lib,src: port isIPv4() to js

Removes a few lines of C++ code while making `isIPv4()` about 3x faster.
`isIPv6()` and `isIP()` for the IPv6 case stay about the same.

I removed the homegrown `isIPv4()` in lib/dns.js that utilized a lookup
table.  It is in fact a little faster than the new `isIPv4()` function
but:

1. The difference is only measurable at around 10M iterations, and
2. The function is a "probably IPv4" heuristic, not a proper validator.

PR-URL: https://github.com/nodejs/node/pull/18398
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

lib/dns.js

@@ -24,7 +24,7 @@
 const util = require('util');
 
 const cares = process.binding('cares_wrap');
-const { isLegalPort } = require('internal/net');
+const { isIP, isIPv4, isLegalPort } = require('internal/net');
 const { customPromisifyArgs } = require('internal/util');
 const errors = require('internal/errors');
 const {
@@ -38,7 +38,6 @@ const {
   GetNameInfoReqWrap,
   QueryReqWrap,
   ChannelWrap,
-  isIP
 } = cares;
 
 function errnoException(err, syscall, hostname) {
@@ -66,30 +65,6 @@ function errnoException(err, syscall, hostname) {
 }
 
 const IANA_DNS_PORT = 53;
-const digits = [
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0-15
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16-31
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 32-47
-  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 48-63
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 64-79
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 80-95
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 96-111
-  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  // 112-127
-];
-function isIPv4(str) {
-  if (!digits[str.charCodeAt(0)]) return false;
-  if (str.length === 1) return false;
-  if (str.charCodeAt(1) === 46/*'.'*/)
-    return true;
-  else if (!digits[str.charCodeAt(1)])
-    return false;
-  if (str.length === 2) return false;
-  if (str.charCodeAt(2) === 46/*'.'*/)
-    return true;
-  else if (!digits[str.charCodeAt(2)])
-    return false;
-  return (str.length > 3 && str.charCodeAt(3) === 46/*'.'*/);
-}
 
 
 function onlookup(err, addresses) {

lib/internal/net.js

@@ -1,8 +1,22 @@
 'use strict';
 
 const Buffer = require('buffer').Buffer;
+const { isIPv6 } = process.binding('cares_wrap');
 const { writeBuffer } = process.binding('fs');
 
+const octet = '(?:[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])';
+const re = new RegExp(`^${octet}[.]${octet}[.]${octet}[.]${octet}$`);
+
+function isIPv4(s) {
+  return re.test(s);
+}
+
+function isIP(s) {
+  if (isIPv4(s)) return 4;
+  if (isIPv6(s)) return 6;
+  return 0;
+}
+
 // Check that the port number is not NaN when coerced to a number,
 // is an integer and that it falls within the legal range of port numbers.
 function isLegalPort(port) {
@@ -33,6 +47,9 @@ function makeSyncWrite(fd) {
 }
 
 module.exports = {
+  isIP,
+  isIPv4,
+  isIPv6,
   isLegalPort,
   makeSyncWrite,
   normalizedArgsSymbol: Symbol('normalizedArgs')

lib/net.js

@@ -26,12 +26,14 @@ const stream = require('stream');
 const util = require('util');
 const internalUtil = require('internal/util');
 const {
+  isIP,
+  isIPv4,
+  isIPv6,
   isLegalPort,
   normalizedArgsSymbol,
   makeSyncWrite
 } = require('internal/net');
 const assert = require('assert');
-const cares = process.binding('cares_wrap');
 const {
   UV_EADDRINUSE,
   UV_EINVAL,
@@ -1066,7 +1068,7 @@ function lookupAndConnect(self, options) {
   var localAddress = options.localAddress;
   var localPort = options.localPort;
 
-  if (localAddress && !cares.isIP(localAddress)) {
+  if (localAddress && !isIP(localAddress)) {
     throw new errors.TypeError('ERR_INVALID_IP_ADDRESS', localAddress);
   }
 
@@ -1091,7 +1093,7 @@ function lookupAndConnect(self, options) {
   port |= 0;
 
   // If host is an IP, skip performing a lookup
-  var addressType = cares.isIP(host);
+  var addressType = isIP(host);
   if (addressType) {
     nextTick(self[async_id_symbol], function() {
       if (self.connecting)
@@ -1775,9 +1777,9 @@ module.exports = {
   connect,
   createConnection: connect,
   createServer,
-  isIP: cares.isIP,
-  isIPv4: cares.isIPv4,
-  isIPv6: cares.isIPv6,
+  isIP: isIP,
+  isIPv4: isIPv4,
+  isIPv6: isIPv6,
   Server,
   Socket,
   Stream: Socket, // Legacy naming

src/cares_wrap.cc

@@ -1886,16 +1886,6 @@ int ParseIP(const char* ip, ParseIPResult* result = nullptr) {
   return 0;
 }
 
-void IsIP(const FunctionCallbackInfo<Value>& args) {
-  node::Utf8Value ip(args.GetIsolate(), args[0]);
-  args.GetReturnValue().Set(ParseIP(*ip));
-}
-
-void IsIPv4(const FunctionCallbackInfo<Value>& args) {
-  node::Utf8Value ip(args.GetIsolate(), args[0]);
-  args.GetReturnValue().Set(4 == ParseIP(*ip));
-}
-
 void IsIPv6(const FunctionCallbackInfo<Value>& args) {
   node::Utf8Value ip(args.GetIsolate(), args[0]);
   args.GetReturnValue().Set(6 == ParseIP(*ip));
@@ -2138,8 +2128,6 @@ void Initialize(Local<Object> target,
 
   env->SetMethod(target, "getaddrinfo", GetAddrInfo);
   env->SetMethod(target, "getnameinfo", GetNameInfo);
-  env->SetMethod(target, "isIP", IsIP);
-  env->SetMethod(target, "isIPv4", IsIPv4);
   env->SetMethod(target, "isIPv6", IsIPv6);
   env->SetMethod(target, "canonicalizeIP", CanonicalizeIP);