/* packet-metamako.c * Routines for dissection of Metamako trailers. Forked from * packet-vssmonitoring.c on 20th December, 2015. * See https://www.metamako.com for further details. * * Copyright VSS-Monitoring 2011 * Copyright Metamako LP 2015 * * 20111205 - First edition by Sake Blok (sake.blok@SYN-bit.nl) * 20151220 - Forked to become packet-metamako.c * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include #include #include #include #define TRAILER_MIN_LENGTH_NO_FCS 16 #define TRAILER_NS_UPPER_BOUND 1000000000 #define TRAILER_SECS_BOUNDS_DFLT "3600-" #define TRAILER_DAYS_DIFF_LIMIT_DFLT 30 #define SECS_IN_ONE_DAY (60 * 60 * 24) void proto_register_metamako(void); void proto_reg_handoff_metamako(void); /* FCS Options */ static gboolean metamako_check_fcs = TRUE; static gint metamako_fcs_len = -1; /* By default, try to autodetect the FCS. */ /* Heuristic Options */ static gint metamako_trailer_present = -1; /* By default, try to autodetect the trailer. */ static range_t* metamako_trailer_secs_bounds = NULL; static guint metamako_trailer_days_diff_limit = TRAILER_DAYS_DIFF_LIMIT_DFLT; /* Protocols and Header Fields */ static int proto_metamako = -1; /* Metamako trailer format 0.............7...............15..............23..............31 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Original FCS | +---------------+---------------+---------------+---------------+ | ... | +---------------+---------------+---------------+---------------+ | TLV Extensions | +---------------+---------------+---------------+---------------+ | ... | +---------------+---------------+---------------+---------------+ | Seconds | +---------------+---------------+---------------+---------------+ | Nanoseconds | +---------------+---------------+---------------+---------------+ | Flags | Device ID | Port ID | +---------------+---------------+---------------+---------------+ */ static int hf_metamako_origfcs = -1; static int hf_metamako_trailerext = -1; static int hf_metamako_unknownext = -1; static int hf_metamako_seqnum = -1; static int hf_metamako_tagstring = -1; static int hf_metamako_fracns = -1; static int hf_metamako_crchash = -1; static int hf_metamako_egress_seqnum = -1; static int hf_metamako_time_abs = -1; static int hf_metamako_time_rel = -1; static int hf_metamako_flags = -1; static int hf_metamako_src_port = -1; static int hf_metamako_src_device = -1; static int hf_metamako_time_diff = -1; static int hf_metamako_fcs = -1; static int hf_metamako_fcs_status = -1; static int hf_metamako_flags_orig_fcs_vld = -1; static int hf_metamako_flags_has_ext = -1; static int hf_metamako_flags_duplicate = -1; static int hf_metamako_flags_ts_degraded = -1; static int hf_metamako_flags_control_block_type = -1; static int hf_metamako_reserved = -1; static gint ett_metamako = -1; static gint ett_metamako_timestamp = -1; static gint ett_metamako_extensions = -1; static gint ett_metamako_flags = -1; static const enum_val_t metamako_fcs_vals[] = { {"heuristic", "According to heuristic", -1}, {"never", "Never", 0}, {"always", "Always", 4}, {NULL, NULL, 0} }; static const enum_val_t metamako_trailer_present_vals[] = { {"heuristic", "According to heuristic", -1}, {"never", "Never", 0}, {"always", "Always", 1}, {NULL, NULL, 0} }; static const value_string tfs_pcs49_btf_vals[] = { { 0x0, "0x33 or 0x66" }, { 0x1, "0x78"}, { 0, NULL } }; static const value_string tfs_orig_fcs_status_vals[] = { { 0x0, "Bad" }, { 0x1, "Good"}, { 0, NULL } }; static int* const