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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/native_messaging/native_messaging_writer.h"
#include <stddef.h>
#include <stdint.h>
#include <string>
#include <utility>
#include "base/json/json_writer.h"
namespace {
// 4-byte type used for the message header.
typedef uint32_t 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;
} // namespace
namespace remoting {
NativeMessagingWriter::NativeMessagingWriter(base::File file)
: write_stream_(std::move(file)), 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 = write_stream_.WriteAtCurrentPos(
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 = write_stream_.WriteAtCurrentPos(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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