Clementine will offer a song before download first. The client can deceide if it want to download it or not. Only when the client accepted the file, Clementine sends it.

ext/libclementine-remote/remotecontrolmessages.proto

@@ -16,7 +16,7 @@ enum MsgType {
   CLOSE_PLAYLIST = 11;
   GET_LYRICS = 14;
   DOWNLOAD_SONGS = 15;
-  SEND_NEXT_SONG = 16;
+  SONG_OFFER_RESPONSE = 16;
   // Lastfm
   LOVE = 12;
   BAN = 13;
@@ -254,6 +254,10 @@ message ResponseSongFileChunk {
   optional int32 size = 8;
 }
 
+message ResponseSongOffer {
+  optional bool accepted = 1; // true = client wants to download item
+}
+
 // The message itself
 message Message {
   optional int32 version = 1 [default=9];
@@ -284,4 +288,5 @@ message Message {
   optional ResponseActiveChanged response_active_changed = 24;
   optional ResponseLyrics response_lyrics = 30;
   optional ResponseSongFileChunk response_song_file_chunk = 32;
+  optional ResponseSongOffer response_song_offer = 33;
 }

src/networkremote/incomingdataparser.cpp

@@ -153,8 +153,9 @@ void IncomingDataParser::Parse(const pb::remote::Message& msg) {
     case pb::remote::DOWNLOAD_SONGS:
                                   emit SendSongs(msg.request_download_songs(), client);
                                   break;
-    case pb::remote::SEND_NEXT_SONG:
-                                  emit SendNextSong(client);
+    case pb::remote::SONG_OFFER_RESPONSE:
+                                  emit ResponseSongOffer(client,
+                                                         msg.response_song_offer().accepted());
                                   break;
     default: break;
   }

src/networkremote/incomingdataparser.h

@@ -46,7 +46,7 @@ signals:
   void RemoveSongs(const QList<int>& indices);
   void SeekTo(int seconds);
   void SendSongs(const pb::remote::RequestDownloadSongs& request, RemoteClient* client);
-  void SendNextSong(RemoteClient* client);
+  void ResponseSongOffer(RemoteClient* client, bool accepted);
 
 private:
   Application* app_;

src/networkremote/networkremote.cpp

@@ -164,9 +164,9 @@ void NetworkRemote::AcceptConnection() {
             outgoing_data_creator_.get(),
             SLOT(SendSongs(pb::remote::RequestDownloadSongs,RemoteClient*)));
     connect(incoming_data_parser_.get(),
-            SIGNAL(SendNextSong(RemoteClient*)),
+            SIGNAL(ResponseSongOffer(RemoteClient*, bool)),
             outgoing_data_creator_.get(),
-            SLOT(SendNextSong(RemoteClient*)));
+            SLOT(ResponseSongOffer(RemoteClient*, bool)));
   }
 
   QTcpServer* server = qobject_cast<QTcpServer*>(sender());

src/networkremote/outgoingdatacreator.cpp

@@ -570,10 +570,37 @@ void OutgoingDataCreator::SendSongs(const pb::remote::RequestDownloadSongs &requ
   }
 
   // Send first file
-  SendNextSong(client);
+  OfferNextSong(client);
 }
 
-void OutgoingDataCreator::SendNextSong(RemoteClient *client) {
+void OutgoingDataCreator::OfferNextSong(RemoteClient *client) {
+  if (!download_queue_.contains(client))
+    return;
+
+  if (download_queue_.value(client).isEmpty())
+    return;
+
+  // Get the item and send the single song
+  DownloadItem item = download_queue_[client].head();
+
+  pb::remote::Message msg;
+  msg.set_type(pb::remote::SONG_FILE_CHUNK);
+  pb::remote::ResponseSongFileChunk* chunk = msg.mutable_response_song_file_chunk();
+
+  // Song offer is chunk no 0
+  chunk->set_chunk_count(0);
+  chunk->set_chunk_number(0);
+  chunk->set_file_count(item.song_count_);
+  chunk->set_file_number(item.song_no_);
+
+  CreateSong(item.song_, item.song_.image(), -1,
+             chunk->mutable_song_metadata());
+
+  msg.set_version(msg.default_instance().version());
+  client->SendData(&msg);
+}
+
+void OutgoingDataCreator::ResponseSongOffer(RemoteClient *client, bool accepted) {
   if (!download_queue_.contains(client))
     return;
 
@@ -582,7 +609,11 @@ void OutgoingDataCreator::SendNextSong(RemoteClient *client) {
 
   // Get the item and send the single song
   DownloadItem item = download_queue_[client].dequeue();
-  SendSingleSong(client, item.song_, item.song_no_, item.song_count_);
+  if (accepted)
+    SendSingleSong(client, item.song_, item.song_no_, item.song_count_);
+
+  // And offer the next song
+  OfferNextSong(client);
 }
 
 void OutgoingDataCreator::SendSingleSong(RemoteClient* client, const Song &song,

src/networkremote/outgoingdatacreator.h

@@ -71,7 +71,7 @@ public slots:
   void GetLyrics();
   void SendLyrics(int id, const SongInfoFetcher::Result& result);
   void SendSongs(const pb::remote::RequestDownloadSongs& request, RemoteClient* client);
-  void SendNextSong(RemoteClient* client);
+  void ResponseSongOffer(RemoteClient* client, bool accepted);
 
 private:
   Application* app_;
@@ -102,6 +102,7 @@ private:
   void SendSingleSong(RemoteClient* client, const Song& song, int song_no, int song_count);
   void SendAlbum(RemoteClient* client, const Song& song);
   void SendPlaylist(RemoteClient* client, int playlist_id);
+  void OfferNextSong(RemoteClient* client);
 };
 
 #endif // OUTGOINGDATACREATOR_H