unix_sockets.h

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/*
 * Copyright (C) 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#pragma once
 
#include <stdint.h>
#include <sys/socket.h>
 
#include <vector>
 
#include "cuttlefish/common/libs/fs/shared_fd.h"
#include "cuttlefish/result/result.h"
 
namespace cuttlefish {
 
struct ControlMessage {
 public:
  static ControlMessage FromRaw(const cmsghdr*);
  static Result<ControlMessage> FromFileDescriptors(
      const std::vector<SharedFD>&);
#ifdef __linux__
  static ControlMessage FromCredentials(const ucred&);
#endif
  ControlMessage(const ControlMessage&) = delete;
  ControlMessage(ControlMessage&&);
  ~ControlMessage();
  ControlMessage& operator=(const ControlMessage&) = delete;
  ControlMessage& operator=(ControlMessage&&);
 
  const cmsghdr* Raw() const;
 
#ifdef __linux__
  bool IsCredentials() const;
  Result<ucred> AsCredentials() const;
#endif
 
  bool IsFileDescriptors() const;
  Result<std::vector<SharedFD>> AsSharedFDs() const;
 
 private:
  friend class UnixMessageSocket;
  ControlMessage() = default;
  cmsghdr* Raw();
 
  std::vector<char> data_;
  std::vector<int> fds_;
};
 
struct UnixSocketMessage {
  std::vector<char> data;
  std::vector<ControlMessage> control;
 
  bool HasFileDescriptors();
  Result<std::vector<SharedFD>> FileDescriptors();
#ifdef __linux__
  bool HasCredentials();
  Result<ucred> Credentials();
#endif
};
 
class UnixMessageSocket {
 public:
  UnixMessageSocket(SharedFD);
  [[nodiscard]] Result<void> WriteMessage(const UnixSocketMessage&);
  Result<UnixSocketMessage> ReadMessage();
 
#ifdef __linux__
  [[nodiscard]] Result<void> EnableCredentials(bool);
#endif
 
 private:
  SharedFD socket_;
  uint32_t max_message_size_;
};
 
}  // namespace cuttlefish