adding sync version of dns resolve

.jshintrc

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+{
+    // Whether the scan should stop on first error.
+    "passfail": false,
+    // Maximum errors before stopping.
+    "maxerr": 100,
+
+
+    // Predefined globals
+
+    // Whether the standard browser globals should be predefined.
+    "browser": false,
+    // Whether the Node.js environment globals should be predefined.
+    "node": true,
+    // Whether the Rhino environment globals should be predefined.
+    "rhino": false,
+    // Whether CouchDB globals should be predefined.
+    "couch": false,
+    // Whether the Windows Scripting Host environment globals should be predefined.
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+    // Whether jQuery globals should be predefined.
+    "jquery": false,
+    // Whether Prototype and Scriptaculous globals should be predefined.
+    "prototypejs": false,
+    // Whether MooTools globals should be predefined.
+    "mootools": false,
+    // Whether Dojo Toolkit globals should be predefined.
+    "dojo": false,
+
+    // Custom predefined globals.
+    "predef": [
+        "describe", "it", "before", "after"
+    ],
+
+    // Development
+
+    // Whether debugger statements should be allowed.
+    "debug": false,
+    // Whether logging globals should be predefined (console, alert, etc.).
+    "devel": false,
+
+
+    // ECMAScript 5
+
+    // Whether the "use strict"; pragma should be required.
+    "strict": true,
+    // Whether global "use strict"; should be allowed (also enables strict).
+    "globalstrict": true,
+
+
+    // The Good Parts
+
+    // Whether automatic semicolon insertion should be allowed.
+    "asi": false,
+    // Whether line breaks should not be checked, e.g. `return [\n] x`.
+    "laxbreak": false,
+    // Whether bitwise operators (&, |, ^, etc.) should be forbidden.
+    "bitwise": false,
+    // Whether assignments inside `if`, `for` and `while` should be allowed. Usually
+    // conditions and loops are for comparison, not assignments.
+    "boss": true,
+    // Whether curly braces around all blocks should be required.
+    "curly": true,
+    // Whether `===` and `!==` should be required (instead of `==` and `!=`).
+    "eqeqeq": true,
+    // Whether `== null` comparisons should be allowed, even if `eqeqeq` is `true`.
+    "eqnull": false,
+    // Whether `eval` should be allowed.
+    "evil": false,
+    // Whether ExpressionStatement should be allowed as Programs.
+    "expr": true,
+    // Whether `for in` loops must filter with `hasOwnPrototype`.
+    "forin": false,
+    // Whether immediate invocations must be wrapped in parens, e.g.
+    // `( function(){}() );`.
+    "immed": true,
+    // Whether use before define should be forbidden.
+    "latedef": false,
+    // Whether functions should be allowed to be defined within loops.
+    "loopfunc": false,
+    // Whether arguments.caller and arguments.callee should be forbidden.
+    "noarg": false,
+    // Whether `.` should be forbidden in regexp literals.
+    "regexp": false,
+    // Whether unescaped first/last dash (-) inside brackets in regexps should be allowed.
+    "regexdash": false,
+    // Whether script-targeted URLs should be allowed.
+    "scripturl": false,
+    // Whether variable shadowing should be allowed.
+    "shadow": false,
+    // Whether `new function () { ... };` and `new Object;` should be allowed.
+    "supernew": false,
+    // Whether variables must be declared before used.
+    "undef": true,
+    // Whether `this` inside a non-constructor function should be allowed.
+    "validthis": false,
+    // Whether smarttabs should be allowed
+    // (http://www.emacswiki.org/emacs/SmartTabs).
+    "smarttabs": true,
+    // Whether the `__proto__` property should be allowed.
+    "proto": false,
+    // Whether one-case switch statements should be allowed.
+    "onecase": false,
+    // Whether non-standard (but widely adopted) globals should be predefined.
+    "nonstandard": false,
+    // Allow multiline strings.
+    "multistr": false,
+    // Whether line breaks should not be checked around commas.
+    "laxcomma": false,
+    // Whether semicolons may be ommitted for the trailing statements inside of a
+    // one-line blocks.
+    "lastsemic": false,
+    // Whether the `__iterator__` property should be allowed.
+    "iterator": false,
+    // Whether only function scope should be used for scope tests.
+    "funcscope": false,
+    // Whether es.next specific syntax should be allowed.
+    "esnext": false,
+
+
+    // Style preferences
+
+    // Whether constructor names must be capitalized.
+    "newcap": false,
+    // Whether empty blocks should be forbidden.
+    "noempty": false,
+    // Whether using `new` for side-effects should be forbidden.
+    "nonew": false,
+    // Whether names should be checked for leading or trailing underscores
+    // (object._attribute would be forbidden).
+    "nomen": false,
+    // Whether only one var statement per function should be allowed.
+    "onevar": false,
+    // Whether increment and decrement (`++` and `--`) should be forbidden.
+    "plusplus": false,
+    // Whether all forms of subscript notation are allowed.
+    "sub": false,
+    // Whether trailing whitespace rules apply.
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+    // Specify indentation.
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+    // Whether strict whitespace rules apply.
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+
+    // Complexity
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+    // Maximum block nesting depth.
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+    // Maximum number of statements per function.
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+    // Maximum cyclomatic complexity.
+    "maxcomplexity": 10
+}