flags[] = { &hf_metamako_flags_control_block_type, &hf_metamako_flags_ts_degraded, &hf_metamako_flags_duplicate, &hf_metamako_flags_has_ext, &hf_metamako_flags_orig_fcs_vld, &hf_metamako_reserved, NULL }; static expert_field ei_metamako_fcs_bad = EI_INIT; static void sub_nanos_base_custom(gchar* result, guint32 value) { double temp_double; temp_double = ((double)value) / (1ULL << 24); snprintf(result, ITEM_LABEL_LENGTH, "%1.9fns", temp_double); } static int validate_metamako_timestamp(nstime_t* metamako_time, packet_info* pinfo) { /* Check that we have a valid nanoseconds field. */ if (metamako_time->nsecs >= TRAILER_NS_UPPER_BOUND) return 0; /* Check that the seconds in the trailer timestamp are in the user-specified bounds. */ if (!value_is_in_range(metamako_trailer_secs_bounds, (guint32)metamako_time->secs)) return 0; /* Check that the number of days between the trailer timestamp and the capture timestamp are within the user-specified bounds. Don't use the abs() function because it is not supported on all platforms and has type ambiguity. */ if (metamako_time->secs > pinfo->abs_ts.secs) { if (metamako_time->secs - pinfo->abs_ts.secs > (time_t)metamako_trailer_days_diff_limit * SECS_IN_ONE_DAY) return 0; } else { if (pinfo->abs_ts.secs - metamako_time->secs > (time_t)metamako_trailer_days_diff_limit * SECS_IN_ONE_DAY) return 0; } return 1; } static int dissect_metamako(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data _U_) { guint i, i_start, i_end, j; proto_tree* ti, * parent, * item; proto_tree* metamako_tree, * timestamp_tree; proto_tree* extensions_tree; guint offset = 0; guint captured_trailer_bytes; guint metamako_trailer_bytes; guint trailer_min_length; gboolean trailer_valid; gboolean has_fcs; nstime_t metamako_time, time_diff, time_rel; guint metamako_meta; guint metamako_tlv_count; guint metamako_tlv_firstword; guint metamako_tlv_len; guint metamako_tlv_tag; guint metamako_tlv_pos; guint metamako_tlv_bytes; guint8 metamako_srcport; guint16 metamako_srcdevice; guint8 metamako_flags; struct tm* tmp; /* The Metamako trailer is made up of: 4 bytes -- original FCS N bytes -- trailer extensions 4 bytes -- seconds 4 bytes -- nanoseconds 1 byte -- flags 2 bytes -- device ID 1 byte -- port ID The new FCS is not a part of the trailer specification, but it may be passed to this dissector in the course of dissecting the Ethernet trailer. If `metamako_fcs_len` is 0, we know it's not present; if `metamako_fcs_len` is 4, we know it's present; if `metamako_fcs_len` is -1, we need some heuristics to determine whether it's present. 4 bytes -- New (valid) FCS (may or may not have been captured) */ /* If the user has told us that the Metamako trailer is not present, then exit immediately. */ if (metamako_trailer_present == 0) return 0; /* First get the captured length of the trailer. */ captured_trailer_bytes = tvb_captured_length(tvb); /* Determine the minimum trailer length required, based on the user's setting of the assumed FCS capture. */ trailer_min_length = metamako_fcs_len == 4 ? TRAILER_MIN_LENGTH_NO_FCS + 4 : TRAILER_MIN_LENGTH_NO_FCS; /* If we have less than `trailer_min_length` bytes captured, we can't read the trailer. */ if (captured_trailer_bytes < trailer_min_length) return 0; /* Adjust the state of the loop variables to account for the user options. */ trailer_valid = FALSE; i_start = metamako_fcs_len == 4 ? 1 : 0; i_end = metamako_fcs_len == 0 ? 