Send the AEffect object over a new control socket

We'll use the same socket to send the configuration data back to the
plugin.

src/plugin/plugin-bridge.cpp

@@ -58,6 +58,7 @@ PluginBridge::PluginBridge(audioMasterCallback host_callback)
       vst_host_callback(io_context),
       host_vst_parameters(io_context),
       host_vst_process_replacing(io_context),
+      host_vst_control(io_context),
       host_callback_function(host_callback),
       logger(Logger::create_from_environment(
           create_logger_prefix(socket_endpoint.path()))),
@@ -109,6 +110,7 @@ PluginBridge::PluginBridge(audioMasterCallback host_callback)
     socket_acceptor.accept(vst_host_callback);
     socket_acceptor.accept(host_vst_parameters);
     socket_acceptor.accept(host_vst_process_replacing);
+    socket_acceptor.accept(host_vst_control);
 
 #ifndef WITH_WINEDBG
     host_guard_handler.request_stop();
@@ -170,10 +172,10 @@ PluginBridge::PluginBridge(audioMasterCallback host_callback)
 
     // Read the plugin's information from the Wine process. This can only be
     // done after we started accepting host callbacks as the plugin will likely
-    // call these during its initialization. We reuse the `dispatcher()` socket
-    // for this since this has to be done only once.
-    const auto initialization_data =
-        read_object<EventResult>(host_vst_dispatch);
+    // call these during its initialization. Any further updates will be sent
+    // over the `dispatcher()` socket. This would happen whenever the plugin
+    // calls `audioMasterIOChanged()` and after the host calls `effOpen()`.
+    const auto initialization_data = read_object<EventResult>(host_vst_control);
     const auto initialized_plugin =
         std::get<AEffect>(initialization_data.payload);
 

src/plugin/plugin-bridge.h

@@ -109,8 +109,7 @@ class PluginBridge {
 
     /**
      * The socket that forwards all `dispatcher()` calls from the VST host to
-     * the plugin. This is also used once at startup to populate the values of
-     * the `AEffect` object.
+     * the plugin.
      */
     boost::asio::local::stream_protocol::socket host_vst_dispatch;
     /**
@@ -120,6 +119,10 @@ class PluginBridge {
      * this MIDI input would just stop working at times.
      */
     boost::asio::local::stream_protocol::socket host_vst_dispatch_midi_events;
+    /**
+     * The socket that forwards all `audioMaster()` calls from the Windows VST
+     * plugin to the host.
+     */
     boost::asio::local::stream_protocol::socket vst_host_callback;
     /**
      * Used for both `getParameter` and `setParameter` since they mostly
@@ -128,6 +131,14 @@ class PluginBridge {
     boost::asio::local::stream_protocol::socket host_vst_parameters;
     boost::asio::local::stream_protocol::socket host_vst_process_replacing;
 
+    /**
+     * A control socket that sends data that is not suitable for the other
+     * sockets. At the moment this is only used to, on startup, send the Windows
+     * VST plugin's `AEffect` object to the native VST plugin, and to then send
+     * the configuration (from `config`) back to the Wine host.
+     */
+    boost::asio::local::stream_protocol::socket host_vst_control;
+
     /**
      * The thread that handles host callbacks.
      */