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Diffstat (limited to 'epan/dissectors/packet-epon.c')
| -rw-r--r-- | epan/dissectors/packet-epon.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/epan/dissectors/packet-epon.c b/epan/dissectors/packet-epon.c new file mode 100644 index 00000000..0ace6ab0 --- /dev/null +++ b/epan/dissectors/packet-epon.c @@ -0,0 +1,299 @@ +/* packet-epon.c + * Routines for Ethernet Passive Optical Network dissection + * Copyright 2014, Philip Rosenberg-Watt <p.rosenberg-watt[at]cablelabs.com> + * + * Wireshark - Network traffic analyzer + * By Gerald Combs <gerald@wireshark.org> + * Copyright 1998 Gerald Combs + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +/* 2014-04 Philip Rosenberg-Watt <p.rosenberg-watt[at]cablelabs.com> + * + EPON preamble with CableLabs DPoE securty byte. + * See IEEE 802.3-2012 Section 5, Clause 65 and + * CableLabs DPoE SEC 1.0 specification. + */ + +#include "config.h" + +#include <epan/packet.h> +#include <epan/expert.h> + +#include <epan/addr_resolv.h> +#include <epan/crc8-tvb.h> + +void proto_register_epon(void); +void proto_reg_handoff_epon(void); + +static dissector_handle_t epon_handle; + +static int proto_epon = -1; +static int hf_epon_dpoe_security = -1; +static int hf_epon_dpoe_encrypted = -1; +static int hf_epon_dpoe_reserved = -1; +static int hf_epon_dpoe_encrypted_data = -1; +static int hf_epon_dpoe_keyid = -1; +static int hf_epon_mode = -1; +static int hf_epon_llid = -1; +static int hf_epon_checksum = -1; +static int hf_epon_checksum_status = -1; + +static expert_field ei_epon_sld_bad = EI_INIT; +static expert_field ei_epon_dpoe_reserved_bad = EI_INIT; +static expert_field ei_epon_dpoe_bad = EI_INIT; +static expert_field ei_epon_dpoe_encrypted_data = EI_INIT; +static expert_field ei_epon_checksum_bad = EI_INIT; + +static dissector_handle_t eth_maybefcs_handle; + +static gint ett_epon = -1; +static gint ett_epon_sec = -1; +static gint ett_epon_checksum = -1; + +static const true_false_string epon_mode_tfs = { + "Broadcast/Multicast", + "Unicast" +}; + +static int +dissect_epon(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, + void *data _U_) +{ + proto_tree *epon_tree; + proto_item *ti; + proto_item *item; + proto_tree *sec_tree; + tvbuff_t *next_tvb; + guint checksum; + guint sent_checksum; + guint offset = 0; + guint dpoe_sec_byte; + gboolean dpoe_encrypted = FALSE; + + /* Start_of_Packet delimiter (/S/) can happen in byte 1, 2 or 3, + * making the captured preamble 8, 7 or 6 bytes in length. If the + * preamble starts with 0x55, then /S/ happened in byte 1, making the + * captured preamble 7 bytes in length. + */ + if (tvb_get_ntohl(tvb, 0) == 0x5555D555) { + offset += 2; + } else if (tvb_get_ntoh24(tvb, 0) == 0x55D555) { + offset += 1; + } else if (tvb_get_ntohs(tvb, 0) == 0xD555) { + offset += 0; + } else { + item = proto_tree_add_item(tree, proto_epon, tvb, offset, 0, ENC_NA); + expert_add_info(pinfo, item, &ei_epon_sld_bad); + return 0; + } + + /* Set the columns */ + col_set_str(pinfo->cinfo, COL_PROTOCOL, "EPON"); + col_set_str(pinfo->cinfo, COL_INFO, "EPON Preamble"); + + /* Create display subtree for the protocol */ + ti = proto_tree_add_item(tree, proto_epon, tvb, 0+offset, 6, ENC_NA); + epon_tree = proto_item_add_subtree(ti, ett_epon); + + /* Decode byte 5 of the preamble according to CableLabs DPoE specification. + * If security is disabled, the DPoE byte will remain 0x55 and no decoding + * is necessary. + */ + dpoe_sec_byte = tvb_get_guint8(tvb, 2+offset); + if (dpoe_sec_byte != 0x55) { + guint dpoe_keyid; + guint dpoe_reserved; + + item = proto_tree_add_item(epon_tree, hf_epon_dpoe_security, + tvb, 2+offset, 1, ENC_BIG_ENDIAN); + sec_tree = proto_item_add_subtree(item, ett_epon_sec); + + /* The DPoE security byte is split into three fields: + * bits 7-2 are reserved in 1G mode + * bit 1 is the encryption mode + * bit 0 is the key ID + */ + dpoe_reserved = dpoe_sec_byte & 0xFC; + dpoe_encrypted = dpoe_sec_byte & 0x02; + dpoe_keyid = dpoe_sec_byte & 0x01; + + /* Add encryption status text to sec_tree subtree + */ + proto_item_append_text(item, " (Encrypted: "); + if (dpoe_encrypted) { + proto_item_append_text(item, "True, Key ID: %x", dpoe_keyid); + } else { + proto_item_append_text(item, "False"); + } + proto_item_append_text(item, ")"); + + /* We don't need to see the reserved bits of the DPoE security byte unless + * there's something wrong with them. + */ + if (dpoe_reserved != 0x54) { + proto_tree_add_item(sec_tree, hf_epon_dpoe_reserved, tvb, 2+offset, 1, + ENC_BIG_ENDIAN); + expert_add_info(pinfo, sec_tree, &ei_epon_dpoe_reserved_bad); + } + + /* Add encryption and key ID bits + * Error if encryption is disabled but key bit is not 1 + */ + proto_tree_add_item(sec_tree, hf_epon_dpoe_encrypted, tvb, 2+offset, 1, + ENC_BIG_ENDIAN); + proto_tree_add_item(sec_tree, hf_epon_dpoe_keyid, tvb, 2+offset, 1, + ENC_BIG_ENDIAN); + if (!dpoe_encrypted && (dpoe_keyid == 0)) { + expert_add_info(pinfo, sec_tree, &ei_epon_dpoe_bad); + } + + } + + /* Mode bit + */ + proto_tree_add_item(epon_tree, hf_epon_mode, tvb, 3+offset, 2, + ENC_BIG_ENDIAN); + + /* LLID + */ + proto_tree_add_item(epon_tree, hf_epon_llid, tvb, 3+offset, 2, + ENC_BIG_ENDIAN); + + /* Verify the CRC-8 checksum + */ + sent_checksum = tvb_get_guint8(tvb, 5+offset); + checksum = get_crc8_ieee8023_epon(tvb, 5, 0+offset); + + proto_tree_add_checksum(epon_tree, tvb, 5+offset, hf_epon_checksum, hf_epon_checksum_status, &ei_epon_checksum_bad, pinfo, checksum, ENC_NA, PROTO_CHECKSUM_VERIFY); + if (sent_checksum != checksum) { + col_append_str(pinfo->cinfo, COL_INFO, " [EPON PREAMBLE CHECKSUM INCORRECT]"); + } + + /* Do not bother parsing encrypted data, otherwise send the rest on to the + * eth dissector. + */ + if (dpoe_encrypted) { + item = proto_tree_add_item(tree, hf_epon_dpoe_encrypted_data, tvb, + 6+offset, -1, ENC_NA); + expert_add_info(pinfo, item, &ei_epon_dpoe_encrypted_data); + col_append_str(pinfo->cinfo, COL_INFO, " [ENCRYPTED]"); + } else { + next_tvb = tvb_new_subset_remaining(tvb, 6+offset); + /* + * XXX - is it guaranteed whether the capture will, or won't, have + * an FCS? + */ + call_dissector(eth_maybefcs_handle, next_tvb, pinfo, tree); + } + + return tvb_captured_length(tvb); +} + +void +proto_register_epon(void) +{ + expert_module_t *expert_epon; + + static hf_register_info hf[] = { + { &hf_epon_dpoe_security, + { "DPoE security", "epon.dpoe.sec", FT_UINT8, BASE_HEX, NULL, 0x0, + "DPoE security octet", HFILL } + }, + { &hf_epon_dpoe_reserved, + { "Reserved", "epon.dpoe.reserved", FT_UINT8, BASE_DEC, NULL, 0xFC, + "Reserved in 1G mode", HFILL } + }, + { &hf_epon_dpoe_encrypted, + { "Encryption enabled", "epon.dpoe.encrypted", FT_BOOLEAN, 8, NULL, 0x02, + "Specifies if this is an encrypted frame", HFILL } + }, + { &hf_epon_dpoe_keyid, + { "Key ID", "epon.dpoe.keyid", FT_UINT8, BASE_HEX, NULL, 0x01, + "Identification number of the key used to encrypt this frame", + HFILL } + }, + { &hf_epon_dpoe_encrypted_data, + { "Encrypted data", "epon.dpoe.encrypted.data", FT_BYTES, BASE_NONE, + NULL, 0x0, "DPoE encrypted data", HFILL } + }, + { &hf_epon_mode, + { "Mode", "epon.mode", FT_BOOLEAN, 16, TFS(&epon_mode_tfs), 0x8000, + "Broadcast/multicast if true, unicast if false", HFILL } + }, + { &hf_epon_llid, + { "LLID", "epon.llid", FT_UINT16, BASE_DEC_HEX, NULL, 0x7FFF, + "Logical Link ID", HFILL } + }, + { &hf_epon_checksum, + { "Frame check sequence", "epon.checksum", FT_UINT8, BASE_HEX, NULL, + 0x0, "EPON preamble checksum", HFILL } + }, + { &hf_epon_checksum_status, + { "Frame check sequence Status", "epon.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), + 0x0, NULL, HFILL } + }, + }; + + static gint *ett[] = { + &ett_epon, + &ett_epon_sec, + &ett_epon_checksum + }; + + /* Setup protocol expert items */ + static ei_register_info ei[] = { + { &ei_epon_checksum_bad, + { "epon.checksum_bad.expert", PI_CHECKSUM, PI_ERROR, + "Bad checksum", EXPFILL } + }, + { &ei_epon_sld_bad, + { "epon.sld_bad.expert", PI_MALFORMED, PI_ERROR, + "Unable to locate SLD or invalid byte sequence: preamble must start with 0xD555", EXPFILL } + }, + { &ei_epon_dpoe_reserved_bad, + { "epon.dpoe.encrypted.expert", PI_MALFORMED, PI_ERROR, + "Bits 7-2 of DPoE security byte must be 010101 in 1G mode.", EXPFILL } + }, + { &ei_epon_dpoe_bad, + { "epon.dpoe.expert", PI_MALFORMED, PI_ERROR, + "DPoE security byte must be 0x55 if encryption is disabled.", EXPFILL } + }, + { &ei_epon_dpoe_encrypted_data, + { "epon.dpoe.encrypted.expert", PI_UNDECODED, PI_NOTE, + "Remaining data is encrypted and will not decode.", EXPFILL } + } + }; + + proto_epon = proto_register_protocol("IEEE 802.3 EPON Preamble", + "EPON", "epon"); + + proto_register_field_array(proto_epon, hf, array_length(hf)); + proto_register_subtree_array(ett, array_length(ett)); + + expert_epon = expert_register_protocol(proto_epon); + expert_register_field_array(expert_epon, ei, array_length(ei)); + + epon_handle = register_dissector("epon", dissect_epon, proto_epon); +} + +void +proto_reg_handoff_epon(void) +{ + dissector_add_uint("wtap_encap", WTAP_ENCAP_EPON, epon_handle); + + eth_maybefcs_handle = find_dissector_add_dependency("eth_maybefcs", proto_epon); +} + +/* + * Editor modelines - https://www.wireshark.org/tools/modelines.html + * + * Local Variables: + * c-basic-offset: 2 + * tab-width: 8 + * indent-tabs-mode: nil + * End: + * + * ex: set shiftwidth=2 tabstop=8 expandtab: + * :indentSize=2:tabSize=8:noTabs=true: + */ |