/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * 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.
 */

#include <folly/net/NetOps.h>

#include <fcntl.h>
#include <cerrno>

#include <cstddef>

#include <folly/Portability.h>
#include <folly/net/detail/SocketFileDescriptorMap.h>

#ifdef _WIN32
#include <event2/util.h> // @manual

#include <MSWSock.h> // @manual

#include <folly/ScopeGuard.h>
#endif

namespace folly {
namespace netops {

namespace {
#ifdef _WIN32
// WSA has to be explicitly initialized.
static struct WinSockInit {
  WinSockInit() {
    WSADATA dat;
    WSAStartup(MAKEWORD(2, 2), &dat);
  }
  ~WinSockInit() {
    WSACleanup();
  }
} winsockInit;

int translate_wsa_error(int wsaErr) {
  switch (wsaErr) {
    case WSAEWOULDBLOCK:
      return EAGAIN;
    default:
      return wsaErr;
  }
}
#endif

template <class R, class F, class... Args>
static R wrapSocketFunction(F f, NetworkSocket s, Args... args) {
  R ret = f(s.data, args...);
#ifdef _WIN32
  errno = translate_wsa_error(WSAGetLastError());
#endif
  return ret;
}
} // namespace

NetworkSocket accept(NetworkSocket s, sockaddr* addr, socklen_t* addrlen) {
  return NetworkSocket(wrapSocketFunction<NetworkSocket::native_handle_type>(
      ::accept, s, addr, addrlen));
}

int bind(NetworkSocket s, const sockaddr* name, socklen_t namelen) {
  if (kIsWindows && name->sa_family == AF_UNIX) {
    // Windows added support for AF_UNIX sockets, but didn't add
    // support for autobind sockets, so detect requests for autobind
    // sockets and treat them as invalid. (otherwise they don't trigger
    // an error, but also don't actually work)
    if (name->sa_data[0] == '\0') {
      errno = EINVAL;
      return -1;
    }
  }
  return wrapSocketFunction<int>(::bind, s, name, namelen);
}

int close(NetworkSocket s) {
  return netops::detail::SocketFileDescriptorMap::close(s.data);
}

int connect(NetworkSocket s, const sockaddr* name, socklen_t namelen) {
  auto r = wrapSocketFunction<int>(::connect, s, name, namelen);
#ifdef _WIN32
  if (r == -1 && WSAGetLastError() == WSAEWOULDBLOCK) {
    errno = EINPROGRESS;
  }
#endif
  return r;
}

int getpeername(NetworkSocket s, sockaddr* name, socklen_t* namelen) {
  return wrapSocketFunction<int>(::getpeername, s, name, namelen);
}

int getsockname(NetworkSocket s, sockaddr* name, socklen_t* namelen) {
  return wrapSocketFunction<int>(::getsockname, s, name, namelen);
}

int getsockopt(
    NetworkSocket s,
    int level,
    int optname,
    void* optval,
    socklen_t* optlen) {
  auto ret = wrapSocketFunction<int>(
      ::getsockopt, s, level, optname, (char*)optval, optlen);
#ifdef _WIN32
  if (optname == TCP_NODELAY && *optlen == 1) {
    // Windows is weird about this value, and documents it as a
    // BOOL (ie. int) but expects the variable to be bool (1-byte),
    // so we get to adapt the interface to work that way.
    *(int*)optval = *(uint8_t*)optval;
    *optlen = sizeof(int);
  }
#endif
  return ret;
}

int inet_aton(const char* cp, in_addr* inp) {
  inp->s_addr = inet_addr(cp);
  return inp->s_addr == INADDR_NONE ? 0 : 1;
}

int listen(NetworkSocket s, int backlog) {
  return wrapSocketFunction<int>(::listen, s, backlog);
}

