--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-udp-ipv6.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,259 @@
+/* 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>
+
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+#include <sys/sysctl.h>
+#endif
+
+#define CHECK_HANDLE(handle)                   \
+  ASSERT_NE((uv_udp_t*)(handle) == &server     \
+         || (uv_udp_t*)(handle) == &client     \
+         || (uv_timer_t*)(handle) == &timeout, 0)
+
+#define CHECK_REQ(req) \
+  ASSERT_PTR_EQ((req), &req_);
+
+static uv_udp_t client;
+static uv_udp_t server;
+static uv_udp_send_t req_;
+static char data[10];
+static uv_timer_t timeout;
+
+static int send_cb_called;
+static int recv_cb_called;
+static int close_cb_called;
+static uint16_t client_port;
+
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+static int can_ipv6_ipv4_dual(void) {
+  int v6only;
+  size_t size = sizeof(int);
+
+  if (sysctlbyname("net.inet6.ip6.v6only", &v6only, &size, NULL, 0))
+    return 0;
+
+  return v6only != 1;
+}
+#endif
+
+
+static void alloc_cb(uv_handle_t* handle,
+                     size_t suggested_size,
+                     uv_buf_t* buf) {
+  static char slab[65536];
+  CHECK_HANDLE(handle);
+  buf->base = slab;
+  buf->len = sizeof(slab);
+}
+
+
+static void close_cb(uv_handle_t* handle) {
+  CHECK_HANDLE(handle);
+  close_cb_called++;
+}
+
+
+static void send_cb(uv_udp_send_t* req, int status) {
+  CHECK_REQ(req);
+  CHECK_HANDLE(req->handle);
+  ASSERT_OK(status);
+  send_cb_called++;
+}
+
+static int is_from_client(const struct sockaddr* addr) {
+  const struct sockaddr_in6* addr6;
+  char dst[256];
+  int r;
+
+  /* Debugging output, and filter out unwanted network traffic */
+  if (addr != NULL) {
+    ASSERT_EQ(addr->sa_family, AF_INET6);
+    addr6 = (struct sockaddr_in6*) addr;
+    r = uv_inet_ntop(addr->sa_family, &addr6->sin6_addr, dst, sizeof(dst));
+    if (r == 0)
+      printf("from [%.*s]:%d\n", (int) sizeof(dst), dst, addr6->sin6_port);
+    if (addr6->sin6_port != client_port)
+      return 0;
+    if (r != 0 || strcmp(dst, "::ffff:127.0.0.1"))
+      return 0;
+  }
+  return 1;
+}
+
+
+static void ipv6_recv_fail(uv_udp_t* handle,
+                           ssize_t nread,
+                           const uv_buf_t* buf,
+                           const struct sockaddr* addr,
+                           unsigned flags) {
+  printf("got %d %.*s\n", (int) nread, nread > 0 ? (int) nread : 0, buf->base);
+  if (!is_from_client(addr) || (nread == 0 && addr == NULL))
+    return;
+  ASSERT(0 && "this function should not have been called");
+}
+
+
+static void ipv6_recv_ok(uv_udp_t* handle,
+                         ssize_t nread,
+                         const uv_buf_t* buf,
+                         const struct sockaddr* addr,
+                         unsigned flags) {
+  CHECK_HANDLE(handle);
+
+  printf("got %d %.*s\n", (int) nread, nread > 0 ? (int) nread : 0, buf->base);
+  if (!is_from_client(addr) || (nread == 0 && addr == NULL))
+    return;
+
+  ASSERT_EQ(9, nread);
+  ASSERT(!memcmp(buf->base, data, 9));
+  recv_cb_called++;
+}
+
+
+static void timeout_cb(uv_timer_t* timer) {
+  uv_close((uv_handle_t*)&server, close_cb);
+  uv_close((uv_handle_t*)&client, close_cb);
