text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #pragma once
  
  #include <AK/Function.h>
  #include <AK/HashMap.h>
  #include <AK/SinglyLinkedList.h>
  #include <AK/WeakPtr.h>
  #include <Kernel/Net/IPv4Socket.h>
  
  namespace Kernel {
  
  class TCPSocket final : public IPv4Socket
      , public Weakable<TCPSocket> {
  public:
      static void for_each(Function<void(const TCPSocket&)>);
      static NonnullRefPtr<TCPSocket> create(int protocol);
      virtual ~TCPSocket() override;
  
      enum class Direction {
          Unspecified,
          Outgoing,
          Incoming,
          Passive,
      };
  
      static const char* to_string(Direction direction)
      {
          switch (direction) {
          case Direction::Unspecified:
              return "Unspecified";
          case Direction::Outgoing:
              return "Outgoing";
          case Direction::Incoming:
              return "Incoming";
          case Direction::Passive:
              return "Passive";
          default:
              return "None";
          }
      }
  
      enum class State {
          Closed,
          Listen,
          SynSent,
          SynReceived,
          Established,
          CloseWait,
          LastAck,
          FinWait1,
          FinWait2,
          Closing,
          TimeWait,
      };
  
      static const char* to_string(State state)
      {
          switch (state) {
          case State::Closed:
              return "Closed";
          case State::Listen:
              return "Listen";
          case State::SynSent:
              return "SynSent";
          case State::SynReceived:
              return "SynReceived";
          case State::Established:
              return "Established";
          case State::CloseWait:
              return "CloseWait";
          case State::LastAck:
              return "LastAck";
          case State::FinWait1:
              return "FinWait1";
          case State::FinWait2:
              return "FinWait2";
          case State::Closing:
              return "Closing";
          case State::TimeWait:
              return "TimeWait";
          default:
              return "None";
          }
      }
  
      enum class Error {
          None,
          FINDuringConnect,
          RSTDuringConnect,
          UnexpectedFlagsDuringConnect,
      };
  
      static const char* to_string(Error error)
      {
          switch (error) {
          case Error::None:
              return "None";
          case Error::FINDuringConnect:
              return "FINDuringConnect";
          case Error::RSTDuringConnect:
              return "RSTDuringConnect";
          case Error::UnexpectedFlagsDuringConnect:
              return "UnexpectedFlagsDuringConnect";
          default:
              return "Invalid";
          }
      }
  
      State state() const { return m_state; }
      void set_state(State state);
  
      Direction direction() const { return m_direction; }
  
      bool has_error() const { return m_error != Error::None; }
      Error error() const { return m_error; }
      void set_error(Error error) { m_error = error; }
  
      void set_ack_number(u32 n) { m_ack_number = n; }
      void set_sequence_number(u32 n) { m_sequence_number = n; }
      u32 ack_number() const { return m_ack_number; }
      u32 sequence_number() const { return m_sequence_number; }
      u32 packets_in() const { return m_packets_in; }
      u32 bytes_in() const { return m_bytes_in; }
      u32 packets_out() const { return m_packets_out; }
      u32 bytes_out() const { return m_bytes_out; }
  
      void send_tcp_packet(u16 flags, const void* = nullptr, size_t = 0);
      void send_outgoing_packets();
      void receive_tcp_packet(const TCPPacket&, u16 size);
  
      static Lockable<HashMap<IPv4SocketTuple, TCPSocket*>>& sockets_by_tuple();
      static RefPtr<TCPSocket> from_tuple(const IPv4SocketTuple& tuple);
      static RefPtr<TCPSocket> from_endpoints(const IPv4Address& local_address, u16 local_port, const IPv4Address& peer_address, u16 peer_port);
  
      static Lockable<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>& closing_sockets();
  
      RefPtr<TCPSocket> create_client(const IPv4Address& local_address, u16 local_port, const IPv4Address& peer_address, u16 peer_port);
      void set_originator(TCPSocket& originator) { m_originator = originator.make_weak_ptr(); }
      bool has_originator() { return !!m_originator; }
      void release_to_originator();
      void release_for_accept(RefPtr<TCPSocket>);
  
      virtual KResult close() override;
  
  protected:
      void set_direction(Direction direction) { m_direction = direction; }
  
  private:
      explicit TCPSocket(int protocol);
      virtual const char* class_name() const override { return "TCPSocket"; }
  
      static NetworkOrdered<u16> compute_tcp_checksum(const IPv4Address& source, const IPv4Address& destination, const TCPPacket&, u16 payload_size);
  
      virtual void shut_down_for_writing() override;
  
      virtual KResultOr<size_t> protocol_receive(const KBuffer&, void* buffer, size_t buffer_size, int flags) override;
      virtual KResultOr<size_t> protocol_send(const void*, size_t) override;
      virtual KResult protocol_connect(FileDescription&, ShouldBlock) override;
      virtual int protocol_allocate_local_port() override;
      virtual bool protocol_is_disconnected() const override;
      virtual KResult protocol_bind() override;
      virtual KResult protocol_listen() override;
  
      WeakPtr<TCPSocket> m_originator;
      HashMap<IPv4SocketTuple, NonnullRefPtr<TCPSocket>> m_pending_release_for_accept;
      Direction m_direction { Direction::Unspecified };
      Error m_error { Error::None };
      RefPtr<NetworkAdapter> m_adapter;
      u32 m_sequence_number { 0 };
      u32 m_ack_number { 0 };
      State m_state { State::Closed };
      u32 m_packets_in { 0 };
      u32 m_bytes_in { 0 };
      u32 m_packets_out { 0 };
      u32 m_bytes_out { 0 };
  
      struct OutgoingPacket {
          u32 ack_number { 0 };
          ByteBuffer buffer;
          int tx_counter { 0 };
          timeval tx_time { 0, 0 };
      };
  
      Lock m_not_acked_lock { "TCPSocket unacked packets" };
      SinglyLinkedList<OutgoingPacket> m_not_acked;
  };
  
  }
  