epan/dissectors/packet-lls.c

   1 /* packet-lls.c
   2  * Routines for ATSC3 LLS(Low Level Signalling) dissection
   3  * Copyright 2023, Sergey V. Lobanov <sergey@lobanov.in>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 /*
  13  * ATSC3 Signaling, Delivery, Synchronization, and Error Protection (A/331)
  14  * https://www.atsc.org/atsc-documents/3312017-signaling-delivery-synchronization-error-protection/
  15  *
  16  * ATSC3 Security and Service Protection (A/360)
  17  * https://www.atsc.org/atsc-documents/3602018-atsc-3-0-security-service-protection/
  18  *
  19  * ATSC Code Point Registry
  20  * https://www.atsc.org/documents/code-point-registry/
  21  */
  22
  23 #include <config.h>
  24 #include <epan/expert.h>
  25 #include <epan/packet.h>
  26
  27 #include "packet-lls.h"
  28
  29 #define LLS_PORT 4937 // IANA Registered (atsc-mh-ssc)
  30
  31 void proto_reg_handoff_lls(void);
  32 void proto_register_lls(void);
  33
  34 static int proto_lls;
  35 static int ett_lls;
  36 static int ett_lls_smt_entry;
  37 static int ett_lls_smt_signature;
  38 static int ett_lls_table_payload;
  39 static int ett_lls_table_payload_xml;
  40
  41 static dissector_handle_t lls_handle;
  42 static dissector_handle_t xml_handle;
  43 static dissector_handle_t cms_handle;
  44
  45 static expert_field ei_lls_table_decompression_failed;
  46
  47 static int hf_lls_table_id;
  48 #define LLS_TABLE_TYPE_SIGNED_MULTI_TABLE 0xFE
  49 #define LLS_TABLE_TYPE_SLT                0x01
  50 static const value_string hf_lls_table_type_vals[] = {
  51     { 0x01, "SLT (Service List Table)" },
  52     { 0x02, "RRT (Rating Region Table)" },
  53     { 0x03, "System Time" },
  54     { 0x04, "AEAT (Advanced Emergency Information Table)" },
  55     { 0x05, "On Screen Message Notification" },
  56     { 0x06, "CDT (Certification Data Table)" },
  57     { 0x07, "DRCT (Dedicated Return Channel Table)" },
  58     { 0x80, "VIT (Version Information Table)" },
  59     { 0x81, "CPT (Content Protection Table)" },
  60     { 0x82, "CAP (Common Alerting Protocol)" },
  61     { 0xFE, "Signed Multi Table" },
  62     { 0xFF, "User Defined" },
  63     { 0x00, NULL }
  64 };
  65 static const value_string hf_lls_table_type_short_vals[] = {
  66     { 0x01, "SLT" },
  67     { 0x02, "RRT" },
  68     { 0x03, "ST" },
  69     { 0x04, "AEAT" },
  70     { 0x05, "OSMN" },
  71     { 0x06, "CDT" },
  72     { 0x07, "DRCT" },
  73     { 0x80, "VIT" },
  74     { 0x81, "CPT" },
  75     { 0x82, "CAP" },
  76     { 0xFE, "SMT" },
  77     { 0xFF, "USD" },
  78     { 0x00, NULL }
  79 };
  80
  81 static int hf_lls_group_id;
  82 static int hf_lls_group_count;
  83 static int hf_lls_table_version;
  84 static int hf_lls_table_payload;
  85 static int hf_lls_table_payload_uncompressed;
  86
  87 static int hf_lls_smt_payload_count;
  88 static int hf_lls_smt_entry;
  89 static int hf_lls_smt_entry_payload_length;
  90 static int hf_lls_smt_signature_length;
  91 static int hf_lls_smt_signature;
  92
  93
  94 static void
  95 dissect_lls_table_payload(uint8_t lls_table_id, tvbuff_t *tvb, packet_info *pinfo, int offset, int len, proto_tree *tree)
  96 {
  97     proto_item *ti = proto_tree_add_item(tree, hf_lls_table_payload, tvb, offset, len, ENC_NA);
  98
  99     if (lls_table_id == LLS_TABLE_TYPE_SIGNED_MULTI_TABLE) {
 100         /* Nested SignedMultiTable decoding is not specified in the standard */
 101         return;
 102     }
 103
 104     proto_tree *uncompress_tree = proto_item_add_subtree(ti, ett_lls_table_payload);
 105     tvbuff_t *uncompress_tvb = tvb_uncompress_zlib(tvb, offset, len);
 106     proto_tree *xml_tree = NULL;
 107     if (uncompress_tvb) {
 108         const char *table_type_short = val_to_str_const(lls_table_id, hf_lls_table_type_short_vals, "Unknown");
 109         char *source_name = wmem_strdup_printf(pinfo->pool, "Table ID %u (%s)", lls_table_id, table_type_short);
 110         add_new_data_source(pinfo, uncompress_tvb, source_name);
 111         unsigned decomp_length = tvb_captured_length(uncompress_tvb);
 112
 113         proto_item *ti_uncomp = proto_tree_add_item(uncompress_tree, hf_lls_table_payload_uncompressed, uncompress_tvb, 0, decomp_length, ENC_ASCII);
