--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/unix/udp.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,1434 @@
+/* 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 "uv.h"
+#include "internal.h"
+
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#if defined(__MVS__)
+#include <xti.h>
+#endif
+#include <sys/un.h>
+
+#if defined(IPV6_JOIN_GROUP) && !defined(IPV6_ADD_MEMBERSHIP)
+# define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
+#endif
+
+#if defined(IPV6_LEAVE_GROUP) && !defined(IPV6_DROP_MEMBERSHIP)
+# define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
+#endif
+
+static void uv__udp_run_completed(uv_udp_t* handle);
+static void uv__udp_io(uv_loop_t* loop, uv__io_t* w, unsigned int revents);
+static void uv__udp_recvmsg(uv_udp_t* handle);
+static void uv__udp_sendmsg(uv_udp_t* handle);
+static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
+                                       int domain,
+                                       unsigned int flags);
+static int uv__udp_sendmsg1(int fd,
+                            const uv_buf_t* bufs,
+                            unsigned int nbufs,
+                            const struct sockaddr* addr);
+
+
+void uv__udp_close(uv_udp_t* handle) {
+  uv__io_close(handle->loop, &handle->io_watcher);
+  uv__handle_stop(handle);
+
+  if (handle->io_watcher.fd != -1) {
+    uv__close(handle->io_watcher.fd);
+    handle->io_watcher.fd = -1;
+  }
+}
+
+
+void uv__udp_finish_close(uv_udp_t* handle) {
+  uv_udp_send_t* req;
+  struct uv__queue* q;
+
+  assert(!uv__io_active(&handle->io_watcher, POLLIN | POLLOUT));
+  assert(handle->io_watcher.fd == -1);
+
+  while (!uv__queue_empty(&handle->write_queue)) {
+    q = uv__queue_head(&handle->write_queue);
+    uv__queue_remove(q);
+
+    req = uv__queue_data(q, uv_udp_send_t, queue);
+    req->status = UV_ECANCELED;
+    uv__queue_insert_tail(&handle->write_completed_queue, &req->queue);
+  }
+
+  uv__udp_run_completed(handle);
+
+  assert(handle->send_queue_size == 0);
+  assert(handle->send_queue_count == 0);
+
+  /* Now tear down the handle. */
+  handle->recv_cb = NULL;
+  handle->alloc_cb = NULL;
+  /* but _do not_ touch close_cb */
+}
+
+
+static void uv__udp_run_completed(uv_udp_t* handle) {
+  uv_udp_send_t* req;
+  struct uv__queue* q;
+
+  assert(!(handle->flags & UV_HANDLE_UDP_PROCESSING));
+  handle->flags |= UV_HANDLE_UDP_PROCESSING;
+
+  while (!uv__queue_empty(&handle->write_completed_queue)) {
+    q = uv__queue_head(&handle->write_completed_queue);
+    uv__queue_remove(q);
+
+    req = uv__queue_data(q, uv_udp_send_t, queue);
+    uv__req_unregister(handle->loop);
+
+    handle->send_queue_size -= uv__count_bufs(req->bufs, req->nbufs);
+    handle->send_queue_count--;
+
+    if (req->bufs != req->bufsml)
+      uv__free(req->bufs);
+    req->bufs = NULL;
+
+    if (req->send_cb == NULL)
+      continue;
+
+    /* req->status >= 0 == bytes written
+     * req->status <  0 == errno
+     */
+    if (req->status >= 0)
+      req->send_cb(req, 0);
+    else
+      req->send_cb(req, req->status);
+  }
+
+  if (uv__queue_empty(&handle->write_queue)) {
+    /* Pending queue and completion queue empty, stop watcher. */
+    uv__io_stop(handle->loop, &handle->io_watcher, POLLOUT);
+    if (!uv__io_active(&handle->io_watcher, POLLIN))
+      uv__handle_stop(handle);
+  }
+
+  handle->flags &= ~UV_HANDLE_UDP_PROCESSING;
+}
+
+
+static void uv__udp_io(uv_loop_t* loop, uv__io_t* w, unsigned int revents) {
+  uv_udp_t* handle;
+
+  handle = container_of(w, uv_udp_t, io_watcher);
+  assert(handle->type == UV_UDP);
+
+  if (revents & POLLIN)
+    uv__udp_recvmsg(handle);
+
+  if (revents & POLLOUT && !uv__is_closing(handle)) {
+    uv__udp_sendmsg(handle);
+    uv__udp_run_completed(handle);
+  }
+}
+
+static int uv__udp_recvmmsg(uv_udp_t* handle, uv_buf_t* buf) {
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__)
+  struct sockaddr_in6 peers[20];
+  struct iovec iov[ARRAY_SIZE(peers)];
+  struct mmsghdr msgs[ARRAY_SIZE(peers)];
+  ssize_t nread;
+  uv_buf_t chunk_buf;
+  size_t chunks;
+  int flags;
+  size_t k;
+
+  /* prepare structures for recvmmsg */
+  chunks = buf->len / UV__UDP_DGRAM_MAXSIZE;
+  if (chunks > ARRAY_SIZE(iov))
+    chunks = ARRAY_SIZE(iov);
+  for (k = 0; k < chunks; ++k) {
