/** Decode IrDA Serial Infrared (SIR) wrapped packets. * @author Shaun Jackman * @copyright Copyright 2004 Shaun Jackman * @license GPL * * $Id$ * * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #include /** Serial infrared port. */ #define TCP_PORT_SIR 6417 /** Beginning of frame. */ #define SIR_BOF 0xc0 /** End of frame. */ #define SIR_EOF 0xc1 /** Control escape. */ #define SIR_CE 0x7d /** Escapes this character. */ #define SIR_ESCAPE(x) ((x)^0x20) /** Protocol handles. */ static dissector_handle_t data_handle; static dissector_handle_t irda_handle; /** Protocol fields. */ static int proto_sir = -1; static int ett_sir = -1; static int hf_sir_bof = -1; static int hf_sir_ce = -1; static int hf_sir_eof = -1; static int hf_sir_fcs = -1; static int hf_sir_fcs_bad = -1; static int hf_sir_length = -1; static int hf_sir_preamble = -1; /** Unescapes the data. */ static tvbuff_t * unescape_data(tvbuff_t *tvb, packet_info *pinfo) { if (tvb_find_guint8(tvb, 0, -1, SIR_CE) == -1) { return tvb; } else { guint length = tvb_length(tvb); guint offset; guint8 *data = g_malloc(length); guint8 *dst = data; tvbuff_t *next_tvb; for (offset = 0; offset < length; ) { guint8 c = tvb_get_guint8(tvb, offset++); if ((c == SIR_CE) && (offset < length)) c = SIR_ESCAPE(tvb_get_guint8(tvb, offset++)); *dst++ = c; } next_tvb = tvb_new_child_real_data(tvb, data, (guint) (dst-data), (guint) (dst-data)); tvb_set_free_cb(next_tvb, g_free); add_new_data_source(pinfo, next_tvb, "Unescaped SIR"); return next_tvb; } } /** Checksums the data. */ static tvbuff_t * checksum_data(tvbuff_t *tvb, proto_tree *tree) { proto_item *hidden_item; int len = tvb_length(tvb) - 2; if (len < 0) return tvb; if (tree) { guint16 actual_fcs = tvb_get_letohs(tvb, len); guint16 calculated_fcs = crc16_ccitt_tvb(tvb, len); if (calculated_fcs == actual_fcs) { proto_tree_add_uint_format(tree, hf_sir_fcs, tvb, len, 2, actual_fcs, "Frame check sequence: 0x%04x (correct)", actual_fcs); } else { hidden_item = proto_tree_add_boolean(tree, hf_sir_fcs_bad, tvb, len, 2, TRUE); PROTO_ITEM_SET_HIDDEN(hidden_item); proto_tree_add_uint_format(tree, hf_sir_fcs, tvb, len, 2, actual_fcs, "Frame check sequence: 0x%04x " "(incorrect, should be 0x%04x)", actual_fcs, calculated_fcs); } } return tvb_new_subset(tvb, 0, len, len); } /** Dissects an SIR packet. */ static void dissect_sir(tvbuff_t *tvb, packet_info *pinfo, proto_tree *root) { gint offset = 0; gint bof_offset; gint eof_offset; while (tvb_length_remaining(tvb, offset) > 0) { bof_offset = tvb_find_guint8(tvb, offset, -1, SIR_BOF); eof_offset = (bof_offset == -1) ? -1 : tvb_find_guint8(tvb, bof_offset, -1, SIR_EOF); if (bof_offset == -1 || eof_offset == -1) { if (pinfo->can_desegment) { pinfo->desegment_offset = offset; pinfo->desegment_len = 1; } return; } else { guint preamble_len = bof_offset - offset; gint data_offset = bof_offset + 1; tvbuff_t* next_tvb = tvb_new_subset(tvb, data_offset, eof_offset - data_offset, -1); next_tvb = unescape_data(next_tvb, pinfo); if (root) { unsigned data_len = tvb_length(next_tvb) < 2 ? 0 : tvb_length(next_tvb) - 2; proto_tree* ti = proto_tree_add_protocol_format(root, proto_sir, tvb, offset, eof_offset - offset + 1, "Serial Infrared, Len: %d", data_len); proto_tree* tree = proto_item_add_subtree(ti, ett_sir); if (preamble_len > 0) proto_tree_add_item(tree, hf_sir_preamble, tvb, offset, preamble_len, ENC_NA); proto_tree_add_item(tree, hf_sir_bof, tvb, bof_offset, 1, ENC_BIG_ENDIAN); proto_tree_add_uint(tree, hf_sir_length, next_tvb, 0, data_len, data_len); next_tvb = checksum_data(next_tvb, tree); proto_tree_add_item(tree, hf_sir_eof, tvb, eof_offset, 1, ENC_BIG_ENDIAN); } else { next_tvb = checksum_data(next_tvb, NULL); } call_dissector(irda_handle, next_tvb, pinfo, root); } offset = eof_offset + 1; } } /** Registers this dissector with the parent dissector. */ void proto_reg_handoff_irsir(void) { dissector_add_uint("tcp.port", TCP_PORT_SIR, find_dissector("sir")); data_handle = find_dissector("data"); irda_handle = find_dissector("irda"); if (irda_handle == NULL) irda_handle = data_handle; } /** Initializes this protocol. */ void proto_register_irsir(void) { static gint* ett[] = { &ett_sir }; static hf_register_info hf_sir[] = { { &hf_sir_bof, { "Beginning of frame", "sir.bof", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL }}, { &hf_sir_ce, { "Command escape", "sir.ce", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL }}, { &hf_sir_eof, { "End of frame", "sir.eof", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL }}, { &hf_sir_fcs, { "Frame check sequence", "sir.fcs", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL }}, { &hf_sir_fcs_bad, { "Bad frame check sequence", "sir.fcs_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL }}, { &hf_sir_length, { "Length", "sir.length", FT_UINT16, BASE_DEC, NULL, 0, NULL, HFILL }}, { &hf_sir_preamble, { "Preamble", "sir.preamble", FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL }} }; proto_sir = proto_register_protocol( "Serial Infrared", "SIR", "sir"); register_dissector("sir", dissect_sir, proto_sir); proto_register_subtree_array(ett, array_length(ett)); proto_register_field_array( proto_sir, hf_sir, array_length(hf_sir)); }