text: /* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to
   * deal in the Software without restriction, including without limitation the
   * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   * sell copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  #include <assert.h>
  #include <stdlib.h>
  
  #include "uv.h"
  #include "internal.h"
  #include "handle-inl.h"
  #include "stream-inl.h"
  #include "req-inl.h"
  
  
  /*
   * Threshold of active tcp streams for which to preallocate tcp read buffers.
   * (Due to node slab allocator performing poorly under this pattern,
   *  the optimization is temporarily disabled (threshold=0).  This will be
   *  revisited once node allocator is improved.)
   */
  const unsigned int uv_active_tcp_streams_threshold = 0;
  
  /*
   * Number of simultaneous pending AcceptEx calls.
   */
  const unsigned int uv_simultaneous_server_accepts = 32;
  
  /* A zero-size buffer for use by uv_tcp_read */
  static char uv_zero_[] = "";
  
  static int uv__tcp_nodelay(uv_tcp_t* handle, SOCKET socket, int enable) {
    if (setsockopt(socket,
                   IPPROTO_TCP,
                   TCP_NODELAY,
                   (const char*)&enable,
                   sizeof enable) == -1) {
      return WSAGetLastError();
    }
    return 0;
  }
  
  
  static int uv__tcp_keepalive(uv_tcp_t* handle, SOCKET socket, int enable, unsigned int delay) {
    if (setsockopt(socket,
                   SOL_SOCKET,
                   SO_KEEPALIVE,
                   (const char*)&enable,
                   sizeof enable) == -1) {
      return WSAGetLastError();
    }
  
    if (enable && setsockopt(socket,
                             IPPROTO_TCP,
                             TCP_KEEPALIVE,
                             (const char*)&delay,
                             sizeof delay) == -1) {
      return WSAGetLastError();
    }
  
    return 0;
  }
  
  
  static int uv_tcp_set_socket(uv_loop_t* loop, uv_tcp_t* handle,
      SOCKET socket, int family, int imported) {
    DWORD yes = 1;
    int non_ifs_lsp;
    int err;
  
    assert(handle->socket == INVALID_SOCKET);
  
    /* Set the socket to nonblocking mode */
    if (ioctlsocket(socket, FIONBIO, &yes) == SOCKET_ERROR) {
      return WSAGetLastError();
    }
  
    /* Associate it with the I/O completion port. */
    /* Use uv_handle_t pointer as completion key. */
    if (CreateIoCompletionPort((HANDLE)socket,
                               loop->iocp,
                               (ULONG_PTR)socket,
                               0) == NULL) {
      if (imported) {
        handle->flags |= UV_HANDLE_EMULATE_IOCP;
      } else {
        return GetLastError();
      }
    }
  
    if (family == AF_INET6) {
      non_ifs_lsp = uv_tcp_non_ifs_lsp_ipv6;
    } else {
      non_ifs_lsp = uv_tcp_non_ifs_lsp_ipv4;
    }
  
    if (pSetFileCompletionNotificationModes &&
        !(handle->flags & UV_HANDLE_EMULATE_IOCP) && !non_ifs_lsp) {
      if (pSetFileCompletionNotificationModes((HANDLE) socket,
          FILE_SKIP_SET_EVENT_ON_HANDLE |
          FILE_SKIP_COMPLETION_PORT_ON_SUCCESS)) {
        handle->flags |= UV_HANDLE_SYNC_BYPASS_IOCP;
      } else if (GetLastError() != ERROR_INVALID_FUNCTION) {
        return GetLastError();
      }
    }
  
    if (handle->flags & UV_HANDLE_TCP_NODELAY) {
      err = uv__tcp_nodelay(handle, socket, 1);
      if (err)
        return err;
    }
  
    /* TODO: Use stored delay. */
    if (handle->flags & UV_HANDLE_TCP_KEEPALIVE) {
      err = uv__tcp_keepalive(handle, socket, 1, 60);
      if (err)
        return err;
    }
  
    handle->socket = socket;
  
    if (family == AF_INET6) {
      handle->flags |= UV_HANDLE_IPV6;
    } else {
      assert(!(handle->flags & UV_HANDLE_IPV6));
    }
  
    return 0;
  }
  
  
  int uv_tcp_init(uv_loop_t* loop, uv_tcp_t* handle) {
    uv_stream_init(loop, (uv_stream_t*) handle, UV_TCP);
  
    handle->accept_reqs = NULL;
    handle->pending_accepts = NULL;
    handle->socket = INVALID_SOCKET;
    handle->reqs_pending = 0;
    handle->func_acceptex = NULL;
    handle->func_connectex = NULL;
    handle->processed_accepts = 0;
  
    return 0;
  }
  
  
  void uv_tcp_endgame(uv_loop_t* loop, uv_tcp_t* handle) {
    int err;
    unsigned int i;
    uv_tcp_accept_t* req;
  
    if (handle->flags & UV_HANDLE_CONNECTION &&
        handle->shutdown_req != NULL &&
        handle->write_reqs_pending == 0) {
  
      UNREGISTER_HANDLE_REQ(loop, handle, handle->shutdown_req);
  
      err = 0;
      if (handle->flags & UV__HANDLE_CLOSING) {
        err = ERROR_OPERATION_ABORTED;
      } else if (shutdown(handle->socket, SD_SEND) == SOCKET_ERROR) {
        err = WSAGetLastError();
      }
  
      if (handle->shutdown_req->cb) {
        handle->shutdown_req->cb(handle->shutdown_req,
                                 uv_translate_sys_error(err));
      }
  
      handle->shutdown_req = NULL;
      DECREASE_PENDING_REQ_COUNT(handle);
      return;
    }
  
    if (handle->flags & UV__HANDLE_CLOSING &&
        handle->reqs_pending == 0) {
      assert(!(handle->flags & UV_HANDLE_CLOSED));
  
      if (!(handle->flags & UV_HANDLE_TCP_SOCKET_CLOSED)) {
        closesocket(handle->socket);
        handle->flags |= UV_HANDLE_TCP_SOCKET_CLOSED;
      }
  
