--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/win/udp.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,1162 @@
+/* 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"
+
+
+/* A zero-size buffer for use by uv_udp_read */
+static char uv_zero_[] = "";
+int uv_udp_getpeername(const uv_udp_t* handle,
+                       struct sockaddr* name,
+                       int* namelen) {
+
+  return uv__getsockpeername((const uv_handle_t*) handle,
+                             getpeername,
+                             name,
+                             namelen,
+                             0);
+}
+
+
+int uv_udp_getsockname(const uv_udp_t* handle,
+                       struct sockaddr* name,
+                       int* namelen) {
+
+  return uv__getsockpeername((const uv_handle_t*) handle,
+                             getsockname,
+                             name,
+                             namelen,
+                             0);
+}
+
+
+static int uv__udp_set_socket(uv_loop_t* loop, uv_udp_t* handle, SOCKET socket,
+    int family) {
+  DWORD yes = 1;
+  WSAPROTOCOL_INFOW info;
+  int opt_len;
+
+  if (handle->socket != INVALID_SOCKET)
+    return UV_EBUSY;
+
+  /* Set the socket to nonblocking mode */
+  if (ioctlsocket(socket, FIONBIO, &yes) == SOCKET_ERROR) {
+    return WSAGetLastError();
+  }
+
+  /* Make the socket non-inheritable */
+  if (!SetHandleInformation((HANDLE)socket, HANDLE_FLAG_INHERIT, 0)) {
+    return GetLastError();
+  }
+
+  /* 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) {
+    return GetLastError();
+  }
+
+  /* All known Windows that support SetFileCompletionNotificationModes have a
+   * bug that makes it impossible to use this function in conjunction with
+   * datagram sockets. We can work around that but only if the user is using
+   * the default UDP driver (AFD) and has no other. LSPs stacked on top. Here
+   * we check whether that is the case. */
+  opt_len = (int) sizeof info;
+  if (getsockopt(
+          socket, SOL_SOCKET, SO_PROTOCOL_INFOW, (char*) &info, &opt_len) ==
+      SOCKET_ERROR) {
+    return GetLastError();
+  }
+
+  if (info.ProtocolChain.ChainLen == 1) {
+    if (SetFileCompletionNotificationModes(
+            (HANDLE) socket,
+            FILE_SKIP_SET_EVENT_ON_HANDLE |
+                FILE_SKIP_COMPLETION_PORT_ON_SUCCESS)) {
+      handle->flags |= UV_HANDLE_SYNC_BYPASS_IOCP;
+      handle->func_wsarecv = uv__wsarecv_workaround;
+      handle->func_wsarecvfrom = uv__wsarecvfrom_workaround;
+    } else if (GetLastError() != ERROR_INVALID_FUNCTION) {
+      return GetLastError();
+    }
+  }
+
+  handle->socket = socket;
+
+  if (family == AF_INET6) {
+    handle->flags |= UV_HANDLE_IPV6;
+  } else {
+    assert(!(handle->flags & UV_HANDLE_IPV6));
+  }
+
+  return 0;
+}
+
+
+int uv__udp_init_ex(uv_loop_t* loop,
+                    uv_udp_t* handle,
+                    unsigned flags,
+                    int domain) {
+  uv__handle_init(loop, (uv_handle_t*) handle, UV_UDP);
+  handle->socket = INVALID_SOCKET;
+  handle->reqs_pending = 0;
+  handle->activecnt = 0;
+  handle->func_wsarecv = WSARecv;
+  handle->func_wsarecvfrom = WSARecvFrom;
+  handle->send_queue_size = 0;
+  handle->send_queue_count = 0;
+  UV_REQ_INIT(&handle->recv_req, UV_UDP_RECV);
+  handle->recv_req.data = handle;
+
+  /* If anything fails beyond this point we need to remove the handle from
+   * the handle queue, since it was added by uv__handle_init.
