mgcp: improve endpoint management

Currently the assignment of endpoint identifiers works by just
incrementing a counter. The mgcpgw only has a limited amount
of endpoint identifiers avaliable, this means we will run out
of endpoints after only a few calls.

This commit adds a mechanism to keep track of used endpoint
identifiers so unused endpoint identifiers can be re-used

1 files changed, 67 insertions, 5 deletions

diff --git a/openbsc/src/libmgcp/mgcpgw_client.c b/openbsc/src/libmgcp/mgcpgw_client.c
index 0c2106704..2cafcf2a0 100644
--- a/openbsc/src/libmgcp/mgcpgw_client.c
+++ b/openbsc/src/libmgcp/mgcpgw_client.c
@@ -40,8 +40,13 @@ struct mgcpgw_client {
 	uint32_t remote_addr;
 	struct osmo_wqueue wq;
 	mgcp_trans_id_t next_trans_id;
-	uint16_t next_endpoint;
 	struct llist_head responses_pending;
+	struct llist_head inuse_endpoints;
+};
+
+struct mgcp_inuse_endpoint {
+	struct llist_head entry;
+	uint16_t id;
 };
 
 void mgcpgw_client_conf_init(struct mgcpgw_client_conf *conf)
@@ -52,13 +57,67 @@ void mgcpgw_client_conf_init(struct mgcpgw_client_conf *conf)
 		.local_port = -1,
 		.remote_addr = NULL,
 		.remote_port = -1,
+		.first_endpoint = 0,
+		.last_endpoint = 0,
 	};
 }
 
-unsigned int mgcpgw_client_next_endpoint(struct mgcpgw_client *client)
+/* Test if a given endpoint id is currently in use */
+static bool endpoint_in_use(uint16_t id, struct mgcpgw_client *client)
 {
-	/* FIXME: wrapping / cleanup + re-use */
-	return client->next_endpoint ++;
+	struct mgcp_inuse_endpoint *endpoint;
+	llist_for_each_entry(endpoint, &client->inuse_endpoints, entry) {
+		if (endpoint->id == id)
+			return true;
+	}
+
+	return false;
+}
+
+/* Find and seize an unsused endpoint id */
+int mgcpgw_client_next_endpoint(struct mgcpgw_client *client)
+{
+	int i;
+	uint16_t first_endpoint = client->actual.first_endpoint;
+	uint16_t last_endpoint = client->actual.last_endpoint;
+	struct mgcp_inuse_endpoint *endpoint;
+
+	/* Use the maximum permitted range if the VTY
+	 * configuration does not specify a range */
+	if (client->actual.last_endpoint == 0) {
+		first_endpoint = 1;
+		last_endpoint = 65534;
+	}
+
+	/* Test the permitted endpoint range for an endpoint
+	 * number that is not in use. When a suitable endpoint
+	 * number can be found, seize it by adding it to the
+	 * inuse list. */
+	for (i=first_endpoint;i<last_endpoint;i++)
+	{
+		if (endpoint_in_use(i,client) == false) {
+			endpoint = talloc_zero(client, struct mgcp_inuse_endpoint);
+			endpoint->id = i;
+			llist_add_tail(&endpoint->entry, &client->inuse_endpoints);
+			return endpoint->id;
+		}
+	}
+
+	/* All endpoints are busy! */
+	return -EINVAL;
+}
+
+/* Release a seized endpoint id to make it available again for other calls */
+void mgcpgw_client_release_endpoint(uint16_t id, struct mgcpgw_client *client)
+{
+	struct mgcp_inuse_endpoint *endpoint;
+	struct mgcp_inuse_endpoint *endpoint_tmp;
+	llist_for_each_entry_safe(endpoint, endpoint_tmp, &client->inuse_endpoints, entry) {
+		if (endpoint->id == id) {
+			llist_del(&endpoint->entry);
+			talloc_free(endpoint);
+		}
+	}
 }
 
 static void mgcpgw_client_handle_response(struct mgcpgw_client *mgcp,
@@ -281,9 +340,9 @@ struct mgcpgw_client *mgcpgw_client_init(void *ctx,
 	mgcp = talloc_zero(ctx, struct mgcpgw_client);
 
 	INIT_LLIST_HEAD(&mgcp->responses_pending);
+	INIT_LLIST_HEAD(&mgcp->inuse_endpoints);
 
 	mgcp->next_trans_id = 1;
-	mgcp->next_endpoint = 1;
 
 	mgcp->actual.local_addr = conf->local_addr ? conf->local_addr :
 		MGCPGW_CLIENT_LOCAL_ADDR_DEFAULT;
@@ -295,6 +354,9 @@ struct mgcpgw_client *mgcpgw_client_init(void *ctx,
 	mgcp->actual.remote_port = conf->remote_port >= 0 ? (uint16_t)conf->remote_port :
 		MGCPGW_CLIENT_REMOTE_PORT_DEFAULT;
 
+	mgcp->actual.first_endpoint = conf->first_endpoint > 0 ? (uint16_t)conf->first_endpoint : 0;
+	mgcp->actual.last_endpoint = conf->last_endpoint > 0 ? (uint16_t)conf->last_endpoint : 0;
+
 	return mgcp;
 }