      if (!(handle->flags & UV_HANDLE_CONNECTION) && handle->accept_reqs) {
        if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
          for (i = 0; i < uv_simultaneous_server_accepts; i++) {
            req = &handle->accept_reqs[i];
            if (req->wait_handle != INVALID_HANDLE_VALUE) {
              UnregisterWait(req->wait_handle);
              req->wait_handle = INVALID_HANDLE_VALUE;
            }
            if (req->event_handle) {
              CloseHandle(req->event_handle);
              req->event_handle = NULL;
            }
          }
        }
  
        free(handle->accept_reqs);
        handle->accept_reqs = NULL;
      }
  
      if (handle->flags & UV_HANDLE_CONNECTION &&
          handle->flags & UV_HANDLE_EMULATE_IOCP) {
        if (handle->read_req.wait_handle != INVALID_HANDLE_VALUE) {
          UnregisterWait(handle->read_req.wait_handle);
          handle->read_req.wait_handle = INVALID_HANDLE_VALUE;
        }
        if (handle->read_req.event_handle) {
          CloseHandle(handle->read_req.event_handle);
          handle->read_req.event_handle = NULL;
        }
      }
  
      uv__handle_close(handle);
      loop->active_tcp_streams--;
    }
  }
  
  
  static int uv_tcp_try_bind(uv_tcp_t* handle,
                             const struct sockaddr* addr,
                             unsigned int addrlen,
                             unsigned int flags) {
    DWORD err;
    int r;
  
    if (handle->socket == INVALID_SOCKET) {
      SOCKET sock;
      
      /* Cannot set IPv6-only mode on non-IPv6 socket. */
      if ((flags & UV_TCP_IPV6ONLY) && addr->sa_family != AF_INET6)
        return ERROR_INVALID_PARAMETER;
  
      sock = socket(addr->sa_family, SOCK_STREAM, 0);
      if (sock == INVALID_SOCKET) {
        return WSAGetLastError();
      }
  
      /* Make the socket non-inheritable */
      if (!SetHandleInformation((HANDLE) sock, HANDLE_FLAG_INHERIT, 0)) {
        err = GetLastError();
        closesocket(sock);
        return err;
      }
  
      err = uv_tcp_set_socket(handle->loop, handle, sock, addr->sa_family, 0);
      if (err) {
        closesocket(sock);
        return err;
      }
    }
  
  #ifdef IPV6_V6ONLY
    if (addr->sa_family == AF_INET6) {
      int on;
  
      on = (flags & UV_TCP_IPV6ONLY) != 0;
  
      /* TODO: how to handle errors? This may fail if there is no ipv4 stack */
      /* available, or when run on XP/2003 which have no support for dualstack */
      /* sockets. For now we're silently ignoring the error. */
      setsockopt(handle->socket,
                 IPPROTO_IPV6,
                 IPV6_V6ONLY,
                 (const char*)&on,
                 sizeof on);
    }
  #endif
  
    r = bind(handle->socket, addr, addrlen);
  
    if (r == SOCKET_ERROR) {
      err = WSAGetLastError();
      if (err == WSAEADDRINUSE) {
        /* Some errors are not to be reported until connect() or listen() */
        handle->bind_error = err;
        handle->flags |= UV_HANDLE_BIND_ERROR;
      } else {
        return err;
      }
    }
  
    handle->flags |= UV_HANDLE_BOUND;
  
    return 0;
  }
  
  
  static void CALLBACK post_completion(void* context, BOOLEAN timed_out) {
    uv_req_t* req;
    uv_tcp_t* handle;
  
    req = (uv_req_t*) context;
    assert(req != NULL);
    handle = (uv_tcp_t*)req->data;
    assert(handle != NULL);
    assert(!timed_out);
  
    if (!PostQueuedCompletionStatus(handle->loop->iocp,
                                    req->overlapped.InternalHigh,
                                    0,
                                    &req->overlapped)) {
      uv_fatal_error(GetLastError(), "PostQueuedCompletionStatus");
    }
  }
  
  
  static void CALLBACK post_write_completion(void* context, BOOLEAN timed_out) {
    uv_write_t* req;
    uv_tcp_t* handle;
  
    req = (uv_write_t*) context;
    assert(req != NULL);
    handle = (uv_tcp_t*)req->handle;
    assert(handle != NULL);
    assert(!timed_out);
  
    if (!PostQueuedCompletionStatus(handle->loop->iocp,
                                    req->overlapped.InternalHigh,
                                    0,
                                    &req->overlapped)) {
      uv_fatal_error(GetLastError(), "PostQueuedCompletionStatus");
    }
  }
  
  
  static void uv_tcp_queue_accept(uv_tcp_t* handle, uv_tcp_accept_t* req) {
    uv_loop_t* loop = handle->loop;
    BOOL success;
    DWORD bytes;
    SOCKET accept_socket;
    short family;
  
    assert(handle->flags & UV_HANDLE_LISTENING);
    assert(req->accept_socket == INVALID_SOCKET);
  
    /* choose family and extension function */
    if (handle->flags & UV_HANDLE_IPV6) {
      family = AF_INET6;
    } else {
      family = AF_INET;
    }
  
    /* Open a socket for the accepted connection. */
    accept_socket = socket(family, SOCK_STREAM, 0);
    if (accept_socket == INVALID_SOCKET) {
      SET_REQ_ERROR(req, WSAGetLastError());
      uv_insert_pending_req(loop, (uv_req_t*)req);
      handle->reqs_pending++;
      return;
    }
  
    /* Make the socket non-inheritable */
    if (!SetHandleInformation((HANDLE) accept_socket, HANDLE_FLAG_INHERIT, 0)) {
      SET_REQ_ERROR(req, GetLastError());
      uv_insert_pending_req(loop, (uv_req_t*)req);
      handle->reqs_pending++;
      closesocket(accept_socket);
      return;
    }
  