 114         proto_item_set_generated(ti_uncomp);
 115
 116         if (xml_handle) {
 117             xml_tree = proto_item_add_subtree(ti_uncomp, ett_lls_table_payload_xml);
 118             call_dissector(xml_handle, uncompress_tvb, pinfo, xml_tree);
 119         }
 120     } else {
 121         expert_add_info(pinfo, ti, &ei_lls_table_decompression_failed);
 122     }
 123
 124     if (lls_table_id == LLS_TABLE_TYPE_SLT && xml_tree != NULL) {
 125         lls_extract_save_slt_table(pinfo, xml_handle);
 126     }
 127 }
 128
 129
 130 static int
 131 dissect_lls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 132 {
 133     col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLS");
 134
 135     proto_item *ti = proto_tree_add_item(tree, proto_lls, tvb, 0, -1, ENC_NA);
 136     proto_tree *lls_tree = proto_item_add_subtree(ti, ett_lls);
 137
 138     int offset = 0;
 139
 140     uint8_t lls_table_id = tvb_get_uint8(tvb, offset);
 141     col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(lls_table_id, hf_lls_table_type_vals, "Unknown"));
 142     proto_tree_add_item(lls_tree, hf_lls_table_id, tvb, offset, 1, ENC_BIG_ENDIAN);
 143     offset++;
 144
 145     proto_tree_add_item(lls_tree, hf_lls_group_id, tvb, offset, 1, ENC_BIG_ENDIAN);
 146     offset++;
 147
 148     uint16_t lls_group_count = tvb_get_uint8(tvb, offset) + 1;
 149     PROTO_ITEM_SET_GENERATED(
 150         proto_tree_add_uint(lls_tree, hf_lls_group_count, tvb, offset, 1, lls_group_count)
 151     );
 152     offset++;
 153
 154     proto_tree_add_item(lls_tree, hf_lls_table_version, tvb, offset, 1, ENC_BIG_ENDIAN);
 155     offset++;
 156
 157     if (lls_table_id == LLS_TABLE_TYPE_SIGNED_MULTI_TABLE) {
 158         uint8_t smt_payload_count = tvb_get_uint8(tvb, offset);
 159         proto_tree_add_item(lls_tree, hf_lls_smt_payload_count, tvb, offset, 1, ENC_BIG_ENDIAN);
 160         offset++;
 161
 162         for(uint8_t i = 0; i < smt_payload_count; i++) {
 163             uint16_t smt_entry_payload_length = tvb_get_uint16(tvb, offset + 2, ENC_BIG_ENDIAN);
 164             proto_item *smt_entry_item = proto_tree_add_item(lls_tree, hf_lls_smt_entry, tvb, offset, smt_entry_payload_length + 4, ENC_NA);
 165             proto_tree *smt_entry_tree = proto_item_add_subtree(smt_entry_item, ett_lls_smt_entry);
 166
 167             uint8_t smt_entry_table_id = tvb_get_uint8(tvb, offset);
 168             const char *table_type_short = val_to_str_const(smt_entry_table_id, hf_lls_table_type_short_vals, "Unknown");
 169             proto_item_append_text(smt_entry_item, " (%u) Table ID=%u (%s)", i, smt_entry_table_id, table_type_short);
 170             col_append_fstr(pinfo->cinfo, COL_INFO, "/%s", table_type_short);
 171             proto_tree_add_item(smt_entry_tree, hf_lls_table_id, tvb, offset, 1, ENC_BIG_ENDIAN);
 172             offset++;
 173
 174             proto_tree_add_item(smt_entry_tree, hf_lls_table_version, tvb, offset, 1, ENC_BIG_ENDIAN);
 175             offset++;
 176
 177             proto_tree_add_item(smt_entry_tree, hf_lls_smt_entry_payload_length, tvb, offset, 2, ENC_BIG_ENDIAN);
 178             offset += 2;
 179
 180             dissect_lls_table_payload(smt_entry_table_id, tvb, pinfo, offset, smt_entry_payload_length, smt_entry_tree);
 181             offset += smt_entry_payload_length;
 182         }
 183
 184         uint16_t smt_signature_length = tvb_get_uint16(tvb, offset, ENC_BIG_ENDIAN);
 185         proto_tree_add_item(lls_tree, hf_lls_smt_signature_length, tvb, offset, 2, ENC_BIG_ENDIAN);
 186         offset += 2;
 187
 188         proto_item *smt_signature_item = proto_tree_add_item(lls_tree, hf_lls_smt_signature, tvb, offset, smt_signature_length, ENC_NA);
 189         if (cms_handle) {
 190             proto_tree *cms_tree = proto_item_add_subtree(smt_signature_item, ett_lls_smt_signature);
 191             tvbuff_t *cms_tvb = tvb_new_subset_length(tvb, offset, smt_signature_length);
 192
 193             /* CMS dissector removes useful info from Protocol and Info columns so store it */
 194             char *col_info_text = wmem_strdup(pinfo->pool, col_get_text(pinfo->cinfo, COL_INFO));
 195             char *col_protocol_text = wmem_strdup(pinfo->pool, col_get_text(pinfo->cinfo, COL_PROTOCOL));
