Rate limit Socket IO communication - WIP (#4036)

Includes settings
    Includes i18n
    Includes a nice notification
    Disconnects on rate limit
    Includes feeding into metrics/stats
    Include console warn to server console.

src/locales/en.json

@@ -87,6 +87,9 @@
   "pad.modals.deleted": "Deleted.",
   "pad.modals.deleted.explanation": "This pad has been removed.",
 
+  "pad.modals.rateLimited": "Rate Limited.",
+  "pad.modals.rateLimited.explanation": "You sent too many messages to this pad so it disconnected you.",
+
   "pad.modals.disconnected": "You have been disconnected.",
   "pad.modals.disconnected.explanation": "The connection to the server was lost",
   "pad.modals.disconnected.cause": "The server may be unavailable. Please notify the service administrator if this continues to happen.",

src/node/handler/PadMessageHandler.js

@@ -37,6 +37,12 @@ var channels = require("channels");
 var stats = require('../stats');
 var remoteAddress = require("../utils/RemoteAddress").remoteAddress;
 const nodeify = require("nodeify");
+const { RateLimiterMemory } = require('rate-limiter-flexible');
+
+const rateLimiter = new RateLimiterMemory({
+  points: settings.commitRateLimiting.points,
+  duration: settings.commitRateLimiting.duration
+});
 
 /**
  * A associative array that saves informations about a session
@@ -164,6 +170,19 @@ exports.handleDisconnect = async function(client)
  */
 exports.handleMessage = async function(client, message)
 {
+  var env = process.env.NODE_ENV || 'development';
+
+  if (env === 'production') {
+    try {
+      await rateLimiter.consume(client.handshake.address); // consume 1 point per event from IP
+    }catch(e){
+      console.warn("Rate limited: ", client.handshake.address, " to reduce the amount of rate limiting that happens edit the rateLimit values in settings.json");
+      stats.meter('rateLimited').mark();
+      client.json.send({disconnect:"rateLimited"});
+      return;
+    }
+  }
+
   if (message == null) {
     return;
   }

src/node/utils/Settings.js

@@ -343,6 +343,22 @@ exports.importExportRateLimiting = {
   "max": 10
 };
 
+/*
+ * From Etherpad 1.9.0 onwards, commits from individual users are rate limited
+ *
+ * The default is to allow at most 10 changes per IP in a 1 second window.
+ * After that the change is rejected.
+ *
+ * See https://github.com/animir/node-rate-limiter-flexible/wiki/Overall-example#websocket-single-connection-prevent-flooding for more options
+ */
+exports.commitRateLimiting = {
+  // duration of the rate limit window (seconds)
+  "duration": 1,
+
+  // maximum number of chanes per IP to allow during the rate limit window
+  "points": 10
+};
+
 /*
  * From Etherpad 1.8.3 onwards, the maximum allowed size for a single imported
  * file is always bounded.

src/package-lock.json

@@ -7472,6 +7472,11 @@
       "resolved": "https://registry.npmjs.org/range-parser/-/range-parser-1.2.1.tgz",
       "integrity": "sha512-Hrgsx+orqoygnmhFbKaHE6c296J+HTAQXoxEF6gNupROmmGJRoyzfG3ccAveqCBrwr/2yxQ5BVd/GTl5agOwSg=="
     },
+    "rate-limiter-flexible": {
+      "version": "2.1.4",
+      "resolved": "https://registry.npmjs.org/rate-limiter-flexible/-/rate-limiter-flexible-2.1.4.tgz",
+      "integrity": "sha512-wtbWcqZbCqyAO1k63moagJlCZuPCEqbJJ6il1y2JVoiUyxlE36+cM7ETta9K6tTom9O5pNK+CxwHMgyyyJ31Gg=="
+    },
     "raw-body": {
       "version": "2.4.0",
       "resolved": "https://registry.npmjs.org/raw-body/-/raw-body-2.4.0.tgz",

src/package.json

@@ -54,6 +54,7 @@
     "nodeify": "1.0.1",
     "npm": "6.14.5",
     "openapi-backend": "2.4.1",
+    "rate-limiter-flexible": "^2.1.4",
     "rehype": "^10.0.0",
     "rehype-format": "^3.0.1",
     "request": "2.88.2",

src/static/js/pad_connectionstatus.js

@@ -63,9 +63,8 @@ var padconnectionstatus = (function()
         what: 'disconnected',
         why: msg
       };
-
       var k = String(msg); // known reason why
-      if (!(k == 'userdup' || k == 'deleted' || k == 'looping' || k == 'slowcommit' || k == 'initsocketfail' || k == 'unauth' || k == 'badChangeset' || k == 'corruptPad'))
+      if (!(k == 'userdup' || k == 'deleted' || k == 'looping' || k == 'slowcommit' || k == 'initsocketfail' || k == 'unauth' || k == 'rateLimited' || k == 'badChangeset' || k == 'corruptPad'))
       {
         k = 'disconnected';
       }

src/templates/pad.html

@@ -279,6 +279,10 @@
             <h1 data-l10n-id="pad.modals.deleted"></h1>
             <p data-l10n-id="pad.modals.deleted.explanation"></p>
           </div>
+          <div class="rateLimited">
+            <h1 data-l10n-id="pad.modals.rateLimited"></h1>
+            <p data-l10n-id="pad.modals.rateLimited.explanation"></p>
+          </div>
           <div class="disconnected with_reconnect_timer">
             <% e.begin_block("disconnected"); %>
             <h1 data-l10n-id="pad.modals.disconnected"></h1>