    /* Prepare the overlapped structure. */
    memset(&(req->overlapped), 0, sizeof(req->overlapped));
    if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
      req->overlapped.hEvent = (HANDLE) ((ULONG_PTR) req->event_handle | 1);
    }
  
    success = handle->func_acceptex(handle->socket,
                                    accept_socket,
                                    (void*)req->accept_buffer,
                                    0,
                                    sizeof(struct sockaddr_storage),
                                    sizeof(struct sockaddr_storage),
                                    &bytes,
                                    &req->overlapped);
  
    if (UV_SUCCEEDED_WITHOUT_IOCP(success)) {
      /* Process the req without IOCP. */
      req->accept_socket = accept_socket;
      handle->reqs_pending++;
      uv_insert_pending_req(loop, (uv_req_t*)req);
    } else if (UV_SUCCEEDED_WITH_IOCP(success)) {
      /* The req will be processed with IOCP. */
      req->accept_socket = accept_socket;
      handle->reqs_pending++;
      if (handle->flags & UV_HANDLE_EMULATE_IOCP &&
          req->wait_handle == INVALID_HANDLE_VALUE &&
          !RegisterWaitForSingleObject(&req->wait_handle,
            req->event_handle, post_completion, (void*) req,
            INFINITE, WT_EXECUTEINWAITTHREAD)) {
        SET_REQ_ERROR(req, GetLastError());
        uv_insert_pending_req(loop, (uv_req_t*)req);
        handle->reqs_pending++;
        return;
      }
    } else {
      /* Make this req pending reporting an error. */
      SET_REQ_ERROR(req, WSAGetLastError());
      uv_insert_pending_req(loop, (uv_req_t*)req);
      handle->reqs_pending++;
      /* Destroy the preallocated client socket. */
      closesocket(accept_socket);
      /* Destroy the event handle */
      if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
        CloseHandle(req->overlapped.hEvent);
        req->event_handle = NULL;
      }
    }
  }
  
  
  static void uv_tcp_queue_read(uv_loop_t* loop, uv_tcp_t* handle) {
    uv_read_t* req;
    uv_buf_t buf;
    int result;
    DWORD bytes, flags;
  
    assert(handle->flags & UV_HANDLE_READING);
    assert(!(handle->flags & UV_HANDLE_READ_PENDING));
  
    req = &handle->read_req;
    memset(&req->overlapped, 0, sizeof(req->overlapped));
  
    /*
     * Preallocate a read buffer if the number of active streams is below
     * the threshold.
    */
    if (loop->active_tcp_streams < uv_active_tcp_streams_threshold) {
      handle->flags &= ~UV_HANDLE_ZERO_READ;
      handle->alloc_cb((uv_handle_t*) handle, 65536, &handle->read_buffer);
      if (handle->read_buffer.len == 0) {
        handle->read_cb((uv_stream_t*) handle, UV_ENOBUFS, &handle->read_buffer);
        return;
      }
      assert(handle->read_buffer.base != NULL);
      buf = handle->read_buffer;
    } else {
      handle->flags |= UV_HANDLE_ZERO_READ;
      buf.base = (char*) &uv_zero_;
      buf.len = 0;
    }
  
    /* Prepare the overlapped structure. */
    memset(&(req->overlapped), 0, sizeof(req->overlapped));
    if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
      assert(req->event_handle);
      req->overlapped.hEvent = (HANDLE) ((ULONG_PTR) req->event_handle | 1);
    }
  
    flags = 0;
    result = WSARecv(handle->socket,
                     (WSABUF*)&buf,
                     1,
                     &bytes,
                     &flags,
                     &req->overlapped,
                     NULL);
  
    if (UV_SUCCEEDED_WITHOUT_IOCP(result == 0)) {
      /* Process the req without IOCP. */
      handle->flags |= UV_HANDLE_READ_PENDING;
      req->overlapped.InternalHigh = bytes;
      handle->reqs_pending++;
      uv_insert_pending_req(loop, (uv_req_t*)req);
    } else if (UV_SUCCEEDED_WITH_IOCP(result == 0)) {
      /* The req will be processed with IOCP. */
      handle->flags |= UV_HANDLE_READ_PENDING;
      handle->reqs_pending++;
      if (handle->flags & UV_HANDLE_EMULATE_IOCP &&
          req->wait_handle == INVALID_HANDLE_VALUE &&
          !RegisterWaitForSingleObject(&req->wait_handle,
            req->event_handle, post_completion, (void*) req,
            INFINITE, WT_EXECUTEINWAITTHREAD)) {
        SET_REQ_ERROR(req, GetLastError());
        uv_insert_pending_req(loop, (uv_req_t*)req);
      }
    } else {
      /* Make this req pending reporting an error. */
      SET_REQ_ERROR(req, WSAGetLastError());
      uv_insert_pending_req(loop, (uv_req_t*)req);
      handle->reqs_pending++;
    }
  }
  
  
  int uv_tcp_listen(uv_tcp_t* handle, int backlog, uv_connection_cb cb) {
    uv_loop_t* loop = handle->loop;
    unsigned int i, simultaneous_accepts;
    uv_tcp_accept_t* req;
    int err;
  
    assert(backlog > 0);
  
    if (handle->flags & UV_HANDLE_LISTENING) {
      handle->connection_cb = cb;
    }
  
    if (handle->flags & UV_HANDLE_READING) {
      return WSAEISCONN;
    }
  
    if (handle->flags & UV_HANDLE_BIND_ERROR) {
      return handle->bind_error;
    }
  
    if (!(handle->flags & UV_HANDLE_BOUND)) {
      err = uv_tcp_try_bind(handle,
                            (const struct sockaddr*) &uv_addr_ip4_any_,
                            sizeof(uv_addr_ip4_any_),
                            0);
      if (err)
        return err;
    }
  
    if (!handle->func_acceptex) {
      if (!uv_get_acceptex_function(handle->socket, &handle->func_acceptex)) {
        return WSAEAFNOSUPPORT;
      }
    }
  
    if (!(handle->flags & UV_HANDLE_SHARED_TCP_SOCKET) &&
        listen(handle->socket, backlog) == SOCKET_ERROR) {
      return WSAGetLastError();
    }
  
    handle->flags |= UV_HANDLE_LISTENING;
    handle->connection_cb = cb;
    INCREASE_ACTIVE_COUNT(loop, handle);
  
