/* packet-mrdisc.c 2001 Ronnie Sahlberg * Routines for IGMP/MRDISC packet disassembly * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ /* MRDISC code 0x24 x 0x25 x 0x26 x MRDISC : IGMP Multicast Router DISCovery Defined in draft-ietf-idmr-igmp-mrdisc-06.txt TTL==1 and IP.DST==224.0.0.2 for all packets. */ #include "config.h" #include #include #include "packet-igmp.h" void proto_register_mrdisc(void); void proto_reg_handoff_mrdisc(void); static dissector_handle_t mrdisc_handle; static int proto_mrdisc = -1; static int hf_checksum = -1; static int hf_checksum_status = -1; static int hf_type = -1; static int hf_advint = -1; static int hf_numopts = -1; static int hf_options = -1; static int hf_option = -1; static int hf_option_len = -1; static int hf_qi = -1; static int hf_rv = -1; static int hf_option_bytes = -1; static int ett_mrdisc = -1; static int ett_options = -1; static expert_field ei_checksum = EI_INIT; #define MC_ALL_ROUTERS 0xe0000002 #define MRDISC_MRA 0x24 #define MRDISC_MRS 0x25 #define MRDISC_MRT 0x26 static const value_string mrdisc_types[] = { {MRDISC_MRA, "Multicast Router Advertisement"}, {MRDISC_MRS, "Multicast Router Solicitation"}, {MRDISC_MRT, "Multicast Router Termination"}, {0, NULL} }; #define MRDISC_QI 0x01 #define MRDISC_RV 0x02 static const value_string mrdisc_options[] = { {MRDISC_QI, "Query Interval"}, {MRDISC_RV, "Robustness Variable"}, {0, NULL} }; static int dissect_mrdisc_mra(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset) { guint16 num; /* Advertising Interval */ proto_tree_add_item(parent_tree, hf_advint, tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1; /* checksum */ igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_status, &ei_checksum, pinfo, 0); offset += 2; /* skip unused bytes */ offset += 2; /* number of options */ num = tvb_get_ntohs(tvb, offset); proto_tree_add_uint(parent_tree, hf_numopts, tvb, offset, 2, num); offset += 2; /* process any options */ while (num--) { proto_tree *tree; proto_item *item; guint8 type,len; int old_offset = offset; item = proto_tree_add_item(parent_tree, hf_options, tvb, offset, -1, ENC_NA); tree = proto_item_add_subtree(item, ett_options); type = tvb_get_guint8(tvb, offset); proto_tree_add_uint(tree, hf_option, tvb, offset, 1, type); offset += 1; len = tvb_get_guint8(tvb, offset); proto_tree_add_uint(tree, hf_option_len, tvb, offset, 1, len); offset += 1; switch (type) { case MRDISC_QI: proto_item_set_text(item,"Option: %s == %d", val_to_str(type, mrdisc_options, "unknown %x"), tvb_get_ntohs(tvb, offset)); proto_tree_add_item(tree, hf_qi, tvb, offset, len, ENC_BIG_ENDIAN); offset += len; break; case MRDISC_RV: proto_item_set_text(item,"Option: %s == %d", val_to_str(type, mrdisc_options, "unknown %x"), tvb_get_ntohs(tvb, offset)); proto_tree_add_item(tree, hf_rv, tvb, offset, len, ENC_BIG_ENDIAN); offset += len; break; default: proto_item_set_text(item,"Option: unknown"); proto_tree_add_item(tree, hf_option_bytes, tvb, offset, len, ENC_NA); offset += len; } proto_item_set_len(item, offset-old_offset); } return offset; } static int dissect_mrdisc_mrst(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset) { /* skip reserved byte */ offset += 1; /* checksum */ igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_status, &ei_checksum, pinfo, 0); offset += 2; return offset; } /* This function is only called from the IGMP dissector */ static int