From f945f0b4961aed3f411804d925227ace7f7b0576 Mon Sep 17 00:00:00 2001
From: tigerbot <seth.gibelyou@daplie.com>
Date: Fri, 8 Sep 2017 10:54:47 -0600
Subject: [PATCH] implemented throttling when we buffer too much data

---
 bin/stunnel.js |   6 +-
 wsclient.js    | 179 +++++++++++++++++++++++++++++++++----------------
 2 files changed, 126 insertions(+), 59 deletions(-)

diff --git a/bin/stunnel.js b/bin/stunnel.js
index fc0c5b6..9261807 100755
--- a/bin/stunnel.js
+++ b/bin/stunnel.js
@@ -8,6 +8,9 @@ var program = require('commander');
 var url = require('url');
 var stunnel = require('../wsclient.js');
 
+var domainsMap = {};
+var services = {};
+
 function collectDomains(val, memo) {
   var vals = val.split(/,/g);
 
@@ -237,9 +240,6 @@ function daplieTunnel() {
   });
 }
 
-var domainsMap = {};
-var services = {};
-
 program.locals = (program.locals || []).concat(program.domains || []);
 program.locals.forEach(function (proxy) {
   // Create a map from which we can derive a list of all domains we want forwarded to us.
diff --git a/wsclient.js b/wsclient.js
index 6fb7503..ce59518 100644
--- a/wsclient.js
+++ b/wsclient.js
@@ -28,15 +28,60 @@ function run(copts) {
   var authenticated = false;
 
   var localclients = {};
+  var pausedClients = [];
   var clientHandlers = {
-    onClose: function (cid, opts, err) {
-      wsHandlers.sendMessage(Packer.pack(opts, null, err && 'error' || 'end'));
-      delete localclients[cid];
-      console.log('[local onClose] closed "' + cid + '" (' + clientHandlers.count() + ' clients)');
+    add: function (conn, cid, opts, servername) {
+      localclients[cid] = conn;
+      console.info("[connect] new client '" + cid + "' for '" + servername + "' (" + clientHandlers.count() + " clients)");
+
+      conn.on('data', function onLocalData(chunk) {
+        if (conn.tunnelClosing) {
+          console.warn("[onLocalData] received data for '"+cid+"' over socket after connection was ended");
+          return;
+        }
+
+        // If we have a lot of buffered data waiting to be sent over the websocket we want to slow
+        // down the data we are getting to send over. We also want to pause all active connections
+        // if any connections are paused to make things more fair so one connection doesn't get
+        // stuff waiting for all other connections to finish because it tried writing near the border.
+        var bufSize = wsHandlers.sendMessage(Packer.pack(opts, chunk));
+        if (pausedClients.length || bufSize > 1024*1024) {
+          console.log('paused connection', cid, 'to allow websocket to catch up');
+          conn.pause();
+          pausedClients.push(conn);
+        }
+      });
+      conn.on('error', function onLocalError(err) {
+        console.info("[onLocalError] connection '" + cid + "' errored:", err);
+        // The 'close' event should fire soon, so let that send on the websocket
+      });
+      conn.on('close', function onLocalClose(hadErr) {
+        delete localclients[cid];
+        console.log('[onLocalClose] closed "' + cid + '" (' + clientHandlers.count() + ' clients)');
+        wsHandlers.sendMessage(Packer.pack(opts, null, hadErr && 'error' || 'end'));
+      });
     }
-  , onError: function(cid, opts, err) {
-      console.info("[local onError] closing '" + cid + "' because '" + err.message + "'");
-      clientHandlers.onClose(cid, opts, err);
+
+  , write: function (cid, opts) {
+      var conn = localclients[cid];
+      if (!conn) {
+        return false;
+      }
+      //console.log("[=>] received data from '" + cid + "' =>", opts.data.byteLength);
+
+      if (conn.tunnelClosing) {
+        console.warn("[onmessage] received data for '"+cid+"' over socket after connection was ended");
+        return true;
+      }
+
+      conn.write(opts.data);
+      if (conn.bufferSize > 1024*1024) {
+        wsHandlers.sendMessage(Packer.pack(opts, null, 'pause'));
+        conn.once('drain', function () {
+          wsHandlers.sendMessage(Packer.pack(opts, null, 'resume'));
+        });
+      }
+      return true;
     }
 
   , closeSingle: function (cid) {
@@ -45,29 +90,39 @@ function run(copts) {
       }
 