int poll(PollDescriptor fds[], nfds_t nfds, int timeout) {
  // Make sure that PollDescriptor is byte-for-byte identical to pollfd,
  // so we don't need extra allocations just for the safety of this shim.
  static_assert(
      alignof(PollDescriptor) == alignof(pollfd),
      "PollDescriptor is misaligned");
  static_assert(
      sizeof(PollDescriptor) == sizeof(pollfd),
      "PollDescriptor is the wrong size");
  static_assert(
      offsetof(PollDescriptor, fd) == offsetof(pollfd, fd),
      "PollDescriptor.fd is at the wrong place");
  static_assert(
      sizeof(decltype(PollDescriptor().fd)) == sizeof(decltype(pollfd().fd)),
      "PollDescriptor.fd is the wrong size");
  static_assert(
      offsetof(PollDescriptor, events) == offsetof(pollfd, events),
      "PollDescriptor.events is at the wrong place");
  static_assert(
      sizeof(decltype(PollDescriptor().events)) ==
          sizeof(decltype(pollfd().events)),
      "PollDescriptor.events is the wrong size");
  static_assert(
      offsetof(PollDescriptor, revents) == offsetof(pollfd, revents),
      "PollDescriptor.revents is at the wrong place");
  static_assert(
      sizeof(decltype(PollDescriptor().revents)) ==
          sizeof(decltype(pollfd().revents)),
      "PollDescriptor.revents is the wrong size");

  // Pun it through
  auto files = reinterpret_cast<pollfd*>(reinterpret_cast<void*>(fds));
#ifdef _WIN32
  return ::WSAPoll(files, (ULONG)nfds, timeout);
#else
  return ::poll(files, nfds, timeout);
#endif
}

ssize_t recv(NetworkSocket s, void* buf, size_t len, int flags) {
#ifdef _WIN32
  if ((flags & MSG_DONTWAIT) == MSG_DONTWAIT) {
    flags &= ~MSG_DONTWAIT;

    u_long pendingRead = 0;
    if (ioctlsocket(s.data, FIONREAD, &pendingRead)) {
      errno = translate_wsa_error(WSAGetLastError());
      return -1;
    }

    fd_set readSet;
    FD_ZERO(&readSet);
    FD_SET(s.data, &readSet);
    timeval timeout{0, 0};
    auto ret = select(1, &readSet, nullptr, nullptr, &timeout);
    if (ret == 0) {
      errno = EWOULDBLOCK;
      return -1;
    }
  }
  return wrapSocketFunction<ssize_t>(::recv, s, (char*)buf, (int)len, flags);
#else
  return wrapSocketFunction<ssize_t>(::recv, s, buf, len, flags);
#endif
}

ssize_t recvfrom(
    NetworkSocket s,
    void* buf,
    size_t len,
    int flags,
    sockaddr* from,
    socklen_t* fromlen) {
#ifdef _WIN32
  if ((flags & MSG_TRUNC) == MSG_TRUNC) {
    SOCKET h = s.data;

    WSABUF wBuf{};
    wBuf.buf = (CHAR*)buf;
    wBuf.len = (ULONG)len;
    WSAMSG wMsg{};
    wMsg.dwBufferCount = 1;
    wMsg.lpBuffers = &wBuf;
    wMsg.name = from;
    if (fromlen != nullptr) {
      wMsg.namelen = *fromlen;
    }

    // WSARecvMsg is an extension, so we don't get
    // the convenience of being able to call it directly, even though
    // WSASendMsg is part of the normal API -_-...
    LPFN_WSARECVMSG WSARecvMsg;
    GUID WSARecgMsg_GUID = WSAID_WSARECVMSG;
    DWORD recMsgBytes;
    WSAIoctl(
        h,
        SIO_GET_EXTENSION_FUNCTION_POINTER,
        &WSARecgMsg_GUID,
        sizeof(WSARecgMsg_GUID),
        &WSARecvMsg,
        sizeof(WSARecvMsg),
        &recMsgBytes,
        nullptr,
        nullptr);

    DWORD bytesReceived;
    int res = WSARecvMsg(h, &wMsg, &bytesReceived, nullptr, nullptr);
    errno = translate_wsa_error(WSAGetLastError());
    if (res == 0) {
      return bytesReceived;
    }
    if (fromlen != nullptr) {
      *fromlen = wMsg.namelen;
    }
    if ((wMsg.dwFlags & MSG_TRUNC) == MSG_TRUNC) {
      return wBuf.len + 1;
    }
    return -1;
  }
  return wrapSocketFunction<ssize_t>(
      ::recvfrom, s, (char*)buf, (int)len, flags, from, fromlen);
#else
  return wrapSocketFunction<ssize_t>(
      ::recvfrom, s, buf, len, flags, from, fromlen);
#endif
}

ssize_t recvmsg(NetworkSocket s, msghdr* message, int flags) {
#ifdef _WIN32
  (void)flags;
  SOCKET h = s.data;