    simultaneous_accepts = handle->flags & UV_HANDLE_TCP_SINGLE_ACCEPT ? 1
      : uv_simultaneous_server_accepts;
  
    if(!handle->accept_reqs) {
      handle->accept_reqs = (uv_tcp_accept_t*)
        malloc(uv_simultaneous_server_accepts * sizeof(uv_tcp_accept_t));
      if (!handle->accept_reqs) {
        uv_fatal_error(ERROR_OUTOFMEMORY, "malloc");
      }
  
      for (i = 0; i < simultaneous_accepts; i++) {
        req = &handle->accept_reqs[i];
        uv_req_init(loop, (uv_req_t*)req);
        req->type = UV_ACCEPT;
        req->accept_socket = INVALID_SOCKET;
        req->data = handle;
  
        req->wait_handle = INVALID_HANDLE_VALUE;
        if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
          req->event_handle = CreateEvent(NULL, 0, 0, NULL);
          if (!req->event_handle) {
            uv_fatal_error(GetLastError(), "CreateEvent");
          }
        } else {
          req->event_handle = NULL;
        }
  
        uv_tcp_queue_accept(handle, req);
      }
  
      /* Initialize other unused requests too, because uv_tcp_endgame */
      /* doesn't know how how many requests were intialized, so it will */
      /* try to clean up {uv_simultaneous_server_accepts} requests. */
      for (i = simultaneous_accepts; i < uv_simultaneous_server_accepts; i++) {
        req = &handle->accept_reqs[i];
        uv_req_init(loop, (uv_req_t*) req);
        req->type = UV_ACCEPT;
        req->accept_socket = INVALID_SOCKET;
        req->data = handle;
        req->wait_handle = INVALID_HANDLE_VALUE;
        req->event_handle = NULL;
      }
    }
  
    return 0;
  }
  
  
  int uv_tcp_accept(uv_tcp_t* server, uv_tcp_t* client) {
    uv_loop_t* loop = server->loop;
    int err = 0;
    int family;
  
    uv_tcp_accept_t* req = server->pending_accepts;
  
    if (!req) {
      /* No valid connections found, so we error out. */
      return WSAEWOULDBLOCK;
    }
  
    if (req->accept_socket == INVALID_SOCKET) {
      return WSAENOTCONN;
    }
  
    if (server->flags & UV_HANDLE_IPV6) {
      family = AF_INET6;
    } else {
      family = AF_INET;
    }
  
    err = uv_tcp_set_socket(client->loop,
                            client,
                            req->accept_socket,
                            family,
                            0);
    if (err) {
      closesocket(req->accept_socket);
    } else {
      uv_connection_init((uv_stream_t*) client);
      /* AcceptEx() implicitly binds the accepted socket. */
      client->flags |= UV_HANDLE_BOUND | UV_HANDLE_READABLE | UV_HANDLE_WRITABLE;
    }
  
    /* Prepare the req to pick up a new connection */
    server->pending_accepts = req->next_pending;
    req->next_pending = NULL;
    req->accept_socket = INVALID_SOCKET;
  
    if (!(server->flags & UV__HANDLE_CLOSING)) {
      /* Check if we're in a middle of changing the number of pending accepts. */
      if (!(server->flags & UV_HANDLE_TCP_ACCEPT_STATE_CHANGING)) {
        uv_tcp_queue_accept(server, req);
      } else {
        /* We better be switching to a single pending accept. */
        assert(server->flags & UV_HANDLE_TCP_SINGLE_ACCEPT);
  
        server->processed_accepts++;
  
        if (server->processed_accepts >= uv_simultaneous_server_accepts) {
          server->processed_accepts = 0;
          /*
           * All previously queued accept requests are now processed.
           * We now switch to queueing just a single accept.
           */
          uv_tcp_queue_accept(server, &server->accept_reqs[0]);
          server->flags &= ~UV_HANDLE_TCP_ACCEPT_STATE_CHANGING;
          server->flags |= UV_HANDLE_TCP_SINGLE_ACCEPT;
        }
      }
    }
  
    loop->active_tcp_streams++;
  
    return err;
  }
  
  
  int uv_tcp_read_start(uv_tcp_t* handle, uv_alloc_cb alloc_cb,
      uv_read_cb read_cb) {
    uv_loop_t* loop = handle->loop;
  
    handle->flags |= UV_HANDLE_READING;
    handle->read_cb = read_cb;
    handle->alloc_cb = alloc_cb;
    INCREASE_ACTIVE_COUNT(loop, handle);
  
    /* If reading was stopped and then started again, there could still be a */
    /* read request pending. */
    if (!(handle->flags & UV_HANDLE_READ_PENDING)) {
      if (handle->flags & UV_HANDLE_EMULATE_IOCP &&
          !handle->read_req.event_handle) {
        handle->read_req.event_handle = CreateEvent(NULL, 0, 0, NULL);
        if (!handle->read_req.event_handle) {
          uv_fatal_error(GetLastError(), "CreateEvent");
        }
      }
      uv_tcp_queue_read(loop, handle);
    }
  
    return 0;
  }
  
  
  static int uv_tcp_try_connect(uv_connect_t* req,
                                uv_tcp_t* handle,
                                const struct sockaddr* addr,
                                unsigned int addrlen,
                                uv_connect_cb cb) {
    uv_loop_t* loop = handle->loop;
    const struct sockaddr* bind_addr;
    BOOL success;
    DWORD bytes;
    int err;
  
    if (handle->flags & UV_HANDLE_BIND_ERROR) {
      return handle->bind_error;
    }
  
    if (!(handle->flags & UV_HANDLE_BOUND)) {
      if (addrlen == sizeof(uv_addr_ip4_any_)) {
        bind_addr = (const struct sockaddr*) &uv_addr_ip4_any_;
      } else if (addrlen == sizeof(uv_addr_ip6_any_)) {
        bind_addr = (const struct sockaddr*) &uv_addr_ip6_any_;
      } else {
        abort();
      }
      err = uv_tcp_try_bind(handle, bind_addr, addrlen, 0);
      if (err)
        return err;
    }
  
