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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 
MessageDecoder()16 MessageDecoder::MessageDecoder()
17     : next_payload_(0),
18       next_payload_known_(false) {
19 }
20 
~MessageDecoder()21 MessageDecoder::~MessageDecoder() {}
22 
AddData(scoped_refptr<net::IOBuffer> data,int data_size)23 void MessageDecoder::AddData(scoped_refptr<net::IOBuffer> data,
24                              int data_size) {
25   buffer_.Append(data.get(), data_size);
26 }
27 
GetNextMessage()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 NULL;
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 
GetPayloadSize(int * size)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
71