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/* packet-lls-slt.c
* Routines for ATSC3 LLS(Low Level Signalling) SLT table dissection
* Copyright 2023, Sergey V. Lobanov <sergey@lobanov.in>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* ATSC3 Signaling, Delivery, Synchronization, and Error Protection (A/331)
* https://www.atsc.org/atsc-documents/3312017-signaling-delivery-synchronization-error-protection/
*/
#include <epan/packet.h>
#include <epan/proto_data.h>
#include <wsutil/inet_addr.h>
#include <wsutil/strtoi.h>
#include "packet-lls.h"
#include "packet-xml.h"
/* Saved SLT Table to use it from another protocols (e.g. ALC/LCT) */
wmem_map_t *lls_slt_table = NULL;
/* Hash functions */
static gint
lls_slt_key_equal(gconstpointer v, gconstpointer w)
{
const lls_slt_key_t *v1 = (const lls_slt_key_t *)v;
const lls_slt_key_t *v2 = (const lls_slt_key_t *)w;
gint result;
result = (v1->src_ip == v2->src_ip &&
v1->dst_ip == v2->dst_ip &&
v1->dst_port == v2->dst_port);
return result;
}
static guint
lls_slt_key_hash(gconstpointer v)
{
const lls_slt_key_t *key = (const lls_slt_key_t *)v;
guint hash_val = key->src_ip ^ key->dst_ip ^ (((guint32)(key->dst_port)) << 16);
return hash_val;
}
/* Init hash table */
static void
lls_check_init_slt_table(void) {
if(lls_slt_table == NULL) {
lls_slt_table = wmem_map_new_autoreset(wmem_epan_scope(), wmem_file_scope(), lls_slt_key_hash, lls_slt_key_equal);
}
}
static gchar *
xml_value_to_gchar(xml_frame_t *xml_frame, wmem_allocator_t *scope) {
gchar *value = NULL;
if (xml_frame->value != NULL) {
guint l = tvb_reported_length(xml_frame->value);
value = (gchar *)wmem_alloc0(scope, l + 1);
tvb_memcpy(xml_frame->value, value, 0, l);
}
return value;
}
void
lls_extract_save_slt_table(packet_info *pinfo, dissector_handle_t xml_handle)
{
/* Extract data saved by xml */
int proto_xml = dissector_handle_get_protocol_index(xml_handle);
xml_frame_t *xml_dissector_frame = (xml_frame_t *)p_get_proto_data(pinfo->pool, pinfo, proto_xml, 0);
if (xml_dissector_frame == NULL) {
return;
}
/* Data from XML dissector */
/* Root level, find SLT tag */
xml_frame_t *xml_frame = xml_dissector_frame->first_child;
xml_frame_t *xml_frame_slt = NULL;
while (xml_frame) {
if (xml_frame->type == XML_FRAME_TAG && g_strcmp0("SLT", xml_frame->name_orig_case) == 0) {
xml_frame_slt = xml_frame;
break; /* SLT tag found */
}
xml_frame = xml_frame->next_sibling;
}
if (xml_frame_slt == NULL)
return;
/* SLT level*/
xml_frame_t *slt_entry = xml_frame_slt->first_child;
while (slt_entry) {
if (!(slt_entry->type == XML_FRAME_TAG && g_strcmp0("Service", slt_entry->name_orig_case) == 0)) {
slt_entry = slt_entry->next_sibling;
continue;
}
/* Service level */
xml_frame_t *service_entry = slt_entry->first_child;
lls_slt_key_t slt_key = {0};
lls_slt_value_t slt_val = {0};
slt_val.major_channel_num = -1;
slt_val.minor_channel_num = -1;
while (service_entry) {
gchar *value = xml_value_to_gchar(service_entry, pinfo->pool);
if (service_entry->type == XML_FRAME_ATTRIB && value != NULL) {
if(g_strcmp0("serviceId", service_entry->name_orig_case) == 0) {
ws_strtou16(value, NULL, &slt_val.service_id);
} else if(g_strcmp0("majorChannelNo", service_entry->name_orig_case) == 0) {
ws_strtoi32(value, NULL, &slt_val.major_channel_num);
} else if(g_strcmp0("minorChannelNo", service_entry->name_orig_case) == 0) {
ws_strtoi32(value, NULL, &slt_val.minor_channel_num);
}
}
wmem_free(pinfo->pool, value);
if (service_entry->type == XML_FRAME_TAG && g_strcmp0("BroadcastSvcSignaling", service_entry->name_orig_case) == 0) {
