Add packet logger and server

webrtc/tools/network_tester/packet_logger.cc

+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "webrtc/tools/network_tester/packet_logger.h"
+
+#include "webrtc/base/checks.h"
+#include "webrtc/base/protobuf_utils.h"
+
+namespace webrtc {
+
+PacketLogger::PacketLogger(const std::string& log_file_path)
+    : packet_logger_stream_(log_file_path,
+                            std::ios_base::out | std::ios_base::binary) {
+  RTC_DCHECK(packet_logger_stream_.is_open());
+  RTC_DCHECK(packet_logger_stream_.good());
+}
+
+PacketLogger::~PacketLogger() = default;
+
+void PacketLogger::LogPacket(const NetworkTesterPacket& packet) {
+  // The protobuffer message will be saved in the following format to the file:
+  // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+  // |      1 byte      |  X byte |      1 byte      | ... |  X byte |
+  // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+  // | Size of the next | proto   | Size of the next | ... | proto   |
+  // | proto message    | message | proto message    |     | message |
+  // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+  ProtoString packet_data;
+  packet.SerializeToString(&packet_data);
+  RTC_DCHECK_LE(packet_data.length(), 255);
+  RTC_DCHECK_GE(packet_data.length(), 0);
+  char proto_size = packet_data.length();
+  packet_logger_stream_.write(&proto_size, sizeof(proto_size));
+  packet_logger_stream_.write(packet_data.data(), packet_data.length());
+}
+
+}  // namespace webrtc