+   */
+
+  if (domain != AF_UNSPEC) {
+    SOCKET sock;
+    DWORD err;
+
+    sock = socket(domain, SOCK_DGRAM, 0);
+    if (sock == INVALID_SOCKET) {
+      err = WSAGetLastError();
+      uv__queue_remove(&handle->handle_queue);
+      return uv_translate_sys_error(err);
+    }
+
+    err = uv__udp_set_socket(handle->loop, handle, sock, domain);
+    if (err) {
+      closesocket(sock);
+      uv__queue_remove(&handle->handle_queue);
+      return uv_translate_sys_error(err);
+    }
+  }
+
+  return 0;
+}
+
+
+void uv__udp_close(uv_loop_t* loop, uv_udp_t* handle) {
+  uv_udp_recv_stop(handle);
+  closesocket(handle->socket);
+  handle->socket = INVALID_SOCKET;
+
+  uv__handle_closing(handle);
+
+  if (handle->reqs_pending == 0) {
+    uv__want_endgame(loop, (uv_handle_t*) handle);
+  }
+}
+
+
+void uv__udp_endgame(uv_loop_t* loop, uv_udp_t* handle) {
+  if (handle->flags & UV_HANDLE_CLOSING &&
+      handle->reqs_pending == 0) {
+    assert(!(handle->flags & UV_HANDLE_CLOSED));
+    uv__handle_close(handle);
+  }
+}
+
+
+int uv_udp_using_recvmmsg(const uv_udp_t* handle) {
+  return 0;
+}
+
+
+static int uv__udp_maybe_bind(uv_udp_t* handle,
+                              const struct sockaddr* addr,
+                              unsigned int addrlen,
+                              unsigned int flags) {
+  int r;
+  int err;
+  DWORD no = 0;
+
+  if (handle->flags & UV_HANDLE_BOUND)
+    return 0;
+
+  /* There is no SO_REUSEPORT on Windows, Windows only knows SO_REUSEADDR.
+   * so we just return an error directly when UV_UDP_REUSEPORT is requested
+   * for binding the socket. */
+  if (flags & UV_UDP_REUSEPORT)
+    return ERROR_NOT_SUPPORTED;
+
+  if ((flags & UV_UDP_IPV6ONLY) && addr->sa_family != AF_INET6) {
+    /* UV_UDP_IPV6ONLY is supported only for IPV6 sockets */
+    return ERROR_INVALID_PARAMETER;
+  }
+
+  if (handle->socket == INVALID_SOCKET) {
+    SOCKET sock = socket(addr->sa_family, SOCK_DGRAM, 0);
+    if (sock == INVALID_SOCKET) {
+      return WSAGetLastError();
+    }
+
+    err = uv__udp_set_socket(handle->loop, handle, sock, addr->sa_family);
+    if (err) {
+      closesocket(sock);
+      return err;
+    }
+  }
+
+  if (flags & UV_UDP_REUSEADDR) {
+    DWORD yes = 1;
+    /* Set SO_REUSEADDR on the socket. */
+    if (setsockopt(handle->socket,
+                   SOL_SOCKET,
+                   SO_REUSEADDR,
+                   (char*) &yes,
+                   sizeof yes) == SOCKET_ERROR) {
+      err = WSAGetLastError();
+      return err;
+    }
+  }
+
+  if (addr->sa_family == AF_INET6)
+    handle->flags |= UV_HANDLE_IPV6;
+
+  if (addr->sa_family == AF_INET6 && !(flags & UV_UDP_IPV6ONLY)) {
+    /* On windows IPV6ONLY is on by default. If the user doesn't specify it
+     * libuv turns it off. */
+
+    /* 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,
+               (char*) &no,
+               sizeof no);
+  }
+
+  r = bind(handle->socket, addr, addrlen);
+  if (r == SOCKET_ERROR) {
+    return WSAGetLastError();
+  }
+
+  handle->flags |= UV_HANDLE_BOUND;
+
+  return 0;
+}
+
+
+static void uv__udp_queue_recv(uv_loop_t* loop, uv_udp_t* handle) {
+  uv_req_t* req;
+  uv_buf_t buf;
+  DWORD bytes, flags;
+  int result;
+
+  assert(handle->flags & UV_HANDLE_READING);
+  assert(!(handle->flags & UV_HANDLE_READ_PENDING));
+
+  req = &handle->recv_req;
+  memset(&req->u.io.overlapped, 0, sizeof(req->u.io.overlapped));
+
+  handle->flags |= UV_HANDLE_ZERO_READ;
+
+  buf.base = (char*) uv_zero_;
+  buf.len = 0;
+  flags = MSG_PEEK;
+
+  result = handle->func_wsarecv(handle->socket,
+                                (WSABUF*) &buf,
+                                1,
+                                &bytes,
+                                &flags,
+                                &req->u.io.overlapped,
+                                NULL);
+
+  if (UV_SUCCEEDED_WITHOUT_IOCP(result == 0)) {
+    /* Process the req without IOCP. */
+    handle->flags |= UV_HANDLE_READ_PENDING;