    if (!handle->func_connectex) {
      if (!uv_get_connectex_function(handle->socket, &handle->func_connectex)) {
        return WSAEAFNOSUPPORT;
      }
    }
  
    uv_req_init(loop, (uv_req_t*) req);
    req->type = UV_CONNECT;
    req->handle = (uv_stream_t*) handle;
    req->cb = cb;
    memset(&req->overlapped, 0, sizeof(req->overlapped));
  
    success = handle->func_connectex(handle->socket,
                                     addr,
                                     addrlen,
                                     NULL,
                                     0,
                                     &bytes,
                                     &req->overlapped);
  
    if (UV_SUCCEEDED_WITHOUT_IOCP(success)) {
      /* Process the req without IOCP. */
      handle->reqs_pending++;
      REGISTER_HANDLE_REQ(loop, handle, req);
      uv_insert_pending_req(loop, (uv_req_t*)req);
    } else if (UV_SUCCEEDED_WITH_IOCP(success)) {
      /* The req will be processed with IOCP. */
      handle->reqs_pending++;
      REGISTER_HANDLE_REQ(loop, handle, req);
    } else {
      return WSAGetLastError();
    }
  
    return 0;
  }
  
  
  int uv_tcp_getsockname(const uv_tcp_t* handle,
                         struct sockaddr* name,
                         int* namelen) {
    int result;
  
    if (!(handle->flags & UV_HANDLE_BOUND)) {
      return UV_EINVAL;
    }
  
    if (handle->flags & UV_HANDLE_BIND_ERROR) {
      return uv_translate_sys_error(handle->bind_error);
    }
  
    result = getsockname(handle->socket, name, namelen);
    if (result != 0) {
      return uv_translate_sys_error(WSAGetLastError());
    }
  
    return 0;
  }
  
  
  int uv_tcp_getpeername(const uv_tcp_t* handle,
                         struct sockaddr* name,
                         int* namelen) {
    int result;
  
    if (!(handle->flags & UV_HANDLE_BOUND)) {
      return UV_EINVAL;
    }
  
    if (handle->flags & UV_HANDLE_BIND_ERROR) {
      return uv_translate_sys_error(handle->bind_error);
    }
  
    result = getpeername(handle->socket, name, namelen);
    if (result != 0) {
      return uv_translate_sys_error(WSAGetLastError());
    }
  
    return 0;
  }
  
  
  int uv_tcp_write(uv_loop_t* loop,
                   uv_write_t* req,
                   uv_tcp_t* handle,
                   const uv_buf_t bufs[],
                   unsigned int nbufs,
                   uv_write_cb cb) {
    int result;
    DWORD bytes;
  
    uv_req_init(loop, (uv_req_t*) req);
    req->type = UV_WRITE;
    req->handle = (uv_stream_t*) handle;
    req->cb = cb;
  
    /* Prepare the overlapped structure. */
    memset(&(req->overlapped), 0, sizeof(req->overlapped));
    if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
      req->event_handle = CreateEvent(NULL, 0, 0, NULL);
      if (!req->event_handle) {
        uv_fatal_error(GetLastError(), "CreateEvent");
      }
      req->overlapped.hEvent = (HANDLE) ((ULONG_PTR) req->event_handle | 1);
      req->wait_handle = INVALID_HANDLE_VALUE;
    }
  
    result = WSASend(handle->socket,
                     (WSABUF*) bufs,
                     nbufs,
                     &bytes,
                     0,
                     &req->overlapped,
                     NULL);
  
    if (UV_SUCCEEDED_WITHOUT_IOCP(result == 0)) {
      /* Request completed immediately. */
      req->queued_bytes = 0;
      handle->reqs_pending++;
      handle->write_reqs_pending++;
      REGISTER_HANDLE_REQ(loop, handle, req);
      uv_insert_pending_req(loop, (uv_req_t*) req);
    } else if (UV_SUCCEEDED_WITH_IOCP(result == 0)) {
      /* Request queued by the kernel. */
      req->queued_bytes = uv_count_bufs(bufs, nbufs);
      handle->reqs_pending++;
      handle->write_reqs_pending++;
      REGISTER_HANDLE_REQ(loop, handle, req);
      handle->write_queue_size += req->queued_bytes;
      if (handle->flags & UV_HANDLE_EMULATE_IOCP &&
          !RegisterWaitForSingleObject(&req->wait_handle,
            req->event_handle, post_write_completion, (void*) req,
            INFINITE, WT_EXECUTEINWAITTHREAD | WT_EXECUTEONLYONCE)) {
        SET_REQ_ERROR(req, GetLastError());
        uv_insert_pending_req(loop, (uv_req_t*)req);
      }
    } else {
      /* Send failed due to an error. */
      return WSAGetLastError();
    }
  
    return 0;
  }
  
  
  void uv_process_tcp_read_req(uv_loop_t* loop, uv_tcp_t* handle,
      uv_req_t* req) {
    DWORD bytes, flags, err;
    uv_buf_t buf;
  
    assert(handle->type == UV_TCP);
  
    handle->flags &= ~UV_HANDLE_READ_PENDING;
  
    if (!REQ_SUCCESS(req)) {
      /* An error occurred doing the read. */
      if ((handle->flags & UV_HANDLE_READING) ||
          !(handle->flags & UV_HANDLE_ZERO_READ)) {
        handle->flags &= ~UV_HANDLE_READING;
        DECREASE_ACTIVE_COUNT(loop, handle);
        buf = (handle->flags & UV_HANDLE_ZERO_READ) ?
              uv_buf_init(NULL, 0) : handle->read_buffer;
  
        err = GET_REQ_SOCK_ERROR(req);
  
        if (err == WSAECONNABORTED) {
          /*
           * Turn WSAECONNABORTED into UV_ECONNRESET to be consistent with Unix.
           */
          err = WSAECONNRESET;
        }
  
        handle->read_cb((uv_stream_t*)handle,
                        uv_translate_sys_error(err),
                        &buf);
      }
    } else {
      if (!(handle->flags & UV_HANDLE_ZERO_READ)) {
        /* The read was done with a non-zero buffer length. */
        if (req->overlapped.InternalHigh > 0) {
          /* Successful read */
          handle->read_cb((uv_stream_t*)handle,
                          req->overlapped.InternalHigh,
                          &handle->read_buffer);
          /* Read again only if bytes == buf.len */
          if (req->overlapped.InternalHigh < handle->read_buffer.len) {
            goto done;
          }
        } else {
          /* Connection closed */
          if (handle->flags & UV_HANDLE_READING) {
            handle->flags &= ~UV_HANDLE_READING;
            DECREASE_ACTIVE_COUNT(loop, handle);
          }
          handle->flags &= ~UV_HANDLE_READABLE;
  
          buf.base = 0;
          buf.len = 0;
          handle->read_cb((uv_stream_t*)handle, UV_EOF, &handle->read_buffer);
          goto done;
        }
      }
  
