From 016b125f4964cea640ac6fec71a1382681aa3e00 Mon Sep 17 00:00:00 2001
From: calzoneman <calzoneman@gmail.com>
Date: Mon, 8 Aug 2016 23:03:16 -0700
Subject: [PATCH] Initial IP session cookie implementation

---
 src/io/ioserver.js                    | 67 +++++++++++++++--------
 src/server.js                         |  5 ++
 src/web/middleware/ipsessioncookie.js | 76 +++++++++++++++++++++++++++
 src/web/webserver.js                  |  1 +
 4 files changed, 127 insertions(+), 22 deletions(-)
 create mode 100644 src/web/middleware/ipsessioncookie.js

diff --git a/src/io/ioserver.js b/src/io/ioserver.js
index 9077f891..603f5b18 100644
--- a/src/io/ioserver.js
+++ b/src/io/ioserver.js
@@ -15,6 +15,7 @@ var crypto = require("crypto");
 var isTorExit = require("../tor").isTorExit;
 var session = require("../session");
 import counters from '../counters';
+import { verifyIPSessionCookie } from '../web/middleware/ipsessioncookie';
 
 var CONNECT_RATE = {
     burst: 5,
@@ -25,33 +26,53 @@ var ipThrottle = {};
 // Keep track of number of connections per IP
 var ipCount = {};
 
+function parseCookies(socket, accept) {
+    var req = socket.request;
+    if (req.headers.cookie) {
+        cookieParser(req, null, () => {
+            accept(null, true);
+        });
+    } else {
+        req.cookies = {};
+        req.signedCookies = {};
+        accept(null, true);
+    }
+}
 /**
  * Called before an incoming socket.io connection is accepted.
  */
 function handleAuth(socket, accept) {
-    var data = socket.request;
-
     socket.user = false;
-    if (data.headers.cookie) {
-        cookieParser(data, null, function () {
-            var auth = data.signedCookies.auth;
-            if (!auth) {
-                return accept(null, true);
-            }
-
-            session.verifySession(auth, function (err, user) {
-                if (!err) {
-                    socket.user = {
-                        name: user.name,
-                        global_rank: user.global_rank
-                    };
-                }
-                accept(null, true);
-            });
-        });
-    } else {
-        accept(null, true);
+    var auth = socket.request.signedCookies.auth;
+    if (!auth) {
+        return accept(null, true);
     }
+
+    session.verifySession(auth, function (err, user) {
+        if (!err) {
+            socket.user = {
+                name: user.name,
+                global_rank: user.global_rank
+            };
+        }
+        accept(null, true);
+    });
+}
+
+function handleIPSessionCookie(socket, accept) {
+    var cookie = socket.request.signedCookies['ip-session'];
+    if (!cookie) {
+        socket.ipSessionFirstSeen = new Date();
+        return accept(null, true);
+    }
+
+    var sessionMatch = verifyIPSessionCookie(socket._realip, cookie);
+    if (sessionMatch) {
+        socket.ipSessionFirstSeen = sessionMatch.date;
+    } else {
+        socket.ipSessionFirstSeen = new Date();
+    }
+    accept(null, true);
 }
 
 function throttleIP(sock) {
@@ -247,8 +268,10 @@ module.exports = {
         };
         var io = sio.instance = sio();
 
-        io.use(handleAuth);
         io.use(ipForwardingMiddleware(webConfig));
+        io.use(parseCookies);
+        io.use(handleIPSessionCookie);
+        io.use(handleAuth);
         io.on("connection", handleConnection);
 
         Config.get("listen").forEach(function (bind) {
diff --git a/src/server.js b/src/server.js
index 593e21b4..3a5c328a 100644
--- a/src/server.js
+++ b/src/server.js
@@ -18,6 +18,11 @@ module.exports = {
             exists || fs.mkdir(chandumppath);
         });
 
+        var statepath = path.join(__dirname, "../state");
+        fs.exists(statepath, function (exists) {
+            exists || fs.mkdir(statepath);
+        });
+
         var gdvttpath = path.join(__dirname, "../google-drive-subtitles");
         fs.exists(gdvttpath, function (exists) {
             exists || fs.mkdir(gdvttpath);
diff --git a/src/web/middleware/ipsessioncookie.js b/src/web/middleware/ipsessioncookie.js
new file mode 100644
index 00000000..c2cd849b
--- /dev/null
+++ b/src/web/middleware/ipsessioncookie.js
@@ -0,0 +1,76 @@
+import path from 'path';
+import fs from 'fs';
+import crypto from 'crypto';
+
+const SALT_PATH = path.resolve(__dirname, '..', '..', '..', 'state', 'ipsessionsalt.json');
+
+var SALT;
+try {
+    SALT = require(SALT_PATH);
+} catch (error) {
+    SALT = crypto.randomBytes(32).toString('base64');
+    fs.writeFileSync(SALT_PATH, SALT);
+}
+
+function sha256(input) {
+    var hash = crypto.createHash("sha256");
+    hash.update(input);
+    return hash.digest("base64");
+}
+
+export function createIPSessionCookie(ip, date) {
+    const hashInput = [
+        ip,
+        date.getTime(),
+        SALT
+    ].join(':');
+
+    return [
+        date.getTime(),
+        sha256(hashInput)
+    ].join(':');
+}
+
+export function verifyIPSessionCookie(ip, cookie) {
+    const parts = cookie.split(':');
+    if (parts.length !== 2) {
+        return false;
+    }
+
+    const timestamp = parseInt(parts[0], 10);
+    if (isNaN(timestamp)) {
+        return false;
+    }
+
+    const date = new Date(timestamp);
+    const expected = createIPSessionCookie(ip, date);
+    if (expected !== cookie) {
+        return false;
+    }
+
+    return {
+        date: date,
+    };
+}
+
+export function ipSessionCookieMiddleware(req, res, next) {
+    var firstSeen = new Date();
+    var hasSession = false;
+    if (req.signedCookies && req.signedCookies['ip-session']) {
+        var sessionMatch = verifyIPSessionCookie(req.realIP, req.signedCookies['ip-session']);
+        if (sessionMatch) {
+            hasSession = true;
+            firstSeen = sessionMatch.date;
+        }
+    }
+
+    if (!hasSession) {
+        res.cookie('ip-session', createIPSessionCookie(req.realIP, firstSeen), {
+            signed: true,
+            httpOnly: true
+        });
+    }
+
+    req.ipSessionFirstSeen = firstSeen;
+    next();
+}
diff --git a/src/web/webserver.js b/src/web/webserver.js
index b428517f..e34a2caf 100644
--- a/src/web/webserver.js
+++ b/src/web/webserver.js
@@ -146,6 +146,7 @@ module.exports = {
         }
         app.use(cookieParser(webConfig.getCookieSecret()));
         app.use(csrf.init(webConfig.getCookieDomain()));
+        app.use('/r/:channel', require('./middleware/ipsessioncookie').ipSessionCookieMiddleware);
         initializeLog(app);
         require('./middleware/authorize')(app, session);