+    req->u.io.overlapped.InternalHigh = bytes;
+    handle->reqs_pending++;
+    uv__insert_pending_req(loop, 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++;
+  } else {
+    /* Make this req pending reporting an error. */
+    SET_REQ_ERROR(req, WSAGetLastError());
+    uv__insert_pending_req(loop, req);
+    handle->reqs_pending++;
+  }
+}
+
+
+int uv__udp_recv_start(uv_udp_t* handle, uv_alloc_cb alloc_cb,
+    uv_udp_recv_cb recv_cb) {
+  uv_loop_t* loop = handle->loop;
+  int err;
+
+  if (handle->flags & UV_HANDLE_READING) {
+    return UV_EALREADY;
+  }
+
+  err = uv__udp_maybe_bind(handle,
+                           (const struct sockaddr*) &uv_addr_ip4_any_,
+                           sizeof(uv_addr_ip4_any_),
+                           0);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  handle->flags |= UV_HANDLE_READING;
+  INCREASE_ACTIVE_COUNT(loop, handle);
+
+  handle->recv_cb = recv_cb;
+  handle->alloc_cb = alloc_cb;
+
+  /* If reading was stopped and then started again, there could still be a recv
+   * request pending. */
+  if (!(handle->flags & UV_HANDLE_READ_PENDING))
+    uv__udp_queue_recv(loop, handle);
+
+  return 0;
+}
+
+
+int uv__udp_recv_stop(uv_udp_t* handle) {
+  if (handle->flags & UV_HANDLE_READING) {
+    handle->flags &= ~UV_HANDLE_READING;
+    DECREASE_ACTIVE_COUNT(loop, handle);
+  }
+
+  return 0;
+}
+
+
+static int uv__send(uv_udp_send_t* req,
+                    uv_udp_t* handle,
+                    const uv_buf_t bufs[],
+                    unsigned int nbufs,
+                    const struct sockaddr* addr,
+                    unsigned int addrlen,
+                    uv_udp_send_cb cb) {
+  uv_loop_t* loop = handle->loop;
+  DWORD result, bytes;
+
+  UV_REQ_INIT(req, UV_UDP_SEND);
+  req->handle = handle;
+  req->cb = cb;
+  memset(&req->u.io.overlapped, 0, sizeof(req->u.io.overlapped));
+
+  result = WSASendTo(handle->socket,
+                     (WSABUF*)bufs,
+                     nbufs,
+                     &bytes,
+                     0,
+                     addr,
+                     addrlen,
+                     &req->u.io.overlapped,
+                     NULL);
+
+  if (UV_SUCCEEDED_WITHOUT_IOCP(result == 0)) {
+    /* Request completed immediately. */
+    req->u.io.queued_bytes = 0;
+    handle->reqs_pending++;
+    handle->send_queue_size += req->u.io.queued_bytes;
+    handle->send_queue_count++;
+    REGISTER_HANDLE_REQ(loop, handle);
+    uv__insert_pending_req(loop, (uv_req_t*)req);
+  } else if (UV_SUCCEEDED_WITH_IOCP(result == 0)) {
+    /* Request queued by the kernel. */
+    req->u.io.queued_bytes = uv__count_bufs(bufs, nbufs);
+    handle->reqs_pending++;
+    handle->send_queue_size += req->u.io.queued_bytes;
+    handle->send_queue_count++;
+    REGISTER_HANDLE_REQ(loop, handle);
+  } else {
+    /* Send failed due to an error. */
+    return WSAGetLastError();
+  }
+
+  return 0;
+}
+
+
+void uv__process_udp_recv_req(uv_loop_t* loop, uv_udp_t* handle,
+    uv_req_t* req) {
+  uv_buf_t buf;
+  int partial;
+
+  assert(handle->type == UV_UDP);
+
+  handle->flags &= ~UV_HANDLE_READ_PENDING;
+
+  if (!REQ_SUCCESS(req)) {
+    DWORD err = GET_REQ_SOCK_ERROR(req);
+    if (err == WSAEMSGSIZE) {
+      /* Not a real error, it just indicates that the received packet was
+       * bigger than the receive buffer. */
+    } else if (err == WSAECONNRESET || err == WSAENETRESET) {
+      /* A previous sendto operation failed; ignore this error. If zero-reading
+       * we need to call WSARecv/WSARecvFrom _without_ the. MSG_PEEK flag to
+       * clear out the error queue. For nonzero reads, immediately queue a new
+       * receive. */
+      if (!(handle->flags & UV_HANDLE_ZERO_READ)) {
+        goto done;
+      }
+    } else {
+      /* A real error occurred. Report the error to the user only if we're
+       * currently reading. */
+      if (handle->flags & UV_HANDLE_READING) {
+        uv_udp_recv_stop(handle);
+        buf = (handle->flags & UV_HANDLE_ZERO_READ) ?
