Initial release

.travis.yml

@@ -0,0 +1,15 @@
+language: node_js
+node_js:
+  - "4"
+
+node_js:
+  - stable
+
+install:
+  - npm install
+
+script:
+  - npm run cover
+
+# Send coverage data to Coveralls
+after_script: "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"

README.md

@@ -1,2 +1,35 @@
 # googlebot-verify
-Verify that a request is from Google using Google's DNS verification steps
+[![Build Status](https://travis-ci.org/jcowley/googlebot-verify.svg?branch=master)](https://travis-ci.org/jcowley/googlebot-verify)
+[![Coverage Status](https://coveralls.io/repos/github/jcowley/googlebot-verify/badge.svg?branch=master)](https://coveralls.io/github/jcowley/googlebot-verify?branch=master)
+## Synopsis
+
+Verify that an IP address is from Google using Google's recommended DNS verification steps.
+
+## Motivation
+
+You may wish to verify that a web crawler accessing your server is Googlebot (or another Google user-agent) and not spammers or other bots scraping your site while claiming to be Googlebot. Since you cannot rely on the `User-Agent` header which is easily spoofed, you need to use DNS look up to verify that the IP address belongs to Google. 
+
+This library implements Google's own verification steps outlined here: https://support.google.com/webmasters/answer/80553?hl=en
+
+## Code Example
+
+Usage in an express application:
+
+```javascript
+  const isGoogle = require('googlebot-verify');
+  const ipAddress = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
+  if (isGoogle(ipAddress)) {
+    ...
+```
+
+## Installation
+
+`npm install googlebot-verify`
+
+## Tests
+
+`npm test`
+
+## License
+
+[MIT](https://github.com/pillarjs/parseurl/blob/master/LICENSE)

index.js

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+'use strict';
+const dns = require('dns');
+const url = require('url');
+
+module.exports = (ip, callback) => {
+  callback = callback || function () {}
+
+  return new Promise(function (resolve, reject) {
+
+    dns.reverse(ip, (error, hosts) => {
+      if (error) {
+        reject(error);
+        return callback(error);
+      }
+
+      const tld = hosts[0] && hosts[0].split('.').slice(-2, -1)[0];
+      if (tld !== "google" && tld !== "googlebot") {
+        resolve(false);
+        return callback(null, false);
+      }
+
+      dns.lookup(hosts[0], (error, address) => {
+        const match = address === ip;
+        resolve(match);
+        return callback(error, match);
+      });
+    });
+  });
+}