       console.log('[closeSingle]', cid);
-      PromiseA.resolve()
-        .then(function () {
-          localclients[cid].end();
+      PromiseA.resolve().then(function () {
+        var conn = localclients[cid];
+        conn.tunnelClosing = true;
+        conn.end();
+
+        // If no data is buffered for writing then we don't need to wait for it to drain.
+        if (!conn.bufferSize) {
           return timeoutPromise(500);
-        })
-        .then(function () {
-          if (localclients[cid]) {
-            console.warn('[closeSingle]', cid, 'connection still present after calling `end`');
-            localclients[cid].destroy();
-            return timeoutPromise(500);
-          }
-        })
-        .then(function () {
-          if (localclients[cid]) {
-            console.error('[closeSingle]', cid, 'connection still present after calling `destroy`');
-            delete localclients[cid];
-          }
-        })
-        .catch(function (err) {
-          console.error('[closeSingle] failed to close connection', cid, err.toString());
+        }
+        // Otherwise we want the connection to be able to finish, but we also want to impose
+        // a time limit for it to drain, since it shouldn't have more than 1MB buffered.
+        return new PromiseA(function (resolve) {
+          var timeoutId = setTimeout(resolve, 60*1000);
+          conn.once('drain', function () {
+            clearTimeout(timeoutId);
+            setTimeout(resolve, 500);
+          });
+        });
+      }).then(function () {
+        if (localclients[cid]) {
+          console.warn('[closeSingle]', cid, 'connection still present after calling `end`');
+          localclients[cid].destroy();
+          return timeoutPromise(500);
+        }
+      }).then(function () {
+        if (localclients[cid]) {
+          console.error('[closeSingle]', cid, 'connection still present after calling `destroy`');
           delete localclients[cid];
-        })
-        ;
+        }
+      }).catch(function (err) {
+        console.error('[closeSingle] failed to close connection', cid, err.toString());
+        delete localclients[cid];
+      });
     }
   , closeAll: function () {
       console.log('[closeAll]');
@@ -169,6 +224,7 @@ function run(copts) {
 
       wsHandlers.sendMessage(Packer.pack(null, [-cmd[0], err], 'control'));
     }
+
   , onmessage: function (opts) {
       var net = copts.net || require('net');
       var cid = Packer.addrToId(opts);
@@ -179,9 +235,7 @@ function run(copts) {
       var str;
       var m;
 
-      if (localclients[cid]) {
-        //console.log("[=>] received data from '" + cid + "' =>", opts.data.byteLength);
-        localclients[cid].write(opts.data);
+      if (clientHandlers.write(cid, opts)) {
         return;
       }
       if (!portList) {
@@ -237,39 +291,39 @@ function run(copts) {
       , remoteAddress: opts.address
       , remotePort: opts.port
       };
-      localclients[cid] = net.createConnection(createOpts, function () {
+      var conn = net.createConnection(createOpts, function () {
         // this will happen before 'data' or 'readable' is triggered
         // We use the data from the createOpts object so that the createConnection function has
         // the oppurtunity of removing/changing it if it wants/needs to handle it differently.
         if (createOpts.data) {
-          localclients[cid].write(createOpts.data);
+          conn.write(createOpts.data);
         }
       });
-      console.info("[connect] new client '" + cid + "' for '" + servername + "' (" + clientHandlers.count() + " clients)");
 
-      localclients[cid].on('readable', function (size) {
-        var chunk;
-
-        if (!localclients[cid]) {
-          console.error("[error] localclients[cid]", cid);
-          return;
-        }
-        if (!localclients[cid].read) {
-          console.error("[error] localclients[cid].read", cid);
-          console.log(localclients[cid]);
-          return;
-        }
-
-        do {
-          chunk = localclients[cid].read(size);
-          if (chunk) {
-            wsHandlers.sendMessage(Packer.pack(opts, chunk));
-          }
-        } while (chunk);
-      });
-      localclients[cid].on('error', clientHandlers.onError.bind(null, cid, opts));
-      localclients[cid].on('end',   clientHandlers.onClose.bind(null, cid, opts));
+      clientHandlers.add(conn, cid, opts, servername);
     }
+
+  , onpause: function (opts) {
+      var cid = Packer.addrToId(opts);
+      console.log('[TunnelPause]', cid);
+      if (localclients[cid]) {
+        localclients[cid].manualPause = true;
+        localclients[cid].pause();
+      } else {
+        wsHandlers.sendMessage(Packer.pack(opts, {message: 'no matching connection', code: 'E_NO_CONN'}, 'error'));
+      }
+    }
+  , onresume: function (opts) {
+      var cid = Packer.addrToId(opts);
+      console.log('[TunnelResume]', cid);
+      if (localclients[cid]) {
+        localclients[cid].manualPause = false;
+        localclients[cid].resume();
+      } else {
+        wsHandlers.sendMessage(Packer.pack(opts, {message: 'no matching connection', code: 'E_NO_CONN'}, 'error'));
+      }
+    }
+
   , onend: function (opts) {
       var cid = Packer.addrToId(opts);
       //console.log("[end] '" + cid + "'");
@@ -280,6 +334,7 @@ function run(copts) {
       //console.log("[error] '" + cid + "'", opts.code || '', opts.message);
       clientHandlers.closeSingle(cid);
     }
+
   , _onConnectError: function (cid, opts, err) {
       console.info("[_onConnectError] opening '" + cid + "' failed because " + err.message);
       wsHandlers.sendMessage(Packer.pack(opts, null, 'error'));
@@ -330,6 +385,17 @@ function run(copts) {
       console.info("[open] connected to '" + copts.stunneld + "'");
       wsHandlers.refreshTimeout();
       timeoutId = setTimeout(wsHandlers.checkTimeout, activityTimeout);
+
+      wstunneler._socket.on('drain', function () {
+        pausedClients.forEach(function (conn) {
+          if (!conn.manualPause) {
+            console.log('resuming connection', conn.tunnelCid, 'now the websocket has caught up');
+            conn.resume();
+          }
+        });
+
+        pausedClients.length = 0;
+      });
     }
 
   , onClose: function () {
@@ -363,6 +429,7 @@ function run(copts) {
       if (wstunneler) {
         try {
           wstunneler.send(msg, {binary: true});
+          return wstunneler._socket.bufferSize;
         } catch (err) {
           // There is a chance that this occurred after the websocket was told to close
           // and before it finished, in which case we don't need to log the error.