+    iov[k].iov_base = buf->base + k * UV__UDP_DGRAM_MAXSIZE;
+    iov[k].iov_len = UV__UDP_DGRAM_MAXSIZE;
+    memset(&msgs[k].msg_hdr, 0, sizeof(msgs[k].msg_hdr));
+    msgs[k].msg_hdr.msg_iov = iov + k;
+    msgs[k].msg_hdr.msg_iovlen = 1;
+    msgs[k].msg_hdr.msg_name = peers + k;
+    msgs[k].msg_hdr.msg_namelen = sizeof(peers[0]);
+    msgs[k].msg_hdr.msg_control = NULL;
+    msgs[k].msg_hdr.msg_controllen = 0;
+    msgs[k].msg_hdr.msg_flags = 0;
+    msgs[k].msg_len = 0;
+  }
+
+#if defined(__APPLE__)
+  do
+    nread = recvmsg_x(handle->io_watcher.fd, msgs, chunks, MSG_DONTWAIT);
+  while (nread == -1 && errno == EINTR);
+#else
+  do
+    nread = recvmmsg(handle->io_watcher.fd, msgs, chunks, 0, NULL);
+  while (nread == -1 && errno == EINTR);
+#endif
+
+  if (nread < 1) {
+    if (nread == 0 || errno == EAGAIN || errno == EWOULDBLOCK)
+      handle->recv_cb(handle, 0, buf, NULL, 0);
+    else
+      handle->recv_cb(handle, UV__ERR(errno), buf, NULL, 0);
+  } else {
+    /* pass each chunk to the application */
+    for (k = 0; k < (size_t) nread && handle->recv_cb != NULL; k++) {
+      flags = UV_UDP_MMSG_CHUNK;
+      if (msgs[k].msg_hdr.msg_flags & MSG_TRUNC)
+        flags |= UV_UDP_PARTIAL;
+
+      chunk_buf = uv_buf_init(iov[k].iov_base, iov[k].iov_len);
+      handle->recv_cb(handle,
+                      msgs[k].msg_len,
+                      &chunk_buf,
+                      msgs[k].msg_hdr.msg_name,
+                      flags);
+    }
+
+    /* one last callback so the original buffer is freed */
+    if (handle->recv_cb != NULL)
+      handle->recv_cb(handle, 0, buf, NULL, UV_UDP_MMSG_FREE);
+  }
+  return nread;
+#else  /* __linux__ || ____FreeBSD__ || __APPLE__ */
+  return UV_ENOSYS;
+#endif  /* __linux__ || ____FreeBSD__ || __APPLE__ */
+}
+
+static void uv__udp_recvmsg(uv_udp_t* handle) {
+  struct sockaddr_storage peer;
+  struct msghdr h;
+  ssize_t nread;
+  uv_buf_t buf;
+  int flags;
+  int count;
+
+  assert(handle->recv_cb != NULL);
+  assert(handle->alloc_cb != NULL);
+
+  /* Prevent loop starvation when the data comes in as fast as (or faster than)
+   * we can read it. XXX Need to rearm fd if we switch to edge-triggered I/O.
+   */
+  count = 32;
+
+  do {
+    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);
+      return;
+    }
+    assert(buf.base != NULL);
+
+    if (uv_udp_using_recvmmsg(handle)) {
+      nread = uv__udp_recvmmsg(handle, &buf);
+      if (nread > 0)
+        count -= nread;
+      continue;
+    }
+
+    memset(&h, 0, sizeof(h));
+    memset(&peer, 0, sizeof(peer));
+    h.msg_name = &peer;
+    h.msg_namelen = sizeof(peer);
+    h.msg_iov = (void*) &buf;
+    h.msg_iovlen = 1;
+
+    do {
+      nread = recvmsg(handle->io_watcher.fd, &h, 0);
+    }
+    while (nread == -1 && errno == EINTR);
+
+    if (nread == -1) {
+      if (errno == EAGAIN || errno == EWOULDBLOCK)
+        handle->recv_cb(handle, 0, &buf, NULL, 0);
+      else
+        handle->recv_cb(handle, UV__ERR(errno), &buf, NULL, 0);
+    }
+    else {
+      flags = 0;
+      if (h.msg_flags & MSG_TRUNC)
+        flags |= UV_UDP_PARTIAL;
+
+      handle->recv_cb(handle, nread, &buf, (const struct sockaddr*) &peer, flags);
+    }
+    count--;
+  }
+  /* recv_cb callback may decide to pause or close the handle */
+  while (nread != -1
+      && count > 0
+      && handle->io_watcher.fd != -1
+      && handle->recv_cb != NULL);
+}
+
+
+/* On the BSDs, SO_REUSEPORT implies SO_REUSEADDR but with some additional
+ * refinements for programs that use multicast. Therefore we preferentially
+ * set SO_REUSEPORT over SO_REUSEADDR here, but we set SO_REUSEPORT only
+ * when that socket option doesn't have the capability of load balancing.
+ * Otherwise, we fall back to SO_REUSEADDR.
+ *
+ * Linux as of 3.9, DragonflyBSD 3.6, AIX 7.2.5 have the SO_REUSEPORT socket
+ * option but with semantics that are different from the BSDs: it _shares_
+ * the port rather than steals it from the current listener. While useful,
+ * it's not something we can emulate on other platforms so we don't enable it.
+ *
+ * zOS does not support getsockname with SO_REUSEPORT option when using
+ * AF_UNIX.
+ *
+ * Solaris 11.4: SO_REUSEPORT will not load balance when SO_REUSEADDR
+ * is also set, but it's not valid for every socket type.
