refactor server tcp handling

- limit on number of tcp connections
- preliminary support for websockets

client.js

@@ -10,6 +10,9 @@ var argv = require('optimist')
         default: 'http://localtunnel.me',
         describe: 'upstream server providing forwarding'
     })
+    .options('subdomain', {
+        describe: 'request this subdomain'
+    })
     .describe('port', 'internal http server port')
     .argv;
 
@@ -29,67 +32,88 @@ var opt = {
 
 var base_uri = 'http://' + opt.host + ':' + opt.port + opt.path;
 
-var internal;
+var prev_id = argv.subdomain || '';
-var upstream;
-var prev_id;
 
 (function connect_proxy() {
     opt.uri = base_uri + ((prev_id) ? prev_id : '?new');
 
     request(opt, function(err, res, body) {
         if (err) {
-            console.error('upstream not available: %s', err.message);
+            console.error('tunnel server not available: %s, retry 1s', err.message);
-            return process.exit(-1);
+
+            // retry interval for id request
+            return setTimeout(function() {
+                connect_proxy();
+            }, 1000);
         }
 
         // our assigned hostname and tcp port
         var port = body.port;
         var host = opt.host;
+        var max_conn = body.max_conn_count || 1;
 
         // store the id so we can try to get the same one
         prev_id = body.id;
 
         console.log('your url is: %s', body.url);
 
-        // connect to remote tcp server
+        var count = 0;
-        upstream = net.createConnection(port, host);
 
-        // reconnect internal
+        // open 5 connections to the localtunnel server
-        connect_internal();
+        // allows for resources to be served faster
-
+        for (var count = 0 ; count < max_conn ; ++count) {
-        upstream.on('end', function() {
+            var upstream = duplex(port, host, local_port, 'localhost');
-            console.log('> upstream connection terminated');
+            upstream.once('end', function() {
-
+                // all upstream connections have been closed
-            // sever connection to internal server
+                if (--count <= 0) {
-            // on reconnect we will re-establish
+                    connect_proxy();
-            internal.end();
+                }
-
+            });
-            setTimeout(function() {
+        }
-                connect_proxy();
-            }, 1000);
-        });
     });
 })();
 
-function connect_internal() {
+function duplex(port, host, local_port, local_host) {
 
-    internal = net.createConnection(local_port);
+    // connect to remote tcp server
-    internal.on('error', function(err) {
+    var upstream = net.createConnection(port, host);
-        console.log('error connecting to local server. retrying in 1s');
+    var internal = net.createConnection(local_port, local_host);
 
-        setTimeout(function() {
+    // when upstream connection is closed, close other associated connections
-            connect_internal();
+    upstream.on('end', function() {
-        }, 1000);
+        console.log('> upstream connection terminated');
+
+        // sever connection to internal server
+        // on reconnect we will re-establish
+        internal.end();
     });
 
-    internal.on('end', function() {
+    upstream.on('error', function(err) {
-        console.log('disconnected from local server. retrying in 1s');
+        console.error(err);
-        setTimeout(function() {
-            connect_internal();
-        }, 1000);
     });
 
-    upstream.pipe(internal);
+    (function connect_internal() {
-    internal.pipe(upstream);
+
+        //internal = net.createConnection(local_port);
+        internal.on('error', function(err) {
+            console.log('error connecting to local server. retrying in 1s');
+            setTimeout(function() {
+                connect_internal();
+            }, 1000);
+        });
+
+        internal.on('end', function() {
+            console.log('disconnected from local server. retrying in 1s');
+            setTimeout(function() {
+                connect_internal();
+            }, 1000);
+        });
+
+        upstream.pipe(internal);
+        internal.pipe(upstream);
+    })();
+
+    return upstream;
 }
 
+

lib/rand_id.js

@@ -0,0 +1,12 @@
+
+var chars = 'abcdefghiklmnopqrstuvwxyz';
+module.exports = function rand_id() {
+    var randomstring = '';
+    for (var i=0; i<4; ++i) {
+        var rnum = Math.floor(Math.random() * chars.length);
+        randomstring += chars[rnum];
+    }
+
+    return randomstring;
+}
+

server.js

@@ -3,47 +3,24 @@
 var http = require('http');
 var net = require('net');
 var url = require('url');
-var FreeList = require('freelist').FreeList;
-
-var argv = require('optimist')
-    .usage('Usage: $0 --port [num]')
-    .options('port', {
-        default: '80',
-        describe: 'listen on this port for outside requests'
-    })
-    .argv;
-
-if (argv.help) {
-    require('optimist').showHelp();
-    process.exit();
-}
 
