Allow SetSocketDualStack to be overridden internally.

PiperOrigin-RevId: 648387426

src/core/lib/event_engine/posix_engine/tcp_socket_utils.cc

@@ -148,15 +148,21 @@ absl::Status PrepareTcpClientSocket(PosixSocketWrapper sock,
   return absl::OkStatus();
 }
 
+#endif  // GRPC_POSIX_SOCKET_UTILS_COMMON
+
+}  // namespace
+
+#ifdef GRPC_POSIX_SOCKET_UTILS_COMMON
+#ifndef GRPC_SET_SOCKET_DUALSTACK_CUSTOM
+
 bool SetSocketDualStack(int fd) {
   const int off = 0;
   return 0 == setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &off, sizeof(off));
 }
 
+#endif  // GRPC_SET_SOCKET_DUALSTACK_CUSTOM
 #endif  // GRPC_POSIX_SOCKET_UTILS_COMMON
 
-}  // namespace
-
 PosixTcpOptions TcpOptionsFromEndpointConfig(const EndpointConfig& config) {
   void* value;
   PosixTcpOptions options;

src/core/lib/event_engine/posix_engine/tcp_socket_utils.h

@@ -323,6 +323,8 @@ struct PosixSocketWrapper::PosixSocketCreateResult {
   EventEngine::ResolvedAddress mapped_target_addr;
 };
 
+bool SetSocketDualStack(int fd);
+
 }  // namespace experimental
 }  // namespace grpc_event_engine