+ */
+static int uv__sock_reuseaddr(int fd) {
+  int yes;
+  yes = 1;
+
+#if defined(SO_REUSEPORT) && defined(__MVS__)
+  struct sockaddr_in sockfd;
+  unsigned int sockfd_len = sizeof(sockfd);
+  if (getsockname(fd, (struct sockaddr*) &sockfd, &sockfd_len) == -1)
+      return UV__ERR(errno);
+  if (sockfd.sin_family == AF_UNIX) {
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)))
+      return UV__ERR(errno);
+  } else {
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes)))
+       return UV__ERR(errno);
+  }
+#elif defined(SO_REUSEPORT) && defined(UV__SOLARIS_11_4) && UV__SOLARIS_11_4
+  if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes))) {
+    if (errno != ENOPROTOOPT)
+      return UV__ERR(errno);
+    /* Not all socket types accept SO_REUSEPORT. */
+    errno = 0;
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)))
+      return UV__ERR(errno);
+  }
+#elif defined(SO_REUSEPORT) && \
+  !defined(__linux__) && !defined(__GNU__) && \
+  !defined(__illumos__) && !defined(__DragonFly__) && !defined(_AIX73)
+  if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes)))
+    return UV__ERR(errno);
+#else
+  if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)))
+    return UV__ERR(errno);
+#endif
+
+  return 0;
+}
+
+/*
+ * The Linux kernel suppresses some ICMP error messages by default for UDP
+ * sockets. Setting IP_RECVERR/IPV6_RECVERR on the socket enables full ICMP
+ * error reporting, hopefully resulting in faster failover to working name
+ * servers.
+ */
+static int uv__set_recverr(int fd, sa_family_t ss_family) {
+#if defined(__linux__)
+  int yes;
+
+  yes = 1;
+  if (ss_family == AF_INET) {
+    if (setsockopt(fd, IPPROTO_IP, IP_RECVERR, &yes, sizeof(yes)))
+      return UV__ERR(errno);
+  } else if (ss_family == AF_INET6) {
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVERR, &yes, sizeof(yes)))
+       return UV__ERR(errno);
+  }
+#endif
+  return 0;
+}
+
+
+int uv__udp_bind(uv_udp_t* handle,
+                 const struct sockaddr* addr,
+                 unsigned int addrlen,
+                 unsigned int flags) {
+  int err;
+  int yes;
+  int fd;
+
+  /* Check for bad flags. */
+  if (flags & ~(UV_UDP_IPV6ONLY | UV_UDP_REUSEADDR |
+                UV_UDP_REUSEPORT | UV_UDP_LINUX_RECVERR))
+    return UV_EINVAL;
+
+  /* Cannot set IPv6-only mode on non-IPv6 socket. */
+  if ((flags & UV_UDP_IPV6ONLY) && addr->sa_family != AF_INET6)
+    return UV_EINVAL;
+
+  fd = handle->io_watcher.fd;
+  if (fd == -1) {
+    err = uv__socket(addr->sa_family, SOCK_DGRAM, 0);
+    if (err < 0)
+      return err;
+    fd = err;
+    handle->io_watcher.fd = fd;
+  }
+
+  if (flags & UV_UDP_LINUX_RECVERR) {
+    err = uv__set_recverr(fd, addr->sa_family);
+    if (err)
+      return err;
+  }
+
+  if (flags & UV_UDP_REUSEADDR) {
+    err = uv__sock_reuseaddr(fd);
+    if (err)
+      return err;
+  }
+
+  if (flags & UV_UDP_REUSEPORT) {
+    err = uv__sock_reuseport(fd);
+    if (err)
+      return err;
+  }
+
+  if (flags & UV_UDP_IPV6ONLY) {
+#ifdef IPV6_V6ONLY
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &yes, sizeof yes) == -1) {
+      err = UV__ERR(errno);
+      return err;
+    }
+#else
+    err = UV_ENOTSUP;
+    return err;
+#endif
+  }
+
+  if (bind(fd, addr, addrlen)) {
+    err = UV__ERR(errno);
+    if (errno == EAFNOSUPPORT)
+      /* OSX, other BSDs and SunoS fail with EAFNOSUPPORT when binding a
+       * socket created with AF_INET to an AF_INET6 address or vice versa. */
+      err = UV_EINVAL;
+    return err;
+  }
+
+  if (addr->sa_family == AF_INET6)
+    handle->flags |= UV_HANDLE_IPV6;
+
+  handle->flags |= UV_HANDLE_BOUND;
+  return 0;
+}
+
+
+static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
+                                       int domain,
+                                       unsigned int flags) {
+  union uv__sockaddr taddr;
+  socklen_t addrlen;
+
+  if (handle->io_watcher.fd != -1)
+    return 0;
+
+  switch (domain) {
+  case AF_INET:
+  {
+    struct sockaddr_in* addr = &taddr.in;
+    memset(addr, 0, sizeof *addr);
+    addr->sin_family = AF_INET;
+    addr->sin_addr.s_addr = INADDR_ANY;
+    addrlen = sizeof *addr;
+    break;
+  }
+  case AF_INET6:
+  {
+    struct sockaddr_in6* addr = &taddr.in6;
+    memset(addr, 0, sizeof *addr);
+    addr->sin6_family = AF_INET6;
+    addr->sin6_addr = in6addr_any;
+    addrlen = sizeof *addr;
+    break;
+  }
+  default:
+    assert(0 && "unsupported address family");
+    abort();
+  }
