wrap potentially non-threadsafe snmp operations in mutex; support snmpwalk in subagent

src/mod/event_handlers/mod_snmp/mod_snmp.c

@@ -38,6 +38,7 @@
 
 static struct {
 	switch_memory_pool_t *pool;
+	switch_mutex_t *mutex;
 	int shutdown;
 } globals;
 
@@ -55,27 +56,13 @@ static int snmp_callback_log(int major, int minor, void *serverarg, void *client
 }
 
 
-static switch_state_handler_table_t state_handlers = {
-	/*.on_init */ NULL,
-	/*.on_routing */ NULL,
-	/*.on_execute */ NULL,
-	/*.on_hangup */ NULL,
-	/*.on_exchange_media */ NULL,
-	/*.on_soft_execute */ NULL,
-	/*.on_consume_media */ NULL,
-	/*.on_hibernate */ NULL,
-	/*.on_reset */ NULL,
-	/*.on_park */ NULL,
-	/*.on_reporting */ NULL
-};
-
-
 static switch_status_t load_config(switch_memory_pool_t *pool)
 {
 	switch_status_t status = SWITCH_STATUS_SUCCESS;
 
 	memset(&globals, 0, sizeof(globals));
 	globals.pool = pool;
+	switch_mutex_init(&globals.mutex, SWITCH_MUTEX_NESTED, globals.pool);
 
 	return status;
 }
@@ -87,7 +74,6 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_snmp_load)
 
 	load_config(pool);
 
-	switch_core_add_state_handler(&state_handlers);
 	*module_interface = switch_loadable_module_create_module_interface(pool, modname);
 
 	/* Register callback function so we get Net-SNMP logging handled by FreeSWITCH */
@@ -114,9 +100,11 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_snmp_load)
 
 SWITCH_MODULE_RUNTIME_FUNCTION(mod_snmp_runtime)
 {
-	while (!globals.shutdown) {
+	if (!globals.shutdown) {
 		/* Block on select() */
+		switch_mutex_lock(globals.mutex);
 		agent_check_and_process(1);
+		switch_mutex_unlock(globals.mutex);
 	}
 
 	return SWITCH_STATUS_SUCCESS;
@@ -126,9 +114,12 @@ SWITCH_MODULE_RUNTIME_FUNCTION(mod_snmp_runtime)
 SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_snmp_shutdown)
 {
 	globals.shutdown = 1;
-	switch_core_remove_state_handler(&state_handlers);
 
+	switch_mutex_lock(globals.mutex);
 	snmp_shutdown("mod_snmp");
+	switch_mutex_unlock(globals.mutex);
+
+	switch_mutex_destroy(globals.mutex);
 
 	return SWITCH_STATUS_SUCCESS;
 }

src/mod/event_handlers/mod_snmp/subagent.c

@@ -63,8 +63,8 @@ void init_subagent(void)
 {
 	DEBUGMSGTL(("init_nstAgentSubagentObject", "Initializing\n"));
 
-	netsnmp_register_handler(netsnmp_create_handler_registration("identity", handle_identity, identity_oid, OID_LENGTH(identity_oid), HANDLER_CAN_RONLY));
-	netsnmp_register_handler(netsnmp_create_handler_registration("systemStats", handle_systemStats, systemStats_oid, OID_LENGTH(systemStats_oid), HANDLER_CAN_RONLY));
+	netsnmp_register_scalar_group(netsnmp_create_handler_registration("identity", handle_identity, identity_oid, OID_LENGTH(identity_oid), HANDLER_CAN_RONLY), 1, 2);
+	netsnmp_register_scalar_group(netsnmp_create_handler_registration("systemStats", handle_systemStats, systemStats_oid, OID_LENGTH(systemStats_oid), HANDLER_CAN_RONLY), 1, 7);
 }
 
 
@@ -76,33 +76,29 @@ int handle_identity(netsnmp_mib_handler *handler, netsnmp_handler_registration *
 	oid subid;
 
 	switch(reqinfo->mode) {
-		case MODE_GET:
-			for (request = requests; request; request = request->next) {
-				subid = request->requestvb->name[OID_LENGTH(systemStats_oid)];
-
-				switch (subid) {
-					case versionString_oid:
-						snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR, (u_char *) &version, strlen(version));
-						break;
-					case uuid_oid:
-						strncpy(uuid, switch_core_get_uuid(), sizeof(uuid));
-						snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR, (u_char *) &uuid, strlen(uuid));
-						break;
-					default:
-						snmp_log(LOG_WARNING, "Unregistered OID-suffix requested (%d)\n", (int) subid);
-						netsnmp_set_request_error(reqinfo, request, SNMP_NOSUCHOBJECT);
-				}
+	case MODE_GET:
+		for (request = requests; request; request = request->next) {
+			subid = request->requestvb->name[reginfo->rootoid_len - 2];
+
+			switch (subid) {
+				case versionString_oid:
+					snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR, (u_char *) &version, strlen(version));
+					break;
+				case uuid_oid:
+					strncpy(uuid, switch_core_get_uuid(), sizeof(uuid));
+					snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR, (u_char *) &uuid, strlen(uuid));
+					break;
+				default:
+					snmp_log(LOG_WARNING, "Unregistered OID-suffix requested (%d)\n", (int) subid);
+					netsnmp_set_request_error(reqinfo, request, SNMP_NOSUCHOBJECT);
 			}
-			break;
+		}
+		break;
 