dissect_mrdisc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_) { proto_tree *tree; proto_item *item; guint8 type; int offset = 0; guint32 dst = g_htonl(MC_ALL_ROUTERS); /* Shouldn't be destined for us */ if ((pinfo->dst.type != AT_IPv4) || memcmp(pinfo->dst.data, &dst, 4)) return 0; col_set_str(pinfo->cinfo, COL_PROTOCOL, "MRDISC"); col_clear(pinfo->cinfo, COL_INFO); item = proto_tree_add_item(parent_tree, proto_mrdisc, tvb, offset, 0, ENC_NA); tree = proto_item_add_subtree(item, ett_mrdisc); type = tvb_get_guint8(tvb, offset); col_add_str(pinfo->cinfo, COL_INFO, val_to_str(type, mrdisc_types, "Unknown Type:0x%02x")); /* type of command */ proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type); offset += 1; switch (type) { case MRDISC_MRA: offset = dissect_mrdisc_mra(tvb, pinfo, tree, offset); break; case MRDISC_MRS: case MRDISC_MRT: /* MRS and MRT packets looks the same */ offset = dissect_mrdisc_mrst(tvb, pinfo, tree, offset); break; } return offset; } void proto_register_mrdisc(void) { static hf_register_info hf[] = { { &hf_type, { "Type", "mrdisc.type", FT_UINT8, BASE_HEX, VALS(mrdisc_types), 0, "MRDISC Packet Type", HFILL }}, { &hf_checksum, { "Checksum", "mrdisc.checksum", FT_UINT16, BASE_HEX, NULL, 0, "MRDISC Checksum", HFILL }}, { &hf_checksum_status, { "Checksum Status", "mrdisc.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0, NULL, HFILL }}, { &hf_advint, { "Advertising Interval", "mrdisc.adv_int", FT_UINT8, BASE_DEC, NULL, 0, "MRDISC Advertising Interval in seconds", HFILL }}, { &hf_numopts, { "Number Of Options", "mrdisc.num_opts", FT_UINT16, BASE_DEC, NULL, 0, "MRDISC Number Of Options", HFILL }}, { &hf_options, { "Options", "mrdisc.options", FT_NONE, BASE_NONE, NULL, 0, "MRDISC Options", HFILL }}, { &hf_option, { "Option", "mrdisc.option", FT_UINT8, BASE_DEC, VALS(mrdisc_options), 0, "MRDISC Option Type", HFILL }}, { &hf_option_len, { "Length", "mrdisc.opt_len", FT_UINT8, BASE_DEC, NULL, 0, "MRDISC Option Length", HFILL }}, { &hf_qi, { "Query Interval", "mrdisc.query_int", FT_UINT16, BASE_DEC, NULL, 0, "MRDISC Query Interval", HFILL }}, { &hf_rv, { "Robustness Variable", "mrdisc.rob_var", FT_UINT16, BASE_DEC, NULL, 0, "MRDISC Robustness Variable", HFILL }}, { &hf_option_bytes, { "Data", "mrdisc.option_data", FT_BYTES, BASE_NONE, NULL, 0, "MRDISC Unknown Option Data", HFILL }}, }; static gint *ett[] = { &ett_mrdisc, &ett_options, }; static ei_register_info ei[] = { { &ei_checksum, { "mrdisc.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }}, }; expert_module_t* expert_mrdisc; proto_mrdisc = proto_register_protocol("Multicast Router DISCovery protocol", "MRDISC", "mrdisc"); proto_register_field_array(proto_mrdisc, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); expert_mrdisc = expert_register_protocol(proto_mrdisc); expert_register_field_array(expert_mrdisc, ei, array_length(ei)); mrdisc_handle = register_dissector("mrdisc", dissect_mrdisc, proto_mrdisc); } void proto_reg_handoff_mrdisc(void) { dissector_add_uint("igmp.type", IGMP_TYPE_0x24, mrdisc_handle); dissector_add_uint("igmp.type", IGMP_TYPE_0x25, mrdisc_handle); dissector_add_uint("igmp.type", IGMP_TYPE_0x26, mrdisc_handle); } /* * Editor modelines - https://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 8 * tab-width: 8 * indent-tabs-mode: t * End: * * vi: set shiftwidth=8 tabstop=8 noexpandtab: * :indentSize=8:tabSize=8:noTabs=false: */