      /* Do nonblocking reads until the buffer is empty */
      while (handle->flags & UV_HANDLE_READING) {
        handle->alloc_cb((uv_handle_t*) handle, 65536, &buf);
        if (buf.len == 0) {
          handle->read_cb((uv_stream_t*) handle, UV_ENOBUFS, &buf);
          break;
        }
        assert(buf.base != NULL);
  
        flags = 0;
        if (WSARecv(handle->socket,
                    (WSABUF*)&buf,
                    1,
                    &bytes,
                    &flags,
                    NULL,
                    NULL) != SOCKET_ERROR) {
          if (bytes > 0) {
            /* Successful read */
            handle->read_cb((uv_stream_t*)handle, bytes, &buf);
            /* Read again only if bytes == buf.len */
            if (bytes < buf.len) {
              break;
            }
          } else {
            /* Connection closed */
            handle->flags &= ~(UV_HANDLE_READING | UV_HANDLE_READABLE);
            DECREASE_ACTIVE_COUNT(loop, handle);
  
            handle->read_cb((uv_stream_t*)handle, UV_EOF, &buf);
            break;
          }
        } else {
          err = WSAGetLastError();
          if (err == WSAEWOULDBLOCK) {
            /* Read buffer was completely empty, report a 0-byte read. */
            handle->read_cb((uv_stream_t*)handle, 0, &buf);
          } else {
            /* Ouch! serious error. */
            handle->flags &= ~UV_HANDLE_READING;
            DECREASE_ACTIVE_COUNT(loop, handle);
  
            if (err == WSAECONNABORTED) {
              /* Turn WSAECONNABORTED into UV_ECONNRESET to be consistent with */
              /* Unix. */
              err = WSAECONNRESET;
            }
  
            handle->read_cb((uv_stream_t*)handle,
                            uv_translate_sys_error(err),
                            &buf);
          }
          break;
        }
      }
  
  done:
      /* Post another read if still reading and not closing. */
      if ((handle->flags & UV_HANDLE_READING) &&
          !(handle->flags & UV_HANDLE_READ_PENDING)) {
        uv_tcp_queue_read(loop, handle);
      }
    }
  
    DECREASE_PENDING_REQ_COUNT(handle);
  }
  
  
  void uv_process_tcp_write_req(uv_loop_t* loop, uv_tcp_t* handle,
      uv_write_t* req) {
    int err;
  
    assert(handle->type == UV_TCP);
  
    assert(handle->write_queue_size >= req->queued_bytes);
    handle->write_queue_size -= req->queued_bytes;
  
    UNREGISTER_HANDLE_REQ(loop, handle, req);
  
    if (handle->flags & UV_HANDLE_EMULATE_IOCP) {
      if (req->wait_handle != INVALID_HANDLE_VALUE) {
        UnregisterWait(req->wait_handle);
        req->wait_handle = INVALID_HANDLE_VALUE;
      }
      if (req->event_handle) {
        CloseHandle(req->event_handle);
        req->event_handle = NULL;
      }
    }
  
    if (req->cb) {
      err = GET_REQ_SOCK_ERROR(req);
      req->cb(req, uv_translate_sys_error(err));
    }
  
    handle->write_reqs_pending--;
    if (handle->shutdown_req != NULL &&
        handle->write_reqs_pending == 0) {
      uv_want_endgame(loop, (uv_handle_t*)handle);
    }
  
    DECREASE_PENDING_REQ_COUNT(handle);
  }
  
  
  void uv_process_tcp_accept_req(uv_loop_t* loop, uv_tcp_t* handle,
      uv_req_t* raw_req) {
    uv_tcp_accept_t* req = (uv_tcp_accept_t*) raw_req;
    int err;
  
    assert(handle->type == UV_TCP);
  
    /* If handle->accepted_socket is not a valid socket, then */
    /* uv_queue_accept must have failed. This is a serious error. We stop */
    /* accepting connections and report this error to the connection */
    /* callback. */
    if (req->accept_socket == INVALID_SOCKET) {
      if (handle->flags & UV_HANDLE_LISTENING) {
        handle->flags &= ~UV_HANDLE_LISTENING;
        DECREASE_ACTIVE_COUNT(loop, handle);
        if (handle->connection_cb) {
          err = GET_REQ_SOCK_ERROR(req);
          handle->connection_cb((uv_stream_t*)handle,
                                uv_translate_sys_error(err));
        }
      }
    } else if (REQ_SUCCESS(req) &&
        setsockopt(req->accept_socket,
                    SOL_SOCKET,
                    SO_UPDATE_ACCEPT_CONTEXT,
                    (char*)&handle->socket,
                    sizeof(handle->socket)) == 0) {
      req->next_pending = handle->pending_accepts;
      handle->pending_accepts = req;
  
      /* Accept and SO_UPDATE_ACCEPT_CONTEXT were successful. */
      if (handle->connection_cb) {
        handle->connection_cb((uv_stream_t*)handle, 0);
      }
    } else {
      /* Error related to accepted socket is ignored because the server */
      /* socket may still be healthy. If the server socket is broken */
      /* uv_queue_accept will detect it. */
      closesocket(req->accept_socket);
      req->accept_socket = INVALID_SOCKET;
      if (handle->flags & UV_HANDLE_LISTENING) {
        uv_tcp_queue_accept(handle, req);
      }
    }
  
