implemented check for hotel/ISP paywall

packages/apis/com.daplie.goldilocks/index.js

@@ -63,6 +63,81 @@ module.exports.create = function (deps, conf) {
     });
   }
 
+  function checkPaywall() {
+    var PromiseA = require('bluebird');
+    var testDomains = [
+      'daplie.com'
+    , 'duckduckgo.com'
+    , 'google.com'
+    , 'amazon.com'
+    , 'facebook.com'
+    , 'msn.com'
+    , 'yahoo.com'
+    ];
+
+    // While this is not being developed behind a paywall the current idea is that
+    // a paywall will either manipulate DNS queries to point to the paywall gate,
+    // or redirect HTTP requests to the paywall gate. So we check for both and
+    // hope we can detect most hotel/ISP paywalls out there in the world.
+
+    return PromiseA.resolve()
+    .then(function () {
+      var dns = PromiseA.promisifyAll(require('dns'));
+      var proms = testDomains.map(function (dom) {
+        return dns.resolve6Async(dom)
+          .catch(function (err) {
+            if (err.code === 'ENODATA') {
+              return dns.resolve4Async(dom);
+            } else {
+              return PromiseA.reject(err);
+            }
+          })
+          .then(function (result) {
+            return result[0];
+          });
+      });
+
+      return PromiseA.all(proms).then(function (addrs) {
+        var unique = addrs.filter(function (value, ind, self) {
+          return value && self.indexOf(value) === ind;
+        });
+        // It is possible some walls might have exceptions that leave some of the domains
+        // we test alone, so we might have more than one unique address even behind an
+        // active paywall.
+        return unique.length < addrs.length;
+      });
+    })
+    .then(function (paywall) {
+      if (paywall) {
+        return paywall;
+      }
+      var request = deps.request.defaults({
+        followRedirect: false
+      , headers: {
+          connection: 'close'
+        }
+      });
+
+      var proms = testDomains.map(function (dom) {
+        return request('https://'+dom).then(function (resp) {
+          if (resp.statusCode >= 300 && resp.statusCode < 400) {
+            return resp.headers.location;
+          } else {
+            return 'https://'+dom;
+          }
+        });
+      });
+
+      return PromiseA.all(proms).then(function (urls) {
+        var unique = urls.filter(function (value, ind, self) {
+          return value && self.indexOf(value) === ind;
+        });
+        return unique.length < urls.length;
+      });
+    })
+    ;
+  }
+
   return {
     init: function (req, res) {
       if (handleCors(req, res, 'POST')) {
@@ -233,6 +308,22 @@ module.exports.create = function (deps, conf) {
       });
       });
     }
+  , paywall_check: function (req, res) {
+      if (handleCors(req, res, 'GET')) {
+        return;
+      }
+      isAuthorized(req, res, function () {
+        res.setHeader('Content-Type', 'application/json;');
+
+        checkPaywall().then(function (paywall) {
+          res.end(JSON.stringify({paywall: paywall}));
+        }, function (err) {
+          err.message = err.message || err.toString();
+          res.statusCode = 500;
+          res.end(JSON.stringify({error: {message: err.message, code: err.code}}));
+        });
+      });
+    }
   , _api: api
   };
 };