src: simplify ParseIP() in cares_wrap.cc

The result argument is never nullptr, so remove special handling of that
case. Also, instead of returning magic values 0/4/6 and then later
translating those into error/AF_INET/AF_INET6, return
AF_UNSPEC/AF_INET/AF_INET6 directly.

src/cares_wrap.cc

@@ -1535,24 +1535,21 @@ void AfterGetNameInfo(uv_getnameinfo_t* req,
 using ParseIPResult =
     decltype(static_cast<ares_addr_port_node*>(nullptr)->addr);
 
-int ParseIP(const char* ip, ParseIPResult* result = nullptr) {
-  ParseIPResult tmp;
-  if (result == nullptr) result = &tmp;
-  if (0 == uv_inet_pton(AF_INET, ip, result)) return 4;
-  if (0 == uv_inet_pton(AF_INET6, ip, result)) return 6;
-  return 0;
+int ParseIP(const char* ip, ParseIPResult* result) {
+  if (0 == uv_inet_pton(AF_INET, ip, result)) return AF_INET;
+  if (0 == uv_inet_pton(AF_INET6, ip, result)) return AF_INET6;
+  return AF_UNSPEC;
 }
 
 void CanonicalizeIP(const FunctionCallbackInfo<Value>& args) {
   Isolate* isolate = args.GetIsolate();
   node::Utf8Value ip(isolate, args[0]);
 
   ParseIPResult result;
-  const int rc = ParseIP(*ip, &result);
-  if (rc == 0) return;
+  const int af = ParseIP(*ip, &result);
+  if (af == AF_UNSPEC) return;
 
   char canonical_ip[INET6_ADDRSTRLEN];
-  const int af = (rc == 4 ? AF_INET : AF_INET6);
   CHECK_EQ(0, uv_inet_ntop(af, &result, canonical_ip, sizeof(canonical_ip)));
   Local<String> val = String::NewFromUtf8(isolate, canonical_ip)
       .ToLocalChecked();