+
+  return uv__udp_bind(handle, &taddr.addr, addrlen, flags);
+}
+
+
+int uv__udp_connect(uv_udp_t* handle,
+                    const struct sockaddr* addr,
+                    unsigned int addrlen) {
+  int err;
+
+  err = uv__udp_maybe_deferred_bind(handle, addr->sa_family, 0);
+  if (err)
+    return err;
+
+  do {
+    errno = 0;
+    err = connect(handle->io_watcher.fd, addr, addrlen);
+  } while (err == -1 && errno == EINTR);
+
+  if (err)
+    return UV__ERR(errno);
+
+  handle->flags |= UV_HANDLE_UDP_CONNECTED;
+
+  return 0;
+}
+
+/* From https://pubs.opengroup.org/onlinepubs/9699919799/functions/connect.html
+ * Any of uv supported UNIXs kernel should be standardized, but the kernel
+ * implementation logic not same, let's use pseudocode to explain the udp
+ * disconnect behaviors:
+ *
+ * Predefined stubs for pseudocode:
+ *   1. sodisconnect: The function to perform the real udp disconnect
+ *   2. pru_connect: The function to perform the real udp connect
+ *   3. so: The kernel object match with socket fd
+ *   4. addr: The sockaddr parameter from user space
+ *
+ * BSDs:
+ *   if(sodisconnect(so) == 0) { // udp disconnect succeed
+ *     if (addr->sa_len != so->addr->sa_len) return EINVAL;
+ *     if (addr->sa_family != so->addr->sa_family) return EAFNOSUPPORT;
+ *     pru_connect(so);
+ *   }
+ *   else return EISCONN;
+ *
+ * z/OS (same with Windows):
+ *   if(addr->sa_len < so->addr->sa_len) return EINVAL;
+ *   if (addr->sa_family == AF_UNSPEC) sodisconnect(so);
+ *
+ * AIX:
+ *   if(addr->sa_len != sizeof(struct sockaddr)) return EINVAL; // ignore ip proto version
+ *   if (addr->sa_family == AF_UNSPEC) sodisconnect(so);
+ *
+ * Linux,Others:
+ *   if(addr->sa_len < sizeof(struct sockaddr)) return EINVAL;
+ *   if (addr->sa_family == AF_UNSPEC) sodisconnect(so);
+ */
+int uv__udp_disconnect(uv_udp_t* handle) {
+    int r;
+#if defined(__MVS__)
+    struct sockaddr_storage addr;
+#else
+    struct sockaddr addr;
+#endif
+
+    memset(&addr, 0, sizeof(addr));
+
+#if defined(__MVS__)
+    addr.ss_family = AF_UNSPEC;
+#else
+    addr.sa_family = AF_UNSPEC;
+#endif
+
+    do {
+      errno = 0;
+#ifdef __PASE__
+      /* On IBMi a connectionless transport socket can be disconnected by
+       * either setting the addr parameter to NULL or setting the
+       * addr_length parameter to zero, and issuing another connect().
+       * https://www.ibm.com/docs/en/i/7.4?topic=ssw_ibm_i_74/apis/connec.htm
+       */
+      r = connect(handle->io_watcher.fd, (struct sockaddr*) NULL, 0);
+#else
+      r = connect(handle->io_watcher.fd, (struct sockaddr*) &addr, sizeof(addr));
+#endif
+    } while (r == -1 && errno == EINTR);
+
+    if (r == -1) {
+#if defined(BSD)  /* The macro BSD is from sys/param.h */
+      if (errno != EAFNOSUPPORT && errno != EINVAL)
+        return UV__ERR(errno);
+#else
+      return UV__ERR(errno);
+#endif
+    }
+
+    handle->flags &= ~UV_HANDLE_UDP_CONNECTED;
+    return 0;
+}
+
+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) {
+  int err;
+  int empty_queue;
+
+  assert(nbufs > 0);
+
+  if (addr) {
+    err = uv__udp_maybe_deferred_bind(handle, addr->sa_family, 0);
+    if (err)
+      return err;
+  }
+
+  /* It's legal for send_queue_count > 0 even when the write_queue is empty;
+   * it means there are error-state requests in the write_completed_queue that
+   * will touch up send_queue_size/count later.
+   */
+  empty_queue = (handle->send_queue_count == 0);
+
+  uv__req_init(handle->loop, req, UV_UDP_SEND);
+  assert(addrlen <= sizeof(req->u.storage));
+  if (addr == NULL)
+    req->u.storage.ss_family = AF_UNSPEC;
+  else
+    memcpy(&req->u.storage, addr, addrlen);
+  req->send_cb = send_cb;
+  req->handle = handle;
+  req->nbufs = nbufs;
+
+  req->bufs = req->bufsml;
+  if (nbufs > ARRAY_SIZE(req->bufsml))
+    req->bufs = uv__malloc(nbufs * sizeof(bufs[0]));
+
+  if (req->bufs == NULL) {
+    uv__req_unregister(handle->loop);
+    return UV_ENOMEM;
+  }
+
+  memcpy(req->bufs, bufs, nbufs * sizeof(bufs[0]));
+  handle->send_queue_size += uv__count_bufs(req->bufs, req->nbufs);
+  handle->send_queue_count++;
+  uv__queue_insert_tail(&handle->write_queue, &req->queue);
+  uv__handle_start(handle);
+
+  if (empty_queue && !(handle->flags & UV_HANDLE_UDP_PROCESSING)) {
+    uv__udp_sendmsg(handle);
+
+    /* `uv__udp_sendmsg` may not be able to do non-blocking write straight
+     * away. In such cases the `io_watcher` has to be queued for asynchronous
+     * write.
