allow write buffer to server stream

packages/grpc-js/src/object-stream.ts

@@ -49,9 +49,9 @@ export interface IntermediateObjectWritable<T> extends Writable {
 }
 
 export interface ObjectWritable<T> extends IntermediateObjectWritable<T> {
-  _write(chunk: T, encoding: string, callback: Function): void;
-  write(chunk: T, cb?: Function): boolean;
-  write(chunk: T, encoding?: any, cb?: Function): boolean;
+  _write(chunk: T | Buffer, encoding: string, callback: Function): void;
+  write(chunk: T | Buffer, cb?: Function): boolean;
+  write(chunk: T | Buffer, encoding?: any, cb?: Function): boolean;
   setDefaultEncoding(encoding: string): this;
   end(): ReturnType<Writable['end']> extends Writable ? this : void;
   end(

packages/grpc-js/src/server-call.ts

@@ -222,7 +222,7 @@ export class ServerWritableStreamImpl<RequestType, ResponseType>
   }
 
   _write(
-    chunk: ResponseType,
+    chunk: ResponseType | Buffer,
     encoding: string,
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     callback: (...args: any[]) => void
@@ -654,15 +654,38 @@ export class Http2ServerCallStream<
     }
   }
 
-  serializeMessage(value: ResponseType) {
+  serializeMessage(value: ResponseType | Buffer) {
+    // TODO(cjihrig): Call compression aware serializeMessage().
+
+    if (value instanceof Buffer) {
+      return this.serializeMessageHandleBuffer(value);
+    }
+
     const messageBuffer = this.handler.serialize(value);
+    return this.addCompressionAndLength(messageBuffer);
+  }
 
-    // TODO(cjihrig): Call compression aware serializeMessage().
-    const byteLength = messageBuffer.byteLength;
+  private serializeMessageHandleBuffer(value: Buffer): Buffer {
+    const byteLength = value.byteLength;
+    // checking if this is a protobuf message or a gRPC frame
+    if (
+      byteLength >= 5 &&
+      (value.readUInt8(0) === 0 || value.readUint8(0) === 1) &&
+      value.readUInt32BE(1) === byteLength - 5
+    ) {
+      return value;
+    }
+
+    return this.addCompressionAndLength(value);
+  }
+
+  private addCompressionAndLength(value: Buffer, compressed = false) {
+    const byteLength = value.byteLength;
+    const compressionByte = compressed ? 1 : 0;
     const output = Buffer.allocUnsafe(byteLength + 5);
-    output.writeUInt8(0, 0);
+    output.writeUInt8(compressionByte, 0);
     output.writeUInt32BE(byteLength, 1);
-    messageBuffer.copy(output, 5);
+    value.copy(output, 5);
     return output;
   }