/* Broadcast svc signalling level*/
xml_frame_t *bcast_svc_entry = service_entry->first_child;
while (bcast_svc_entry) {
value = xml_value_to_gchar(bcast_svc_entry, pinfo->pool);
if (bcast_svc_entry->type == XML_FRAME_ATTRIB && value != NULL) {
if (g_strcmp0("slsProtocol", bcast_svc_entry->name_orig_case) == 0) {
ws_strtou8(value, NULL, &slt_val.sls_protocol);
} else if (g_strcmp0("slsDestinationIpAddress", bcast_svc_entry->name_orig_case) == 0) {
ws_inet_pton4(value, &slt_key.dst_ip);
} else if (g_strcmp0("slsSourceIpAddress", bcast_svc_entry->name_orig_case) == 0) {
ws_inet_pton4(value, &slt_key.src_ip);
} else if (g_strcmp0("slsDestinationUdpPort", bcast_svc_entry->name_orig_case) == 0) {
ws_strtou16(value, NULL, &slt_key.dst_port);
}
}
wmem_free(pinfo->pool, value);
bcast_svc_entry = bcast_svc_entry->next_sibling;
}
}
service_entry = service_entry->next_sibling;
}
if (slt_key.dst_ip != 0) {
/* Save found service entry to hashmap */
lls_slt_key_t *slt_key_m = wmem_new(wmem_file_scope(), lls_slt_key_t);
lls_slt_value_t *slt_val_m = wmem_new(wmem_file_scope(), lls_slt_value_t);
*slt_key_m = slt_key;
*slt_val_m = slt_val;
lls_check_init_slt_table();
wmem_map_insert(lls_slt_table, (void *)slt_key_m, (void *)slt_val_m);
}
slt_entry = slt_entry->next_sibling;
}
}
static lls_slt_value_t *
get_lls_slt_val(packet_info *pinfo) {
/* This routine is for ATSC3 ALC/LCT packets (ipv4 only protocol by design)
so ipv6 is not supported by this test */
if (!(pinfo->net_src.type == AT_IPv4)) {
return NULL;
}
/* No ability to lookup a record */
if (lls_slt_table == NULL) {
return NULL;
}
/* Prepare for lookup in LLS SLT table */
lls_slt_key_t slt_key;
slt_key.src_ip = *(guint32 *)pinfo->net_src.data;
slt_key.dst_ip = *(guint32 *)pinfo->net_dst.data;
slt_key.dst_port = (guint16)pinfo->destport;
/* Try to lookup by src_ip + dst_ip + dst_port */
lls_slt_value_t *slt_val = (lls_slt_value_t *)wmem_map_lookup(lls_slt_table, (const void *)(&slt_key));
if(slt_val == NULL) {
/* No record in SLT table. src_ip is optional according to A/331 so try to lookup by dst ip + port */
slt_key.src_ip = 0; /* LLS SLT dissector sets it to 0 if source ip is not specified */
slt_val = (lls_slt_value_t *)wmem_map_lookup(lls_slt_table, (const void *)(&slt_key));
if (slt_val == NULL) {
/* Record not found by dst ip + port */
return NULL;
}
}
return slt_val;
}
/* Heuristics test. Checks if packet is ALC using LLS SLT table */
gboolean
test_alc_over_slt(packet_info *pinfo, tvbuff_t *tvb _U_, int offset _U_, void *data _U_)
{
lls_slt_value_t *slt_val = get_lls_slt_val(pinfo);
if (slt_val == NULL)
return FALSE;
if (slt_val->sls_protocol == 1) {
/* slsProtocol=1 is ALC/LCT ROUTE/DASH */
return TRUE;
} else {
/* ACL/LCT is used only for ROUTE/DASH so return false */
return FALSE;
}
}
/* Returns channel info or NULL if no info in SLT table*/
gchar *
get_slt_channel_info(packet_info *pinfo)
{
lls_slt_value_t *slt_val = get_lls_slt_val(pinfo);
if (slt_val == NULL)
return NULL;
gint32 major_channel_num = slt_val->major_channel_num;
gint32 minor_channel_num = slt_val->minor_channel_num;
gchar *ret;
if (major_channel_num > 0 && minor_channel_num > 0) {
ret = wmem_strdup_printf(pinfo->pool, "ServiceID: %u Channel: %d.%d", slt_val->service_id,
major_channel_num, minor_channel_num);
} else {
ret = wmem_strdup_printf(pinfo->pool, "ServiceID: %u", slt_val->service_id);
}
return ret;
}
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