+              uv_buf_init(NULL, 0) : handle->recv_buffer;
+        handle->recv_cb(handle, uv_translate_sys_error(err), &buf, NULL, 0);
+      }
+      goto done;
+    }
+  }
+
+  if (!(handle->flags & UV_HANDLE_ZERO_READ)) {
+    /* Successful read */
+    partial = !REQ_SUCCESS(req);
+    handle->recv_cb(handle,
+                    req->u.io.overlapped.InternalHigh,
+                    &handle->recv_buffer,
+                    (const struct sockaddr*) &handle->recv_from,
+                    partial ? UV_UDP_PARTIAL : 0);
+  } else if (handle->flags & UV_HANDLE_READING) {
+    DWORD bytes, err, flags;
+    struct sockaddr_storage from;
+    int from_len;
+    int count;
+
+    /* Prevent loop starvation when the data comes in as fast as
+     * (or faster than) we can read it. */
+    count = 32;
+
+    do {
+      /* Do at most `count` nonblocking receive. */
+      buf = uv_buf_init(NULL, 0);
+      handle->alloc_cb((uv_handle_t*) handle, UV__UDP_DGRAM_MAXSIZE, &buf);
+      if (buf.base == NULL || buf.len == 0) {
+        handle->recv_cb(handle, UV_ENOBUFS, &buf, NULL, 0);
+        goto done;
+      }
+
+      memset(&from, 0, sizeof from);
+      from_len = sizeof from;
+
+      flags = 0;
+
+      if (WSARecvFrom(handle->socket,
+                      (WSABUF*)&buf,
+                      1,
+                      &bytes,
+                      &flags,
+                      (struct sockaddr*) &from,
+                      &from_len,
+                      NULL,
+                      NULL) != SOCKET_ERROR) {
+
+        /* Message received */
+        err = ERROR_SUCCESS;
+        handle->recv_cb(handle, bytes, &buf, (const struct sockaddr*) &from, 0);
+      } else {
+        err = WSAGetLastError();
+        if (err == WSAEMSGSIZE) {
+          /* Message truncated */
+          handle->recv_cb(handle,
+                          bytes,
+                          &buf,
+                          (const struct sockaddr*) &from,
+                          UV_UDP_PARTIAL);
+        } else if (err == WSAEWOULDBLOCK) {
+          /* Kernel buffer empty */
+          handle->recv_cb(handle, 0, &buf, NULL, 0);
+        } else if (err == WSAECONNRESET || err == WSAENETRESET) {
+          /* WSAECONNRESET/WSANETRESET is ignored because this just indicates
+           * that a previous sendto operation failed.
+           */
+          handle->recv_cb(handle, 0, &buf, NULL, 0);
+        } else {
+          /* Any other error that we want to report back to the user. */
+          uv_udp_recv_stop(handle);
+          handle->recv_cb(handle, uv_translate_sys_error(err), &buf, NULL, 0);
+        }
+      }
+    }
+    while (err == ERROR_SUCCESS &&
+           count-- > 0 &&
+           /* The recv_cb callback may decide to pause or close the handle. */
+           (handle->flags & UV_HANDLE_READING) &&
+           !(handle->flags & UV_HANDLE_READ_PENDING));
+  }
+
+done:
+  /* Post another read if still reading and not closing. */
+  if ((handle->flags & UV_HANDLE_READING) &&
+      !(handle->flags & UV_HANDLE_READ_PENDING)) {
+    uv__udp_queue_recv(loop, handle);
+  }
+
+  DECREASE_PENDING_REQ_COUNT(handle);
+}
+
+
+void uv__process_udp_send_req(uv_loop_t* loop, uv_udp_t* handle,
+    uv_udp_send_t* req) {
+  int err;
+
+  assert(handle->type == UV_UDP);
+
+  assert(handle->send_queue_size >= req->u.io.queued_bytes);
+  assert(handle->send_queue_count >= 1);
+  handle->send_queue_size -= req->u.io.queued_bytes;
+  handle->send_queue_count--;
+
+  UNREGISTER_HANDLE_REQ(loop, handle);
+
+  if (req->cb) {
+    err = 0;
+    if (!REQ_SUCCESS(req)) {
+      err = GET_REQ_SOCK_ERROR(req);
+    }
+    req->cb(req, uv_translate_sys_error(err));
+  }
+
+  DECREASE_PENDING_REQ_COUNT(handle);
+}
+
+
+static int uv__udp_set_membership4(uv_udp_t* handle,
+                                   const struct sockaddr_in* multicast_addr,
+                                   const char* interface_addr,
+                                   uv_membership membership) {
+  int err;
+  int optname;
+  struct ip_mreq mreq;
+
+  if (handle->flags & UV_HANDLE_IPV6)
+    return UV_EINVAL;
+
+  /* If the socket is unbound, bind to inaddr_any. */
+  err = uv__udp_maybe_bind(handle,
+                           (const struct sockaddr*) &uv_addr_ip4_any_,
+                           sizeof(uv_addr_ip4_any_),
+                           UV_UDP_REUSEADDR);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  memset(&mreq, 0, sizeof mreq);
+
+  if (interface_addr) {
+    err = uv_inet_pton(AF_INET, interface_addr, &mreq.imr_interface.s_addr);