  // Don't currently support the name translation.
  if (message->msg_name != nullptr || message->msg_namelen != 0) {
    return (ssize_t)-1;
  }
  WSAMSG msg;
  msg.name = nullptr;
  msg.namelen = 0;
  msg.Control.buf = (CHAR*)message->msg_control;
  msg.Control.len = (ULONG)message->msg_controllen;
  msg.dwFlags = 0;
  msg.dwBufferCount = (DWORD)message->msg_iovlen;
  msg.lpBuffers = new WSABUF[message->msg_iovlen];
  SCOPE_EXIT {
    delete[] msg.lpBuffers;
  };
  for (size_t i = 0; i < message->msg_iovlen; i++) {
    msg.lpBuffers[i].buf = (CHAR*)message->msg_iov[i].iov_base;
    msg.lpBuffers[i].len = (ULONG)message->msg_iov[i].iov_len;
  }

  // WSARecvMsg is an extension, so we don't get
  // the convenience of being able to call it directly, even though
  // WSASendMsg is part of the normal API -_-...
  LPFN_WSARECVMSG WSARecvMsg;
  GUID WSARecgMsg_GUID = WSAID_WSARECVMSG;
  DWORD recMsgBytes;
  WSAIoctl(
      h,
      SIO_GET_EXTENSION_FUNCTION_POINTER,
      &WSARecgMsg_GUID,
      sizeof(WSARecgMsg_GUID),
      &WSARecvMsg,
      sizeof(WSARecvMsg),
      &recMsgBytes,
      nullptr,
      nullptr);

  DWORD bytesReceived;
  int res = WSARecvMsg(h, &msg, &bytesReceived, nullptr, nullptr);
  errno = translate_wsa_error(WSAGetLastError());
  return res == 0 ? (ssize_t)bytesReceived : -1;
#else
  return wrapSocketFunction<ssize_t>(::recvmsg, s, message, flags);
#endif
}

int recvmmsg(
    NetworkSocket s,
    mmsghdr* msgvec,
    unsigned int vlen,
    unsigned int flags,
    timespec* timeout) {
#if FOLLY_HAVE_RECVMMSG
  return wrapSocketFunction<int>(::recvmmsg, s, msgvec, vlen, flags, timeout);
#else
  // implement via recvmsg
  for (unsigned int i = 0; i < vlen; i++) {
    ssize_t ret = recvmsg(s, &msgvec[i].msg_hdr, flags);
    // in case of an error
    // we return the number of msgs received if > 0
    // or an error if no msg was sent
    if (ret < 0) {
      if (i) {
        return static_cast<int>(i);
      }
      return static_cast<int>(ret);
    }
  }
  return static_cast<int>(vlen);
#endif
}

ssize_t send(NetworkSocket s, const void* buf, size_t len, int flags) {
#ifdef _WIN32
  return wrapSocketFunction<ssize_t>(
      ::send, s, (const char*)buf, (int)len, flags);
#else
  return wrapSocketFunction<ssize_t>(::send, s, buf, len, flags);
#endif
}

ssize_t sendmsg(NetworkSocket socket, const msghdr* message, int flags) {
#ifdef _WIN32
  (void)flags;
  SOCKET h = socket.data;

  // Unfortunately, WSASendMsg requires the socket to have been opened
  // as either SOCK_DGRAM or SOCK_RAW, but sendmsg has no such requirement,
  // so we have to implement it based on send instead :(
  ssize_t bytesSent = 0;
  for (size_t i = 0; i < message->msg_iovlen; i++) {
    int r = -1;
    if (message->msg_name != nullptr) {
      r = ::sendto(
          h,
          (const char*)message->msg_iov[i].iov_base,
          (int)message->msg_iov[i].iov_len,
          message->msg_flags,
          (const sockaddr*)message->msg_name,
          (int)message->msg_namelen);
    } else {
      r = ::send(
          h,
          (const char*)message->msg_iov[i].iov_base,
          (int)message->msg_iov[i].iov_len,
          message->msg_flags);
    }
    if (r == -1 || size_t(r) != message->msg_iov[i].iov_len) {
      errno = translate_wsa_error(WSAGetLastError());
      if (WSAGetLastError() == WSAEWOULDBLOCK && bytesSent > 0) {
        return bytesSent;
      }
      return -1;
    }
    bytesSent += r;
  }
  return bytesSent;
#else
  return wrapSocketFunction<ssize_t>(::sendmsg, socket, message, flags);
#endif
}

