add tcp support

README.md

@@ -89,6 +89,8 @@ Options
 +time=<seconds>             Sets the timeout for a query in seconds.
 +norecurse                  Set `ra` flag to 0. Do not perform recursion.
 +aaonly                     Set `aa` flag to 1. Do not respond with non-authoritative responses.
++notcp                      Disable TCP server (default in v1.2)
++tcp                        Enable TCP server (default in v1.3)
 
 --debug                     verbose output
 ```

bin/digd.js

@@ -5,9 +5,7 @@
 var cli = require('cli');
 var pkg = require('../package.json');
 var dig = require('dig.js/dns-request');
-var dgram = require('dgram');
 var dnsjs = require('dns-suite');
-var crypto = require('crypto');
 var common = require('dig.js/common');
 var defaultNameservers = require('dns').getServers();
 var hexdump;
@@ -49,8 +47,32 @@ cli.main(function (args, cli) {
       cli.norecurse = true;
       return;
     }
+    if (arg === '+notcp') {
+      if (cli.notcp) {
+        console.error("'+notcp' was specified more than once");
+        process.exit(1);
+        return;
+      }
+      cli.notcp = true;
+      return;
+    }
+    if (arg === '+tcp') {
+      if (cli.tcp) {
+        console.error("'+tcp' was specified more than once");
+        process.exit(1);
+        return;
+      }
+      cli.tcp = true;
+      return;
+    }
   });
 
+  if (!cli.tcp) {
+    if (!cli.notcp) {
+      console.info("[WARNING] Set '+notcp' to disable tcp connections. The default behavior changes to +tcp in v1.3");
+    }
+  }
+
   if (cli.mdns) {
     if (!cli.type) {
       cli.type = cli.t = 'PTR';
@@ -73,32 +95,10 @@ cli.main(function (args, cli) {
     }
   }
 
-  var handlers = {};
+  var dnsd = {};
-  var server = dgram.createSocket({
+  dnsd.onMessage = function (nb, cb) {
-    type: cli.udp6 ? 'udp6' : 'udp4'
+    var byteOffset = nb._dnsByteOffset || nb.byteOffset;
-  , reuseAddr: true
+    var queryAb = nb.buffer.slice(byteOffset, byteOffset + nb.byteLength);
-  });
-  server.bind({
-    port: cli.port
-  , address: cli.address
-  });
-
-  handlers.onError = function (err) {
-    if ('EACCES' === err.code) {
-      console.error("");
-      console.error("EACCES: Couldn't bind to port. You probably need to use sudo, authbind, or setcap.");
-      console.error("");
-      process.exit(123);
-      return;
-    }
-    console.error("error:", err.stack);
-    server.close();
-  };
-
-  handlers.onMessage = function (nb, rinfo) {
-    console.log('[DEBUG] got a message');
-
-    var queryAb = nb.buffer.slice(nb.byteOffset, nb.byteOffset + nb.byteLength);
     var query;
     var count;
 
@@ -215,12 +215,11 @@ cli.main(function (args, cli) {
         console.error("Could not write empty DNS response");
         console.error(e);
         console.error(emptyResp);
+        cb(e, null, '[DEV] response sent (empty)');
         return;
       }
 
-      server.send(newAb, rinfo.port, rinfo.address, function () {
+      cb(null, newAb, '[DEV] response sent (empty)');
-        console.log('[DEV] response sent (empty)', rinfo.port, rinfo.address);
-      });
     }
 
     function sendResponse(newPacket) {
@@ -232,12 +231,11 @@ cli.main(function (args, cli) {
         console.error("Could not write DNS response from local");
         console.error(e);
         console.error(newPacket);
+        cb(e, null, '[DEV] response sent (local query)');
         return;
       }
 
-      server.send(newAb, rinfo.port, rinfo.address, function () {
+      cb(null, newAb, '[DEV] response sent (local query)');
-        console.log('[DEV] response sent (local query)', rinfo.port, rinfo.address);
-      });
     }
 
     function recurse() {
@@ -290,12 +288,11 @@ cli.main(function (args, cli) {
             } catch(e) {
               console.error("Could not write DNS response");
               console.error(newResponse);
+              cb(e, null, '[DEV] response sent');
               return;
             }
 
-            server.send(newAb, rinfo.port, rinfo.address, function () {
+            cb(null, newAb, '[DEV] response sent');
-              console.log('[DEV] response sent', rinfo.port, rinfo.address);
-            });
           }
         }
 
@@ -335,7 +332,8 @@ cli.main(function (args, cli) {
               console.log('request sent to', res.nameserver);
             }
             */
-            console.log('[DEV] query sent (recurse)', rinfo.port, rinfo.address);
+            //console.log('[DEV] query sent (recurse)', rinfo.port, rinfo.address);
+            //dnsd.onSent('[DEV] query sent (recurse)');
           }
         , onTimeout: function (res) {
             console.log(";; [" + q.name + "] connection timed out; no servers could be reached");
@@ -393,32 +391,24 @@ cli.main(function (args, cli) {
       return;
     }
     require('../lib/digd.js').query(engine, query, respondWithResults);
-
   };
 
-  handlers.onListening = function () {
+  cli.defaultNameservers = defaultNameservers;
-    /*jshint validthis:true*/
+  require('../lib/udpd.js').create(cli, dnsd).on('listening', function () {
-    var server = this;