    DECREASE_PENDING_REQ_COUNT(handle);
  }
  
  
  void uv_process_tcp_connect_req(uv_loop_t* loop, uv_tcp_t* handle,
      uv_connect_t* req) {
    int err;
  
    assert(handle->type == UV_TCP);
  
    UNREGISTER_HANDLE_REQ(loop, handle, req);
  
    err = 0;
    if (REQ_SUCCESS(req)) {
      if (setsockopt(handle->socket,
                      SOL_SOCKET,
                      SO_UPDATE_CONNECT_CONTEXT,
                      NULL,
                      0) == 0) {
        uv_connection_init((uv_stream_t*)handle);
        handle->flags |= UV_HANDLE_READABLE | UV_HANDLE_WRITABLE;
        loop->active_tcp_streams++;
      } else {
        err = WSAGetLastError();
      }
    } else {
      err = GET_REQ_SOCK_ERROR(req);
    }
    req->cb(req, uv_translate_sys_error(err));
  
    DECREASE_PENDING_REQ_COUNT(handle);
  }
  
  
  int uv_tcp_import(uv_tcp_t* tcp, WSAPROTOCOL_INFOW* socket_protocol_info,
      int tcp_connection) {
    int err;
  
    SOCKET socket = WSASocketW(FROM_PROTOCOL_INFO,
                               FROM_PROTOCOL_INFO,
                               FROM_PROTOCOL_INFO,
                               socket_protocol_info,
                               0,
                               WSA_FLAG_OVERLAPPED);
  
    if (socket == INVALID_SOCKET) {
      return WSAGetLastError();
    }
  
    if (!SetHandleInformation((HANDLE) socket, HANDLE_FLAG_INHERIT, 0)) {
      err = GetLastError();
      closesocket(socket);
      return err;
    }
  
    err = uv_tcp_set_socket(tcp->loop,
                            tcp,
                            socket,
                            socket_protocol_info->iAddressFamily,
                            1);
    if (err) {
      closesocket(socket);
      return err;
    }
  
    if (tcp_connection) {
      uv_connection_init((uv_stream_t*)tcp);
      tcp->flags |= UV_HANDLE_READABLE | UV_HANDLE_WRITABLE;
    }
  
    tcp->flags |= UV_HANDLE_BOUND;
    tcp->flags |= UV_HANDLE_SHARED_TCP_SOCKET;
  
    tcp->loop->active_tcp_streams++;
    return 0;
  }
  
  
  int uv_tcp_nodelay(uv_tcp_t* handle, int enable) {
    int err;
  
    if (handle->socket != INVALID_SOCKET) {
      err = uv__tcp_nodelay(handle, handle->socket, enable);
      if (err)
        return err;
    }
  
    if (enable) {
      handle->flags |= UV_HANDLE_TCP_NODELAY;
    } else {
      handle->flags &= ~UV_HANDLE_TCP_NODELAY;
    }
  
    return 0;
  }
  
  
  int uv_tcp_keepalive(uv_tcp_t* handle, int enable, unsigned int delay) {
    int err;
  
    if (handle->socket != INVALID_SOCKET) {
      err = uv__tcp_keepalive(handle, handle->socket, enable, delay);
      if (err)
        return err;
    }
  
    if (enable) {
      handle->flags |= UV_HANDLE_TCP_KEEPALIVE;
    } else {
      handle->flags &= ~UV_HANDLE_TCP_KEEPALIVE;
    }
  
    /* TODO: Store delay if handle->socket isn't created yet. */
  
    return 0;
  }
  
  
  int uv_tcp_duplicate_socket(uv_tcp_t* handle, int pid,
      LPWSAPROTOCOL_INFOW protocol_info) {
    if (!(handle->flags & UV_HANDLE_CONNECTION)) {
      /*
       * We're about to share the socket with another process.  Because
       * this is a listening socket, we assume that the other process will
       * be accepting connections on it.  So, before sharing the socket
       * with another process, we call listen here in the parent process.
       */
  
      if (!(handle->flags & UV_HANDLE_LISTENING)) {
        if (!(handle->flags & UV_HANDLE_BOUND)) {
          return ERROR_INVALID_PARAMETER;
        }
  
        /* Report any deferred bind errors now. */
        if (handle->flags & UV_HANDLE_BIND_ERROR) {
          return handle->bind_error;
        }
  
        if (listen(handle->socket, SOMAXCONN) == SOCKET_ERROR) {
          return WSAGetLastError();
        }
      }
    }
  
    if (WSADuplicateSocketW(handle->socket, pid, protocol_info)) {
      return WSAGetLastError();
    }
  
    handle->flags |= UV_HANDLE_SHARED_TCP_SOCKET;
  
    return 0;
  }
  
  
  int uv_tcp_simultaneous_accepts(uv_tcp_t* handle, int enable) {
    if (handle->flags & UV_HANDLE_CONNECTION) {
      return UV_EINVAL;
    }
  
    /* Check if we're already in the desired mode. */
    if ((enable && !(handle->flags & UV_HANDLE_TCP_SINGLE_ACCEPT)) ||
        (!enable && handle->flags & UV_HANDLE_TCP_SINGLE_ACCEPT)) {
      return 0;
    }
  
    /* Don't allow switching from single pending accept to many. */
    if (enable) {
      return UV_ENOTSUP;
    }
  
    /* Check if we're in a middle of changing the number of pending accepts. */
    if (handle->flags & UV_HANDLE_TCP_ACCEPT_STATE_CHANGING) {
      return 0;
    }
  
    handle->flags |= UV_HANDLE_TCP_SINGLE_ACCEPT;
  
    /* Flip the changing flag if we have already queued multiple accepts. */
    if (handle->flags & UV_HANDLE_LISTENING) {
      handle->flags |= UV_HANDLE_TCP_ACCEPT_STATE_CHANGING;
    }
  
    return 0;
  }
  
  
  static int uv_tcp_try_cancel_io(uv_tcp_t* tcp) {
    SOCKET socket = tcp->socket;
    int non_ifs_lsp;
  
