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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "extensions/browser/api/cast_channel/cast_framer.h"
#include <stdlib.h>
#include <limits>
#include "base/numerics/safe_conversions.h"
#include "base/strings/string_number_conversions.h"
#include "base/sys_byteorder.h"
#include "extensions/common/api/cast_channel/cast_channel.pb.h"
namespace extensions {
namespace api {
namespace cast_channel {
MessageFramer::MessageFramer(scoped_refptr<net::GrowableIOBuffer> input_buffer)
: input_buffer_(input_buffer), error_(false) {
Reset();
}
MessageFramer::~MessageFramer() {
}
MessageFramer::MessageHeader::MessageHeader() : message_size(0) {
}
void MessageFramer::MessageHeader::SetMessageSize(size_t size) {
DCHECK_LT(size, static_cast<size_t>(std::numeric_limits<uint32_t>::max()));
DCHECK_GT(size, 0U);
message_size = size;
}
// TODO(mfoltz): Investigate replacing header serialization with base::Pickle,
// if bit-for-bit compatible.
void MessageFramer::MessageHeader::PrependToString(std::string* str) {
MessageHeader output = *this;
output.message_size = base::HostToNet32(message_size);
size_t header_size = MessageHeader::header_size();
scoped_ptr<char, base::FreeDeleter> char_array(
static_cast<char*>(malloc(header_size)));
memcpy(char_array.get(), &output, header_size);
str->insert(0, char_array.get(), header_size);
}
// TODO(mfoltz): Investigate replacing header deserialization with base::Pickle,
// if bit-for-bit compatible.
void MessageFramer::MessageHeader::Deserialize(char* data,
MessageHeader* header) {
uint32_t message_size;
memcpy(&message_size, data, header_size());
header->message_size =
base::checked_cast<size_t>(base::NetToHost32(message_size));
}
// static
size_t MessageFramer::MessageHeader::header_size() {
return sizeof(uint32_t);
}
// static
size_t MessageFramer::MessageHeader::max_message_size() {
return 65535;
}
std::string MessageFramer::MessageHeader::ToString() {
return "{message_size: " +
base::UintToString(static_cast<uint32_t>(message_size)) + "}";
}
// static
bool MessageFramer::Serialize(const CastMessage& message_proto,
std::string* message_data) {
DCHECK(message_data);
message_proto.SerializeToString(message_data);
size_t message_size = message_data->size();
if (message_size > MessageHeader::max_message_size()) {
message_data->clear();
return false;
}
MessageHeader header;
header.SetMessageSize(message_size);
header.PrependToString(message_data);
return true;
}
size_t MessageFramer::BytesRequested() {
size_t bytes_left;
if (error_) {
return 0;
}
switch (current_element_) {
case HEADER:
bytes_left = MessageHeader::header_size() - message_bytes_received_;
DCHECK_LE(bytes_left, MessageHeader::header_size());
VLOG(2) << "Bytes needed for header: " << bytes_left;
return bytes_left;
case BODY:
bytes_left =
(body_size_ + MessageHeader::header_size()) - message_bytes_received_;
DCHECK_LE(
bytes_left,
MessageHeader::max_message_size() - MessageHeader::header_size());
VLOG(2) << "Bytes needed for body: " << bytes_left;
return bytes_left;
default:
NOTREACHED() << "Unhandled packet element type.";
return 0;
}
}
scoped_ptr<CastMessage> MessageFramer::Ingest(size_t num_bytes,
size_t* message_length,
ChannelError* error) {
DCHECK(error);
DCHECK(message_length);
if (error_) {
*error = CHANNEL_ERROR_INVALID_MESSAGE;
return scoped_ptr<CastMessage>();
}
DCHECK_EQ(base::checked_cast<int32_t>(message_bytes_received_),
input_buffer_->offset());
CHECK_LE(num_bytes, BytesRequested());
message_bytes_received_ += num_bytes;
*error = CHANNEL_ERROR_NONE;
*message_length = 0;
switch (current_element_) {
case HEADER:
if (BytesRequested() == 0) {
MessageHeader header;
MessageHeader::Deserialize(input_buffer_.get()->StartOfBuffer(),
&header);
if (header.message_size > MessageHeader::max_message_size()) {
VLOG(1) << "Error parsing header (message size too large).";
*error = CHANNEL_ERROR_INVALID_MESSAGE;
error_ = true;
return scoped_ptr<CastMessage>();
}
current_element_ = BODY;
body_size_ = header.message_size;
}
break;
case BODY:
if (BytesRequested() == 0) {
scoped_ptr<CastMessage> parsed_message(new CastMessage);
if (!parsed_message->ParseFromArray(
input_buffer_->StartOfBuffer() + MessageHeader::header_size(),
body_size_)) {
VLOG(1) << "Error parsing packet body.";
*error = CHANNEL_ERROR_INVALID_MESSAGE;
error_ = true;
return scoped_ptr<CastMessage>();
}
*message_length = body_size_;
Reset();
return parsed_message;
}
break;
default:
NOTREACHED() << "Unhandled packet element type.";
return scoped_ptr<CastMessage>();
}
input_buffer_->set_offset(message_bytes_received_);
return scoped_ptr<CastMessage>();
}
void MessageFramer::Reset() {
current_element_ = HEADER;
message_bytes_received_ = 0;
body_size_ = 0;
input_buffer_->set_offset(0);
}
} // namespace cast_channel
} // namespace api
} // namespace extensions
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