implemented UDP forwarding for DNS

bin/goldilocks.js

@@ -61,6 +61,9 @@ function readConfigAndRun(args) {
       );
     }
   }
+  if (!config.dns) {
+    config.dns = { proxy: { port: 3053 } };
+  }
   if (!config.tcp) {
     config.tcp = {};
   }
@@ -116,24 +119,63 @@ function readConfigAndRun(args) {
   config.addresses = addresses;
   config.device = { hostname: 'daplien-pod' };
 
+  var PromiseA = require('bluebird');
+  var tcpProm, dnsProm;
+
   if (config.tcp.ports) {
-    run(config);
-    return;
+    tcpProm = PromiseA.resolve();
+  } else {
+    tcpProm = new PromiseA(function (resolve, reject) {
+      require('../lib/check-ports').checkTcpPorts(function (failed, bound) {
+        config.tcp.ports = Object.keys(bound);
+        if (config.tcp.ports.length) {
+          resolve();
+        } else {
+          reject(failed);
+        }
+      });
+    });
   }
 
-  require('../lib/check-ports.js').checkPorts(config, function (failed, bound) {
-    config.tcp.ports = Object.keys(bound);
+  if (config.dns.bind) {
+    dnsProm = PromiseA.resolve();
+  } else {
+    dnsProm = new PromiseA(function (resolve) {
+      require('../lib/check-ports').checkUdpPorts(function (failed, bound) {
+        var ports = Object.keys(bound);
 
-    if (!config.tcp.ports.length) {
+        if (ports.length === 0) {
+          // I don't think we want to prevent the rest of the app from running in
+          // this case like we do for TCP, do don't call reject.
+          console.warn('could not bind to the desired ports for DNS');
+          Object.keys(failed).forEach(function (key) {
+            console.log('[error bind]', key, failed[key].code);
+          });
+        }
+        else if (ports.length === 1) {
+          config.dns.bind = parseInt(ports[0], 10);
+        }
+        else {
+          config.dns.bind = ports.map(function (numStr) {
+            return parseInt(numStr, 10);
+          });
+        }
+
+        resolve();
+      });
+    });
+  }
+
+  PromiseA.all([tcpProm, dnsProm])
+    .then(function () {
+      run(config);
+    })
+    .catch(function (failed) {
       console.warn("could not bind to the desired ports");
       Object.keys(failed).forEach(function (key) {
         console.log('[error bind]', key, failed[key].code);
       });
-      return;
-    }
-
-    run(config);
-  });
+    });
 }
 
 function readEnv(args) {

lib/check-ports.js

@@ -11,7 +11,18 @@ function bindTcpAndRelease(port, cb) {
   });
 }
 
-function checkPorts(config, cb) {
+function bindUdpAndRelease(port, cb) {
+  var socket = require('dgram').createSocket('udp4');
+  socket.on('error', function (e) {
+    cb(e);
+  });
+  socket.bind(port, function () {
+    socket.close();
+    cb();
+  });
+}
+
+function checkTcpPorts(cb) {
   var bound = {};
   var failed = {};
 
@@ -32,7 +43,6 @@ function checkPorts(config, cb) {
       }
 
       if (bound['80'] && bound['443']) {
-        //config.tcp.ports = [ 80, 443 ];
         cb(null, bound);
         return;
       }
@@ -52,4 +62,34 @@ function checkPorts(config, cb) {
   });
 }
 
-module.exports.checkPorts = checkPorts;
+function checkUdpPorts(cb) {
+  var bound = {};
+  var failed = {};
+
+  bindUdpAndRelease(53, function (e) {
+    if (e) {
+      failed[53] = e;
+    } else {
+      bound[53] = true;
+    }
+
+    if (bound[53]) {
+      cb(null, bound);
+      return;
+    }
+
+    console.warn("default DNS port 53 not available, trying 8053");
+    bindUdpAndRelease(8053, function (e) {
+      if (e) {
+        failed[8053] = e;
+      } else {
+        bound[8053] = true;
+      }
+
+      cb(null, bound);
+    });
+  });
+}
+
+module.exports.checkTcpPorts = checkTcpPorts;
+module.exports.checkUdpPorts = checkUdpPorts;

lib/goldilocks.js

@@ -236,6 +236,12 @@ module.exports.create = function (deps, config) {
     });
   }
 
+  function dnsListener(msg) {
+    var dgram = require('dgram');
+    var socket = dgram.createSocket('udp4');
+    socket.send(msg, config.dns.proxy.port, config.dns.proxy.address || '127.0.0.1');
+  }
+
   function approveDomains(opts, certs, cb) {
     // This is where you check your database and associated
     // email addresses with domains and agreements and such
@@ -448,7 +454,19 @@ module.exports.create = function (deps, config) {
     });
   });
 
-  PromiseA.all(config.tcp.ports.map(function (port) {
+  var listenPromises = config.tcp.ports.map(function (port) {
     return listeners.tcp.add(port, netHandler);
-  }));
+  });
+
+  if (config.dns.bind) {
+    if (Array.isArray(config.dns.bind)) {
+      listenPromises = listenPromises.concat(config.dns.bind.map(function (port) {
+        return listeners.udp.add(port, dnsListener);
+      }));
+    } else {
+      listenPromises.push(listeners.udp.add(config.dns.bind, dnsListener));
+    }
+  }
+
+  return PromiseA.all(listenPromises);
 };