degesch: clean up the async code a bit

degesch.c

@@ -1065,9 +1065,9 @@ struct transport
 	void (*cleanup) (struct server *s);
 
 	/// The underlying socket may have become readable, update `read_buffer'
-	enum transport_io_result (*on_readable) (struct server *s);
+	enum transport_io_result (*try_read) (struct server *s);
 	/// The underlying socket may have become writeable, flush `write_buffer'
-	enum transport_io_result (*on_writeable) (struct server *s);
+	enum transport_io_result (*try_write) (struct server *s);
 	/// Return event mask to use in the poller
 	int (*get_poll_events) (struct server *s);
 
@@ -3203,7 +3203,9 @@ irc_send (struct server *s, const char *format, ...)
 		print_debug ("tried sending a message to a dead server connection");
 		return;
 	}
-	if (s->state == IRC_CLOSING)
+
+	if (s->state == IRC_CLOSING
+	 || s->state == IRC_HALF_CLOSED)
 		return;
 
 	va_list ap;
@@ -3329,7 +3331,7 @@ initiate_quit (struct app_context *ctx)
 }
 
 static void
-on_irc_disconnected (struct server *s)
+irc_disconnect (struct server *s)
 {
 	hard_assert (irc_is_connected (s));
 
@@ -3337,6 +3339,7 @@ on_irc_disconnected (struct server *s)
 	if (s->transport
 	 && s->transport->cleanup)
 		s->transport->cleanup (s);
+	s->transport = NULL;
 
 	xclose (s->socket);
 	s->socket = -1;
@@ -3403,7 +3406,7 @@ on_irc_ping_timeout (void *user_data)
 {
 	struct server *s = user_data;
 	log_server_error (s, s->buffer, "Connection timeout");
-	on_irc_disconnected (s);
+	irc_disconnect (s);
 }
 
 static void
@@ -3419,74 +3422,91 @@ on_irc_timeout (void *user_data)
 static void irc_process_message
 	(const struct irc_message *msg, const char *raw, void *user_data);
 
-static void
-on_irc_ready (const struct pollfd *pfd, struct server *s)
+static enum transport_io_result
+irc_try_read (struct server *s)
 {
-	struct transport *transport = s->transport;
-	enum transport_io_result result;
-
-	if ((result = transport->on_readable (s)) == TRANSPORT_IO_ERROR)
-		goto error;
-	bool read_eof = result == TRANSPORT_IO_EOF;
-
+	enum transport_io_result result = s->transport->try_read (s);
+	if (result == TRANSPORT_IO_OK)
+	{
 		if (s->read_buffer.len >= (1 << 20))
 		{
 			// XXX: this is stupid; if anything, count it in dependence of time
 			log_server_error (s, s->buffer,
 				"The IRC server seems to spew out data frantically");
-		goto disconnect;
+			return TRANSPORT_IO_ERROR;
 		}
 		if (s->read_buffer.len)
 			irc_process_buffer (&s->read_buffer, irc_process_message, s);
+	}
+	return result;
+}
 
-	if ((result = transport->on_writeable (s)) == TRANSPORT_IO_ERROR)
-		goto error;
-	bool write_eof = result == TRANSPORT_IO_EOF;
-
-	// FIXME: this may probably fire multiple times if we're flushing after it,
-	//   we should probably store this information next to the state
-	if (read_eof || write_eof)
-		log_server_error (s, s->buffer, "The IRC server closed the connection");
-
-	// It makes no sense to flush anything if the write needs to read
-	// and we receive an EOF -> disconnect right away
-	if (write_eof)
-		goto disconnect;
-
-	// If we've been asked to flush the write buffer and our job is complete,
-	// we send an EOF to the server, changing the state to IRC_HALF_CLOSED
+static enum transport_io_result
+irc_try_write (struct server *s)
+{
+	enum transport_io_result result = s->transport->try_write (s);
+	if (result == TRANSPORT_IO_OK)
+	{
+		// If we're flushing the write buffer and our job is complete, we send
+		// an EOF to the server, changing the state to IRC_HALF_CLOSED
 		if (s->state == IRC_CLOSING && !s->write_buffer.len)
 			irc_real_shutdown (s);
+	}
+	return result;
+}
 
