AsyncUDPSocket.h

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * 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 <memory>

#include <folly/ScopeGuard.h>
#include <folly/SocketAddress.h>
#include <folly/io/IOBuf.h>
#include <folly/io/async/AsyncSocketBase.h>
#include <folly/io/async/AsyncSocketException.h>
#include <folly/io/async/EventBase.h>
#include <folly/io/async/EventHandler.h>
#include <folly/net/NetOps.h>
#include <folly/net/NetworkSocket.h>

namespace folly {

class AsyncUDPSocket : public EventHandler {
 public:
  enum class FDOwnership { OWNS, SHARED };

  class ReadCallback {
   public:
    virtual void getReadBuffer(void** buf, size_t* len) noexcept = 0;

    virtual void onDataAvailable(
        const folly::SocketAddress& client,
        size_t len,
        bool truncated) noexcept = 0;

    virtual void onReadError(const AsyncSocketException& ex) noexcept = 0;

    virtual void onReadClosed() noexcept = 0;

    virtual ~ReadCallback() = default;
  };

  class ErrMessageCallback {
   public:
    virtual ~ErrMessageCallback() = default;

    virtual void errMessage(const cmsghdr& cmsg) noexcept = 0;

    virtual void errMessageError(const AsyncSocketException& ex) noexcept = 0;
  };

  explicit AsyncUDPSocket(EventBase* evb);
  ~AsyncUDPSocket() override;

  virtual const folly::SocketAddress& address() const {
    CHECK_NE(NetworkSocket(), fd_) << "Server not yet bound to an address";
    return localAddress_;
  }

  virtual void bind(const folly::SocketAddress& address);

  void setFD(int fd, FDOwnership ownership) {
    setFD(NetworkSocket::fromFd(fd), ownership);
  }
  virtual void setFD(NetworkSocket fd, FDOwnership ownership);

  virtual ssize_t write(
      const folly::SocketAddress& address,
      const std::unique_ptr<folly::IOBuf>& buf);

  virtual ssize_t writeGSO(
      const folly::SocketAddress& address,
      const std::unique_ptr<folly::IOBuf>& buf,
      int gso);

  virtual ssize_t writev(
      const folly::SocketAddress& address,
      const struct iovec* vec,
      size_t veclen,
      int gso);

  virtual ssize_t writev(
      const folly::SocketAddress& address,
      const struct iovec* vec,
      size_t veclen);

  virtual void resumeRead(ReadCallback* cob);

  virtual void pauseRead();

  virtual void close();

  virtual int getFD() const {
    CHECK_NE(NetworkSocket(), fd_) << "Need to bind before getting FD out";
    return fd_.toFd();
  }

  virtual void setReusePort(bool reusePort) {
    reusePort_ = reusePort;
  }

  virtual void setReuseAddr(bool reuseAddr) {
    reuseAddr_ = reuseAddr;
  }

  virtual void setRcvBuf(int rcvBuf) {
    rcvBuf_ = rcvBuf;
  }

  virtual void setSndBuf(int sndBuf) {
    sndBuf_ = sndBuf;
  }

  virtual void setBusyPoll(int busyPollUs) {
    busyPollUs_ = busyPollUs;
  }

  EventBase* getEventBase() const {
    return eventBase_;
  }

  virtual void dontFragment(bool df);

  virtual void setErrMessageCallback(ErrMessageCallback* errMessageCallback);

  virtual int connect(const folly::SocketAddress& address);

  virtual bool isBound() const {
    return fd_ != NetworkSocket();
  }

  virtual void detachEventBase();

  virtual void attachEventBase(folly::EventBase* evb);

  // generic segmentation offload get/set
  // negative return value means GSO is not available
  int getGSO();

  bool setGSO(int val);

 protected:
  virtual ssize_t
  sendmsg(NetworkSocket socket, const struct msghdr* message, int flags) {
    return netops::sendmsg(socket, message, flags);
  }

  size_t handleErrMessages() noexcept;

  void failErrMessageRead(const AsyncSocketException& ex);

  // Non-null only when we are reading
  ReadCallback* readCallback_;

 private:
  AsyncUDPSocket(const AsyncUDPSocket&) = delete;
  AsyncUDPSocket& operator=(const AsyncUDPSocket&) = delete;

  // EventHandler
  void handlerReady(uint16_t events) noexcept override;

  void handleRead() noexcept;
  bool updateRegistration() noexcept;

  EventBase* eventBase_;
  folly::SocketAddress localAddress_;

  NetworkSocket fd_;
  FDOwnership ownership_;

  // Temp space to receive client address
  folly::SocketAddress clientAddress_;

  bool reuseAddr_{true};
  bool reusePort_{false};
  int rcvBuf_{0};
  int sndBuf_{0};
  int busyPollUs_{0};

  // generic segmentation offload value, if available
  // See https://lwn.net/Articles/188489/ for more details
  folly::Optional<int> gso_;

  ErrMessageCallback* errMessageCallback_{nullptr};
};

} // namespace folly