lookip: Disconnect asynchronously to avoid dead-locking watcher unregistration

While it really would be desirable to allow stream destruction during on_read()
callbacks, this does not work anymore since e49b2998. Until we have a proper
solution for this issue, use asynchronous disconnects for the only user doing
so.

Fixes #518.

src/libcharon/plugins/lookip/lookip_socket.c

@@ -87,10 +87,21 @@ static void entry_destroy(entry_t *entry)
 }
 
 /**
- * Disconnect a stream, remove connection entry
+ * Data for async disconnect job
  */
-static void disconnect(private_lookip_socket_t *this, stream_t *stream)
+typedef struct {
+	/** socket ref */
+	private_lookip_socket_t *this;
+	/** stream to disconnect */
+	stream_t *stream;
+} disconnect_data_t;
+
+/**
+ * Disconnect a stream asynchronously, remove connection entry
+ */
+static job_requeue_t disconnect_async(disconnect_data_t *data)
 {
+	private_lookip_socket_t *this = data->this;
 	enumerator_t *enumerator;
 	entry_t *entry;
 
@@ -98,7 +109,7 @@ static void disconnect(private_lookip_socket_t *this, stream_t *stream)
 	enumerator = this->connected->create_enumerator(this->connected);
 	while (enumerator->enumerate(enumerator, &entry))
 	{
-		if (entry->stream == stream)
+		if (entry->stream == data->stream)
 		{
 			this->connected->remove_at(this->connected, enumerator);
 			if (entry->up || entry->down)
@@ -113,6 +124,22 @@ static void disconnect(private_lookip_socket_t *this, stream_t *stream)
 	this->mutex->unlock(this->mutex);
 }
 
+/**
+ * Queue async disconnect job
+ */
+static void disconnect(private_lookip_socket_t *this, stream_t *stream)
+{
+	disconnect_data_t *data;
+
+	INIT(data,
+		.this = this,
+		.stream = stream,
+	);
+
+	lib->processor->queue_job(lib->processor,
+			(job_t*)callback_job_create(disconnect_async, data, free, NULL));
+}
+
 /**
  * Callback function for listener up/down events
  */

src/libstrongswan/networking/streams/stream.h

@@ -39,9 +39,8 @@ typedef stream_t*(*stream_constructor_t)(char *uri);
 /**
  * Callback function prototype, called when stream is ready.
  *
- * It is allowed to destroy the stream during the callback, but only if it has
- * no other active on_read()/on_write() callback and returns FALSE. It is not
- * allowed to to call on_read()/on_write/() during the callback.
+ * It is not allowed to destroy the stream nor to call on_read()/on_write/()
+ * during the callback.
  *
  * As select() may return even if a read()/write() would actually block, it is
  * recommended to use the non-blocking calls and handle return values