+    if (err)
+      return err;
+  } else {
+    mreq.imr_interface.s_addr = htonl(INADDR_ANY);
+  }
+
+  mreq.imr_multiaddr.s_addr = multicast_addr->sin_addr.s_addr;
+
+  switch (membership) {
+    case UV_JOIN_GROUP:
+      optname = IP_ADD_MEMBERSHIP;
+      break;
+    case UV_LEAVE_GROUP:
+      optname = IP_DROP_MEMBERSHIP;
+      break;
+    default:
+      return UV_EINVAL;
+  }
+
+  if (setsockopt(handle->socket,
+                 IPPROTO_IP,
+                 optname,
+                 (char*) &mreq,
+                 sizeof mreq) == SOCKET_ERROR) {
+    return uv_translate_sys_error(WSAGetLastError());
+  }
+
+  return 0;
+}
+
+
+int uv__udp_set_membership6(uv_udp_t* handle,
+                            const struct sockaddr_in6* multicast_addr,
+                            const char* interface_addr,
+                            uv_membership membership) {
+  int optname;
+  int err;
+  struct ipv6_mreq mreq;
+  struct sockaddr_in6 addr6;
+
+  if ((handle->flags & UV_HANDLE_BOUND) && !(handle->flags & UV_HANDLE_IPV6))
+    return UV_EINVAL;
+
+  err = uv__udp_maybe_bind(handle,
+                           (const struct sockaddr*) &uv_addr_ip6_any_,
+                           sizeof(uv_addr_ip6_any_),
+                           UV_UDP_REUSEADDR);
+
+  if (err)
+    return uv_translate_sys_error(err);
+
+  memset(&mreq, 0, sizeof(mreq));
+
+  if (interface_addr) {
+    if (uv_ip6_addr(interface_addr, 0, &addr6))
+      return UV_EINVAL;
+    mreq.ipv6mr_interface = addr6.sin6_scope_id;
+  } else {
+    mreq.ipv6mr_interface = 0;
+  }
+
+  mreq.ipv6mr_multiaddr = multicast_addr->sin6_addr;
+
+  switch (membership) {
+  case UV_JOIN_GROUP:
+    optname = IPV6_ADD_MEMBERSHIP;
+    break;
+  case UV_LEAVE_GROUP:
+    optname = IPV6_DROP_MEMBERSHIP;
+    break;
+  default:
+    return UV_EINVAL;
+  }
+
+  if (setsockopt(handle->socket,
+                 IPPROTO_IPV6,
+                 optname,
+                 (char*) &mreq,
+                 sizeof mreq) == SOCKET_ERROR) {
+    return uv_translate_sys_error(WSAGetLastError());
+  }
+
+  return 0;
+}
+
+
+static int uv__udp_set_source_membership4(uv_udp_t* handle,
+                                          const struct sockaddr_in* multicast_addr,
+                                          const char* interface_addr,
+                                          const struct sockaddr_in* source_addr,
+                                          uv_membership membership) {
+  struct ip_mreq_source mreq;
+  int optname;
+  int err;
+
+  if (handle->flags & UV_HANDLE_IPV6)
+    return UV_EINVAL;
+
+  /* If the socket is unbound, bind to inaddr_any. */
+  err = uv__udp_maybe_bind(handle,
+                           (const struct sockaddr*) &uv_addr_ip4_any_,
+                           sizeof(uv_addr_ip4_any_),
+                           UV_UDP_REUSEADDR);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  memset(&mreq, 0, sizeof(mreq));
+
+  if (interface_addr != NULL) {
+    err = uv_inet_pton(AF_INET, interface_addr, &mreq.imr_interface.s_addr);
+    if (err)
+      return err;
+  } else {
+    mreq.imr_interface.s_addr = htonl(INADDR_ANY);
+  }
+
+  mreq.imr_multiaddr.s_addr = multicast_addr->sin_addr.s_addr;
+  mreq.imr_sourceaddr.s_addr = source_addr->sin_addr.s_addr;
+
+  if (membership == UV_JOIN_GROUP)
+    optname = IP_ADD_SOURCE_MEMBERSHIP;
+  else if (membership == UV_LEAVE_GROUP)
+    optname = IP_DROP_SOURCE_MEMBERSHIP;
+  else
+    return UV_EINVAL;
+
+  if (setsockopt(handle->socket,
+                 IPPROTO_IP,
+                 optname,
+                 (char*) &mreq,
+                 sizeof(mreq)) == SOCKET_ERROR) {
+    return uv_translate_sys_error(WSAGetLastError());
+  }
+
+  return 0;
+}
+
+
+int uv__udp_set_source_membership6(uv_udp_t* handle,
+                                   const struct sockaddr_in6* multicast_addr,
+                                   const char* interface_addr,
+                                   const struct sockaddr_in6* source_addr,
+                                   uv_membership membership) {
+  struct group_source_req mreq;
+  struct sockaddr_in6 addr6;
+  int optname;
+  int err;
+
+  STATIC_ASSERT(sizeof(mreq.gsr_group) >= sizeof(*multicast_addr));
+  STATIC_ASSERT(sizeof(mreq.gsr_source) >= sizeof(*source_addr));
+
+  if ((handle->flags & UV_HANDLE_BOUND) && !(handle->flags & UV_HANDLE_IPV6))
+    return UV_EINVAL;
+
+  err = uv__udp_maybe_bind(handle,
+                           (const struct sockaddr*) &uv_addr_ip6_any_,
+                           sizeof(uv_addr_ip6_any_),