.travis.yml

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+language: node_js
+
+node_js:
+  - "0.10"

Makefile

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+REPORTER = spec
+BASE = .
+JSHINT = ./node_modules/.bin/jshint
+
+all: lint test
+
+test:
+	@NODE_ENV=test ./node_modules/.bin/mocha \
+		--reporter $(REPORTER)
+
+lint:
+	$(JSHINT) index.js --config $(BASE)/.jshintrc && \
+	$(JSHINT) ./lib --config $(BASE)/.jshintrc && \
+	$(JSHINT) ./test --config $(BASE)/.jshintrc
+
+.PHONY: test docs

README.md

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 node-dns-sync
 =============
+
+[![Build Status](https://travis-ci.org/skoranga/node-dns-sync.png)](https://travis-ci.org/skoranga/node-dns-sync)
+
+Sync/Blocking DNS resolve. Main usecase is in node server startup.
+
+### How to Use
+```javascript
+var dnsSync = require('dns-sync');
+
+console.log(dnsSync.resolve('www.paypal.com'));     //should return the IP address
+console.log(dnsSync.resolve('www.yahoo.com'));
+console.log(dnsSync.resolve('www.non-host.something')); //should return null
+```

index.js

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+exports = module.exports = require('./lib/dns-sync');

lib/dns-sync.js

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+'use strict';
+
+var net = require('net'),
+    util = require('util'),
+    path = require('path'),
+    shell = require('shelljs'),
+    debug = require('debug')('dns-sync');
+
+/**
+ * Resolve hostname to IP address,
+ * returns null in case of error
+ */
+module.exports = {
+    resolve: function resolve(hostname) {
+        var output,
+            nodeBinary = process.execPath,
+            scriptPath = path.join(__dirname, "../scripts/dns-lookup-script"),
+            response,
+            cmd = util.format('"%s" "%s" %s', nodeBinary, scriptPath, hostname);
+
+        response = shell.exec(cmd, {silent: true});
+        if (response && response.code === 0) {
+            output = response.output;
+            if (output && net.isIP(output)) {
+                return output;
+            }
+        }
+        debug('hostname', "fail to resolve hostname " + hostname);
+        return null;
+    }
+};

package.json

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+{
+  "name": "dns-sync",
+  "version": "0.1.0",
+  "description": "dns-sync",
+  "main": "index.js",
+  "scripts": {
+    "test": "make test"
+  },
+  "homepage": "https://github.com/skoranga/node-dns-sync",
+  "repository": {
+    "type": "git",
+    "url": "[email protected]:skoranga/node-dns-sync.git"
+  },
+  "keywords": [
+    "dns sync",
+    "server startup",
+    "nodejs"
+  ],
+  "author": "Sanjeev Koranga",
+  "license": "MIT",
+  "readmeFilename": "README.md",
+  "dependencies": {
+    "debug" : "~0.7",
+    "shelljs": "~0.2"
+  },
+  "devDependencies": {
+    "mocha" : "~1",
+    "jshint" : "*"
+  }
+}

scripts/dns-lookup-script.js

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+'use strict';
+
+var dns = require('dns'),
+    name = process.argv[2],
+    debug = require('debug')('dns-sync');
+
+dns.lookup(name, function (err, ip) {
+    if (err) {
+        process.exit(1);
+        debug(err);
+    } else {
+        debug(name, 'resolved to', ip);
+        process.stdout.write(ip);
+    }
+});

test/test.js

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+'use strict';
+
+var assert = require('assert'),
+    dnsSync = require('../index');
+
+describe('dns sync', function () {
+
+    it('should resolve dns', function () {
+        assert.ok(dnsSync.resolve('www.paypal.com'));
+        assert.ok(dnsSync.resolve('www.google.com'));
+        assert.ok(dnsSync.resolve('www.yahoo.com'));
+    });
+
+    it('should fail to resolve dns', function () {
+        assert.ok(!dnsSync.resolve('www.paypal.con'));
+        assert.ok(!dnsSync.resolve('www.not-google.first'));
+        assert.ok(!dnsSync.resolve('www.hello-yahoo.next'));
+    });
+});