 // here be dragons
 var HTTPParser = process.binding('http_parser').HTTPParser;
 var ServerResponse = http.ServerResponse;
 var IncomingMessage = http.IncomingMessage;
 
+// vendor
 var log = require('book');
 
-var chars = 'abcdefghiklmnopqrstuvwxyz';
+// local
-function rand_id() {
+var rand_id = require('./lib/rand_id');
-    var randomstring = '';
-    for (var i=0; i<4; ++i) {
-        var rnum = Math.floor(Math.random() * chars.length);
-        randomstring += chars[rnum];
-    }
-
-    return randomstring;
-}
 
 var server = http.createServer();
 
 // id -> client http server
 var clients = {};
 
-// id -> list of sockets waiting for a valid response
+// available parsers
-var wait_list = {};
-
 var parsers = http.parsers;
 
 // data going back to a client (the last client that made a request)
@@ -52,23 +29,26 @@ function socketOnData(d, start, end) {
     var socket = this;
     var req = this._httpMessage;
 
-    var current = clients[socket.subdomain].current;
+    var response_socket = socket.respond_socket;
-
+    if (!response_socket) {
-    if (!current) {
+        log.error('no response socket assigned for http response from backend');
-        log.error('no current for http response from backend');
         return;
     }
 
-    // send the goodies
+    // pass the response from our client back to the requesting socket
-    current.write(d.slice(start, end));
+    response_socket.write(d.slice(start, end));
 
-    // invoke parsing so we know when all the goodies have been sent
+    if (socket.for_websocket) {
-    var parser = current.out_parser;
+        return;
+    }
+
+    // invoke parsing so we know when the response is complete
+    var parser = response_socket.out_parser;
     parser.socket = socket;
 
     var ret = parser.execute(d, start, end - start);
     if (ret instanceof Error) {
-        debug('parse error');
+        log.error(ret);
         freeParser(parser, req);
         socket.destroy(ret);
     }
@@ -99,83 +79,103 @@ server.on('connection', function(socket) {
 
     var self = this;
 
-    var for_client = false;
+    // parser handles incoming requests for the socket
-    var client_id;
+    // the request is what lets us know if we proxy or not
-
-    var request;
-
     var parser = parsers.alloc();
     parser.socket = socket;
     parser.reinitialize(HTTPParser.REQUEST);
 
+    function our_request(req) {
+        var res = new ServerResponse(req);
+        res.assignSocket(socket);
+        self.emit('request', req, res);
+        return;
+    }
+
     // a full request is complete
     // we wait for the response from the server
     parser.onIncoming = function(req, shouldKeepAlive) {
 
         log.trace('request', req.url);
-        request = req;
 
-        for_client = false;
+        // default is that the data is not for the client
+        delete parser.sock;
+        delete parser.buffer;
+        delete parser.client;
 
         var hostname = req.headers.host;
-
         if (!hostname) {
             log.trace('no hostname: %j', req.headers);
-            // normal processing if not proxy
+            return our_request(req);
-            var res = new ServerResponse(req);
-
-            // TODO(shtylman) skip favicon for now, it caused problems
-            if (req.url === '/favicon.ico') {
-                return;
-            }
-
-            res.assignSocket(parser.socket);
-            self.emit('request', req, res);
-            return;
         }
 
         var match = hostname.match(/^([a-z]{4})[.].*/);
-
         if (!match) {
-            // normal processing if not proxy
+            return our_request(req);
-            var res = new ServerResponse(req);
+        }
 
-            // TODO(shtylman) skip favicon for now, it caused problems
+        var client_id = match[1];
-            if (req.url === '/favicon.ico') {
+        var client = clients[client_id];
-                return;
-            }
 
