unix,win: add uv_udp_try_send2

Add a version of uv_udp_try_send that can send multiple datagrams.

Uses sendmmsg(2) on platforms that support it (Linux, FreeBSD, macOS),
falls back to a regular sendmsg(2) loop elsewhere.

This work was sponsored by ISC, the Internet Systems Consortium.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/unix/udp.c b/src/unix/udp.c
index 045e5fe8..67c01f7d 100644
--- a/src/unix/udp.c
+++ b/src/unix/udp.c
@@ -1401,3 +1401,18 @@ again:
 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);
+}