2 * Reliable Multicast Transport (RMT)
3 * ALC Protocol Instantiation dissector
4 * Copyright 2005, Stefano Pettini <spettini@users.sourceforge.net>
6 * Asynchronous Layered Coding (ALC):
7 * ----------------------------------
9 * A massively scalable reliable content delivery protocol.
10 * Asynchronous Layered Coding combines the Layered Coding Transport
11 * (LCT) building block, a multiple rate congestion control building
12 * block and the Forward Error Correction (FEC) building block to
13 * provide congestion controlled reliable asynchronous delivery of
14 * content to an unlimited number of concurrent receivers from a single
18 * RFC 3450, Asynchronous Layered Coding protocol instantiation
22 * Wireshark - Network traffic analyzer
23 * By Gerald Combs <gerald@wireshark.org>
24 * Copyright 1998 Gerald Combs
26 * This program is free software; you can redistribute it and/or
27 * modify it under the terms of the GNU General Public License
28 * as published by the Free Software Foundation; either version 2
29 * of the License, or (at your option) any later version.
31 * This program is distributed in the hope that it will be useful,
32 * but WITHOUT ANY WARRANTY; without even the implied warranty of
33 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
34 * GNU General Public License for more details.
36 * You should have received a copy of the GNU General Public License
37 * along with this program; if not, write to the Free Software
38 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
51 #include <epan/packet.h>
52 #include <epan/prefs.h>
54 #include "packet-rmt-alc.h"
56 /* Initialize the protocol and registered fields */
57 /* ============================================= */
59 static int proto = -1;
61 static struct _alc_hf hf;
62 static struct _alc_ett ett;
64 static struct _alc_prefs preferences;
65 dissector_handle_t xml_handle;
71 /* Set/Reset preferences to default values */
72 static void alc_prefs_set_default(struct _alc_prefs *prefs)
74 prefs->use_default_udp_port = FALSE;
75 prefs->default_udp_port = 4001;
77 lct_prefs_set_default(&prefs->lct);
78 fec_prefs_set_default(&prefs->fec);
81 /* Register preferences */
82 static void alc_prefs_register(struct _alc_prefs *prefs, module_t *module)
84 prefs_register_bool_preference(module,
85 "default.udp_port.enabled",
86 "Use default UDP port",
87 "Whether that payload of UDP packets with a specific destination port should be automatically dissected as ALC packets",
88 &prefs->use_default_udp_port);
90 prefs_register_uint_preference(module,
92 "Default UDP destination port",
93 "Specifies the UDP destination port for automatic dissection of ALC packets",
94 10, &prefs->default_udp_port);
96 lct_prefs_register(&prefs->lct, module);
97 fec_prefs_register(&prefs->fec, module);
100 /* Save preferences to alc_prefs_old */
101 static void alc_prefs_save(struct _alc_prefs *p, struct _alc_prefs *p_old)
106 /* Code to actually dissect the packets */
107 /* ==================================== */
109 static void dissect_alc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
111 /* Logical packet representation */
114 /* Offset for subpacket dissection */
117 /* Set up structures needed to add the protocol subtree and manage it */
119 proto_tree *alc_tree;
123 gboolean is_flute = FALSE;
125 /* Structures and variables initialization */
127 memset(&alc, 0, sizeof(struct _alc));
129 /* Update packet info */
130 pinfo->current_proto = "ALC";
132 /* Make entries in Protocol column and Info column on summary display */
133 col_set_str(pinfo->cinfo, COL_PROTOCOL, "ALC");
134 col_clear(pinfo->cinfo, COL_INFO);
136 /* ALC header dissection */
137 /* --------------------- */
139 alc.version = hi_nibble(tvb_get_guint8(tvb, offset));
143 /* Create subtree for the ALC protocol */
144 ti = proto_tree_add_item(tree, proto, tvb, offset, -1, FALSE);
145 alc_tree = proto_item_add_subtree(ti, ett.main);
147 /* Fill the ALC subtree */
148 proto_tree_add_uint(alc_tree, hf.version, tvb, offset, 1, alc.version);
153 /* This dissector supports only ALCv1 packets.