+     */
+    if (!uv__queue_empty(&handle->write_queue))
+      uv__io_start(handle->loop, &handle->io_watcher, POLLOUT);
+  } else {
+    uv__io_start(handle->loop, &handle->io_watcher, POLLOUT);
+  }
+
+  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) {
+  int err;
+
+  if (nbufs < 1)
+    return UV_EINVAL;
+
+  /* already sending a message */
+  if (handle->send_queue_count != 0)
+    return UV_EAGAIN;
+
+  if (addr) {
+    err = uv__udp_maybe_deferred_bind(handle, addr->sa_family, 0);
+    if (err)
+      return err;
+  } else {
+    assert(handle->flags & UV_HANDLE_UDP_CONNECTED);
+  }
+
+  err = uv__udp_sendmsg1(handle->io_watcher.fd, bufs, nbufs, addr);
+  if (err > 0)
+    return uv__count_bufs(bufs, nbufs);
+
+  return err;
+}
+
+
+static int uv__udp_set_membership4(uv_udp_t* handle,
+                                   const struct sockaddr_in* multicast_addr,
+                                   const char* interface_addr,
+                                   uv_membership membership) {
+  struct ip_mreq mreq;
+  int optname;
+  int 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->io_watcher.fd,
+                 IPPROTO_IP,
+                 optname,
+                 &mreq,
+                 sizeof(mreq))) {
+#if defined(__MVS__)
+  if (errno == ENXIO)
+    return UV_ENODEV;
+#endif
+    return UV__ERR(errno);
+  }
+
+  return 0;
+}
+
+
+static int uv__udp_set_membership6(uv_udp_t* handle,
+                                   const struct sockaddr_in6* multicast_addr,
+                                   const char* interface_addr,
+                                   uv_membership membership) {
+  int optname;
+  struct ipv6_mreq mreq;
+  struct sockaddr_in6 addr6;
+
+  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->io_watcher.fd,
+                 IPPROTO_IPV6,
+                 optname,
+                 &mreq,
+                 sizeof(mreq))) {
+#if defined(__MVS__)
+  if (errno == ENXIO)
+    return UV_ENODEV;
+#endif
+    return UV__ERR(errno);
+  }
+
+  return 0;
+}
+
+
+#if !defined(__OpenBSD__) &&                                        \
+    !defined(__NetBSD__) &&                                         \
+    !defined(__ANDROID__) &&                                        \
+    !defined(__DragonFly__) &&                                      \
+    !defined(__QNX__) &&                                            \
+    !defined(__GNU__)
+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;
+
+  err = uv__udp_maybe_deferred_bind(handle, AF_INET, UV_UDP_REUSEADDR);
+  if (err)
+    return 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->io_watcher.fd,
+                 IPPROTO_IP,
+                 optname,
+                 &mreq,
+                 sizeof(mreq))) {
+    return UV__ERR(errno);
+  }
+
+  return 0;
+}
+
+
+static 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;
+
+  err = uv__udp_maybe_deferred_bind(handle, AF_INET6, UV_UDP_REUSEADDR);
+  if (err)
+    return 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;
+  }
+
+  STATIC_ASSERT(sizeof(mreq.gsr_group) >= sizeof(*multicast_addr));
+  STATIC_ASSERT(sizeof(mreq.gsr_source) >= sizeof(*source_addr));
+  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->io_watcher.fd,
+                 IPPROTO_IPV6,
+                 optname,
+                 &mreq,
+                 sizeof(mreq))) {
+    return UV__ERR(errno);
+  }
+
+  return 0;
+}
+#endif
+
+
+int uv__udp_init_ex(uv_loop_t* loop,
+                    uv_udp_t* handle,
+                    unsigned flags,
+                    int domain) {
+  int fd;
+
+  fd = -1;
+  if (domain != AF_UNSPEC) {
+    fd = uv__socket(domain, SOCK_DGRAM, 0);
+    if (fd < 0)
+      return fd;
+  }
+
+  uv__handle_init(loop, (uv_handle_t*)handle, UV_UDP);
+  handle->alloc_cb = NULL;
+  handle->recv_cb = NULL;
+  handle->send_queue_size = 0;
+  handle->send_queue_count = 0;
+  uv__io_init(&handle->io_watcher, uv__udp_io, fd);
+  uv__queue_init(&handle->write_queue);
+  uv__queue_init(&handle->write_completed_queue);
+
+  return 0;
+}
+
+
+int uv_udp_using_recvmmsg(const uv_udp_t* handle) {
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__)
+  if (handle->flags & UV_HANDLE_UDP_RECVMMSG)
+    return 1;
+#endif
+  return 0;
+}
+
+
+int uv_udp_open(uv_udp_t* handle, uv_os_sock_t sock) {
+  int err;
+
+  /* Check for already active socket. */
+  if (handle->io_watcher.fd != -1)
+    return UV_EBUSY;