    /* Check if we have any non-IFS LSPs stacked on top of TCP */
    non_ifs_lsp = (tcp->flags & UV_HANDLE_IPV6) ? uv_tcp_non_ifs_lsp_ipv6 :
                                                  uv_tcp_non_ifs_lsp_ipv4;
  
    /* If there are non-ifs LSPs then try to obtain a base handle for the */
    /* socket. This will always fail on Windows XP/3k. */
    if (non_ifs_lsp) {
      DWORD bytes;
      if (WSAIoctl(socket,
                   SIO_BASE_HANDLE,
                   NULL,
                   0,
                   &socket,
                   sizeof socket,
                   &bytes,
                   NULL,
                   NULL) != 0) {
        /* Failed. We can't do CancelIo. */
        return -1;
      }
    }
  
    assert(socket != 0 && socket != INVALID_SOCKET);
  
    if (!CancelIo((HANDLE) socket)) {
      return GetLastError();
    }
  
    /* It worked. */
    return 0;
  }
  
  
  void uv_tcp_close(uv_loop_t* loop, uv_tcp_t* tcp) {
    int close_socket = 1;
  
    if (tcp->flags & UV_HANDLE_READ_PENDING) {
      /* In order for winsock to do a graceful close there must not be any */
      /* any pending reads, or the socket must be shut down for writing */
      if (!(tcp->flags & UV_HANDLE_SHARED_TCP_SOCKET)) {
        /* Just do shutdown on non-shared sockets, which ensures graceful close. */
        shutdown(tcp->socket, SD_SEND);
  
      } else if (uv_tcp_try_cancel_io(tcp) == 0) {
        /* In case of a shared socket, we try to cancel all outstanding I/O, */
        /* If that works, don't close the socket yet - wait for the read req to */
        /* return and close the socket in uv_tcp_endgame. */
        close_socket = 0;
  
      } else {
        /* When cancelling isn't possible - which could happen when an LSP is */
        /* present on an old Windows version, we will have to close the socket */
        /* with a read pending. That is not nice because trailing sent bytes */
        /* may not make it to the other side. */
      }
  
    } else if ((tcp->flags & UV_HANDLE_SHARED_TCP_SOCKET) &&
               tcp->accept_reqs != NULL) {
      /* Under normal circumstances closesocket() will ensure that all pending */
      /* accept reqs are canceled. However, when the socket is shared the */
      /* presence of another reference to the socket in another process will */
      /* keep the accept reqs going, so we have to ensure that these are */
      /* canceled. */
      if (uv_tcp_try_cancel_io(tcp) != 0) {
        /* When cancellation is not possible, there is another option: we can */
        /* close the incoming sockets, which will also cancel the accept */
        /* operations. However this is not cool because we might inadvertedly */
        /* close a socket that just accepted a new connection, which will */
        /* cause the connection to be aborted. */
        unsigned int i;
        for (i = 0; i < uv_simultaneous_server_accepts; i++) {
          uv_tcp_accept_t* req = &tcp->accept_reqs[i];
          if (req->accept_socket != INVALID_SOCKET &&
              !HasOverlappedIoCompleted(&req->overlapped)) {
            closesocket(req->accept_socket);
            req->accept_socket = INVALID_SOCKET;
          }
        }
      }
    }
  
    if (tcp->flags & UV_HANDLE_READING) {
      tcp->flags &= ~UV_HANDLE_READING;
      DECREASE_ACTIVE_COUNT(loop, tcp);
    }
  
    if (tcp->flags & UV_HANDLE_LISTENING) {
      tcp->flags &= ~UV_HANDLE_LISTENING;
      DECREASE_ACTIVE_COUNT(loop, tcp);
    }
  
    if (close_socket) {
      closesocket(tcp->socket);
      tcp->flags |= UV_HANDLE_TCP_SOCKET_CLOSED;
    }
  
    tcp->flags &= ~(UV_HANDLE_READABLE | UV_HANDLE_WRITABLE);
    uv__handle_closing(tcp);
  
    if (tcp->reqs_pending == 0) {
      uv_want_endgame(tcp->loop, (uv_handle_t*)tcp);
    }
  }
  
  
  int uv_tcp_open(uv_tcp_t* handle, uv_os_sock_t sock) {
    WSAPROTOCOL_INFOW protocol_info;
    int opt_len;
    int err;
  
    /* Detect the address family of the socket. */
    opt_len = (int) sizeof protocol_info;
    if (getsockopt(sock,
                   SOL_SOCKET,
                   SO_PROTOCOL_INFOW,
                   (char*) &protocol_info,
                   &opt_len) == SOCKET_ERROR) {
      return uv_translate_sys_error(GetLastError());
    }
  
    /* Make the socket non-inheritable */
    if (!SetHandleInformation((HANDLE) sock, HANDLE_FLAG_INHERIT, 0)) {
      return uv_translate_sys_error(GetLastError());
    }
  
    err = uv_tcp_set_socket(handle->loop,
                            handle,
                            sock,
                            protocol_info.iAddressFamily,
                            1);
    if (err) {
      return uv_translate_sys_error(err);
    }
  
    return 0;
  }
  
  
  /* This function is an egress point, i.e. it returns libuv errors rather than
   * system errors.
   */
  int uv__tcp_bind(uv_tcp_t* handle,
                   const struct sockaddr* addr,
                   unsigned int addrlen,
                   unsigned int flags) {
    int err;
  
    err = uv_tcp_try_bind(handle, addr, addrlen, flags);
    if (err)
      return uv_translate_sys_error(err);
  
    return 0;
  }
  
  
  /* This function is an egress point, i.e. it returns libuv errors rather than
   * system errors.
   */
  int uv__tcp_connect(uv_connect_t* req,
                      uv_tcp_t* handle,
                      const struct sockaddr* addr,
                      unsigned int addrlen,
                      uv_connect_cb cb) {
    int err;
  
    err = uv_tcp_try_connect(req, handle, addr, addrlen, cb);
    if (err)
      return uv_translate_sys_error(err);
  
    return 0;
  }
  