309 lines
10 KiB
C
309 lines
10 KiB
C
/* packet-epon.c
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* Routines for Ethernet Passive Optical Network dissection
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* Copyright 2014, Philip Rosenberg-Watt <p.rosenberg-watt[at]cablelabs.com>
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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 modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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 along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/* 2014-04 Philip Rosenberg-Watt <p.rosenberg-watt[at]cablelabs.com>
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* + EPON preamble with CableLabs DPoE securty byte.
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* See IEEE 802.3-2012 Section 5, Clause 65 and
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* CableLabs DPoE SEC 1.0 specification.
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/expert.h>
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#include <epan/addr_resolv.h>
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#include <epan/crc8-tvb.h>
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void proto_register_epon(void);
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void proto_reg_handoff_epon(void);
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static int proto_epon = -1;
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static int hf_epon_dpoe_security = -1;
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static int hf_epon_dpoe_encrypted = -1;
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static int hf_epon_dpoe_reserved = -1;
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static int hf_epon_dpoe_encrypted_data = -1;
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static int hf_epon_dpoe_keyid = -1;
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static int hf_epon_mode = -1;
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static int hf_epon_llid = -1;
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static int hf_epon_checksum = -1;
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static expert_field ei_epon_sld_bad = EI_INIT;
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static expert_field ei_epon_dpoe_reserved_bad = EI_INIT;
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static expert_field ei_epon_dpoe_bad = EI_INIT;
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static expert_field ei_epon_dpoe_encrypted_data = EI_INIT;
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static expert_field ei_epon_checksum_bad = EI_INIT;
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static dissector_handle_t eth_handle;
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static gint ett_epon = -1;
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static gint ett_epon_sec = -1;
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static gint ett_epon_checksum = -1;
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static const true_false_string epon_mode_tfs = {
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"Broadcast/Multicast",
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"Unicast"
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};
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static int
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dissect_epon(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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void *data _U_)
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{
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proto_tree *epon_tree;
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proto_item *ti;
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proto_item *item;
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proto_tree *sec_tree;
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tvbuff_t *next_tvb;
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guint checksum;
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guint sent_checksum;
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guint offset = 0;
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guint dpoe_sec_byte;
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gboolean dpoe_encrypted = FALSE;
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/* Start_of_Packet delimiter (/S/) can either happen in byte 1 or byte 2,
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* making the captured preamble either 7 or 6 bytes in length. If the
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* preamble starts with 0x55, then /S/ happened in byte 1, making the
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* captured preamble 7 bytes in length.
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*/
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if (tvb_get_ntoh24(tvb, 0) == 0x55D555) {
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offset += 1;
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} else if (tvb_get_ntohs(tvb, 0) == 0xD555) {
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offset += 0;
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} else {
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item = proto_tree_add_item(tree, proto_epon, tvb, offset, 0, ENC_NA);
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expert_add_info(pinfo, item, &ei_epon_sld_bad);
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return 0;
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}
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/* Set the columns */
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "EPON");
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col_set_str(pinfo->cinfo, COL_INFO, "EPON Preamble");
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/* Create display subtree for the protocol */
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ti = proto_tree_add_item(tree, proto_epon, tvb, 0+offset, 6, ENC_NA);
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epon_tree = proto_item_add_subtree(ti, ett_epon);
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/* Decode byte 5 of the preamble according to CableLabs DPoE specification.
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* If security is disabled, the DPoE byte will remain 0x55 and no decoding
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* is necessary.
