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proto_item *sdlc_ti;
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guint8 address;
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guint16 control;
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int sdlc_header_len;
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gboolean is_response;
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tvbuff_t *next_tvb;
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "SDLC");
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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address = tvb_get_guint8(tvb, 0);
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sdlc_header_len = 1; /* address */
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/*
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* XXX - is there something in the SDLC header that indicates
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* how to interpret "command vs. response" based on the
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* direction?
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*/
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if (pinfo->p2p_dir == P2P_DIR_SENT) {
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is_response = FALSE;
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if (check_col(pinfo->cinfo, COL_RES_DL_DST))
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
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if (check_col(pinfo->cinfo, COL_RES_DL_SRC))
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
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}
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else {
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/* XXX - what if the direction is unknown? */
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is_response = TRUE;
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if (check_col(pinfo->cinfo, COL_RES_DL_DST))
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col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
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if (check_col(pinfo->cinfo, COL_RES_DL_SRC))
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col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
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}
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if (tree) {
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sdlc_ti = proto_tree_add_item(tree, proto_sdlc, tvb, 0, -1,
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FALSE);
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sdlc_tree = proto_item_add_subtree(sdlc_ti, ett_sdlc);
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proto_tree_add_uint(sdlc_tree, hf_sdlc_address, tvb, 0, 1,
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address);
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} else {
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sdlc_ti = NULL;
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sdlc_tree = NULL;
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}
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/*
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* XXX - SDLC has a mod-128 mode as well as a mod-7 mode.
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* We can infer the mode from an SNRM/SRME frame, but if
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* we don't see one of them, we may have to have a preference
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* to control what to use.
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*/
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control = dissect_xdlc_control(tvb, 1, pinfo, sdlc_tree, hf_sdlc_control,
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ett_sdlc_control, &sdlc_cf_items, NULL, NULL, NULL,
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is_response, FALSE, FALSE);
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sdlc_header_len += XDLC_CONTROL_LEN(control, FALSE);
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if (tree)
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proto_item_set_len(sdlc_ti, sdlc_header_len);
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/*
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* XXX - is there an FCS at the end, at least in Sniffer
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* captures? (There doesn't appear to be.)
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*/
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next_tvb = tvb_new_subset(tvb, sdlc_header_len, -1, -1);
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if (XDLC_IS_INFORMATION(control)) {
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/* call the SNA dissector */
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call_dissector(sna_handle, next_tvb, pinfo, tree);
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} else
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call_dissector(data_handle, next_tvb, pinfo, tree);
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}
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void
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proto_register_sdlc(void)
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{
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static hf_register_info hf[] = {
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{ &hf_sdlc_address,
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{ "Address Field", "sdlc.address", FT_UINT8, BASE_HEX,
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NULL, 0x0, "Address", HFILL }},
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{ &hf_sdlc_control,
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{ "Control Field", "sdlc.control", FT_UINT16, BASE_HEX,
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NULL, 0x0, "Control field", HFILL }},
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{ &hf_sdlc_n_r,
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{ "N(R)", "sdlc.control.n_r", FT_UINT8, BASE_DEC,
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NULL, XDLC_N_R_MASK, "", HFILL }},
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{ &hf_sdlc_n_s,
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{ "N(S)", "sdlc.control.n_s", FT_UINT8, BASE_DEC,
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NULL, XDLC_N_S_MASK, "", HFILL }},
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{ &hf_sdlc_p,
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{ "Poll", "sdlc.control.p", FT_BOOLEAN, 8,
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TFS(&flags_set_truth), XDLC_P_F, "", HFILL }},
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{ &hf_sdlc_f,
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{ "Final", "sdlc.control.f", FT_BOOLEAN, 8,
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TFS(&flags_set_truth), XDLC_P_F, "", HFILL }},
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{ &hf_sdlc_s_ftype,
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{ "Supervisory frame type", "sdlc.control.s_ftype", FT_UINT8, BASE_HEX,
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VALS(stype_vals), XDLC_S_FTYPE_MASK, "", HFILL }},
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{ &hf_sdlc_u_modifier_cmd,
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{ "Command", "sdlc.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
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VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, "", HFILL }},
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{ &hf_sdlc_u_modifier_resp,
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{ "Response", "sdlc.control.u_modifier_resp", FT_UINT8, BASE_HEX,
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VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, "", HFILL }},
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{ &hf_sdlc_ftype_i,
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{ "Frame type", "sdlc.control.ftype", FT_UINT8, BASE_HEX,
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VALS(ftype_vals), XDLC_I_MASK, "", HFILL }},
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{ &hf_sdlc_ftype_s_u,
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{ "Frame type", "sdlc.control.ftype", FT_UINT8, BASE_HEX,
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VALS(ftype_vals), XDLC_S_U_MASK, "", HFILL }},
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};
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static gint *ett[] = {
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&ett_sdlc,
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&ett_sdlc_control,
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};
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proto_sdlc = proto_register_protocol(
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"Synchronous Data Link Control (SDLC)", "SDLC", "sdlc");
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proto_register_field_array(proto_sdlc, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_sdlc(void)
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{
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dissector_handle_t sdlc_handle;
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/*
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* Get handle for the SNA dissector.
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*/
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sna_handle = find_dissector("sna");
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data_handle = find_dissector("data");
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sdlc_handle = create_dissector_handle(dissect_sdlc, proto_sdlc);
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dissector_add("wtap_encap", WTAP_ENCAP_SDLC, sdlc_handle);
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}
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