text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #include <Kernel/Arch/x86/InterruptDisabler.h>
  #include <Kernel/Heap/kmalloc.h>
  #include <Kernel/Net/EtherType.h>
  #include <Kernel/Net/NetworkAdapter.h>
  #include <Kernel/Net/NetworkingManagement.h>
  #include <Kernel/Process.h>
  #include <Kernel/StdLib.h>
  
  namespace Kernel {
  
  NetworkAdapter::NetworkAdapter(NonnullOwnPtr<KString> interface_name)
      : m_name(move(interface_name))
  {
  }
  
  NetworkAdapter::~NetworkAdapter() = default;
  
  void NetworkAdapter::send_packet(ReadonlyBytes packet)
  {
      m_packets_out++;
      m_bytes_out += packet.size();
      send_raw(packet);
  }
  
  void NetworkAdapter::send(const MACAddress& destination, const ARPPacket& packet)
  {
      size_t size_in_bytes = sizeof(EthernetFrameHeader) + sizeof(ARPPacket);
      auto buffer_result = NetworkByteBuffer::create_zeroed(size_in_bytes);
      if (buffer_result.is_error()) {
          dbgln("Dropping ARP packet targeted at {} as there is not enough memory to buffer it", packet.target_hardware_address().to_string());
          return;
      }
      auto* eth = (EthernetFrameHeader*)buffer_result.value().data();
      eth->set_source(mac_address());
      eth->set_destination(destination);
      eth->set_ether_type(EtherType::ARP);
      memcpy(eth->payload(), &packet, sizeof(ARPPacket));
      send_packet({ (const u8*)eth, size_in_bytes });
  }
  
  void NetworkAdapter::fill_in_ipv4_header(PacketWithTimestamp& packet, IPv4Address const& source_ipv4, MACAddress const& destination_mac, IPv4Address const& destination_ipv4, IPv4Protocol protocol, size_t payload_size, u8 type_of_service, u8 ttl)
  {
      size_t ipv4_packet_size = sizeof(IPv4Packet) + payload_size;
      VERIFY(ipv4_packet_size <= mtu());
  
      size_t ethernet_frame_size = ipv4_payload_offset() + payload_size;
      VERIFY(packet.buffer->size() == ethernet_frame_size);
      memset(packet.buffer->data(), 0, ipv4_payload_offset());
      auto& eth = *(EthernetFrameHeader*)packet.buffer->data();
      eth.set_source(mac_address());
      eth.set_destination(destination_mac);
      eth.set_ether_type(EtherType::IPv4);
      auto& ipv4 = *(IPv4Packet*)eth.payload();
      ipv4.set_version(4);
      ipv4.set_internet_header_length(5);
      ipv4.set_dscp_and_ecn(type_of_service);
      ipv4.set_source(source_ipv4);
      ipv4.set_destination(destination_ipv4);
      ipv4.set_protocol((u8)protocol);
      ipv4.set_length(sizeof(IPv4Packet) + payload_size);
      ipv4.set_ident(1);
      ipv4.set_ttl(ttl);
      ipv4.set_checksum(ipv4.compute_checksum());
  }
  
  void NetworkAdapter::did_receive(ReadonlyBytes payload)
  {
      InterruptDisabler disabler;
      m_packets_in++;
      m_bytes_in += payload.size();
  
      if (m_packet_queue_size == max_packet_buffers) {
          // FIXME: Keep track of the number of dropped packets
          return;
      }
  
      auto packet = acquire_packet_buffer(payload.size());
      if (!packet) {
          dbgln("Discarding packet because we're out of memory");
          return;
      }
  
      memcpy(packet->buffer->data(), payload.data(), payload.size());
  
      m_packet_queue.append(*packet);
      m_packet_queue_size++;
  
      if (on_receive)
          on_receive();
  }
  
  size_t NetworkAdapter::dequeue_packet(u8* buffer, size_t buffer_size, Time& packet_timestamp)
  {
      InterruptDisabler disabler;
      if (m_packet_queue.is_empty())
          return 0;
      auto packet_with_timestamp = m_packet_queue.take_first();
      m_packet_queue_size--;
      packet_timestamp = packet_with_timestamp->timestamp;
      auto& packet_buffer = packet_with_timestamp->buffer;
      size_t packet_size = packet_buffer->size();
      VERIFY(packet_size <= buffer_size);
      memcpy(buffer, packet_buffer->data(), packet_size);
      release_packet_buffer(*packet_with_timestamp);
      return packet_size;
  }
  
  RefPtr<PacketWithTimestamp> NetworkAdapter::acquire_packet_buffer(size_t size)
  {
      InterruptDisabler disabler;
      if (m_unused_packets.is_empty()) {
          auto buffer_or_error = KBuffer::try_create_with_size(size, Memory::Region::Access::ReadWrite, "Packet Buffer", AllocationStrategy::AllocateNow);
          if (buffer_or_error.is_error())
              return {};
          auto buffer = buffer_or_error.release_value();
          auto packet = adopt_ref_if_nonnull(new (nothrow) PacketWithTimestamp { move(buffer), kgettimeofday() });
          if (!packet)
              return {};
          packet->buffer->set_size(size);
          return packet;
      }
  
      auto packet = m_unused_packets.take_first();
      if (packet->buffer->capacity() >= size) {
          packet->timestamp = kgettimeofday();
          packet->buffer->set_size(size);
          return packet;
      }
  
      auto buffer_or_error = KBuffer::try_create_with_size(size, Memory::Region::Access::ReadWrite, "Packet Buffer", AllocationStrategy::AllocateNow);
      if (buffer_or_error.is_error())
          return {};
      packet = adopt_ref_if_nonnull(new (nothrow) PacketWithTimestamp { buffer_or_error.release_value(), kgettimeofday() });
      if (!packet)
          return {};
      packet->buffer->set_size(size);
      return packet;
  }
  
  void NetworkAdapter::release_packet_buffer(PacketWithTimestamp& packet)
  {
      InterruptDisabler disabler;
      m_unused_packets.append(packet);
  }
  
  void NetworkAdapter::set_ipv4_address(const IPv4Address& address)
  {
      m_ipv4_address = address;
  }
  
  void NetworkAdapter::set_ipv4_netmask(const IPv4Address& netmask)
  {
      m_ipv4_netmask = netmask;
  }
  
  void NetworkAdapter::set_ipv4_gateway(const IPv4Address& gateway)
  {
      m_ipv4_gateway = gateway;
  }
  
  }
  