// 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/ipc_util.h"

#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/win/scoped_handle.h"
#include "base/win/win_util.h"
#include "ipc/ipc_channel.h"
#include "ipc/ipc_channel_proxy.h"
#include "remoting/host/win/security_descriptor.h"

using base::win::ScopedHandle;

namespace remoting {

// Pipe name prefix used by Chrome IPC channels to convert a channel name into
// a pipe name.
const char kChromePipeNamePrefix[] = "\\\\.\\pipe\\chrome.";

bool CreateConnectedIpcChannel(
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
    IPC::Listener* listener,
    IPC::PlatformFileForTransit* client_out,
    scoped_ptr<IPC::ChannelProxy>* server_out) {
  // presubmit: allow wstring
  std::wstring user_sid;
  if (!base::win::GetUserSidString(&user_sid)) {
    LOG(ERROR) << "Failed to query the current user SID.";
    return false;
  }

  // Create a security descriptor that will be used to protect the named pipe in
  // between CreateNamedPipe() and CreateFile() calls before it will be passed
  // to the network process. It gives full access to the account that
  // the calling code is running under and  denies access by anyone else.
  std::string security_descriptor = base::StringPrintf(
      "O:%1$sG:%1$sD:(A;;GA;;;%1$s)", WideToUTF8(user_sid).c_str());

  // Generate a unique name for the channel.
  std::string channel_name = IPC::Channel::GenerateUniqueRandomChannelID();

  // Create the server end of the channel.
  ScopedHandle pipe;
  if (!CreateIpcChannel(channel_name, security_descriptor, &pipe)) {
    return false;
  }

  // Wrap the pipe into an IPC channel.
  scoped_ptr<IPC::ChannelProxy> server(new IPC::ChannelProxy(
      IPC::ChannelHandle(pipe),
      IPC::Channel::MODE_SERVER,
      listener,
      io_task_runner));

  // Convert the channel name to the pipe name.
  std::string pipe_name(kChromePipeNamePrefix);
  pipe_name.append(channel_name);

  SECURITY_ATTRIBUTES security_attributes = {0};
  security_attributes.nLength = sizeof(security_attributes);
  security_attributes.lpSecurityDescriptor = NULL;
  security_attributes.bInheritHandle = TRUE;

  // Create the client end of the channel. This code should match the code in
  // IPC::Channel.
  ScopedHandle client;
  client.Set(CreateFile(UTF8ToUTF16(pipe_name).c_str(),
                        GENERIC_READ | GENERIC_WRITE,
                        0,
                        &security_attributes,
                        OPEN_EXISTING,
                        SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION |
                            FILE_FLAG_OVERLAPPED,
                        NULL));
  if (!client.IsValid()) {
    LOG_GETLASTERROR(ERROR) << "Failed to connect to '" << pipe_name << "'";
    return false;
  }

  *client_out = client.Take();
  *server_out = server.Pass();
  return true;
}

bool CreateIpcChannel(
    const std::string& channel_name,
    const std::string& pipe_security_descriptor,
    base::win::ScopedHandle* pipe_out) {
  // Create security descriptor for the channel.
  ScopedSd sd = ConvertSddlToSd(pipe_security_descriptor);
  if (!sd) {
    LOG_GETLASTERROR(ERROR) <<
        "Failed to create a security descriptor for the Chromoting IPC channel";
    return false;
  }

  SECURITY_ATTRIBUTES security_attributes = {0};
  security_attributes.nLength = sizeof(security_attributes);
  security_attributes.lpSecurityDescriptor = sd.get();
  security_attributes.bInheritHandle = FALSE;

  // Convert the channel name to the pipe name.
  std::string pipe_name(kChromePipeNamePrefix);
  pipe_name.append(channel_name);

  // Create the server end of the pipe. This code should match the code in
  // IPC::Channel with exception of passing a non-default security descriptor.
  base::win::ScopedHandle pipe;
  pipe.Set(CreateNamedPipe(
      UTF8ToUTF16(pipe_name).c_str(),
      PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED | FILE_FLAG_FIRST_PIPE_INSTANCE,
      PIPE_TYPE_BYTE | PIPE_READMODE_BYTE,
      1,
      IPC::Channel::kReadBufferSize,
      IPC::Channel::kReadBufferSize,
      5000,
      &security_attributes));
  if (!pipe.IsValid()) {
    LOG_GETLASTERROR(ERROR) <<
        "Failed to create the server end of the Chromoting IPC channel";
    return false;
  }

  *pipe_out = pipe.Pass();
  return true;
}

} // namespace remoting