+                           UV_UDP_REUSEADDR);
+
+  if (err)
+    return uv_translate_sys_error(err);
+
+  memset(&mreq, 0, sizeof(mreq));
+
+  if (interface_addr != NULL) {
+    err = uv_ip6_addr(interface_addr, 0, &addr6);
+    if (err)
+      return err;
+    mreq.gsr_interface = addr6.sin6_scope_id;
+  } else {
+    mreq.gsr_interface = 0;
+  }
+
+  memcpy(&mreq.gsr_group, multicast_addr, sizeof(*multicast_addr));
+  memcpy(&mreq.gsr_source, source_addr, sizeof(*source_addr));
+
+  if (membership == UV_JOIN_GROUP)
+    optname = MCAST_JOIN_SOURCE_GROUP;
+  else if (membership == UV_LEAVE_GROUP)
+    optname = MCAST_LEAVE_SOURCE_GROUP;
+  else
+    return UV_EINVAL;
+
+  if (setsockopt(handle->socket,
+                 IPPROTO_IPV6,
+                 optname,
+                 (char*) &mreq,
+                 sizeof(mreq)) == SOCKET_ERROR) {
+    return uv_translate_sys_error(WSAGetLastError());
+  }
+
+  return 0;
+}
+
+
+int uv_udp_set_membership(uv_udp_t* handle,
+                          const char* multicast_addr,
+                          const char* interface_addr,
+                          uv_membership membership) {
+  struct sockaddr_in addr4;
+  struct sockaddr_in6 addr6;
+
+  if (uv_ip4_addr(multicast_addr, 0, &addr4) == 0)
+    return uv__udp_set_membership4(handle, &addr4, interface_addr, membership);
+  else if (uv_ip6_addr(multicast_addr, 0, &addr6) == 0)
+    return uv__udp_set_membership6(handle, &addr6, interface_addr, membership);
+  else
+    return UV_EINVAL;
+}
+
+
+int uv_udp_set_source_membership(uv_udp_t* handle,
+                                 const char* multicast_addr,
+                                 const char* interface_addr,
+                                 const char* source_addr,
+                                 uv_membership membership) {
+  int err;
+  struct sockaddr_storage mcast_addr;
+  struct sockaddr_in* mcast_addr4;
+  struct sockaddr_in6* mcast_addr6;
+  struct sockaddr_storage src_addr;
+  struct sockaddr_in* src_addr4;
+  struct sockaddr_in6* src_addr6;
+
+  mcast_addr4 = (struct sockaddr_in*)&mcast_addr;
+  mcast_addr6 = (struct sockaddr_in6*)&mcast_addr;
+  src_addr4 = (struct sockaddr_in*)&src_addr;
+  src_addr6 = (struct sockaddr_in6*)&src_addr;
+
+  err = uv_ip4_addr(multicast_addr, 0, mcast_addr4);
+  if (err) {
+    err = uv_ip6_addr(multicast_addr, 0, mcast_addr6);
+    if (err)
+      return err;
+    err = uv_ip6_addr(source_addr, 0, src_addr6);
+    if (err)
+      return err;
+    return uv__udp_set_source_membership6(handle,
+                                          mcast_addr6,
+                                          interface_addr,
+                                          src_addr6,
+                                          membership);
+  }
+  
+  err = uv_ip4_addr(source_addr, 0, src_addr4);
+  if (err)
+    return err;
+  return uv__udp_set_source_membership4(handle,
+                                        mcast_addr4,
+                                        interface_addr,
+                                        src_addr4,
+                                        membership);
+}
+
+
+int uv_udp_set_multicast_interface(uv_udp_t* handle, const char* interface_addr) {
+  struct sockaddr_storage addr_st;
+  struct sockaddr_in* addr4;
+  struct sockaddr_in6* addr6;
+
+  addr4 = (struct sockaddr_in*) &addr_st;
+  addr6 = (struct sockaddr_in6*) &addr_st;
+
+  if (!interface_addr) {
+    memset(&addr_st, 0, sizeof addr_st);
+    if (handle->flags & UV_HANDLE_IPV6) {
+      addr_st.ss_family = AF_INET6;
+      addr6->sin6_scope_id = 0;
+    } else {
+      addr_st.ss_family = AF_INET;
+      addr4->sin_addr.s_addr = htonl(INADDR_ANY);
+    }
+  } else if (uv_ip4_addr(interface_addr, 0, addr4) == 0) {
+    /* nothing, address was parsed */
+  } else if (uv_ip6_addr(interface_addr, 0, addr6) == 0) {
+    /* nothing, address was parsed */
+  } else {
+    return UV_EINVAL;
+  }
+
+  if (handle->socket == INVALID_SOCKET)
+    return UV_EBADF;
+
+  if (addr_st.ss_family == AF_INET) {
+    if (setsockopt(handle->socket,
+                   IPPROTO_IP,
+                   IP_MULTICAST_IF,
+                   (char*) &addr4->sin_addr,
+                   sizeof(addr4->sin_addr)) == SOCKET_ERROR) {
+      return uv_translate_sys_error(WSAGetLastError());
+    }
+  } else if (addr_st.ss_family == AF_INET6) {
+    if (setsockopt(handle->socket,
+                   IPPROTO_IPV6,
+                   IPV6_MULTICAST_IF,
+                   (char*) &addr6->sin6_scope_id,
+                   sizeof(addr6->sin6_scope_id)) == SOCKET_ERROR) {