154 * If alc.version > 1 print only version field and quit.
156 if (alc.version == 1) {
164 l.prefs = &preferences.lct;
169 f.prefs = &preferences.fec;
171 /* LCT header dissection */
172 /* --------------------- */
174 is_flute = lct_dissector(l, f, tvb, alc_tree, &offset);
176 /* FEC header dissection */
177 /* --------------------- */
179 /* Only if it's present and if LCT dissector has determined FEC Encoding ID
180 * FEC dissector should be called with fec->encoding_id* and fec->instance_id* filled
182 if (alc.fec.encoding_id_present && tvb_length(tvb) > offset)
183 fec_dissector(f, tvb, alc_tree, &offset);
185 /* Add the Payload item */
186 if (tvb_length(tvb) > offset){
188 new_tvb = tvb_new_subset(tvb,offset,-1,-1);
189 call_dissector(xml_handle, new_tvb, pinfo, alc_tree);
191 proto_tree_add_none_format(alc_tree, hf.payload, tvb, offset, -1, "Payload (%u bytes)", tvb_length(tvb) - offset);
195 /* Complete entry in Info column on summary display */
196 /* ------------------------------------------------ */
198 if (check_col(pinfo->cinfo, COL_INFO))
200 lct_info_column(&alc.lct, pinfo);
201 fec_info_column(&alc.fec, pinfo);
204 /* Free g_allocated memory */
205 lct_dissector_free(&alc.lct);
206 fec_dissector_free(&alc.fec);
211 proto_tree_add_text(alc_tree, tvb, 0, -1, "Sorry, this dissector supports ALC version 1 only");
213 /* Complete entry in Info column on summary display */
214 if (check_col(pinfo->cinfo, COL_INFO))
215 col_add_fstr(pinfo->cinfo, COL_INFO, "Version: %u (not supported)", alc.version);
219 void proto_reg_handoff_alc(void)
221 static dissector_handle_t handle;
222 static gboolean preferences_initialized = FALSE;
223 static struct _alc_prefs preferences_old;
225 if (!preferences_initialized)
227 preferences_initialized = TRUE;
228 handle = create_dissector_handle(dissect_alc, proto);
229 dissector_add_handle("udp.port", handle);
230 xml_handle = find_dissector("xml");
234 if (preferences_old.use_default_udp_port)
235 dissector_delete("udp.port", preferences_old.default_udp_port, handle);
238 if (preferences.use_default_udp_port)
239 dissector_add("udp.port", preferences.default_udp_port, handle);
241 alc_prefs_save(&preferences, &preferences_old);
245 void proto_register_alc(void)
247 /* Setup ALC header fields */
248 static hf_register_info hf_ptr[] = {
251 { "Version", "alc.version", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
253 LCT_FIELD_ARRAY(hf.lct, "alc"),
254 FEC_FIELD_ARRAY(hf.fec, "alc"),
257 { "Payload", "alc.payload", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }}
260 /* Setup protocol subtree array */
261 static gint *ett_ptr[] = {
264 LCT_SUBTREE_ARRAY(ett.lct),
265 FEC_SUBTREE_ARRAY(ett.fec)
270 /* Clear hf and ett fields */
271 memset(&hf, 0xff, sizeof(struct _alc_hf));
272 memset(&ett, 0xff, sizeof(struct _alc_ett));
274 /* Register the protocol name and description */
275 proto = proto_register_protocol("Asynchronous Layered Coding", "ALC", "alc");
277 /* Register the header fields and subtrees used */
278 proto_register_field_array(proto, hf_ptr, array_length(hf_ptr));
279 proto_register_subtree_array(ett_ptr, array_length(ett_ptr));
281 /* Reset preferences */
282 alc_prefs_set_default(&preferences);
284 /* Register preferences */
285 module = prefs_register_protocol(proto, proto_reg_handoff_alc);
286 alc_prefs_register(&preferences, module);