/* packet-rmt-alc.c * Reliable Multicast Transport (RMT) * ALC Protocol Instantiation dissector * Copyright 2005, Stefano Pettini * * Asynchronous Layered Coding (ALC): * ---------------------------------- * * A massively scalable reliable content delivery protocol. * Asynchronous Layered Coding combines the Layered Coding Transport * (LCT) building block, a multiple rate congestion control building * block and the Forward Error Correction (FEC) building block to * provide congestion controlled reliable asynchronous delivery of * content to an unlimited number of concurrent receivers from a single * sender. * * References: * RFC 3450, Asynchronous Layered Coding protocol instantiation * * 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 "packet-rmt-common.h" /* Initialize the protocol and registered fields */ /* ============================================= */ void proto_register_alc(void); void proto_reg_handoff_alc(void); static int proto_rmt_alc = -1; static int hf_version = -1; static int hf_payload = -1; static int ett_main = -1; static expert_field ei_version1_only = EI_INIT; static dissector_handle_t xml_handle; static dissector_handle_t rmt_lct_handle; static dissector_handle_t rmt_fec_handle; static gboolean g_codepoint_as_fec_encoding = TRUE; static gint g_ext_192 = LCT_PREFS_EXT_192_FLUTE; static gint g_ext_193 = LCT_PREFS_EXT_193_FLUTE; /* Code to actually dissect the packets */ /* ==================================== */ static int dissect_alc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) { guint8 version; lct_data_exchange_t lct; fec_data_exchange_t fec; int len; /* Offset for subpacket dissection */ guint offset = 0; /* Set up structures needed to add the protocol subtree and manage it */ proto_item *ti; proto_tree *alc_tree; tvbuff_t *new_tvb; /* Make entries in Protocol column and Info column on summary display */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "ALC"); col_clear(pinfo->cinfo, COL_INFO); /* ALC header dissection */ /* --------------------- */ version = hi_nibble(tvb_get_guint8(tvb, offset)); /* Create subtree for the ALC protocol */ ti = proto_tree_add_item(tree, proto_rmt_alc, tvb, offset, -1, ENC_NA); alc_tree = proto_item_add_subtree(ti, ett_main); /* Fill the ALC subtree */ ti = proto_tree_add_uint(alc_tree, hf_version, tvb, offset, 1, version); /* This dissector supports only ALCv1 packets. * If version > 1 print only version field and quit. */ if (version != 1) { expert_add_info(pinfo, ti, &ei_version1_only); /* Complete entry in Info column on summary display */ col_add_fstr(pinfo->cinfo, COL_INFO, "Version: %u (not supported)", version); return 0; } /* LCT header dissection */ /* --------------------- */ new_tvb = tvb_new_subset_remaining(tvb,offset); lct.ext_192 = g_ext_192; lct.ext_193 = g_ext_193; lct.codepoint = 0; lct.is_flute = FALSE; len = call_dissector_with_data(rmt_lct_handle, new_tvb, pinfo, alc_tree, &lct); if (len < 0) return offset; offset += len; /* FEC header dissection */ /* --------------------- */ /* Only if LCT dissector has determined FEC Encoding ID */ /* FEC dissector needs to be called with encoding_id filled */ if (g_codepoint_as_fec_encoding && tvb_reported_length(tvb) > offset) { fec.encoding_id = lct.codepoint; new_tvb = tvb_new_subset_remaining(tvb,offset); len = call_dissector_with_data(rmt_fec_handle, new_tvb, pinfo, alc_tree, &fec); if (len < 0) return offset; offset += len; } /* Add the Payload item */ if (tvb_reported_length(tvb) > offset){ if(lct.is_flute){ new_tvb = tvb_new_subset_remaining(tvb,offset); call_dissector(xml_handle, new_tvb, pinfo, alc_tree); }else{ proto_tree_add_item(alc_tree, hf_payload, tvb, offset, -1, ENC_NA); } } return tvb_reported_length(tvb); } void proto_register_alc(void) { /* Setup ALC header fields */ static hf_register_info hf_ptr[] = { { &hf_version, { "Version", "alc.version", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_payload, { "Payload", "alc.payload", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }} }; /* Setup protocol subtree array */ static gint *ett_ptr[] = { &ett_main, }; static ei_register_info ei[] = { { &ei_version1_only, { "alc.version1_only", PI_PROTOCOL, PI_WARN, "Sorry, this dissector supports ALC version 1 only", EXPFILL }}, }; module_t *module; expert_module_t* expert_rmt_alc; /* Register the protocol name and description */ proto_rmt_alc = proto_register_protocol("Asynchronous Layered Coding", "ALC", "alc"); register_dissector("alc", dissect_alc, proto_rmt_alc); /* Register the header fields and subtrees used */ proto_register_field_array(proto_rmt_alc, hf_ptr, array_length(hf_ptr)); proto_register_subtree_array(ett_ptr, array_length(ett_ptr)); expert_rmt_alc = expert_register_protocol(proto_rmt_alc); expert_register_field_array(expert_rmt_alc, ei, array_length(ei)); /* Register preferences */ module = prefs_register_protocol(proto_rmt_alc, NULL); prefs_register_obsolete_preference(module, "default.udp_port.enabled"); prefs_register_bool_preference(module, "lct.codepoint_as_fec_id", "LCT Codepoint as FEC Encoding ID", "Whether the LCT header Codepoint field should be considered the FEC Encoding ID of carried object", &g_codepoint_as_fec_encoding); prefs_register_enum_preference(module, "lct.ext.192", "LCT header extension 192", "How to decode LCT header extension 192", &g_ext_192, enum_lct_ext_192, FALSE); prefs_register_enum_preference(module, "lct.ext.193", "LCT header extension 193", "How to decode LCT header extension 193", &g_ext_193, enum_lct_ext_193, FALSE); } void proto_reg_handoff_alc(void) { dissector_handle_t handle; handle = create_dissector_handle(dissect_alc, proto_rmt_alc); dissector_add_for_decode_as_with_preference("udp.port", handle); xml_handle = find_dissector_add_dependency("xml", proto_rmt_alc); rmt_lct_handle = find_dissector_add_dependency("rmt-lct", proto_rmt_alc); rmt_fec_handle = find_dissector_add_dependency("rmt-fec", proto_rmt_alc); } /* * Editor modelines - http://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 4 * tab-width: 8 * indent-tabs-mode: nil * End: * * ex: set shiftwidth=4 tabstop=8 expandtab: * :indentSize=4:tabSize=8:noTabs=true: */