1 : 2; /* Loop through the trailer bytes, trying to find a valid trailer. * When: * i == 0, we assume there IS NO trailing FCS * i == 1, we assume ther IS a trailing FCS */ for (i = i_start; i < i_end && !trailer_valid; i++) { has_fcs = i == 1; captured_trailer_bytes -= 4 * i; metamako_trailer_bytes = captured_trailer_bytes; /* Start at the tail of the trailer and work inwards. */ metamako_meta = tvb_get_ntohl(tvb, metamako_trailer_bytes - 4); metamako_flags = (metamako_meta >> 24) & 0xFF; metamako_trailer_bytes -= 4; metamako_time.nsecs = tvb_get_ntohl(tvb, metamako_trailer_bytes - 4); metamako_trailer_bytes -= 4; metamako_time.secs = tvb_get_ntohl(tvb, metamako_trailer_bytes - 4); metamako_trailer_bytes -= 4; /* Check the validity of the candidate timestamp. */ if ((metamako_trailer_present == 1) || validate_metamako_timestamp(&metamako_time, pinfo)) { metamako_tlv_bytes = 0; metamako_tlv_count = 0; /* If the trailer has TLV extensions, "walk" them backwards to the Orig FCS field. */ if (metamako_flags & 0x2) { /* Extensions are flagged as included, check if there is bytes * to support this, and try to decode. */ while (metamako_trailer_bytes >= 4) { /* Bytes are here, decode as TLVs. */ metamako_tlv_firstword = tvb_get_ntohl(tvb, metamako_trailer_bytes - 4); metamako_tlv_count++; metamako_tlv_bytes += 4; metamako_trailer_bytes -= 4; /* Extract length */ metamako_tlv_len = (metamako_tlv_firstword >> 6) & 0x3; /* If it's a secondary tag header, extract the extended length. */ if ((metamako_tlv_firstword & 0x1F) == 0x1F) metamako_tlv_len = ((metamako_tlv_firstword >> 6) & 0x3FF) + 1; /* Skip over the data and find the next tag. We do this in a loop rather than subtracting `4 * metamako_tlv_len` in case the dissection has picked up an invalid TLV length in its heuristic search. This prevents the "walk" from going past the original length of the trailer. */ while ((metamako_tlv_len > 0) && (metamako_trailer_bytes >= 4)) { metamako_tlv_len--; metamako_tlv_bytes += 4; metamako_trailer_bytes -= 4; } /* If this is flagged as the last TLV, stop. */ if ((metamako_tlv_firstword >> 5) & 0x1) { break; } } } /* There should be at least enough bytes for the Orig FCS field. * Any bytes before this are padding. */ if (metamako_trailer_bytes >= 4) { /* Decrement by the number of bytes in the Orig FCS field. */ metamako_trailer_bytes -= 4; /* This byte offset is the beginning of the Metamako trailer. */ offset = metamako_trailer_bytes; /* If we've made it this far, it appears we've got a valid trailer. */ trailer_valid = TRUE; } } } /* Did we find a valid trailer? */ if (!trailer_valid) return 0; /* Everything looks good! Now dissect the trailer. */ col_append_str(pinfo->cinfo, COL_INFO, " with Metamako trailer"); ti = proto_tree_add_item(tree, proto_metamako, tvb, offset, (captured_trailer_bytes - offset), ENC_NA); metamako_tree = proto_item_add_subtree(ti, ett_metamako); /* Original FCS */ proto_tree_add_item(metamako_tree, hf_metamako_origfcs, tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4; /* TLV Extensions */ if (metamako_tlv_bytes > 0) { parent = proto_tree_add_item(metamako_tree, hf_metamako_trailerext, tvb, captured_trailer_bytes - 12 - metamako_tlv_bytes, metamako_tlv_bytes, ENC_NA); extensions_tree = proto_item_add_subtree(parent, ett_metamako_extensions); while (metamako_tlv_count > 0) { metamako_tlv_pos = captured_trailer_bytes - 16; i = metamako_tlv_count; do { /* Read TLV word and decode. */ metamako_tlv_firstword = tvb_get_ntohl(tvb, metamako_tlv_pos); metamako_tlv_len = (metamako_tlv_firstword >> 6) & 0x3; metamako_tlv_bytes = (metamako_tlv_len * 4) + 3; metamako_tlv_tag = (metamako_tlv_firstword & 0x1F); /* If this is a Secondary Tag Header, decode the