+
+  if (uv__fd_exists(handle->loop, sock))
+    return UV_EEXIST;
+
+  err = uv__nonblock(sock, 1);
+  if (err)
+    return err;
+
+  err = uv__sock_reuseaddr(sock);
+  if (err)
+    return err;
+
+  handle->io_watcher.fd = sock;
+  if (uv__udp_is_connected(handle))
+    handle->flags |= UV_HANDLE_UDP_CONNECTED;
+
+  return 0;
+}
+
+
+int uv_udp_set_membership(uv_udp_t* handle,
+                          const char* multicast_addr,
+                          const char* interface_addr,
+                          uv_membership membership) {
+  int err;
+  struct sockaddr_in addr4;
+  struct sockaddr_in6 addr6;
+
+  if (uv_ip4_addr(multicast_addr, 0, &addr4) == 0) {
+    err = uv__udp_maybe_deferred_bind(handle, AF_INET, UV_UDP_REUSEADDR);
+    if (err)
+      return err;
+    return uv__udp_set_membership4(handle, &addr4, interface_addr, membership);
+  } else if (uv_ip6_addr(multicast_addr, 0, &addr6) == 0) {
+    err = uv__udp_maybe_deferred_bind(handle, AF_INET6, UV_UDP_REUSEADDR);
+    if (err)
+      return err;
+    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) {
+#if !defined(__OpenBSD__) &&                                        \
+    !defined(__NetBSD__) &&                                         \
+    !defined(__ANDROID__) &&                                        \
+    !defined(__DragonFly__) &&                                      \
+    !defined(__QNX__) &&                                            \
+    !defined(__GNU__)
+  int err;
+  union uv__sockaddr mcast_addr;
+  union uv__sockaddr src_addr;
+
+  err = uv_ip4_addr(multicast_addr, 0, &mcast_addr.in);
+  if (err) {
+    err = uv_ip6_addr(multicast_addr, 0, &mcast_addr.in6);
+    if (err)
+      return err;
+    err = uv_ip6_addr(source_addr, 0, &src_addr.in6);
+    if (err)
+      return err;
+    return uv__udp_set_source_membership6(handle,
+                                          &mcast_addr.in6,
+                                          interface_addr,
+                                          &src_addr.in6,
+                                          membership);
+  }
+
+  err = uv_ip4_addr(source_addr, 0, &src_addr.in);
+  if (err)
+    return err;
+  return uv__udp_set_source_membership4(handle,
+                                        &mcast_addr.in,
+                                        interface_addr,
+                                        &src_addr.in,
+                                        membership);
+#else
+  return UV_ENOSYS;
+#endif
+}
+
+
+static int uv__setsockopt(uv_udp_t* handle,
+                         int option4,
+                         int option6,
+                         const void* val,
+                         socklen_t size) {
+  int r;
+
+  if (handle->flags & UV_HANDLE_IPV6)
+    r = setsockopt(handle->io_watcher.fd,
+                   IPPROTO_IPV6,
+                   option6,
+                   val,
+                   size);
+  else
+    r = setsockopt(handle->io_watcher.fd,
+                   IPPROTO_IP,
+                   option4,
+                   val,
+                   size);
+  if (r)
+    return UV__ERR(errno);
+
+  return 0;
+}
+
+static int uv__setsockopt_maybe_char(uv_udp_t* handle,
+                                     int option4,
+                                     int option6,
+                                     int val) {
+#if defined(__sun) || defined(_AIX) || defined(__MVS__)
+  char arg = val;
+#elif defined(__OpenBSD__)
+  unsigned char arg = val;
+#else
+  int arg = val;
+#endif
+
+  if (val < 0 || val > 255)
+    return UV_EINVAL;
+
+  return uv__setsockopt(handle, option4, option6, &arg, sizeof(arg));
+}
+
+
+int uv_udp_set_broadcast(uv_udp_t* handle, int on) {
+  if (setsockopt(handle->io_watcher.fd,
+                 SOL_SOCKET,
+                 SO_BROADCAST,
+                 &on,
+                 sizeof(on))) {
+    return UV__ERR(errno);
+  }
+
+  return 0;
+}
+
+
+int uv_udp_set_ttl(uv_udp_t* handle, int ttl) {
+  if (ttl < 1 || ttl > 255)
+    return UV_EINVAL;
+
+#if defined(__MVS__)
+  if (!(handle->flags & UV_HANDLE_IPV6))
+    return UV_ENOTSUP;  /* zOS does not support setting ttl for IPv4 */
+#endif
+
+/*
+ * On Solaris and derivatives such as SmartOS, the length of socket options
+ * is sizeof(int) for IP_TTL and IPV6_UNICAST_HOPS,
+ * so hardcode the size of these options on this platform,
+ * and use the general uv__setsockopt_maybe_char call on other platforms.
