socketio: Mimic what Express does to get client IP address

This also makes it easier for plugins to get the client IP address.

src/node/handler/PadMessageHandler.js

@@ -35,7 +35,6 @@ var _ = require('underscore');
 var hooks = require("ep_etherpad-lite/static/js/pluginfw/hooks.js");
 var channels = require("channels");
 var stats = require('../stats');
-var remoteAddress = require("../utils/RemoteAddress").remoteAddress;
 const assert = require('assert').strict;
 const nodeify = require("nodeify");
 const { RateLimiterMemory } = require('rate-limiter-flexible');
@@ -127,19 +126,11 @@ exports.handleDisconnect = async function(client)
 
   // if this connection was already etablished with a handshake, send a disconnect message to the others
   if (session && session.author) {
-    // Get the IP address from our persistant object
-    let ip = remoteAddress[client.id];
-
-    // Anonymize the IP address if IP logging is disabled
-    if (settings.disableIPlogging) {
-      ip = 'ANONYMOUS';
-    }
-
     const {session: {user} = {}} = client.client.request;
     accessLogger.info('[LEAVE]' +
                       ` pad:${session.padId}` +
                       ` socket:${client.id}` +
-                      ` IP:${ip}` +
+                      ` IP:${settings.disableIPlogging ? 'ANONYMOUS' : client.request.ip}` +
                       ` authorID:${session.author}` +
                       ((user && user.username) ? ` username:${user.username}` : ''));
 
@@ -181,11 +172,11 @@ exports.handleMessage = async function(client, message)
   var env = process.env.NODE_ENV || 'development';
 
   if (env === 'production') {
-    const clientIPAddress = remoteAddress[client.id];
     try {
-      await rateLimiter.consume(clientIPAddress); // consume 1 point per event from IP
+      await rateLimiter.consume(client.request.ip); // consume 1 point per event from IP
     } catch (e) {
-      console.warn("Rate limited: ", clientIPAddress, " to reduce the amount of rate limiting that happens edit the rateLimit values in settings.json");
+      console.warn(`Rate limited: ${client.request.ip} to reduce the amount of rate limiting ` +
+                   'that happens edit the rateLimit values in settings.json');
       stats.meter('rateLimited').mark();
       client.json.send({disconnect:"rateLimited"});
       return;
@@ -239,7 +230,7 @@ exports.handleMessage = async function(client, message)
         'Rejecting message from client because the author ID changed mid-session.' +
         ' Bad or missing token or sessionID?' +
         ` socket:${client.id}` +
-        ` IP:${settings.disableIPlogging ? ANONYMOUS : remoteAddress[client.id]}` +
+        ` IP:${settings.disableIPlogging ? 'ANONYMOUS' : client.request.ip}` +
         ` originalAuthorID:${thisSession.author}` +
         ` newAuthorID:${authorID}` +
         ((user && user.username) ? ` username:${user.username}` : '') +
@@ -967,19 +958,11 @@ async function handleClientReady(client, message, authorID)
   sessionInfo.readonly =
       padIds.readonly || !webaccess.userCanModify(message.padId, client.client.request);
 
-  // Log creation/(re-)entering of a pad
-  let ip = remoteAddress[client.id];
-
-  // Anonymize the IP address if IP logging is disabled
-  if (settings.disableIPlogging) {
-    ip = 'ANONYMOUS';
-  }
-
   const {session: {user} = {}} = client.client.request;
   accessLogger.info(`[${pad.head > 0 ? 'ENTER' : 'CREATE'}]` +
                     ` pad:${padIds.padId}` +
                     ` socket:${client.id}` +
-                    ` IP:${ip}` +
+                    ` IP:${settings.disableIPlogging ? 'ANONYMOUS' : client.request.ip}` +
                     ` authorID:${authorID}` +
                     ((user && user.username) ? ` username:${user.username}` : ''));
 

src/node/handler/SocketIORouter.js

@@ -23,7 +23,6 @@ var log4js = require('log4js');
 var messageLogger = log4js.getLogger("message");
 var securityManager = require("../db/SecurityManager");
 var readOnlyManager = require("../db/ReadOnlyManager");
-var remoteAddress = require("../utils/RemoteAddress").remoteAddress;
 var settings = require('../utils/Settings');
 
 /**
@@ -56,15 +55,6 @@ exports.setSocketIO = function(_socket) {
 
   socket.sockets.on('connection', function(client)
   {
-    // Broken: See http://stackoverflow.com/questions/4647348/send-message-to-specific-client-with-socket-io-and-node-js
-    // Fixed by having a persistant object, ideally this would actually be in the database layer
-    // TODO move to database layer
-    if (settings.trustProxy && client.handshake.headers['x-forwarded-for'] !== undefined) {
-      remoteAddress[client.id] = client.handshake.headers['x-forwarded-for'];
-    } else {
-      remoteAddress[client.id] = client.handshake.address;
-    }
-
     // wrap the original send function to log the messages
     client._send = client.send;
     client.send = function(message) {

src/node/hooks/express/socketio.js

@@ -1,4 +1,5 @@
 const express = require("../express");
+const proxyaddr = require('proxy-addr');
 var settings = require('../../utils/Settings');
 var socketio = require('socket.io');
 var socketIORouter = require("../../handler/SocketIORouter");
@@ -38,6 +39,14 @@ exports.expressCreateServer = function (hook_name, args, cb) {
 
   io.use((socket, next) => {
     const req = socket.request;
+    // Express sets req.ip but socket.io does not. Replicate Express's behavior here.
+    if (req.ip == null) {
+      if (settings.trustProxy) {
+        req.ip = proxyaddr(req, args.app.get('trust proxy fn'));
+      } else {
+        req.ip = socket.handshake.address;
+      }
+    }
     if (!req.headers.cookie) {
       // socketio.js-client on node.js doesn't support cookies (see https://git.io/JU8u9), so the
       // token and express_sid cookies have to be passed via a query parameter for unit tests.

src/node/utils/RemoteAddress.js

@@ -1 +0,0 @@
-exports.remoteAddress = {};

src/package.json

@@ -55,6 +55,7 @@
     "nodeify": "1.0.1",
     "npm": "6.14.8",
     "openapi-backend": "2.4.1",
+    "proxy-addr": "^2.0.6",
     "rate-limiter-flexible": "^2.1.4",
     "rehype": "^10.0.0",
     "rehype-format": "^3.0.1",