tag extensions. */ if ((metamako_tlv_firstword & 0x1F) == 0x1F) { metamako_tlv_len = ((metamako_tlv_firstword >> 6) & 0x3FF) + 1; metamako_tlv_bytes = (metamako_tlv_len * 4); metamako_tlv_tag += ((metamako_tlv_firstword >> 16) & 0xFFFF); } /* Decrement TLV count. */ i--; /* Skip over the data if this is not our destination. */ if (i != 0) metamako_tlv_pos -= (metamako_tlv_len + 1) * 4; } while (i > 0); metamako_tlv_pos -= (metamako_tlv_len + 1) * 4; /* We've skipped to the i-th TLV, decode it. */ switch (metamako_tlv_tag) { case 0x00: /* Ingress Sequence Number */ proto_tree_add_item(extensions_tree, hf_metamako_seqnum, tvb, metamako_tlv_pos + 5, 2, ENC_BIG_ENDIAN); proto_item_append_text(parent, ", Sequence No: %d", tvb_get_ntohs(tvb, metamako_tlv_pos + 5)); break; case 0x01: /* Sub-nanoseconds */ proto_tree_add_item(extensions_tree, hf_metamako_fracns, tvb, metamako_tlv_pos + 4, 3, ENC_BIG_ENDIAN); proto_item_append_text(parent, ", Sub-nanoseconds: %1.9fns", ((double)(tvb_get_ntohl(tvb, metamako_tlv_pos + 3) & 0x00FFFFFF)) / (1ULL << 24)); break; case 0x02: /* Deduplication CRC64 Hash */ proto_tree_add_item(extensions_tree, hf_metamako_crchash, tvb, metamako_tlv_pos + 4, 8, ENC_BIG_ENDIAN); proto_item_append_text(parent, ", CRC64 ECMA Hash: 0x%" PRIx64, tvb_get_ntoh64(tvb, metamako_tlv_pos + 4)); break; case 0x03: /* Egress Sequence Number */ proto_tree_add_item(extensions_tree, hf_metamako_egress_seqnum, tvb, metamako_tlv_pos + 4, 3, ENC_BIG_ENDIAN); proto_item_append_text(parent, ", Egress Sequence No: %d", tvb_get_ntohl(tvb, metamako_tlv_pos + 3) & 0x000FFFFF); break; case 0x1F: /* Tag String */ proto_tree_add_item(extensions_tree, hf_metamako_tagstring, tvb, metamako_tlv_pos + 4, metamako_tlv_len * 4, ENC_ASCII); break; default: /* Unknown tag: just print it's ID and Data. */ item = proto_tree_add_item(extensions_tree, hf_metamako_unknownext, tvb, metamako_tlv_pos + 4, metamako_tlv_bytes, ENC_NA); /* Start with the Tag */ proto_item_set_text(item, "Unknown Tag [0x%05" PRIx32 "]: ", metamako_tlv_tag); /* Iterate through the data appending as we go */ for (j = 0; j < metamako_tlv_bytes; j++) { proto_item_append_text(item, "%02" PRIx8, tvb_get_guint8(tvb, metamako_tlv_pos + 4 + j)); if ((28 + j * 2) >= ITEM_LABEL_LENGTH) { proto_item_append_text(item, "..."); break; } } break; } /* Increment the offset by the Data + Tag size */ offset += (metamako_tlv_len + 1) * 4; /* Decrement count as we've just decoded a TLV */ metamako_tlv_count--; } } /* Timestamp */ item = proto_tree_add_time(metamako_tree, hf_metamako_time_abs, tvb, offset, 8, &metamako_time); timestamp_tree = proto_item_add_subtree(item, ett_metamako_timestamp); tmp = localtime(&metamako_time.secs); if (tmp) proto_item_append_text(ti, ", Timestamp: %02d:%02d:%02d.%09ld", tmp->tm_hour, tmp->tm_min, tmp->tm_sec, (long)metamako_time.nsecs); else proto_item_append_text(ti, ", Timestamp: "); /* [Timestamp in seconds] */ item = proto_tree_add_time_item(timestamp_tree, hf_metamako_time_rel, tvb, offset, 8, ENC_BIG_ENDIAN, &time_rel, NULL, NULL); proto_item_set_generated(item); /* [Timestamp difference - capture timestamp minus trailer timestamp] */ nstime_delta(&time_diff, &pinfo->abs_ts, &metamako_time); item = proto_tree_add_time(timestamp_tree, hf_metamako_time_diff, tvb, offset, 8, &time_diff); proto_item_set_generated(item); offset += 8; /* Flags */ proto_tree_add_bitmask(metamako_tree, tvb, offset, hf_metamako_flags, ett_metamako_flags, flags, ENC_BIG_ENDIAN); offset++; /* Source device */ metamako_srcdevice = tvb_get_ntohs(tvb, offset); proto_tree_add_item(metamako_tree, hf_metamako_src_device, tvb, offset, 2, ENC_BIG_ENDIAN); proto_item_append_text(ti, ", Source Device: %d", metamako_srcdevice); offset += 2; /* Source port */ metamako_srcport = tvb_get_guint8(tvb, offset); proto_tree_add_item(metamako_tree, hf_metamako_src_port, tvb, offset, 1, ENC_BIG_ENDIAN); proto_item_append_text(ti, ", Source Port: %d", metamako_srcport); offset++; if (has_fcs) { guint32 sent_fcs = tvb_get_ntohl(tvb, offset); if (metamako_check_fcs) { tvbuff_t* parent_tvb = tvb_get_ds_tvb(tvb); guint32 fcs = crc32_802_tvb(parent_tvb, tvb_captured_length(parent_tvb) - 4); proto_tree_add_checksum(tree, tvb, offset, hf_metamako_fcs, hf_metamako_fcs_status, &ei_metamako_fcs_bad, pinfo, fcs, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY); if (fcs != sent_fcs) { col_append_str(pinfo->cinfo, COL_INFO, " [ETHERNET FRAME CHECK SEQUENCE INCORRECT]"); } } else { proto_tree_add_checksum(tree, tvb, offset, hf_metamako_fcs, hf_metamako_fcs_status, &ei_metamako_fcs_bad, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS); } offset += 4; } return offset; } void proto_register_metamako(void) { static hf_register_info hf[] = { { &hf_metamako_origfcs, { "Original FCS", "metamako.orig_fcs", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_trailerext, { "Trailer Extensions", "metamako.ext", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_unknownext, { "Unknown Tag", "metamako.unknown", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_seqnum, { "Sequence Number", "metamako.seqnum", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_fracns, { "Sub-nanoseconds", "metamako.subns", FT_UINT24, BASE_CUSTOM, CF_FUNC(sub_nanos_base_custom), 0x0, NULL, HFILL }}, { &hf_metamako_crchash, { "CRC64 ECMA Hash", "metamako.crchash", FT_UINT64, BASE_HEX, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_egress_seqnum, { "Egress Sequence Number", "metamako.egrseqnum", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_tagstring, { "Tag String", "metamako.tagstring", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_time_abs, { "Timestamp", "metamako.time.abs", FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_time_rel, { "Timestamp", "metamako.time.rel", FT_RELATIVE_TIME, ENC_BIG_ENDIAN, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_time_diff, { "Time Difference", "metamako.time.diff", FT_RELATIVE_TIME, BASE_NONE, NULL, 0x0, "Capture timestamp minus trailer timestamp", HFILL }}, {&hf_metamako_flags, { "Flags", "metamako.flags", FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL}}, {&hf_metamako_reserved, { "Reserved", "metamako.reserved", FT_UINT8, BASE_HEX, NULL, 0xC8, NULL, HFILL}}, {&hf_metamako_flags_control_block_type, { "Clause 49 BTF", "metamako.flags.pcs49_btf", FT_UINT8, BASE_HEX, VALS(tfs_pcs49_btf_vals), 0x20, NULL, HFILL}}, {&hf_metamako_flags_ts_degraded, { "Timestamp degraded", "metamako.flags.ts_degraded", FT_BOOLEAN, 8, TFS(&tfs_true_false), 0x10, NULL, HFILL}}, {&hf_metamako_flags_duplicate, { "Duplicate Packet", "metamako.flags.is_duplicate", FT_BOOLEAN, 8, TFS(&tfs_true_false), 0x04, NULL, HFILL}}, {&hf_metamako_flags_has_ext, { "Has Trailer Extensions", "metamako.flags.has_extensions", FT_BOOLEAN, 8, TFS(&tfs_true_false), 0x02, NULL, HFILL}}, {&hf_metamako_flags_orig_fcs_vld, { "Original FCS Status", "metamako.flags.orig_fcs_status", FT_UINT8, BASE_HEX, VALS(tfs_orig_fcs_status_vals), 0x01, NULL, HFILL}}, { &hf_metamako_src_device, { "Source Device ID", "metamako.src.device_id", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_src_port, { "Source Port", "metamako.src.port", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_metamako_fcs, { "Frame check sequence", "metamako.fcs", FT_UINT32, BASE_HEX, NULL, 0x0, "Ethernet checksum", HFILL }}, { &hf_metamako_fcs_status, { "FCS Status", "metamako.fcs.