+ */
+#if defined(__sun) || defined(_AIX) || defined(__OpenBSD__) || \
+    defined(__MVS__) || defined(__QNX__)
+
+  return uv__setsockopt(handle,
+                        IP_TTL,
+                        IPV6_UNICAST_HOPS,
+                        &ttl,
+                        sizeof(ttl));
+
+#else /* !(defined(__sun) || defined(_AIX) || defined (__OpenBSD__) ||
+           defined(__MVS__) || defined(__QNX__)) */
+
+  return uv__setsockopt_maybe_char(handle,
+                                   IP_TTL,
+                                   IPV6_UNICAST_HOPS,
+                                   ttl);
+
+#endif /* defined(__sun) || defined(_AIX) || defined (__OpenBSD__) ||
+          defined(__MVS__) || defined(__QNX__) */
+}
+
+
+int uv_udp_set_multicast_ttl(uv_udp_t* handle, int ttl) {
+/*
+ * On Solaris and derivatives such as SmartOS, the length of socket options
+ * is sizeof(int) for IPV6_MULTICAST_HOPS and sizeof(char) for
+ * IP_MULTICAST_TTL, so hardcode the size of the option in the IPv6 case,
+ * and use the general uv__setsockopt_maybe_char call otherwise.
+ */
+#if defined(__sun) || defined(_AIX) || defined(__OpenBSD__) || \
+    defined(__MVS__) || defined(__QNX__)
+  if (handle->flags & UV_HANDLE_IPV6)
+    return uv__setsockopt(handle,
+                          IP_MULTICAST_TTL,
+                          IPV6_MULTICAST_HOPS,
+                          &ttl,
+                          sizeof(ttl));
+#endif /* defined(__sun) || defined(_AIX) || defined(__OpenBSD__) || \
+    defined(__MVS__) || defined(__QNX__) */
+
+  return uv__setsockopt_maybe_char(handle,
+                                   IP_MULTICAST_TTL,
+                                   IPV6_MULTICAST_HOPS,
+                                   ttl);
+}
+
+
+int uv_udp_set_multicast_loop(uv_udp_t* handle, int on) {
+/*
+ * On Solaris and derivatives such as SmartOS, the length of socket options
+ * is sizeof(int) for IPV6_MULTICAST_LOOP and sizeof(char) for
+ * IP_MULTICAST_LOOP, so hardcode the size of the option in the IPv6 case,
+ * and use the general uv__setsockopt_maybe_char call otherwise.
+ */
+#if defined(__sun) || defined(_AIX) || defined(__OpenBSD__) || \
+    defined(__MVS__) || defined(__QNX__)
+  if (handle->flags & UV_HANDLE_IPV6)
+    return uv__setsockopt(handle,
+                          IP_MULTICAST_LOOP,
+                          IPV6_MULTICAST_LOOP,
+                          &on,
+                          sizeof(on));
+#endif /* defined(__sun) || defined(_AIX) ||defined(__OpenBSD__) ||
+    defined(__MVS__) || defined(__QNX__) */
+
+  return uv__setsockopt_maybe_char(handle,
+                                   IP_MULTICAST_LOOP,
+                                   IPV6_MULTICAST_LOOP,
+                                   on);
+}
+
+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 (addr_st.ss_family == AF_INET) {
+    if (setsockopt(handle->io_watcher.fd,
+                   IPPROTO_IP,
+                   IP_MULTICAST_IF,
+                   (void*) &addr4->sin_addr,
+                   sizeof(addr4->sin_addr)) == -1) {
+      return UV__ERR(errno);
+    }
+  } else if (addr_st.ss_family == AF_INET6) {
+    if (setsockopt(handle->io_watcher.fd,
+                   IPPROTO_IPV6,
+                   IPV6_MULTICAST_IF,
+                   &addr6->sin6_scope_id,
+                   sizeof(addr6->sin6_scope_id)) == -1) {
+      return UV__ERR(errno);
+    }
+  } else {
+    assert(0 && "unexpected address family");
+    abort();
+  }
+
+  return 0;
+}
+
+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);
+}
+
+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);
+}
+
+
+int uv__udp_recv_start(uv_udp_t* handle,
+                       uv_alloc_cb alloc_cb,
+                       uv_udp_recv_cb recv_cb) {
+  int err;
+
+  if (alloc_cb == NULL || recv_cb == NULL)
+    return UV_EINVAL;
+
+  if (uv__io_active(&handle->io_watcher, POLLIN))
+    return UV_EALREADY;  /* FIXME(bnoordhuis) Should be UV_EBUSY. */
+
+  err = uv__udp_maybe_deferred_bind(handle, AF_INET, 0);
+  if (err)
+    return err;
+
+  handle->alloc_cb = alloc_cb;
+  handle->recv_cb = recv_cb;
+
+  uv__io_start(handle->loop, &handle->io_watcher, POLLIN);
+  uv__handle_start(handle);
+
+  return 0;
+}
+
+
+int uv__udp_recv_stop(uv_udp_t* handle) {
+  uv__io_stop(handle->loop, &handle->io_watcher, POLLIN);
+
+  if (!uv__io_active(&handle->io_watcher, POLLOUT))
+    uv__handle_stop(handle);
+
+  handle->alloc_cb = NULL;
+  handle->recv_cb = NULL;
+
+  return 0;
+}
+
+
+static int uv__udp_prep_pkt(struct msghdr* h,
+                            const uv_buf_t* bufs,
+                            const unsigned int nbufs,
+                            const struct sockaddr* addr) {
+  memset(h, 0, sizeof(*h));
+  h->msg_name = (void*) addr;
+  h->msg_iov = (void*) bufs;
+  h->msg_iovlen = nbufs;
+  if (addr == NULL)
+    return 0;
+  switch (addr->sa_family) {
+  case AF_INET:
+    h->msg_namelen = sizeof(struct sockaddr_in);
+    return 0;
+  case AF_INET6:
+    h->msg_namelen = sizeof(struct sockaddr_in6);
+    return 0;
+  case AF_UNIX:
+    h->msg_namelen = sizeof(struct sockaddr_un);
+    return 0;
+  case AF_UNSPEC:
+    h->msg_name = NULL;
+    return 0;
+  }
+  return UV_EINVAL;
+}
+
+
+static int uv__udp_sendmsg1(int fd,
+                            const uv_buf_t* bufs,
+                            unsigned int nbufs,
+                            const struct sockaddr* addr) {
+  struct msghdr h;
+  int r;
+
+  if ((r = uv__udp_prep_pkt(&h, bufs, nbufs, addr)))
+    return r;
+
+  do
+    r = sendmsg(fd, &h, 0);
+  while (r == -1 && errno == EINTR);
+
+  if (r < 0) {
+    r = UV__ERR(errno);
+    if (errno == EAGAIN || errno == EWOULDBLOCK || errno == ENOBUFS)
+      r = UV_EAGAIN;
+    return r;
+  }
+
+  /* UDP sockets don't EOF so we don't have to handle r=0 specially,
+   * that only happens when the input was a zero-sized buffer.
