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Diffstat (limited to 'epan/dissectors/packet-sdlc.c')
| -rw-r--r-- | epan/dissectors/packet-sdlc.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/epan/dissectors/packet-sdlc.c b/epan/dissectors/packet-sdlc.c new file mode 100644 index 0000000000..12a6e2c140 --- /dev/null +++ b/epan/dissectors/packet-sdlc.c @@ -0,0 +1,222 @@ +/* packet-sdlc.c + * Routines for SDLC frame disassembly + * + * $Id$ + * + * Ethereal - Network traffic analyzer + * By Gerald Combs <gerald@ethereal.com> + * Copyright 1998 + * + * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +#include <stdio.h> +#include <glib.h> +#include <string.h> +#include <epan/packet.h> +#include "xdlc.h" + +/* + * See + * + * http://www.protocols.com/pbook/sna.htm + */ + +static int proto_sdlc = -1; +static int hf_sdlc_address = -1; +static int hf_sdlc_control = -1; +static int hf_sdlc_n_r = -1; +static int hf_sdlc_n_s = -1; +static int hf_sdlc_p = -1; +static int hf_sdlc_f = -1; +static int hf_sdlc_s_ftype = -1; +static int hf_sdlc_u_modifier_cmd = -1; +static int hf_sdlc_u_modifier_resp = -1; +static int hf_sdlc_ftype_i = -1; +static int hf_sdlc_ftype_s_u = -1; + +static gint ett_sdlc = -1; +static gint ett_sdlc_control = -1; + +static dissector_handle_t sna_handle; +static dissector_handle_t data_handle; + +static const xdlc_cf_items sdlc_cf_items = { + &hf_sdlc_n_r, + &hf_sdlc_n_s, + &hf_sdlc_p, + &hf_sdlc_f, + &hf_sdlc_s_ftype, + &hf_sdlc_u_modifier_cmd, + &hf_sdlc_u_modifier_resp, + &hf_sdlc_ftype_i, + &hf_sdlc_ftype_s_u +}; + +static void +dissect_sdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) +{ + proto_tree *sdlc_tree; + proto_item *sdlc_ti; + guint8 address; + guint16 control; + int sdlc_header_len; + gboolean is_response; + tvbuff_t *next_tvb; + + if (check_col(pinfo->cinfo, COL_PROTOCOL)) + col_set_str(pinfo->cinfo, COL_PROTOCOL, "SDLC"); + if (check_col(pinfo->cinfo, COL_INFO)) + col_clear(pinfo->cinfo, COL_INFO); + + address = tvb_get_guint8(tvb, 0); + sdlc_header_len = 1; /* address */ + + /* + * XXX - is there something in the SDLC header that indicates + * how to interpret "command vs. response" based on the + * direction? + */ + if (pinfo->p2p_dir == P2P_DIR_SENT) { + is_response = FALSE; + if (check_col(pinfo->cinfo, COL_RES_DL_DST)) + col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE"); + if (check_col(pinfo->cinfo, COL_RES_DL_SRC)) + col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE"); + } + else { + /* XXX - what if the direction is unknown? */ + is_response = TRUE; + if (check_col(pinfo->cinfo, COL_RES_DL_DST)) + col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE"); + if (check_col(pinfo->cinfo, COL_RES_DL_SRC)) + col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE"); + } + + if (tree) { + sdlc_ti = proto_tree_add_item(tree, proto_sdlc, tvb, 0, -1, + FALSE); + sdlc_tree = proto_item_add_subtree(sdlc_ti, ett_sdlc); + + proto_tree_add_uint(sdlc_tree, hf_sdlc_address, tvb, 0, 1, + address); + } else { + sdlc_ti = NULL; + sdlc_tree = NULL; + } + + /* + * XXX - SDLC has a mod-128 mode as well as a mod-7 mode. + * We can infer the mode from an SNRM/SRME frame, but if + * we don't see one of them, we may have to have a preference + * to control what to use. + */ + control = dissect_xdlc_control(tvb, 1, pinfo, sdlc_tree, hf_sdlc_control, + ett_sdlc_control, &sdlc_cf_items, NULL, NULL, NULL, + is_response, FALSE, FALSE); + sdlc_header_len += XDLC_CONTROL_LEN(control, FALSE); + + if (tree) + proto_item_set_len(sdlc_ti, sdlc_header_len); + + /* + * XXX - is there an FCS at the end, at least in Sniffer + * captures? (There doesn't appear to be.) + */ + next_tvb = tvb_new_subset(tvb, sdlc_header_len, -1, -1); + if (XDLC_IS_INFORMATION(control)) { + /* call the SNA dissector */ + call_dissector(sna_handle, next_tvb, pinfo, tree); + } else + call_dissector(data_handle, next_tvb, pinfo, tree); +} + +void +proto_register_sdlc(void) +{ + static hf_register_info hf[] = { + { &hf_sdlc_address, + { "Address Field", "sdlc.address", FT_UINT8, BASE_HEX, + NULL, 0x0, "Address", HFILL }}, + + { &hf_sdlc_control, + { "Control Field", "sdlc.control", FT_UINT16, BASE_HEX, + NULL, 0x0, "Control field", HFILL }}, + + { &hf_sdlc_n_r, + { "N(R)", "sdlc.control.n_r", FT_UINT8, BASE_DEC, + NULL, XDLC_N_R_MASK, "", HFILL }}, + + { &hf_sdlc_n_s, + { "N(S)", "sdlc.control.n_s", FT_UINT8, BASE_DEC, + NULL, XDLC_N_S_MASK, "", HFILL }}, + + { &hf_sdlc_p, + { "Poll", "sdlc.control.p", FT_BOOLEAN, 8, + TFS(&flags_set_truth), XDLC_P_F, "", HFILL }}, + + { &hf_sdlc_f, + { "Final", "sdlc.control.f", FT_BOOLEAN, 8, + TFS(&flags_set_truth), XDLC_P_F, "", HFILL }}, + + { &hf_sdlc_s_ftype, + { "Supervisory frame type", "sdlc.control.s_ftype", FT_UINT8, BASE_HEX, + VALS(stype_vals), XDLC_S_FTYPE_MASK, "", HFILL }}, + + { &hf_sdlc_u_modifier_cmd, + { "Command", "sdlc.control.u_modifier_cmd", FT_UINT8, BASE_HEX, + VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, "", HFILL }}, + + { &hf_sdlc_u_modifier_resp, + { "Response", "sdlc.control.u_modifier_resp", FT_UINT8, BASE_HEX, + VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, "", HFILL }}, + + { &hf_sdlc_ftype_i, + { "Frame type", "sdlc.control.ftype", FT_UINT8, BASE_HEX, + VALS(ftype_vals), XDLC_I_MASK, "", HFILL }}, + + { &hf_sdlc_ftype_s_u, + { "Frame type", "sdlc.control.ftype", FT_UINT8, BASE_HEX, + VALS(ftype_vals), XDLC_S_U_MASK, "", HFILL }}, + }; + static gint *ett[] = { + &ett_sdlc, + &ett_sdlc_control, + }; + + proto_sdlc = proto_register_protocol( + "Synchronous Data Link Control (SDLC)", "SDLC", "sdlc"); + proto_register_field_array(proto_sdlc, hf, array_length(hf)); + proto_register_subtree_array(ett, array_length(ett)); +} + +void +proto_reg_handoff_sdlc(void) +{ + dissector_handle_t sdlc_handle; + + /* + * Get handle for the SNA dissector. + */ + sna_handle = find_dissector("sna"); + data_handle = find_dissector("data"); + + sdlc_handle = create_dissector_handle(dissect_sdlc, proto_sdlc); + dissector_add("wtap_encap", WTAP_ENCAP_SDLC, sdlc_handle); +} |