+  uv_close((uv_handle_t*)&timeout, close_cb);
+}
+
+
+static void do_test(uv_udp_recv_cb recv_cb, int bind_flags) {
+  struct sockaddr_in6 addr6;
+  struct sockaddr_in addr;
+  int addr6_len;
+  int addr_len;
+  uv_buf_t buf;
+  char dst[256];
+  int r;
+
+  ASSERT_OK(uv_ip6_addr("::0", TEST_PORT, &addr6));
+
+  r = uv_udp_init(uv_default_loop(), &server);
+  ASSERT_OK(r);
+
+  r = uv_udp_bind(&server, (const struct sockaddr*) &addr6, bind_flags);
+  ASSERT_OK(r);
+
+  addr6_len = sizeof(addr6);
+  ASSERT_OK(uv_udp_getsockname(&server,
+                               (struct sockaddr*) &addr6,
+                               &addr6_len));
+  ASSERT_OK(uv_inet_ntop(addr6.sin6_family,
+                         &addr6.sin6_addr,
+                         dst,
+                         sizeof(dst)));
+  printf("on [%.*s]:%d\n", (int) sizeof(dst), dst, addr6.sin6_port);
+
+  r = uv_udp_recv_start(&server, alloc_cb, recv_cb);
+  ASSERT_OK(r);
+
+  r = uv_udp_init(uv_default_loop(), &client);
+  ASSERT_OK(r);
+
+  ASSERT_OK(uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+  ASSERT_OK(uv_inet_ntop(addr.sin_family, &addr.sin_addr, dst, sizeof(dst)));
+  printf("to [%.*s]:%d\n", (int) sizeof(dst), dst, addr.sin_port);
+
+  /* Create some unique data to send */
+  ASSERT_EQ(9, snprintf(data,
+                        sizeof(data),
+                        "PING%5u",
+                        uv_os_getpid() & 0xFFFF));
+  buf = uv_buf_init(data, 9);
+  printf("sending %s\n", data);
+
+  r = uv_udp_send(&req_,
+                  &client,
+                  &buf,
+                  1,
+                  (const struct sockaddr*) &addr,
+                  send_cb);
+  ASSERT_OK(r);
+
+  addr_len = sizeof(addr);
+  ASSERT_OK(uv_udp_getsockname(&client, (struct sockaddr*) &addr, &addr_len));
+  ASSERT_OK(uv_inet_ntop(addr.sin_family, &addr.sin_addr, dst, sizeof(dst)));
+  printf("from [%.*s]:%d\n", (int) sizeof(dst), dst, addr.sin_port);
+  client_port = addr.sin_port;
+
+  r = uv_timer_init(uv_default_loop(), &timeout);
+  ASSERT_OK(r);
+
+  r = uv_timer_start(&timeout, timeout_cb, 500, 0);
+  ASSERT_OK(r);
+
+  ASSERT_OK(close_cb_called);
+  ASSERT_OK(send_cb_called);
+  ASSERT_OK(recv_cb_called);
+
+  uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+
+  ASSERT_EQ(3, close_cb_called);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+}
+
+
+TEST_IMPL(udp_dual_stack) {
+#if defined(__CYGWIN__) || defined(__MSYS__)
+  /* FIXME: Does Cygwin support this?  */
+  RETURN_SKIP("FIXME: This test needs more investigation on Cygwin");
+#endif
+
+  if (!can_ipv6())
+    RETURN_SKIP("IPv6 not supported");
+
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+  if (!can_ipv6_ipv4_dual())
+    RETURN_SKIP("IPv6-IPv4 dual stack not supported");
+#elif defined(__OpenBSD__)
+  RETURN_SKIP("IPv6-IPv4 dual stack not supported");
+#endif
+
+  do_test(ipv6_recv_ok, 0);
+
+  printf("recv_cb_called %d\n", recv_cb_called);
+  printf("send_cb_called %d\n", send_cb_called);
+  ASSERT_EQ(1, recv_cb_called);
+  ASSERT_EQ(1, send_cb_called);
+
+  return 0;
+}
+
+
+TEST_IMPL(udp_ipv6_only) {
+  if (!can_ipv6())
+    RETURN_SKIP("IPv6 not supported");
+
+  do_test(ipv6_recv_fail, UV_UDP_IPV6ONLY);
+
+  ASSERT_OK(recv_cb_called);
+  ASSERT_EQ(1, send_cb_called);
+
+  return 0;
+}