remoting/protocol/message_decoder.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/protocol/message_decoder.h"
   6
   7 #include "base/logging.h"
   8 #include "net/base/io_buffer.h"
   9 #include "remoting/base/compound_buffer.h"
  10 #include "remoting/proto/internal.pb.h"
  11 #include "third_party/webrtc/base/byteorder.h"
  12
  13 namespace remoting {
  14 namespace protocol {
  15
  16 MessageDecoder::MessageDecoder()
  17     : next_payload_(0),
  18       next_payload_known_(false) {
  19 }
  20
  21 MessageDecoder::~MessageDecoder() {}
  22
  23 void MessageDecoder::AddData(scoped_refptr<net::IOBuffer> data,
  24                              int data_size) {
  25   buffer_.Append(data.get(), data_size);
  26 }
  27
  28 CompoundBuffer* MessageDecoder::GetNextMessage() {
  29   // Determine the payload size. If we already know it then skip this part.
  30   // We may not have enough data to determine the payload size so use a
  31   // utility function to find out.
  32   int next_payload = -1;
  33   if (!next_payload_known_ && GetPayloadSize(&next_payload)) {
  34     DCHECK_NE(-1, next_payload);
  35     next_payload_ = next_payload;
  36     next_payload_known_ = true;
  37   }
  38
  39   // If the next payload size is still not known or we don't have enough
  40   // data for parsing then exit.
  41   if (!next_payload_known_ || buffer_.total_bytes() < next_payload_)
  42     return nullptr;
  43
  44   CompoundBuffer* message_buffer = new CompoundBuffer();
  45   message_buffer->CopyFrom(buffer_, 0, next_payload_);
  46   message_buffer->Lock();
  47   buffer_.CropFront(next_payload_);
  48   next_payload_known_ = false;
  49
  50   return message_buffer;
  51 }
  52
  53 bool MessageDecoder::GetPayloadSize(int* size) {
  54   // The header has a size of 4 bytes.
  55   const int kHeaderSize = sizeof(int32);
  56
  57   if (buffer_.total_bytes() < kHeaderSize)
  58     return false;
  59
  60   CompoundBuffer header_buffer;
  61   char header[kHeaderSize];
  62   header_buffer.CopyFrom(buffer_, 0, kHeaderSize);
  63   header_buffer.CopyTo(header, kHeaderSize);
  64   *size = rtc::GetBE32(header);
  65   buffer_.CropFront(kHeaderSize);
  66   return true;
  67 }
  68
  69 }  // namespace protocol
  70 }  // namespace remoting