extensions/browser/api/cast_channel/cast_framer.cc

   1 // Copyright 2014 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 "extensions/browser/api/cast_channel/cast_framer.h"
   6
   7 #include <stdlib.h>
   8
   9 #include "base/numerics/safe_conversions.h"
  10 #include "base/strings/string_number_conversions.h"
  11 #include "base/sys_byteorder.h"
  12 #include "extensions/common/api/cast_channel/cast_channel.pb.h"
  13
  14 namespace extensions {
  15 namespace core_api {
  16 namespace cast_channel {
  17 MessageFramer::MessageFramer(scoped_refptr<net::GrowableIOBuffer> input_buffer)
  18     : input_buffer_(input_buffer), error_(false) {
  19   Reset();
  20 }
  21
  22 MessageFramer::~MessageFramer() {
  23 }
  24
  25 MessageFramer::MessageHeader::MessageHeader() : message_size(0) {
  26 }
  27
  28 void MessageFramer::MessageHeader::SetMessageSize(size_t size) {
  29   DCHECK_LT(size, static_cast<size_t>(kuint32max));
  30   DCHECK_GT(size, 0U);
  31   message_size = size;
  32 }
  33
  34 // TODO(mfoltz): Investigate replacing header serialization with base::Pickle,
  35 // if bit-for-bit compatible.
  36 void MessageFramer::MessageHeader::PrependToString(std::string* str) {
  37   MessageHeader output = *this;
  38   output.message_size = base::HostToNet32(message_size);
  39   size_t header_size = MessageHeader::header_size();
  40   scoped_ptr<char, base::FreeDeleter> char_array(
  41       static_cast<char*>(malloc(header_size)));
  42   memcpy(char_array.get(), &output, header_size);
  43   str->insert(0, char_array.get(), header_size);
  44 }
  45
  46 // TODO(mfoltz): Investigate replacing header deserialization with base::Pickle,
  47 // if bit-for-bit compatible.
  48 void MessageFramer::MessageHeader::Deserialize(char* data,
  49                                                MessageHeader* header) {
  50   uint32 message_size;
  51   memcpy(&message_size, data, header_size());
  52   header->message_size =
  53       base::checked_cast<size_t>(base::NetToHost32(message_size));
  54 }
  55
  56 // static
  57 size_t MessageFramer::MessageHeader::header_size() {
  58   return sizeof(uint32);
  59 }
  60
  61 // static
  62 size_t MessageFramer::MessageHeader::max_message_size() {
  63   return 65535;
  64 }
  65
  66 std::string MessageFramer::MessageHeader::ToString() {
  67   return "{message_size: " +
  68          base::UintToString(static_cast<uint32>(message_size)) + "}";
  69 }
  70
  71 // static
  72 bool MessageFramer::Serialize(const CastMessage& message_proto,
  73                               std::string* message_data) {
  74   DCHECK(message_data);
  75   message_proto.SerializeToString(message_data);
  76   size_t message_size = message_data->size();
  77   if (message_size > MessageHeader::max_message_size()) {
  78     message_data->clear();
  79     return false;
  80   }
  81   MessageHeader header;
  82   header.SetMessageSize(message_size);
  83   header.PrependToString(message_data);
  84   return true;
  85 }
  86
  87 size_t MessageFramer::BytesRequested() {
  88   size_t bytes_left;
  89   if (error_) {
  90     return 0;
  91   }
  92
  93   switch (current_element_) {
  94     case HEADER:
  95       bytes_left = MessageHeader::header_size() - message_bytes_received_;
  96       DCHECK_LE(bytes_left, MessageHeader::header_size());
  97       VLOG(2) << "Bytes needed for header: " << bytes_left;
  98       return bytes_left;
  99     case BODY:
 100       bytes_left =
 101           (body_size_ + MessageHeader::header_size()) - message_bytes_received_;
 102       DCHECK_LE(
 103           bytes_left,
 104           MessageHeader::max_message_size() - MessageHeader::header_size());
 105       VLOG(2) << "Bytes needed for body: " << bytes_left;
 106       return bytes_left;
 107     default:
 108       NOTREACHED() << "Unhandled packet element type.";
 109       return 0;
 110   }
 111 }
 112
 113 scoped_ptr<CastMessage> MessageFramer::Ingest(size_t num_bytes,
 114                                               size_t* message_length,
 115                                               ChannelError* error) {
 116   DCHECK(error);
 117   DCHECK(message_length);
 118   if (error_) {
 119     *error = CHANNEL_ERROR_INVALID_MESSAGE;
 120     return scoped_ptr<CastMessage>();
 121   }
 122
 123   DCHECK_EQ(base::checked_cast<int32>(message_bytes_received_),
 124             input_buffer_->offset());
 125   CHECK_LE(num_bytes, BytesRequested());
 126   message_bytes_received_ += num_bytes;
 127   *error = CHANNEL_ERROR_NONE;
 128   *message_length = 0;
 129   switch (current_element_) {
 130     case HEADER:
 131       if (BytesRequested() == 0) {
 132         MessageHeader header;
 133         MessageHeader::Deserialize(input_buffer_.get()->StartOfBuffer(),
 134                                    &header);
 135         if (header.message_size > MessageHeader::max_message_size()) {
 136           VLOG(1) << "Error parsing header (message size too large).";
 137           *error = CHANNEL_ERROR_INVALID_MESSAGE;
 138           error_ = true;
 139           return scoped_ptr<CastMessage>();
 140         }
 141         current_element_ = BODY;
 142         body_size_ = header.message_size;
 143       }
 144       break;
 145     case BODY:
 146       if (BytesRequested() == 0) {
 147         scoped_ptr<CastMessage> parsed_message(new CastMessage);
 148         if (!parsed_message->ParseFromArray(
 149                 input_buffer_->StartOfBuffer() + MessageHeader::header_size(),
 150                 body_size_)) {
 151           VLOG(1) << "Error parsing packet body.";
 152           *error = CHANNEL_ERROR_INVALID_MESSAGE;
 153           error_ = true;
 154           return scoped_ptr<CastMessage>();
 155         }
 156         *message_length = body_size_;
 157         Reset();
 158         return parsed_message.Pass();
 159       }
 160       break;
 161     default:
 162       NOTREACHED() << "Unhandled packet element type.";
 163       return scoped_ptr<CastMessage>();
 164   }
 165
 166   input_buffer_->set_offset(message_bytes_received_);
 167   return scoped_ptr<CastMessage>();
 168 }
 169
 170 void MessageFramer::Reset() {
 171   current_element_ = HEADER;
 172   message_bytes_received_ = 0;
 173   body_size_ = 0;
 174   input_buffer_->set_offset(0);
 175 }
 176
 177 }  // namespace cast_channel
 178 }  // namespace core_api
 179 }  // namespace extensions