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// Copyright 2013 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 "remoting/host/setup/native_messaging_writer.h"
#include <string>
#include "base/basictypes.h"
#include "base/json/json_writer.h"
namespace {
// 4-byte type used for the message header.
typedef uint32 MessageLengthType;
// Defined as an int, for passing to APIs that take an int, to avoid
// signed/unsigned warnings about implicit cast.
const int kMessageHeaderSize = sizeof(MessageLengthType);
// Limit the size of sent messages, since Chrome will not accept messages
// larger than 1MB, and this helps deal with the problem of integer overflow
// when passing sizes to net::FileStream APIs that take |int| parameters.
// This is defined as size_t (unsigned type) so it can be compared with the
// result of std::string::length() without compiler warnings.
const size_t kMaximumMessageSize = 1024 * 1024;
// Performs the same task as FileStream::WriteSync(), but ensures that exactly
// |buffer_length| bytes are written. Unlike WriteSync(), a partial write may
// only occur as a result of end-of-file or fatal error. Returns the number of
// bytes written (buffer_length) or an error-code <= 0.
//
// TODO(lambroslambrou): Add this method to net::FileStream, with unit-tests.
// See http://crbug.com/232202.
int WriteUntilComplete(net::FileStream* out,
const char* buffer, int buffer_length) {
int written = 0;
while (written < buffer_length) {
int result = out->WriteSync(buffer + written, buffer_length - written);
if (result <= 0) {
return result;
}
DCHECK_LE(result, buffer_length - written);
written += result;
}
return written;
}
} // namespace
namespace remoting {
NativeMessagingWriter::NativeMessagingWriter(base::PlatformFile handle)
: write_stream_(handle, base::PLATFORM_FILE_WRITE, NULL),
fail_(false) {
}
NativeMessagingWriter::~NativeMessagingWriter() {
}
bool NativeMessagingWriter::WriteMessage(const base::Value& message) {
if (fail_) {
LOG(ERROR) << "Stream marked as corrupt.";
return false;
}
std::string message_json;
base::JSONWriter::Write(&message, &message_json);
CHECK_LE(message_json.length(), kMaximumMessageSize);
// Cast from size_t to the proper header type. The check above ensures this
// won't overflow.
MessageLengthType message_length =
static_cast<MessageLengthType>(message_json.length());
int result = WriteUntilComplete(
&write_stream_, reinterpret_cast<char*>(&message_length),
kMessageHeaderSize);
if (result != kMessageHeaderSize) {
LOG(ERROR) << "Failed to send message header, write returned " << result;
fail_ = true;
return false;
}
// The length check above ensures that the cast won't overflow a signed
// 32-bit int.
int message_length_as_int = message_length;
// CHECK needed since data() is undefined on an empty std::string.
CHECK(!message_json.empty());
result = WriteUntilComplete(&write_stream_, message_json.data(),
message_length_as_int);
if (result != message_length_as_int) {
LOG(ERROR) << "Failed to send message body, write returned " << result;
fail_ = true;
return false;
}
return true;
}
} // namespace remoting
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