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*/
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dpoe_sec_byte = tvb_get_guint8(tvb, 2+offset);
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if (dpoe_sec_byte != 0x55) {
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guint dpoe_keyid;
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guint dpoe_reserved;
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item = proto_tree_add_item(epon_tree, hf_epon_dpoe_security,
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tvb, 2+offset, 1, ENC_BIG_ENDIAN);
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sec_tree = proto_item_add_subtree(item, ett_epon_sec);
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/* The DPoE security byte is split into three fields:
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* bits 7-2 are reserved in 1G mode
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* bit 1 is the encryption mode
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* bit 0 is the key ID
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*/
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dpoe_reserved = dpoe_sec_byte & 0xFC;
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dpoe_encrypted = dpoe_sec_byte & 0x02;
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dpoe_keyid = dpoe_sec_byte & 0x01;
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/* Add encryption status text to sec_tree subtree
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*/
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proto_item_append_text(item, " (Encrypted: ");
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if (dpoe_encrypted) {
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proto_item_append_text(item, "True, Key ID: %x", dpoe_keyid);
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} else {
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proto_item_append_text(item, "False");
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}
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proto_item_append_text(item, ")");
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/* We don't need to see the reserved bits of the DPoE security byte unless
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* there's something wrong with them.
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*/
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if (dpoe_reserved != 0x54) {
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proto_tree_add_item(sec_tree, hf_epon_dpoe_reserved, tvb, 2+offset, 1,
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ENC_BIG_ENDIAN);
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expert_add_info(pinfo, sec_tree, &ei_epon_dpoe_reserved_bad);
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}
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/* Add encryption and key ID bits
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* Error if encryption is disabled but key bit is not 1
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*/
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proto_tree_add_item(sec_tree, hf_epon_dpoe_encrypted, tvb, 2+offset, 1,
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ENC_BIG_ENDIAN);
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proto_tree_add_item(sec_tree, hf_epon_dpoe_keyid, tvb, 2+offset, 1,
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ENC_BIG_ENDIAN);
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if (!dpoe_encrypted && (dpoe_keyid == 0)) {
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expert_add_info(pinfo, sec_tree, &ei_epon_dpoe_bad);
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}
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}
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/* Mode bit
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*/
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proto_tree_add_item(epon_tree, hf_epon_mode, tvb, 3+offset, 2,
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ENC_BIG_ENDIAN);
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/* LLID
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*/
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proto_tree_add_item(epon_tree, hf_epon_llid, tvb, 3+offset, 2,
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ENC_BIG_ENDIAN);
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/* Verify the CRC-8 checksum
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*/
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sent_checksum = tvb_get_guint8(tvb, 5+offset);
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checksum = get_crc8_ieee8023_epon(tvb, 5, 0+offset);
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if (sent_checksum == checksum) {
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proto_tree_add_uint_format_value(epon_tree, hf_epon_checksum, tvb,
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5+offset, 1, sent_checksum,
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"0x%01x [correct]", sent_checksum);
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} else {
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item = proto_tree_add_uint_format_value(epon_tree, hf_epon_checksum, tvb,
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5+offset, 1, sent_checksum,
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"0x%01x [incorrect, should be 0x%01x]",
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sent_checksum, checksum);
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expert_add_info(pinfo, item, &ei_epon_checksum_bad);
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col_append_str(pinfo->cinfo, COL_INFO, " [EPON PREAMBLE CHECKSUM INCORRECT]");
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}
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/* Do not bother parsing encrypted data, otherwise send the rest on to the
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* eth dissector.