int sendmmsg(
    NetworkSocket socket,
    mmsghdr* msgvec,
    unsigned int vlen,
    int flags) {
#if FOLLY_HAVE_SENDMMSG
  return wrapSocketFunction<int>(::sendmmsg, socket, msgvec, vlen, flags);
#else
  // implement via sendmsg
  for (unsigned int i = 0; i < vlen; i++) {
    ssize_t ret = sendmsg(socket, &msgvec[i].msg_hdr, flags);
    // in case of an error
    // we return the number of msgs sent if > 0
    // or an error if no msg was sent
    if (ret < 0) {
      if (i) {
        return static_cast<int>(i);
      }

      return static_cast<int>(ret);
    }
  }

  return static_cast<int>(vlen);
#endif
}

ssize_t sendto(
    NetworkSocket s,
    const void* buf,
    size_t len,
    int flags,
    const sockaddr* to,
    socklen_t tolen) {
#ifdef _WIN32
  return wrapSocketFunction<ssize_t>(
      ::sendto, s, (const char*)buf, (int)len, flags, to, (int)tolen);
#else
  return wrapSocketFunction<ssize_t>(::sendto, s, buf, len, flags, to, tolen);
#endif
}

int setsockopt(
    NetworkSocket s,
    int level,
    int optname,
    const void* optval,
    socklen_t optlen) {
#ifdef _WIN32
  if (optname == SO_REUSEADDR) {
    // We don't have an equivelent to the Linux & OSX meaning of this
    // on Windows, so ignore it.
    return 0;
  } else if (optname == SO_REUSEPORT) {
    // Windows's SO_REUSEADDR option is closer to SO_REUSEPORT than
    // it is to the Linux & OSX meaning of SO_REUSEADDR.
    return -1;
  }
  return wrapSocketFunction<int>(
      ::setsockopt, s, level, optname, (char*)optval, optlen);
#else
  return wrapSocketFunction<int>(
      ::setsockopt, s, level, optname, optval, optlen);
#endif
}

int shutdown(NetworkSocket s, int how) {
  return wrapSocketFunction<int>(::shutdown, s, how);
}

NetworkSocket socket(int af, int type, int protocol) {
  return NetworkSocket(::socket(af, type, protocol));
}

int socketpair(int domain, int type, int protocol, NetworkSocket sv[2]) {
#ifdef _WIN32
  if (domain != PF_UNIX || type != SOCK_STREAM || protocol != 0) {
    return -1;
  }
  intptr_t pair[2];
  auto r = evutil_socketpair(AF_INET, type, protocol, pair);
  if (r == -1) {
    return r;
  }
  sv[0] = NetworkSocket(static_cast<SOCKET>(pair[0]));
  sv[1] = NetworkSocket(static_cast<SOCKET>(pair[1]));
  return r;
#else
  int pair[2];
  auto r = ::socketpair(domain, type, protocol, pair);
  if (r == -1) {
    return r;
  }
  sv[0] = NetworkSocket(pair[0]);
  sv[1] = NetworkSocket(pair[1]);
  return r;
#endif
}

int set_socket_non_blocking(NetworkSocket s) {
#ifdef _WIN32
  u_long nonBlockingEnabled = 1;
  return ioctlsocket(s.data, FIONBIO, &nonBlockingEnabled);
#else
  int flags = fcntl(s.data, F_GETFL, 0);
  if (flags == -1) {
    return -1;
  }
  return fcntl(s.data, F_SETFL, flags | O_NONBLOCK);
#endif
}

int set_socket_close_on_exec(NetworkSocket s) {
#ifdef _WIN32
  if (SetHandleInformation((HANDLE)s.data, HANDLE_FLAG_INHERIT, 0)) {
    return 0;
  }
  return -1;
#else
  return fcntl(s.data, F_SETFD, FD_CLOEXEC);
#endif
}
} // namespace netops
} // namespace folly