res_hep: Provide an option to pick the UUID type

At one point in time, it seemed like a good idea to use the Asterisk
channel name as the HEP correlation UUID. In particular, it felt like
this would be a useful identifier to tie PJSIP messages and RTCP
messages together, along with whatever other data we may eventually send
to Homer. This also had the benefit of keeping the correlation UUID
channel technology agnostic.

In practice, it isn't as useful as hoped, for two reasons:
1) The first INVITE request received doesn't have a channel. As a
   result, there is always an 'odd message out', leading it to be
   potentially uncorrelated in Homer.
2) Other systems sending capture packets (Kamailio) use the SIP Call-ID.
   This causes RTCP information to be uncorrelated to the SIP message
   traffic seen by those capture nodes.

In order to support both (in case someone is trying to use res_hep_rtcp
with a non-PJSIP channel), this patch adds a new option, uuid_type, with
two valid values - 'call-id' and 'channel'. The uuid_type option is used
by a module to determine the preferred UUID type. When available, that
source of a correlation UUID is used; when not, the more readily available
source is used.

For res_hep_pjsip:
 - uuid_type = call-id: the module uses the SIP Call-ID header value
 - uuid_type = channel: the module uses the channel name if available,
                        falling back to SIP Call-ID if not
For res_hep_rtcp:
 - uuid_type = call-id: the module uses the SIP Call-ID header if the
                        channel type is PJSIP and we have a channel,
                        falling back to the Stasis event provided
                        channel name if not
 - uuid_type = channel: the module uses the channel name

ASTERISK-25352 #close

Change-Id: Ide67e59a52d9c806e3cc0a797ea1a4b88a00122c

1 files changed, 37 insertions, 0 deletions

diff --git a/res/res_hep.c b/res/res_hep.c
index e831fff02..45201359d 100644
--- a/res/res_hep.c
+++ b/res/res_hep.c
@@ -60,6 +60,15 @@
 						</enumlist>
 					</description>
 				</configOption>
+				<configOption name="uuid_type" default="call-id">
+					<synopsis>The preferred type of UUID to pass to Homer.</synopsis>
+					<description>
+						<enumlist>
+							<enum name="call-id"><para>Use the PJSIP Call-Id</para></enum>
+							<enum name="channel"><para>Use the Asterisk channel name</para></enum>
+						</enumlist>
+					</description>
+				</configOption>
 				<configOption name="capture_address" default="192.168.1.1:9061">
 					<synopsis>The address and port of the Homer server to send packets to.</synopsis>
 				</configOption>
@@ -231,6 +240,7 @@ struct hep_generic {
 struct hepv3_global_config {
 	unsigned int enabled;                    /*!< Whether or not sending is enabled */
 	unsigned int capture_id;                 /*!< Capture ID for this agent */
+	enum hep_uuid_type uuid_type;            /*!< The preferred type of the UUID */
 	AST_DECLARE_STRING_FIELDS(
 		AST_STRING_FIELD(capture_address);   /*!< Address to send to */
 		AST_STRING_FIELD(capture_password);  /*!< Password for Homer server */
@@ -329,6 +339,25 @@ static void *module_config_alloc(void)
 	return config;
 }
 
+/*! \brief Handler for the uuid_type attribute */
+static int uuid_type_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
+{
+	struct hepv3_global_config *global_config = obj;
+
+	if (strcasecmp(var->name, "uuid_type")) {
+		return -1;
+	}
+
+	if (!strcasecmp(var->value, "channel")) {
+		global_config->uuid_type = HEP_UUID_TYPE_CHANNEL;
+	} else if (!strcasecmp(var->value, "call-id")) {
+		global_config->uuid_type = HEP_UUID_TYPE_CALL_ID;
+	} else {
+		return -1;
+	}
+	return 0;
+}
+
 /*! \brief HEPv3 run-time data destructor */
 static void hepv3_data_dtor(void *obj)
 {
@@ -376,6 +405,13 @@ static void capture_info_dtor(void *obj)
 	ast_free(info->payload);
 }
 
+enum hep_uuid_type hepv3_get_uuid_type(void)
+{
+	RAII_VAR(struct module_config *, config, ao2_global_obj_ref(global_config), ao2_cleanup);
+
+	return config->general->uuid_type;
+}
+
 struct hepv3_capture_info *hepv3_create_capture_info(const void *payload, size_t len)
 {
 	struct hepv3_capture_info *info;
@@ -607,6 +643,7 @@ static int load_module(void)
 	aco_option_register(&cfg_info, "capture_address", ACO_EXACT, global_options, DEFAULT_HEP_SERVER, OPT_STRINGFIELD_T, 0, STRFLDSET(struct hepv3_global_config, capture_address));
 	aco_option_register(&cfg_info, "capture_password", ACO_EXACT, global_options, "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct hepv3_global_config, capture_password));
 	aco_option_register(&cfg_info, "capture_id", ACO_EXACT, global_options, "0", OPT_UINT_T, 0, STRFLDSET(struct hepv3_global_config, capture_id));
+	aco_option_register_custom(&cfg_info, "uuid_type", ACO_EXACT, global_options, "call-id", uuid_type_handler, 0);
 
 	if (aco_process_config(&cfg_info, 0) == ACO_PROCESS_ERROR) {
 		goto error;