 196
 197             call_dissector(cms_handle, cms_tvb, pinfo, cms_tree);
 198
 199             /* Restore Protocol and Info columns */
 200             col_set_str(pinfo->cinfo, COL_INFO, col_info_text);
 201             col_set_str(pinfo->cinfo, COL_PROTOCOL, col_protocol_text);
 202         }
 203     } else {
 204         int table_payload_length = tvb_captured_length(tvb) - 4;
 205         dissect_lls_table_payload(lls_table_id, tvb, pinfo, offset, table_payload_length, lls_tree);
 206     }
 207
 208     return tvb_captured_length(tvb);
 209 }
 210
 211 void
 212 proto_register_lls(void)
 213 {
 214     static hf_register_info hf[] = {
 215         { &hf_lls_table_id, {
 216             "Table ID", "lls.table.id",
 217             FT_UINT8, BASE_DEC, VALS(hf_lls_table_type_vals), 0, NULL, HFILL
 218         } },
 219         { &hf_lls_group_id, {
 220             "Group ID", "lls.group.id",
 221             FT_UINT8, BASE_DEC, 0, 0, NULL, HFILL
 222         } },
 223         { &hf_lls_group_count, {
 224             "Group Count", "lls.group.count",
 225             FT_UINT16, BASE_DEC, 0, 0, NULL, HFILL
 226         } },
 227         { &hf_lls_table_version, {
 228             "Table Version", "lls.table.version",
 229             FT_UINT8, BASE_DEC, 0, 0, NULL, HFILL
 230         } },
 231         { &hf_lls_table_payload, {
 232             "Table Payload", "lls.table.payload",
 233             FT_NONE, BASE_NONE, 0, 0, NULL, HFILL
 234         } },
 235         { &hf_lls_table_payload_uncompressed, {
 236             "Table Payload Uncompressed", "lls.table.payload.uncompressed",
 237             FT_STRING, BASE_NONE, 0, 0, NULL, HFILL
 238         } },
 239
 240
 241         { &hf_lls_smt_payload_count, {
 242             "Signed Multi Table Payload Count", "lls.smt.payload_count",
 243             FT_UINT8, BASE_DEC, 0, 0, NULL, HFILL
 244         } },
 245         { &hf_lls_smt_entry, {
 246             "Signed Multi Table Entry", "lls.smt.entry",
 247             FT_NONE, BASE_NONE, NULL, 0, NULL, HFILL
 248         } },
 249
 250         { &hf_lls_smt_entry_payload_length, {
 251             "Payload Length", "lls.smt.entry.payload_length",
 252             FT_UINT16, BASE_DEC, 0, 0, NULL, HFILL
 253         } },
 254
 255         { &hf_lls_smt_signature_length, {
 256             "Signed Multi Table Signature Length", "lls.smt.signature_length",
 257             FT_UINT16, BASE_DEC, 0, 0, NULL, HFILL
 258         } },
 259         { &hf_lls_smt_signature, {
 260             "Signed Multi Table Signature", "lls.smt.signature",
 261             FT_NONE, BASE_NONE, 0, 0, NULL, HFILL
 262         } },
 263     };
 264
 265     static int *ett[] = {
 266         &ett_lls,
 267         &ett_lls_smt_entry,
 268         &ett_lls_table_payload,
 269         &ett_lls_table_payload_xml,
 270         &ett_lls_smt_signature,
 271     };
 272
 273     static ei_register_info ei[] = {
 274         { &ei_lls_table_decompression_failed,
 275           { "lls.table.decompression.failed", PI_MALFORMED, PI_ERROR,
 276             "LLS table payload decompression failed",
 277             EXPFILL }
 278         },
 279     };
 280
 281     proto_lls = proto_register_protocol("ATSC3 Low Level Signalling", "LLS", "lls");
 282
 283     expert_module_t *expert_lls = expert_register_protocol(proto_lls);
 284     expert_register_field_array(expert_lls, ei, array_length(ei));
 285
 286     proto_register_field_array(proto_lls, hf, array_length(hf));
 287     proto_register_subtree_array(ett, array_length(ett));
 288 }
 289
 290 void
 291 proto_reg_handoff_lls(void)
 292 {
 293     lls_handle = create_dissector_handle(dissect_lls, proto_lls);
 294     xml_handle = find_dissector_add_dependency("xml", proto_lls);
 295     cms_handle = find_dissector_add_dependency("cms", proto_lls);
 296     dissector_add_uint_with_preference("udp.port", LLS_PORT, lls_handle);
 297
 298 }
 299
 300 /*
 301  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 302  *
 303  * Local variables:
 304  * c-basic-offset: 4
 305  * tab-width: 8
 306  * indent-tabs-mode: nil
 307  * End:
 308  *
 309  * vi: set shiftwidth=4 tabstop=8 expandtab:
 310  * :indentSize=4:tabSize=8:noTabs=true:
 311  */