Don't leak sockets.

lib/mosquitto_internal.h

@@ -110,6 +110,7 @@ enum mosquitto_client_state {
 	mosq_cs_connecting = 16,
 	mosq_cs_duplicate = 17, /* client that has been taken over by another with the same id */
 	mosq_cs_disconnect_with_will = 18,
+	mosq_cs_disused = 19, /* client that has been added to the disused list to be freed */
 };
 
 enum mosquitto__protocol {

src/context.c

@@ -251,19 +251,19 @@ void context__send_will(struct mosquitto_db *db, struct mosquitto *ctxt)
 
 void context__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 {
+	context->disconnect_t = time(NULL);
+	net__socket_close(db, context);
+
 	if(context->session_expiry_interval == 0){
 		context__send_will(db, context);
 
-		context->disconnect_t = time(NULL);
-		net__socket_close(db, context);
-
 #ifdef WITH_BRIDGE
 		if(!context->bridge)
 #endif
 		{
 
 			if(context->will_delay_interval == 0){
-				/* This will be done later, after the will is published */
+				/* This will be done later, after the will is published for delay>0. */
 				context__add_to_disused(db, context);
 				if(context->id){
 					context__remove_from_by_id(db, context);
@@ -280,6 +280,10 @@ void context__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 
 void context__add_to_disused(struct mosquitto_db *db, struct mosquitto *context)
 {
+	if(context->state == mosq_cs_disused) return;
+
+	context->state = mosq_cs_disused;
+
 	if(db->ll_for_free){
 		context->for_free_next = db->ll_for_free;
 		db->ll_for_free = context;