https: reuse TLS sessions in Agent

Fix: #1499
PR-URL: #2228
Reviewed-By: Shigeki Ohtsu <ohtsu@iij.ad.jp>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

lib/_http_agent.js

@@ -171,6 +171,7 @@ Agent.prototype.createSocket = function(req, options) {
   }
 
   var name = self.getName(options);
+  options._agentKey = name;
 
   debug('createConnection', name, options);
   options.encoding = null;

lib/_tls_wrap.js

@@ -584,6 +584,17 @@ TLSSocket.prototype._start = function() {
   this._handle.start();
 };
 
+TLSSocket.prototype._isSessionResumed = function _isSessionResumed(session) {
+  if (!session)
+    return false;
+
+  var next = this.getSession();
+  if (!next)
+    return false;
+
+  return next.equals(session);
+};
+
 TLSSocket.prototype.setServername = function(name) {
   this._handle.setServername(name);
 };
@@ -999,7 +1010,8 @@ exports.connect = function(/* [port, host], options, cb */) {
     var verifyError = socket._handle.verifyError();
 
     // Verify that server's identity matches it's certificate's names
-    if (!verifyError) {
+    // Unless server has resumed our existing session
+    if (!verifyError && !socket._isSessionResumed(options.session)) {
       var cert = socket.getPeerCertificate();
       verifyError = options.checkServerIdentity(hostname, cert);
     }

lib/https.js

@@ -58,14 +58,40 @@ function createConnection(port, host, options) {
   }
 
   debug('createConnection', options);
-  return tls.connect(options);
+
+  if (options._agentKey) {
+    const session = this._getSession(options._agentKey);
+    if (session) {
+      debug('reuse session for %j', options._agentKey);
+      options = util._extend({
+        session: session
+      }, options);
+    }
+  }
+
+  const self = this;
+  const socket = tls.connect(options, function() {
+    if (!options._agentKey)
+      return;
+
+    self._cacheSession(options._agentKey, socket.getSession());
+  });
+  return socket;
 }
 
 
 function Agent(options) {
   http.Agent.call(this, options);
   this.defaultPort = 443;
   this.protocol = 'https:';
+  this.maxCachedSessions = this.options.maxCachedSessions;
+  if (this.maxCachedSessions === undefined)
+    this.maxCachedSessions = 100;
+
+  this._sessionCache = {
+    map: {},
+    list: []
+  };
 }
 inherits(Agent, http.Agent);
 Agent.prototype.createConnection = createConnection;
@@ -100,6 +126,28 @@ Agent.prototype.getName = function(options) {
   return name;
 };
 
+Agent.prototype._getSession = function _getSession(key) {
+  return this._sessionCache.map[key];
+};
+
+Agent.prototype._cacheSession = function _cacheSession(key, session) {
+  // Fast case - update existing entry
+  if (this._sessionCache.map[key]) {
+    this._sessionCache.map[key] = session;
+    return;
+  }
+
+  // Put new entry
+  if (this._sessionCache.list.length >= this.maxCachedSessions) {
+    const oldKey = this._sessionCache.list.shift();
+    debug('evicting %j', oldKey);
+    delete this._sessionCache.map[oldKey];
+  }
+
+  this._sessionCache.list.push(key);
+  this._sessionCache.map[key] = session;
+};
+
 const globalAgent = new Agent();
 
 exports.globalAgent = globalAgent;

test/parallel/test-https-agent-session-reuse.js

@@ -0,0 +1,130 @@
+'use strict';
+var common = require('../common');
+var assert = require('assert');
+
+if (!common.hasCrypto) {
+  console.log('1..0 # Skipped: missing crypto');
+  return;
+}
+
+var https = require('https');
+var crypto = require('crypto');
+
+var fs = require('fs');
+
+var options = {
+  key: fs.readFileSync(common.fixturesDir + '/keys/agent1-key.pem'),
+  cert: fs.readFileSync(common.fixturesDir + '/keys/agent1-cert.pem')
+};
+
+var ca = fs.readFileSync(common.fixturesDir + '/keys/ca1-cert.pem');
+
+var clientSessions = {};
+var serverRequests = 0;
+
+var agent = new https.Agent({
+  maxCachedSessions: 1
+});
+
+var server = https.createServer(options, function(req, res) {
+  if (req.url === '/drop-key')
+    server.setTicketKeys(crypto.randomBytes(48));
+
+  serverRequests++;
+  res.end('ok');
+}).listen(common.PORT, function() {
+  var queue = [
+    {
+      name: 'first',
+
+      method: 'GET',
+      path: '/',
+      servername: 'agent1',
+      ca: ca,
+      port: common.PORT
+    },
+    {
+      name: 'first-reuse',
+
+      method: 'GET',
+      path: '/',
+      servername: 'agent1',
+      ca: ca,
+      port: common.PORT
+    },
+    {
+      name: 'cipher-change',
+
+      method: 'GET',
+      path: '/',
+      servername: 'agent1',
+
+      // Choose different cipher to use different cache entry
+      ciphers: 'AES256-SHA',
+      ca: ca,
+      port: common.PORT
+    },
+    // Change the ticket key to ensure session is updated in cache
+    {
+      name: 'before-drop',
+
+      method: 'GET',
+      path: '/drop-key',
+      servername: 'agent1',
+      ca: ca,
+      port: common.PORT
+    },
+
+    // Ticket will be updated starting from this
+    {
+      name: 'after-drop',
+
+      method: 'GET',
+      path: '/',
+      servername: 'agent1',
+      ca: ca,
+      port: common.PORT
+    },
+    {
+      name: 'after-drop-reuse',
+
+      method: 'GET',
+      path: '/',
+      servername: 'agent1',
+      ca: ca,
+      port: common.PORT
+    }
+  ];
+
+  function request() {
+    var options = queue.shift();
+    options.agent = agent;
+    https.request(options, function(res) {
+      clientSessions[options.name] = res.socket.getSession();
+
+      res.resume();
+      res.on('end', function() {
+        if (queue.length !== 0)
+          return request();
+        server.close();
+      });
+    }).end();
+  }
+  request();
+});
+
+process.on('exit', function() {
+  assert.equal(serverRequests, 6);
+  assert.equal(clientSessions['first'].toString('hex'),
+               clientSessions['first-reuse'].toString('hex'));
+  assert.notEqual(clientSessions['first'].toString('hex'),
+                  clientSessions['cipher-change'].toString('hex'));
+  assert.notEqual(clientSessions['first'].toString('hex'),
+                  clientSessions['before-drop'].toString('hex'));
+  assert.notEqual(clientSessions['cipher-change'].toString('hex'),
+                  clientSessions['before-drop'].toString('hex'));
+  assert.notEqual(clientSessions['before-drop'].toString('hex'),
+                  clientSessions['after-drop'].toString('hex'));
+  assert.equal(clientSessions['after-drop'].toString('hex'),
+               clientSessions['after-drop-reuse'].toString('hex'));
+});