-		case MODE_GETNEXT:
-			snmp_log(LOG_ERR, "MODE_GETNEXT not supported (yet)\n");
-			break;
-
-		default:
-			/* we should never get here, so this is a really bad error */
-			snmp_log(LOG_ERR, "Unknown mode (%d) in handle_versionString\n", reqinfo->mode );
-			return SNMP_ERR_GENERR;
+	default:
+		/* we should never get here, so this is a really bad error */
+		snmp_log(LOG_ERR, "Unknown mode (%d) in handle_identity\n", reqinfo->mode );
+		return SNMP_ERR_GENERR;
 	}
 
 	return SNMP_ERR_NOERROR;
@@ -117,59 +113,55 @@ int handle_systemStats(netsnmp_mib_handler *handler, netsnmp_handler_registratio
 	uint32_t int_val;
 
 	switch(reqinfo->mode) {
-		case MODE_GET:
-			for (request = requests; request; request = request->next) {
-				subid = request->requestvb->name[OID_LENGTH(systemStats_oid)];
-
-				switch (subid) {
-					case uptime_oid:
-						uptime = switch_core_uptime() / 10000;
-						snmp_set_var_typed_value(requests->requestvb, ASN_TIMETICKS, (u_char *) &uptime, sizeof(uptime));
-						break;
-					case sessionsSinceStartup_oid:
-						int_val = switch_core_session_id() - 1;
-						snmp_set_var_typed_value(requests->requestvb, ASN_COUNTER, (u_char *) &int_val, sizeof(int_val));
-						break;
-					case currentSessions_oid:
-						int_val = switch_core_session_count();
-						snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
-						break;
-					case maxSessions_oid:
-						switch_core_session_ctl(SCSC_MAX_SESSIONS, &int_val);;
-						snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
-						break;
-					case currentCalls_oid:
-						/*
-						 * This is zero for now, since there is no convenient way to get total call
-						 * count (not to be confused with session count), without touching the
-						 * database.
-						 */
-						int_val = 0;
-						snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
-						break;
-					case sessionsPerSecond_oid:
-						switch_core_session_ctl(SCSC_LAST_SPS, &int_val);
-						snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
-						break;
-					case maxSessionsPerSecond_oid:
-						switch_core_session_ctl(SCSC_SPS, &int_val);
-						snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
-						break;
-					default:
-						snmp_log(LOG_WARNING, "Unregistered OID-suffix requested (%d)\n", (int) subid);
-						netsnmp_set_request_error(reqinfo, request, SNMP_NOSUCHOBJECT);
-				}
+	case MODE_GET:
+		for (request = requests; request; request = request->next) {
+			subid = request->requestvb->name[reginfo->rootoid_len - 2];
+
+			switch (subid) {
+				case uptime_oid:
+					uptime = switch_core_uptime() / 10000;
+					snmp_set_var_typed_value(requests->requestvb, ASN_TIMETICKS, (u_char *) &uptime, sizeof(uptime));
+					break;
+				case sessionsSinceStartup_oid:
+					int_val = switch_core_session_id() - 1;
+					snmp_set_var_typed_value(requests->requestvb, ASN_COUNTER, (u_char *) &int_val, sizeof(int_val));
+					break;
+				case currentSessions_oid:
+					int_val = switch_core_session_count();
+					snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
+					break;
+				case maxSessions_oid:
+					switch_core_session_ctl(SCSC_MAX_SESSIONS, &int_val);;
+					snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
+					break;
+				case currentCalls_oid:
+					/*
+					 * This is zero for now, since there is no convenient way to get total call
+					 * count (not to be confused with session count), without touching the
+					 * database.
+					 */
+					int_val = 0;
+					snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
+					break;
+				case sessionsPerSecond_oid:
+					switch_core_session_ctl(SCSC_LAST_SPS, &int_val);
+					snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
+					break;
+				case maxSessionsPerSecond_oid:
+					switch_core_session_ctl(SCSC_SPS, &int_val);
+					snmp_set_var_typed_value(requests->requestvb, ASN_GAUGE, (u_char *) &int_val, sizeof(int_val));
+					break;
+				default:
+					snmp_log(LOG_WARNING, "Unregistered OID-suffix requested (%d)\n", (int) subid);
+					netsnmp_set_request_error(reqinfo, request, SNMP_NOSUCHOBJECT);
 			}
-			break;
-
-		case MODE_GETNEXT:
-			snmp_log(LOG_ERR, "MODE_GETNEXT not supported (yet)\n");
-			break;
+		}
+		break;
 
-		default:
-			/* we should never get here, so this is a really bad error */
-			snmp_log(LOG_ERR, "Unknown mode (%d) in handle_systemStats\n", reqinfo->mode);
-			return SNMP_ERR_GENERR;
+	default:
+		/* we should never get here, so this is a really bad error */
+		snmp_log(LOG_ERR, "Unknown mode (%d) in handle_systemStats\n", reqinfo->mode);
+		return SNMP_ERR_GENERR;
 	}
 
 	return SNMP_ERR_NOERROR;