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0, NULL, HFILL }}, }; static gint* ett[] = { &ett_metamako, &ett_metamako_extensions, &ett_metamako_timestamp, &ett_metamako_flags }; static ei_register_info ei[] = { { &ei_metamako_fcs_bad, { "metamako.fcs_bad", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }}, }; module_t* metamako_module; /* Register the Metamako trailer. */ proto_metamako = proto_register_protocol("Metamako ethernet trailer", "Metamako", "metamako"); /* Register header fields. */ proto_register_field_array(proto_metamako, hf, array_length(hf)); /* Register subtree types. */ proto_register_subtree_array(ett, array_length(ett)); /* Register the expert module. */ expert_register_field_array(expert_register_protocol(proto_metamako), ei, array_length(ei)); /* Register configuration preferences */ metamako_module = prefs_register_protocol(proto_metamako, NULL); range_convert_str(wmem_epan_scope(), &metamako_trailer_secs_bounds, TRAILER_SECS_BOUNDS_DFLT, 0xffffffff); prefs_register_range_preference(metamako_module, "secs_bounds", "Heuristic: Bounds of the seconds value in the trailer timestamp", "If the trailer is found using heuristics, then the trailer may or may not be added " "and the FCS may or may not be captured. One of the heuristics is the timestamp seconds " "value being within specified bounds. " "Set ranges of valid seconds to adjust this particular heuristic.", &metamako_trailer_secs_bounds, 0xffffffff); prefs_register_uint_preference(metamako_module, "days_diff_limit", "Heuristic: Max. number of days difference between capture and trailer timestamps", "If the trailer is found using heuristics, then the trailer may or may not be added " "and the FCS may or may not be captured. One of the heuristics is the number of days " "difference between the capture (PCAP) timestamp and the Ethernet trailer timestamp. " "Set an upper bound (in days) to adjust this particular heuristic.", 10, &metamako_trailer_days_diff_limit); prefs_register_enum_preference(metamako_module, "trailer_present", "Assume packets have a Metamako trailer", "This option can override the trailer detection heuristic so that the Metamako " "trailer is either never or always present.", &metamako_trailer_present, metamako_trailer_present_vals, FALSE); prefs_register_enum_preference(metamako_module, "fcs", "Assume packets have FCS", "Some Ethernet adapters and drivers include the FCS at the end of a packet, others do not. " "Some capture file formats and protocols do not indicate whether or not the FCS is included. " "The Metamako dissector attempts to guess whether a captured packet has an FCS, " "but it cannot always guess correctly. This option can override that heuristic " "and assume that the FCS is either never or always present.", &metamako_fcs_len, metamako_fcs_vals, FALSE); prefs_register_bool_preference(metamako_module, "check_fcs", "Validate the Ethernet checksum if possible", "Whether to validate the Frame Check Sequence", &metamako_check_fcs); } void proto_reg_handoff_metamako(void) { heur_dissector_add("eth.trailer", dissect_metamako, "Metamako ethernet trailer", "metamako_eth", proto_metamako, HEURISTIC_DISABLE); } /* * 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: */