-            res.assignSocket(parser.socket);
+        // requesting a subdomain that doesn't exist
-            self.emit('request', req, res);
+        if (!client) {
+            return socket.end();
+        }
+
+        parser.client = client;
+
+        // assigned socket for the client
+        var sock = client.sockets.shift();
+
+        // no free sockets, queue
+        if (!sock) {
+            parser.buffer = true;
             return;
         }
 
-        client_id = match[1];
+        // for tcp proxying
-        for_client = true;
+        parser.sock = sock;
+
+        // set who we will respond back to
+        sock.respond_socket = socket;
 
         var out_parser = parsers.alloc();
         out_parser.reinitialize(HTTPParser.RESPONSE);
         socket.out_parser = out_parser;
 
-        // we have a response
+        // we have completed a response
-        out_parser.onIncoming = function(res) {
+        // the tcp socket is free again
+        out_parser.onIncoming = function (res) {
             res.on('end', function() {
                 log.trace('done with response for: %s', req.url);
 
                 // done with the parser
                 parsers.free(out_parser);
 
-                var next = wait_list[client_id].shift();
+                // unset the response
-
+                delete sock.respond_socket;
-                clients[client_id].current = next;
 
+                var next = client.waiting.shift();
                 if (!next) {
+                    // return socket to available
+                    client.sockets.push(sock);
                     return;
                 }
 
-                // write original bytes that we held cause client was busy
+                // reuse avail socket for next connection
-                clients[client_id].write(next.queue);
+                sock.respond_socket = next;
+
+                // needed to know when this response will be done
+                out_parser.reinitialize(HTTPParser.RESPONSE);
+                next.out_parser = out_parser;
+
+                // write original bytes we held cause we were busy
+                sock.write(next.queue);
+
+                // continue with other bytes
                 next.resume();
+
+                return;
             });
         };
     };
@@ -183,68 +183,87 @@ server.on('connection', function(socket) {
     // process new data on the client socket
     // we may need to forward this it the backend
     socket.ondata = function(d, start, end) {
+
+        // run through request parser to determine if we should pass to tcp
+        // onIncoming will be run before this returns
         var ret = parser.execute(d, start, end - start);
 
         // invalid request from the user
         if (ret instanceof Error) {
-            debug('parse error');
+            log.error(ret);
             socket.destroy(ret);
             return;
         }
 
-        // only write data if previous request to this client is done?
+        // websocket stuff
-        log.trace('%s %s', parser.incoming && parser.incoming.upgrade, for_client);
-
-        // what if the subdomains are treated differently
-        // as individual channels to the backend if available?
-        // how can I do that?
-
         if (parser.incoming && parser.incoming.upgrade) {
-            // websocket shit
+            log.trace('upgrade request');
-        }
 
-        // wtf do you do with upgraded connections?
+            parser.finish();
 
-        // forward the data to the backend
+            var hostname = parser.incoming.headers.host;
-        if (for_client) {
+
+            var match = hostname.match(/^([a-z]{4})[.].*/);
+            if (!match) {
+                return our_request(req);
+            }
+
+            var client_id = match[1];
             var client = clients[client_id];
 
-            // requesting a subdomain that doesn't exist
+            var sock = client.sockets.shift();
-            if (!client) {
+            sock.respond_socket = socket;
-                return;
+            sock.for_websocket = true;
+
+            socket.ondata = function(d, start, end) {
+                sock.write(d.slice(start, end));
+            };
+
+            socket.end = function() {
+                log.trace('websocket end');
+
+                delete sock.respond_socket;
+                client.sockets.push(sock);
             }
 
-            // if the client is already processing something
+            sock.write(d.slice(start, end));
-            // then new connections need to go into pause mode
-            // and when they are revived, then they can send data along
-            if (client.current && client.current !== socket) {
-                log.trace('pausing', request.url);
-                // prevent new data from gathering for this connection
-                // we are waiting for a response to a previous request
-                socket.pause();
 