+      return uv_translate_sys_error(WSAGetLastError());
+    }
+  } else {
+    assert(0 && "unexpected address family");
+    abort();
+  }
+
+  return 0;
+}
+
+
+int uv_udp_set_broadcast(uv_udp_t* handle, int value) {
+  BOOL optval = (BOOL) value;
+
+  if (handle->socket == INVALID_SOCKET)
+    return UV_EBADF;
+
+  if (setsockopt(handle->socket,
+                 SOL_SOCKET,
+                 SO_BROADCAST,
+                 (char*) &optval,
+                 sizeof optval)) {
+    return uv_translate_sys_error(WSAGetLastError());
+  }
+
+  return 0;
+}
+
+
+int uv__udp_is_bound(uv_udp_t* handle) {
+  struct sockaddr_storage addr;
+  int addrlen;
+
+  addrlen = sizeof(addr);
+  if (uv_udp_getsockname(handle, (struct sockaddr*) &addr, &addrlen) != 0)
+    return 0;
+
+  return addrlen > 0;
+}
+
+
+int uv_udp_open(uv_udp_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());
+  }
+
+  err = uv__udp_set_socket(handle->loop,
+                           handle,
+                           sock,
+                           protocol_info.iAddressFamily);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  if (uv__udp_is_bound(handle))
+    handle->flags |= UV_HANDLE_BOUND;
+
+  if (uv__udp_is_connected(handle))
+    handle->flags |= UV_HANDLE_UDP_CONNECTED;
+
+  return 0;
+}
+
+
+#define SOCKOPT_SETTER(name, option4, option6, validate)                      \
+  int uv_udp_set_##name(uv_udp_t* handle, int value) {                        \
+    DWORD optval = (DWORD) value;                                             \
+                                                                              \
+    if (!(validate(value))) {                                                 \
+      return UV_EINVAL;                                                       \
+    }                                                                         \
+                                                                              \
+    if (handle->socket == INVALID_SOCKET)                                     \
+      return UV_EBADF;                                                        \
+                                                                              \
+    if (!(handle->flags & UV_HANDLE_IPV6)) {                                  \
+      /* Set IPv4 socket option */                                            \
+      if (setsockopt(handle->socket,                                          \
+                     IPPROTO_IP,                                              \
+                     option4,                                                 \
+                     (char*) &optval,                                         \
+                     sizeof optval)) {                                        \
+        return uv_translate_sys_error(WSAGetLastError());                     \
+      }                                                                       \
+    } else {                                                                  \
+      /* Set IPv6 socket option */                                            \
+      if (setsockopt(handle->socket,                                          \
+                     IPPROTO_IPV6,                                            \
+                     option6,                                                 \
+                     (char*) &optval,                                         \
+                     sizeof optval)) {                                        \
+        return uv_translate_sys_error(WSAGetLastError());                     \
+      }                                                                       \
+    }                                                                         \
+    return 0;                                                                 \
+  }
+
+#define VALIDATE_TTL(value) ((value) >= 1 && (value) <= 255)
+#define VALIDATE_MULTICAST_TTL(value) ((value) >= -1 && (value) <= 255)
+#define VALIDATE_MULTICAST_LOOP(value) (1)
+
+SOCKOPT_SETTER(ttl,
+               IP_TTL,
+               IPV6_HOPLIMIT,
+               VALIDATE_TTL)
+SOCKOPT_SETTER(multicast_ttl,
+               IP_MULTICAST_TTL,
+               IPV6_MULTICAST_HOPS,
+               VALIDATE_MULTICAST_TTL)
+SOCKOPT_SETTER(multicast_loop,
+               IP_MULTICAST_LOOP,
+               IPV6_MULTICAST_LOOP,
+               VALIDATE_MULTICAST_LOOP)
+
+#undef SOCKOPT_SETTER
+#undef VALIDATE_TTL
+#undef VALIDATE_MULTICAST_TTL
+#undef VALIDATE_MULTICAST_LOOP
+
+
+/* This function is an egress point, i.e. it returns libuv errors rather than
+ * system errors.
