downloader: dbg upgrade whitelist (#213)

downloader/downloader.proto

@@ -10,8 +10,12 @@ package downloader;
 service Downloader {
   // Erigon "download once" - means restart/upgrade/downgrade will not download files (and will be fast)
   // After "download once" - Erigon will produce and seed new files
-  // Downloader will able: seed new files (already existing on FS), download uncomplete parts of existing files (if Verify found some bad parts)
-  rpc ProhibitNewDownloads (ProhibitNewDownloadsRequest) returns (google.protobuf.Empty) {}
+  // After `Prohibit` call - downloader stil will able:
+  //    - seed new (generated by Erigon) files
+  //    - seed existing on Disk files
+  //    - download uncomplete parts of existing on Disk files (if Verify found some bad parts)
+  // `Prohibit` has `whitelist` feature - based on file-type
+  rpc Prohibit (ProhibitRequest) returns (ProhibitReply) {}
 
   // Adding new file to downloader: non-existing files it will download, existing - seed
   rpc Add (AddRequest) returns (google.protobuf.Empty) {}
@@ -46,8 +50,12 @@ message VerifyRequest {
 message StatsRequest {
 }
 
-message ProhibitNewDownloadsRequest {
-  string type = 1;
+message ProhibitRequest {
+  repeated string whitelistAdd = 1; // nil - means "don't modify". non-nil - means "merge with current whitelist".
+  repeated string whitelistRemove = 2; // nil - means "don't modify"
+}
+message ProhibitReply {
+  repeated string whitelist = 1; // current whitelist
 }
 
 message StatsReply {