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*/
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if (dpoe_encrypted) {
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item = proto_tree_add_item(tree, hf_epon_dpoe_encrypted_data, tvb,
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6+offset, -1, ENC_NA);
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expert_add_info(pinfo, item, &ei_epon_dpoe_encrypted_data);
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col_append_str(pinfo->cinfo, COL_INFO, " [ENCRYPTED]");
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} else {
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next_tvb = tvb_new_subset_remaining(tvb, 6+offset);
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call_dissector(eth_handle, next_tvb, pinfo, tree);
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}
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return tvb_captured_length(tvb);
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}
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void
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proto_register_epon(void)
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{
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expert_module_t *expert_epon;
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static hf_register_info hf[] = {
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{ &hf_epon_dpoe_security,
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{ "DPoE security", "epon.dpoe.sec", FT_UINT8, BASE_HEX, NULL, 0x0,
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"DPoE security octet", HFILL }
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},
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{ &hf_epon_dpoe_reserved,
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{ "Reserved", "epon.dpoe.reserved", FT_UINT8, BASE_DEC, NULL, 0xFC,
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"Reserved in 1G mode", HFILL }
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},
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{ &hf_epon_dpoe_encrypted,
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{ "Encryption enabled", "epon.dpoe.encrypted", FT_BOOLEAN, 8, NULL, 0x02,
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"Specifies if this is an encrypted frame", HFILL }
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},
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{ &hf_epon_dpoe_keyid,
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{ "Key ID", "epon.dpoe.keyid", FT_UINT8, BASE_HEX, NULL, 0x01,
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"Identification number of the key used to encrypt this frame",
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HFILL }
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},
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{ &hf_epon_dpoe_encrypted_data,
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{ "Encrypted data", "epon.dpoe.encrypted.data", FT_BYTES, BASE_NONE,
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NULL, 0x0, "DPoE encrypted data", HFILL }
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},
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{ &hf_epon_mode,
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{ "Mode", "epon.mode", FT_BOOLEAN, 16, TFS(&epon_mode_tfs), 0x8000,
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"Broadcast/multicast if true, unicast if false", HFILL }
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},
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{ &hf_epon_llid,
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{ "LLID", "epon.llid", FT_UINT16, BASE_DEC_HEX, NULL, 0x7FFF,
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"Logical Link ID", HFILL }
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},
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{ &hf_epon_checksum,
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{ "Frame check sequence", "epon.checksum", FT_UINT8, BASE_HEX, NULL,
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0x0, "EPON preamble checksum", HFILL }
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},
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};
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static gint *ett[] = {
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&ett_epon,
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&ett_epon_sec,
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&ett_epon_checksum
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};
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/* Setup protocol expert items */
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static ei_register_info ei[] = {
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{ &ei_epon_checksum_bad,
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{ "epon.checksum_bad.expert", PI_CHECKSUM, PI_ERROR,
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"Bad checksum", EXPFILL }
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},
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{ &ei_epon_sld_bad,
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{ "epon.sld_bad.expert", PI_MALFORMED, PI_ERROR,
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"Unable to locate SLD or invalid byte sequence: preamble must start with 0xD555", EXPFILL }
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},
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{ &ei_epon_dpoe_reserved_bad,
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{ "epon.dpoe.encrypted.expert", PI_MALFORMED, PI_ERROR,
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"Bits 7-2 of DPoE security byte must be 010101 in 1G mode.", EXPFILL }
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},
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{ &ei_epon_dpoe_bad,
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{ "epon.dpoe.expert", PI_MALFORMED, PI_ERROR,
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"DPoE security byte must be 0x55 if encryption is disabled.", EXPFILL }
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},
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{ &ei_epon_dpoe_encrypted_data,
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{ "epon.dpoe.encrypted.expert", PI_UNDECODED, PI_NOTE,
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"Remaining data is encrypted and will not decode.", EXPFILL }
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}
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};
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proto_epon = proto_register_protocol("IEEE 802.3 EPON Preamble",
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"EPON", "epon");
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proto_register_field_array(proto_epon, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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expert_epon = expert_register_protocol(proto_epon);
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expert_register_field_array(expert_epon, ei, array_length(ei));
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}
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void
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proto_reg_handoff_epon(void)
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{
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dissector_handle_t epon_handle;
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epon_handle = create_dissector_handle(dissect_epon, proto_epon);
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dissector_add_uint("wtap_encap", WTAP_ENCAP_EPON, epon_handle);
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eth_handle = find_dissector("eth");
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local Variables:
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* c-basic-offset: 2
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* ex: set shiftwidth=2 tabstop=8 expandtab:
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* :indentSize=2:tabSize=8:noTabs=true:
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*/
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