Added telemetry to repeater interface.

lib/helpers/buffer_writer.dart

@@ -0,0 +1,57 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+class BufferWriter {
+  final BytesBuilder _builder = BytesBuilder();
+
+  Uint8List toBytes() {
+    return _builder.toBytes();
+  }
+
+  void writeBytes(Uint8List bytes) {
+    _builder.add(bytes);
+  }
+
+  void writeByte(int byte) {
+    _builder.addByte(byte);
+  }
+
+  void writeUInt16LE(int num) {
+    final bytes = Uint8List(2);
+    final data = ByteData.view(bytes.buffer);
+    data.setUint16(0, num, Endian.little);
+    writeBytes(bytes);
+  }
+
+  void writeUInt32LE(int num) {
+    final bytes = Uint8List(4);
+    final data = ByteData.view(bytes.buffer);
+    data.setUint32(0, num, Endian.little);
+    writeBytes(bytes);
+  }
+
+  void writeInt32LE(int num) {
+    final bytes = Uint8List(4);
+    final data = ByteData.view(bytes.buffer);
+    data.setInt32(0, num, Endian.little);
+    writeBytes(bytes);
+  }
+
+  void writeString(String string) {
+    writeBytes(Uint8List.fromList(utf8.encode(string)));
+  }
+
+  void writeCString(String string, int maxLength) {
+    final bytes = Uint8List(maxLength);
+    final encodedString = utf8.encode(string);
+
+    for (var i = 0; i < maxLength && i < encodedString.length; i++) {
+      bytes[i] = encodedString[i];
+    }
+
+    // ensure the last byte is always a null terminator
+    bytes[maxLength - 1] = 0;
+
+    writeBytes(bytes);
+  }
+}