-	if (read_eof)
+static bool
+irc_try_read_write (struct server *s)
+{
+	enum transport_io_result read_result;
+	enum transport_io_result write_result;
+	if ((read_result  = irc_try_read  (s)) == TRANSPORT_IO_ERROR
+	 || (write_result = irc_try_write (s)) == TRANSPORT_IO_ERROR)
 	{
-		// Both ends closed, we're done
-		if (s->state == IRC_HALF_CLOSED)
-			goto disconnect;
-
-		// Otherwise we want to flush the write buffer
-		irc_shutdown (s);
-
-		// If that went well, we can disconnect now
-		if (s->state == IRC_HALF_CLOSED)
-			goto disconnect;
+		log_server_error (s, s->buffer, "Server connection failed");
+		return false;
 	}
 
+	// FIXME: this may probably fire multiple times when we're flushing,
+	//   we should probably store a flag next to the state
+	if (read_result  == TRANSPORT_IO_EOF
+	 || write_result == TRANSPORT_IO_EOF)
+		log_server_error (s, s->buffer, "Server closed the connection");
+
+	// If the write needs to read and we receive an EOF, we can't flush
+	if (write_result == TRANSPORT_IO_EOF)
+		return false;
+
+	if (read_result  == TRANSPORT_IO_EOF)
+	{
+		// Eventually initiate shutdown to flush the write buffer
+		irc_shutdown (s);
+
+		// If there's nothing to write, we can disconnect now
+		if (s->state == IRC_HALF_CLOSED)
+			return false;
+	}
+	return true;
+}
+
+static void
+on_irc_ready (const struct pollfd *pfd, struct server *s)
+{
+	if (irc_try_read_write (s))
+	{
 		// XXX: shouldn't we rather wait for PONG messages?
 		irc_reset_connection_timeouts (s);
 		irc_update_poller (s, pfd);
-	return;
-
-error:
-	log_server_error (s, s->buffer, "Reading from the IRC server failed");
-disconnect:
-	on_irc_disconnected (s);
+	}
+	else
+		// We don't want to keep the socket anymore
+		irc_disconnect (s);
 }
 
 // --- Plain transport ---------------------------------------------------------
 
 static enum transport_io_result
-transport_plain_on_readable (struct server *s)
+transport_plain_try_read (struct server *s)
 {
 	struct str *buf = &s->read_buffer;
 	ssize_t n_read;
@@ -3516,7 +3536,7 @@ transport_plain_on_readable (struct server *s)
 }
 
 static enum transport_io_result
-transport_plain_on_writeable (struct server *s)
+transport_plain_try_write (struct server *s)
 {
 	struct str *buf = &s->write_buffer;
 	ssize_t n_written;
@@ -3552,8 +3572,8 @@ transport_plain_get_poll_events (struct server *s)
 
 static struct transport g_transport_plain =
 {
-	.on_readable      = transport_plain_on_readable,
-	.on_writeable     = transport_plain_on_writeable,
+	.try_read         = transport_plain_try_read,
+	.try_write        = transport_plain_try_write,
 	.get_poll_events  = transport_plain_get_poll_events,
 };
 
@@ -3696,7 +3716,7 @@ transport_tls_cleanup (struct server *s)
 }
 
 static enum transport_io_result
-transport_tls_on_readable (struct server *s)
+transport_tls_try_read (struct server *s)
 {
 	struct transport_tls_data *data = s->transport_data;
 	if (data->ssl_tx_want_rx)
@@ -3733,7 +3753,7 @@ transport_tls_on_readable (struct server *s)
 }
 
 static enum transport_io_result
-transport_tls_on_writeable (struct server *s)
+transport_tls_try_write (struct server *s)
 {
 	struct transport_tls_data *data = s->transport_data;
 	if (data->ssl_rx_want_tx)
@@ -3794,8 +3814,8 @@ static struct transport g_transport_tls =
 {
 	.init               = transport_tls_init,
 	.cleanup            = transport_tls_cleanup,
-	.on_readable        = transport_tls_on_readable,
-	.on_writeable       = transport_tls_on_writeable,
+	.try_read           = transport_tls_try_read,
+	.try_write          = transport_tls_try_write,
 	.get_poll_events    = transport_tls_get_poll_events,
 	.in_before_shutdown = transport_tls_in_before_shutdown,
 };