     cli.chosenNameserver = cli.nameserver;
     var index;
 
     if (!cli.chosenNameserver) {
-      index = crypto.randomBytes(2).readUInt16BE(0) % defaultNameservers.length;
+      index = require('crypto').randomBytes(2).readUInt16BE(0) % cli.defaultNameservers.length;
-      cli.chosenNameserver = defaultNameservers[index];
+      cli.chosenNameserver = cli.defaultNameservers[index];
       if (cli.debug) {
-        console.log('index, defaultNameservers', index, defaultNameservers);
+        console.log('index, defaultNameservers', index, cli.defaultNameservers);
       }
     }
-
+  });
-    if (cli.mdns || '224.0.0.251' === cli.nameserver) {
+  if (cli.tcp /* TODO v1.3 !cli.notcp */) {
-      server.setBroadcast(true);
+    require('../lib/tcpd.js').create(cli, dnsd);
-      server.addMembership(cli.nameserver);
+  }
-    }
-
-    console.log('');
-    console.log('Bound and Listening:');
-    console.log(server.address().address + '#' + server.address().port + ' (' + server.type + ')');
-  };
 
   console.log('');
   if (!cli.nocmd) {
@@ -426,7 +416,4 @@ cli.main(function (args, cli) {
     console.log(';; global options: +cmd');
   }
 
-  server.on('error', handlers.onError);
-  server.on('message', handlers.onMessage);
-  server.on('listening', handlers.onListening);
 });

lib/tcpd.js

@@ -0,0 +1,70 @@
+'use strict';
+
+module.exports.create = function (cli, dnsd) {
+  function runTcp() {
+    var tcpServer = require('net').createServer({ }, function (c) {
+      c.on('error', function (err) {
+        console.warn("TCP Connection Error:");
+        console.warn(err);
+      });
+      c.on('data', function (nb) {
+        //console.log('TCP data.length:', nb.length);
+        //console.log(nb.toString('hex'));
+
+        // DNS packets include a 2-byte length header
+        var count = nb.length;
+        var length = nb[0] << 8;
+        length = length | nb[1];
+        count -= 2;
+        // TODO slice?
+        nb._dnsByteOffset = nb.byteOffset + 2;
+
+        if (length !== count) {
+          console.error("Handling TCP packets > 512 bytes not implemented.");
+          c.end();
+          return;
+        }
+
+        // TODO pad two bytes for lengths
+        dnsd.onMessage(nb, function (err, newAb, dbgmsg) {
+          var lenbuf = Buffer.from([ newAb.length >> 8, newAb.length & 255 ]);
+          // TODO XXX generate legit error packet
+          if (err) { console.error("Error", err); c.end(); return; }
+          console.log('TCP ' + dbgmsg);
+
+          c.write(lenbuf);
+          c.end(newAb);
+        });
+      });
+      c.on('end', function () {
+        console.log('TCP client disconnected from server');
+      });
+    });
+
+    tcpServer.on('error', function (err) {
+      if ('EADDRINUSE' === err.code) {
+        console.error("Port '" + cli.port + "' is already in use.");
+        tcpServer.close();
+        process.exit(0);
+      }
+      if ('EACCES' === err.code) {
+        console.error("Could not bind on port '" + cli.port + "': EACCESS (you probably need root permissions)");
+        tcpServer.close();
+        process.exit(0);
+      }
+      console.error("TCP Server Error:");
+      console.error(err);
+      tcpServer.close(function () {
+        setTimeout(runTcp, 1000);
+      });
+    });
+
+    tcpServer.listen(cli.port, function () {
+      console.log('TCP Server bound');
+    });
+
+    return tcpServer;
+  }
+
+  return runTcp();
+};

lib/udpd.js

@@ -0,0 +1,58 @@
+'use strict';
+
+module.exports.create = function (cli, dnsd) {
+  var server = require('dgram').createSocket({
+    type: cli.udp6 ? 'udp6' : 'udp4'
+  , reuseAddr: true
+  });
+  server.bind({
+    port: cli.port
+  , address: cli.address
+  });
+
+  var handlers = {};
+  handlers.onError = function (err) {
+    if ('EACCES' === err.code) {
+      console.error("");
+      console.error("EACCES: Couldn't bind to port. You probably need to use sudo, authbind, or setcap.");
+      console.error("");
+      process.exit(123);
+      return;
+    }
+    console.error("error:", err.stack);
+    server.close();
+  };
+
+  handlers.onMessage = function (nb, rinfo) {
+    //console.log('[DEBUG] got a UDP message', nb.length);
+    //console.log(nb.toString('hex'));
+
+    dnsd.onMessage(nb, function (err, newAb, dbgmsg) {
+      // TODO send legit error message
+      if (err) { server.send(Buffer.from([0x00])); return; }
+      server.send(newAb, rinfo.port, rinfo.address, function () {
+        console.log(dbgmsg, rinfo.port, rinfo.address);
+      });
+    });
+  };
+
+  handlers.onListening = function () {
+    /*jshint validthis:true*/
+    var server = this;
+
+    if (cli.mdns || '224.0.0.251' === cli.nameserver) {
+      server.setBroadcast(true);
+      server.addMembership(cli.nameserver);
+    }
+
+    console.log('');
+    console.log('Bound and Listening:');
+    console.log(server.address().address + '#' + server.address().port + ' (' + server.type + ')');
+  };
+
+  server.on('error', handlers.onError);
+  server.on('message', handlers.onMessage);
+  server.on('listening', handlers.onListening);
+
+  return server;
+};