233 lines
7.5 KiB
C
233 lines
7.5 KiB
C
/* packet-rmt-alc.c
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* Reliable Multicast Transport (RMT)
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* ALC Protocol Instantiation dissector
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* Copyright 2005, Stefano Pettini <spettini@users.sourceforge.net>
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*
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* Asynchronous Layered Coding (ALC):
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* ----------------------------------
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*
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* A massively scalable reliable content delivery protocol.
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* Asynchronous Layered Coding combines the Layered Coding Transport
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* (LCT) building block, a multiple rate congestion control building
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* block and the Forward Error Correction (FEC) building block to
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* provide congestion controlled reliable asynchronous delivery of
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* content to an unlimited number of concurrent receivers from a single
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* sender.
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*
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* References:
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* RFC 3450, Asynchronous Layered Coding protocol instantiation
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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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* SPDX-License-Identifier: GPL-2.0-or-later
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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/prefs.h>
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#include <epan/expert.h>
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#include "packet-rmt-common.h"
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/* Initialize the protocol and registered fields */
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/* ============================================= */
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void proto_register_alc(void);
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void proto_reg_handoff_alc(void);
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static int proto_rmt_alc = -1;
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static int hf_version = -1;
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static int hf_payload = -1;
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static int ett_main = -1;
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static expert_field ei_version1_only = EI_INIT;
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static dissector_handle_t xml_handle;
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static dissector_handle_t rmt_lct_handle;
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static dissector_handle_t rmt_fec_handle;
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static gboolean g_codepoint_as_fec_encoding = TRUE;
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static gint g_ext_192 = LCT_PREFS_EXT_192_FLUTE;
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static gint g_ext_193 = LCT_PREFS_EXT_193_FLUTE;
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/* Code to actually dissect the packets */
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/* ==================================== */
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static int
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dissect_alc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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guint8 version;
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lct_data_exchange_t lct;
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fec_data_exchange_t fec;
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int len;
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/* Offset for subpacket dissection */
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guint offset = 0;
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/* Set up structures needed to add the protocol subtree and manage it */
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proto_item *ti;
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proto_tree *alc_tree;
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tvbuff_t *new_tvb;
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/* Make entries in Protocol column and Info column on summary display */
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "ALC");
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col_clear(pinfo->cinfo, COL_INFO);
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/* ALC header dissection */
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/* --------------------- */
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version = hi_nibble(tvb_get_guint8(tvb, offset));
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/* Create subtree for the ALC protocol */
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ti = proto_tree_add_item(tree, proto_rmt_alc, tvb, offset, -1, ENC_NA);
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alc_tree = proto_item_add_subtree(ti, ett_main);
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/* Fill the ALC subtree */
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ti = proto_tree_add_uint(alc_tree, hf_version, tvb, offset, 1, version);
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/* This dissector supports only ALCv1 packets.
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* If version > 1 print only version field and quit.
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*/
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if (version != 1) {
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expert_add_info(pinfo, ti, &ei_version1_only);
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/* Complete entry in Info column on summary display */
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col_add_fstr(pinfo->cinfo, COL_INFO, "Version: %u (not supported)", version);
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return 0;
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}
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/* LCT header dissection */
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/* --------------------- */
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new_tvb = tvb_new_subset_remaining(tvb,offset);
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lct.ext_192 = g_ext_192;
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lct.ext_193 = g_ext_193;
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lct.codepoint = 0;
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lct.is_flute = FALSE;
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len = call_dissector_with_data(rmt_lct_handle, new_tvb, pinfo, alc_tree, &lct);
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if (len < 0)
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return offset;
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offset += len;
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/* FEC header dissection */
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/* --------------------- */
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/* Only if LCT dissector has determined FEC Encoding ID */
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/* FEC dissector needs to be called with encoding_id filled */
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if (g_codepoint_as_fec_encoding && tvb_reported_length(tvb) > offset)
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{
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fec.encoding_id = lct.codepoint;
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new_tvb = tvb_new_subset_remaining(tvb,offset);
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len = call_dissector_with_data(rmt_fec_handle, new_tvb, pinfo, alc_tree, &fec);
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if (len < 0)
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return offset;
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offset += len;
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}
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/* Add the Payload item */
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if (tvb_reported_length(tvb) > offset){
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if(lct.is_flute){
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new_tvb = tvb_new_subset_remaining(tvb,offset);
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call_dissector(xml_handle, new_tvb, pinfo, alc_tree);
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}else{
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proto_tree_add_item(alc_tree, hf_payload, tvb, offset, -1, ENC_NA);
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}
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}
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return tvb_reported_length(tvb);
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}
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void proto_register_alc(void)
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{
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/* Setup ALC header fields */
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static hf_register_info hf_ptr[] = {
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{ &hf_version,
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{ "Version", "alc.version", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
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{ &hf_payload,
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{ "Payload", "alc.payload", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }}
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};
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/* Setup protocol subtree array */
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static gint *ett_ptr[] = {
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&ett_main,
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};
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static ei_register_info ei[] = {
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{ &ei_version1_only, { "alc.version1_only", PI_PROTOCOL, PI_WARN, "Sorry, this dissector supports ALC version 1 only", EXPFILL }},
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};
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module_t *module;
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expert_module_t* expert_rmt_alc;
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/* Register the protocol name and description */
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proto_rmt_alc = proto_register_protocol("Asynchronous Layered Coding", "ALC", "alc");
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register_dissector("alc", dissect_alc, proto_rmt_alc);
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/* Register the header fields and subtrees used */
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proto_register_field_array(proto_rmt_alc, hf_ptr, array_length(hf_ptr));
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proto_register_subtree_array(ett_ptr, array_length(ett_ptr));
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expert_rmt_alc = expert_register_protocol(proto_rmt_alc);
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expert_register_field_array(expert_rmt_alc, ei, array_length(ei));
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/* Register preferences */
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module = prefs_register_protocol(proto_rmt_alc, NULL);
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prefs_register_obsolete_preference(module, "default.udp_port.enabled");
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prefs_register_bool_preference(module,
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"lct.codepoint_as_fec_id",
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"LCT Codepoint as FEC Encoding ID",
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"Whether the LCT header Codepoint field should be considered the FEC Encoding ID of carried object",
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&g_codepoint_as_fec_encoding);
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prefs_register_enum_preference(module,
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"lct.ext.192",
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"LCT header extension 192",
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"How to decode LCT header extension 192",
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&g_ext_192,
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enum_lct_ext_192,
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FALSE);
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prefs_register_enum_preference(module,
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"lct.ext.193",
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"LCT header extension 193",
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"How to decode LCT header extension 193",
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&g_ext_193,
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enum_lct_ext_193,
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FALSE);
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}
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void proto_reg_handoff_alc(void)
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{
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dissector_handle_t handle;
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handle = create_dissector_handle(dissect_alc, proto_rmt_alc);
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dissector_add_for_decode_as_with_preference("udp.port", handle);
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xml_handle = find_dissector_add_dependency("xml", proto_rmt_alc);
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rmt_lct_handle = find_dissector_add_dependency("rmt-lct", proto_rmt_alc);
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rmt_fec_handle = find_dissector_add_dependency("rmt-fec", proto_rmt_alc);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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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=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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