-                var copy = Buffer(end - start);
+            return;
-                d.copy(copy, 0, start, end);
-                socket.queue = copy;
-
-                wait_list[client_id].push(socket);
-
-                return;
-            }
-
-            // this socket needs to receive responses
-            client.current = socket;
-
-            // send through tcp tunnel
-            client.write(d.slice(start, end));
         }
+
+        // if no available socket, buffer the request for later
+        if (parser.buffer) {
+
+            // pause any further data on this socket
+            socket.pause();
+
+            // copy the current data since we have already received it
+            var copy = Buffer(end - start);
+            d.copy(copy, 0, start, end);
+            socket.queue = copy;
+
+            // add socket to queue
+            parser.client.waiting.push(socket);
+
+            return;
+        }
+
+        if (!parser.sock) {
+            return;
+        }
+
+        // assert, respond socket should be set
+
+        // send through tcp tunnel
+        // responses will go back to the respond_socket
+        parser.sock.write(d.slice(start, end));
     };
 
     socket.onend = function() {
         var ret = parser.finish();
 
         if (ret instanceof Error) {
-            log.trace('parse error');
+            log.error(ret);
             socket.destroy(ret);
             return;
         }
@@ -271,8 +290,12 @@ server.on('request', function(req, res) {
     if (req.url === '/' && !parsed.query.new) {
         res.writeHead(301, { Location: 'http://shtylman.github.com/localtunnel/' });
         res.end();
+        return;
     }
 
+    // at this point, the client is requesting a new tunnel setup
+    // either generate an id or use the one they requested
+
     var match = req.url.match(/\/([a-z]{4})?/);
 
     // user can request a particular set of characters
@@ -285,17 +308,17 @@ server.on('request', function(req, res) {
     }
 
     var id = requested_id || rand_id();
-    if (wait_list[id]) {
-        // new id
-        id = rand_id();
-    }
 
-    // generate new shit for client
+    // maximum number of tcp connections the client can setup
-    if (wait_list[id]) {
+    // each tcp channel allows for more parallel requests
-        wait_list[id].forEach(function(waiting) {
+    var max_tcp_sockets = 4;
-            waiting.end();
+
-        });
+    // sockets is a list of available sockets for the connection
-    }
+    // waiting is?
+    var client = clients[id] = {
+        sockets: [],
+        waiting: []
+    };
 
     var client_server = net.createServer();
     client_server.listen(function() {
@@ -305,7 +328,12 @@ server.on('request', function(req, res) {
         var url = 'http://' + id + '.' + req.headers.host;
 
         res.writeHead(200, { 'Content-Type': 'application/json' });
-        res.end(JSON.stringify({ url: url, id: id, port: port }));
+        res.end(JSON.stringify({
+            url: url,
+            id: id,
+            port: port,
+            max_conn_count: max_tcp_sockets
+        }));
     });
 
     // user has 5 seconds to connect before their slot is given up
@@ -313,31 +341,50 @@ server.on('request', function(req, res) {
         client_server.close();
     }, 5000);
 
+    // no longer accepting connections for this id
+    client_server.on('close', function() {
+        delete clients[id];
+    });
+
+    var count = 0;
     client_server.on('connection', function(socket) {
 
-        // who the info should route back to
+        // no more socket connections allowed
-        socket.subdomain = id;
+        if (count++ >= max_tcp_sockets) {
+            return socket.end();
+        }
+
+        log.trace('new connection for id: %s', id);
 
         // multiplexes socket data out to clients
         socket.ondata = socketOnData;
 
+        // no need to close the client server
         clearTimeout(conn_timeout);
 
-        log.trace('new connection for id: %s', id);
+        // add socket to pool for this id
-        clients[id] = socket;
+        var idx = client.sockets.push(socket) - 1;
-        wait_list[id] = [];
 
-        socket.on('end', function() {
+        socket.on('close', function(had_error) {
-            delete clients[id];
+            count--;
+            client.sockets.splice(idx, 1);
+
+            // no more sockets for this ident
+            if (client.sockets.length === 0) {
+                delete clients[id];
+            }
+        });
+
+        // close will be emitted after this
+        socket.on('error', function(err) {
+            log.error(err);
         });
     });
 
-    client_server.on('err', function(err) {
+    client_server.on('error', function(err) {
         log.error(err);
     });
 });
 
-server.listen(argv.port, function() {
+module.exports = server;
-    log.info('server listening on port: %d', server.address().port);
-});