--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-udp-send-unreachable.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,201 @@
+/* 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 "task.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define CHECK_HANDLE(handle) \
+  ASSERT_NE((uv_udp_t*)(handle) == &client || (uv_udp_t*)(handle) == &client2, 0)
+
+static uv_udp_t client;
+static uv_udp_t client2;
+static uv_timer_t timer;
+
+static int send_cb_called;
+static int recv_cb_called;
+static int close_cb_called;
+static int alloc_cb_called;
+static int timer_cb_called;
+static int can_recverr;
+
+
+static void alloc_cb(uv_handle_t* handle,
+                     size_t suggested_size,
+                     uv_buf_t* buf) {
+  static char slab[65536];
+  CHECK_HANDLE(handle);
+  ASSERT_LE(suggested_size, sizeof(slab));
+  buf->base = slab;
+  buf->len = sizeof(slab);
+  alloc_cb_called++;
+}
+
+
+static void close_cb(uv_handle_t* handle) {
+  ASSERT_EQ(1, uv_is_closing(handle));
+  close_cb_called++;
+}
+
+
+static void send_cb(uv_udp_send_t* req, int status) {
+  ASSERT_NOT_NULL(req);
+  ASSERT_OK(status);
+  ASSERT_OK(status);
+  CHECK_HANDLE(req->handle);
+  send_cb_called++;
+}
+
+static void send_cb_recverr(uv_udp_send_t* req, int status) {
+  ASSERT_PTR_NE(req, NULL);
+  ASSERT(status == 0 || status == UV_ECONNREFUSED);
+  CHECK_HANDLE(req->handle);
+  send_cb_called++;
+}
+
+static void recv_cb(uv_udp_t* handle,
+                       ssize_t nread,
+                       const uv_buf_t* rcvbuf,
+                       const struct sockaddr* addr,
+                       unsigned flags) {
+  CHECK_HANDLE(handle);
+  recv_cb_called++;
+
+  if (nread < 0) {
+    ASSERT(0 && "unexpected error");
+  } else if (nread == 0) {
+    /* Returning unused buffer */
+    ASSERT_NULL(addr);
+  } else {
+    ASSERT_NOT_NULL(addr);
+  }
+}
+
+
+static void timer_cb(uv_timer_t* h) {
+  ASSERT_PTR_EQ(h, &timer);
+  timer_cb_called++;
+  uv_close((uv_handle_t*) &client, close_cb);
+  if (can_recverr)
+    uv_close((uv_handle_t*) &client2, close_cb);
+  uv_close((uv_handle_t*) h, close_cb);
+}
+
+
+TEST_IMPL(udp_send_unreachable) {
+  struct sockaddr_in addr;
+  struct sockaddr_in addr2;
+  struct sockaddr_in addr3;
+  uv_udp_send_t req1, req2, req3, req4;
+  uv_buf_t buf;
+  int r;
+
+#ifdef __linux__
+  can_recverr = 1;
+#endif
+
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT_2, &addr2));
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT_3, &addr3));
+
+  r = uv_timer_init( uv_default_loop(), &timer );
+  ASSERT_OK(r);
+
+  r = uv_timer_start( &timer, timer_cb, 1000, 0 );
+  ASSERT_OK(r);
+
+  r = uv_udp_init(uv_default_loop(), &client);
+  ASSERT_OK(r);
+
+  r = uv_udp_bind(&client, (const struct sockaddr*) &addr2, 0);
+  ASSERT_OK(r);
+
+  r = uv_udp_recv_start(&client, alloc_cb, recv_cb);
+  ASSERT_OK(r);
+
+  /* client sends "PING", then "PANG" */
+  buf = uv_buf_init("PING", 4);
+
+  r = uv_udp_send(&req1,
+                  &client,
+                  &buf,
+                  1,
+                  (const struct sockaddr*) &addr,
+                  send_cb);
+  ASSERT_OK(r);
+
+  buf = uv_buf_init("PANG", 4);
+
+  r = uv_udp_send(&req2,
+                  &client,
+                  &buf,
+                  1,
+                  (const struct sockaddr*) &addr,
+                  send_cb);
+  ASSERT_OK(r);
+
+  if (can_recverr) {
+    r = uv_udp_init(uv_default_loop(), &client2);
+    ASSERT_OK(r);
+
+    r = uv_udp_bind(&client2,
+                    (const struct sockaddr*) &addr3,
+                    UV_UDP_LINUX_RECVERR);
+    ASSERT_OK(r);
+
+    r = uv_udp_recv_start(&client2, alloc_cb, recv_cb);
+    ASSERT_OK(r);
+
+    /* client sends "PING", then "PANG" */
+    buf = uv_buf_init("PING", 4);
+
+    r = uv_udp_send(&req3,
+                    &client2,
+                    &buf,
+                    1,
+                    (const struct sockaddr*) &addr,
+                    send_cb_recverr);
+    ASSERT_OK(r);
+
+    buf = uv_buf_init("PANG", 4);
+
+    r = uv_udp_send(&req4,
+                    &client2,
+                    &buf,
+                    1,
+                    (const struct sockaddr*) &addr,
+                    send_cb_recverr);
+    ASSERT_OK(r);
+  }
+
+  uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+
+  ASSERT_EQ(send_cb_called, (long)(can_recverr ? 4 : 2));
+  ASSERT_EQ(recv_cb_called, alloc_cb_called);
+  ASSERT_EQ(1, timer_cb_called);
+  ASSERT_EQ(close_cb_called, (long)(can_recverr ? 3 : 2));
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}