+   */
+  return 1;
+}
+
+
+static int uv__udp_sendmsgv(int fd,
+                            unsigned int count,
+                            uv_buf_t* bufs[/*count*/],
+                            unsigned int nbufs[/*count*/],
+                            struct sockaddr* addrs[/*count*/]) {
+  unsigned int i;
+  int nsent;
+  int r;
+
+  r = 0;
+  nsent = 0;
+
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__) || \
+  (defined(__sun__) && defined(MSG_WAITFORONE))
+  if (count > 1) {
+    for (i = 0; i < count; /*empty*/) {
+      struct mmsghdr m[20];
+      unsigned int n;
+
+      for (n = 0; i < count && n < ARRAY_SIZE(m); i++, n++)
+        if ((r = uv__udp_prep_pkt(&m[n].msg_hdr, bufs[i], nbufs[i], addrs[i])))
+          goto exit;
+
+      do
+#if defined(__APPLE__)
+        r = sendmsg_x(fd, m, n, MSG_DONTWAIT);
+#else
+        r = sendmmsg(fd, m, n, 0);
+#endif
+      while (r == -1 && errno == EINTR);
+
+      if (r < 1)
+        goto exit;
+
+      nsent += r;
+      i += r;
+    }
+
+    goto exit;
+  }
+#endif  /* defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__) ||
+	 * (defined(__sun__) && defined(MSG_WAITFORONE))
+	 */
+
+  for (i = 0; i < count; i++, nsent++)
+    if ((r = uv__udp_sendmsg1(fd, bufs[i], nbufs[i], addrs[i])))
+      goto exit;  /* goto to avoid unused label warning. */
+
+exit:
+
+  if (nsent > 0)
+    return nsent;
+
+  if (r < 0) {
+    r = UV__ERR(errno);
+    if (errno == EAGAIN || errno == EWOULDBLOCK || errno == ENOBUFS)
+      r = UV_EAGAIN;
+  }
+
+  return r;
+}
+
+
+static void uv__udp_sendmsg(uv_udp_t* handle) {
+  static const int N = 20;
+  struct sockaddr* addrs[N];
+  unsigned int nbufs[N];
+  uv_buf_t* bufs[N];
+  struct uv__queue* q;
+  uv_udp_send_t* req;
+  int n;
+
+  if (uv__queue_empty(&handle->write_queue))
+    return;
+
+again:
+  n = 0;
+  q = uv__queue_head(&handle->write_queue);
+  do {
+    req = uv__queue_data(q, uv_udp_send_t, queue);
+    addrs[n] = &req->u.addr;
+    nbufs[n] = req->nbufs;
+    bufs[n] = req->bufs;
+    q = uv__queue_next(q);
+    n++;
+  } while (n < N && q != &handle->write_queue);
+
+  n = uv__udp_sendmsgv(handle->io_watcher.fd, n, bufs, nbufs, addrs);
+  while (n > 0) {
+    q = uv__queue_head(&handle->write_queue);
+    req = uv__queue_data(q, uv_udp_send_t, queue);
+    req->status = uv__count_bufs(req->bufs, req->nbufs);
+    uv__queue_remove(&req->queue);
+    uv__queue_insert_tail(&handle->write_completed_queue, &req->queue);
+    n--;
+  }
+
+  if (n == 0) {
+    if (uv__queue_empty(&handle->write_queue))
+      goto feed;
+    goto again;
+  }
+
+  if (n == UV_EAGAIN)
+    return;
+
+  /* Register the error against first request in queue because that
+   * is the request that uv__udp_sendmsgv tried but failed to send,
+   * because if it did send any requests, it won't return an error.
+   */
+  q = uv__queue_head(&handle->write_queue);
+  req = uv__queue_data(q, uv_udp_send_t, queue);
+  req->status = n;
+  uv__queue_remove(&req->queue);
+  uv__queue_insert_tail(&handle->write_completed_queue, &req->queue);
+feed:
+  uv__io_feed(handle->loop, &handle->io_watcher);
+}
+
+
+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*/]) {
+  int fd;
+
+  fd = handle->io_watcher.fd;
+  if (fd == -1)
+    return UV_EINVAL;
+
+  return uv__udp_sendmsgv(fd, count, bufs, nbufs, addrs);
+}