+ */
+int uv__udp_bind(uv_udp_t* handle,
+                 const struct sockaddr* addr,
+                 unsigned int addrlen,
+                 unsigned int flags) {
+  int err;
+
+  err = uv__udp_maybe_bind(handle, addr, addrlen, flags);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  return 0;
+}
+
+
+int uv__udp_connect(uv_udp_t* handle,
+                    const struct sockaddr* addr,
+                    unsigned int addrlen) {
+  const struct sockaddr* bind_addr;
+  int err;
+
+  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
+      return UV_EINVAL;
+
+    err = uv__udp_maybe_bind(handle, bind_addr, addrlen, 0);
+    if (err)
+      return uv_translate_sys_error(err);
+  }
+
+  err = connect(handle->socket, addr, addrlen);
+  if (err)
+    return uv_translate_sys_error(WSAGetLastError());
+
+  handle->flags |= UV_HANDLE_UDP_CONNECTED;
+
+  return 0;
+}
+
+
+int uv__udp_disconnect(uv_udp_t* handle) {
+    int err;
+    struct sockaddr_storage addr;
+
+    memset(&addr, 0, sizeof(addr));
+
+    err = connect(handle->socket, (struct sockaddr*) &addr, sizeof(addr));
+    if (err)
+      return uv_translate_sys_error(WSAGetLastError());
+
+    handle->flags &= ~UV_HANDLE_UDP_CONNECTED;
+    return 0;
+}
+
+
+/* This function is an egress point, i.e. it returns libuv errors rather than
+ * system errors.
+ */
+int uv__udp_send(uv_udp_send_t* req,
+                 uv_udp_t* handle,
+                 const uv_buf_t bufs[],
+                 unsigned int nbufs,
+                 const struct sockaddr* addr,
+                 unsigned int addrlen,
+                 uv_udp_send_cb send_cb) {
+  const struct sockaddr* bind_addr;
+  int err;
+
+  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
+      return UV_EINVAL;
+
+    err = uv__udp_maybe_bind(handle, bind_addr, addrlen, 0);
+    if (err)
+      return uv_translate_sys_error(err);
+  }
+
+  err = uv__send(req, handle, bufs, nbufs, addr, addrlen, send_cb);
+  if (err)
+    return uv_translate_sys_error(err);
+
+  return 0;
+}
+
+
+int uv__udp_try_send(uv_udp_t* handle,
+                     const uv_buf_t bufs[],
+                     unsigned int nbufs,
+                     const struct sockaddr* addr,
+                     unsigned int addrlen) {
+  DWORD bytes;
+  const struct sockaddr* bind_addr;
+  struct sockaddr_storage converted;
+  int err;
+
+  if (nbufs < 1)
+    return UV_EINVAL;
+
+  if (addr != NULL) {
+    err = uv__convert_to_localhost_if_unspecified(addr, &converted);
+    if (err)
+      return err;
+    addr = (const struct sockaddr*) &converted;
+  }
+
+  /* Already sending a message.*/
+  if (handle->send_queue_count != 0)
+    return UV_EAGAIN;
+
+  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
+      return UV_EINVAL;
+    err = uv__udp_maybe_bind(handle, bind_addr, addrlen, 0);
+    if (err)
+      return uv_translate_sys_error(err);
+  }
+
+  err = WSASendTo(handle->socket,
+                  (WSABUF*)bufs,
+                  nbufs,
+                  &bytes,
+                  0,
+                  addr,
+                  addrlen,
+                  NULL,
+                  NULL);
+
+  if (err)
+    return uv_translate_sys_error(WSAGetLastError());
+
+  return bytes;
+}
+
+
+int uv__udp_try_send2(uv_udp_t* handle,
+                      unsigned int count,
+                      uv_buf_t* bufs[/*count*/],
+                      unsigned int nbufs[/*count*/],
+                      struct sockaddr* addrs[/*count*/]) {
+  unsigned int i;
+  int r;
+
+  for (i = 0; i < count; i++) {
+    r = uv_udp_try_send(handle, bufs[i], nbufs[i], addrs[i]);
+    if (r < 0)
+      return i > 0 ? i : r;  /* Error if first packet, else send count. */
+  }
+
+  return i;
+}