text: // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  var assert = require('assert');
  var crypto = require('crypto');
  var events = require('events');
  var stream = require('stream');
  var tls = require('tls');
  var util = require('util');
  
  var Timer = process.binding('timer_wrap').Timer;
  var Connection = null;
  try {
    Connection = process.binding('crypto').Connection;
  } catch (e) {
    throw new Error('node.js not compiled with openssl crypto support.');
  }
  
  var debug = util.debuglog('tls-legacy');
  
  function SlabBuffer() {
    this.create();
  }
  
  
  SlabBuffer.prototype.create = function create() {
    this.isFull = false;
    this.pool = new Buffer(tls.SLAB_BUFFER_SIZE);
    this.offset = 0;
    this.remaining = this.pool.length;
  };
  
  
  SlabBuffer.prototype.use = function use(context, fn, size) {
    if (this.remaining === 0) {
      this.isFull = true;
      return 0;
    }
  
    var actualSize = this.remaining;
  
    if (!util.isNull(size)) actualSize = Math.min(size, actualSize);
  
    var bytes = fn.call(context, this.pool, this.offset, actualSize);
    if (bytes > 0) {
      this.offset += bytes;
      this.remaining -= bytes;
    }
  
    assert(this.remaining >= 0);
  
    return bytes;
  };
  
  
  var slabBuffer = null;
  
  
  // Base class of both CleartextStream and EncryptedStream
  function CryptoStream(pair, options) {
    stream.Duplex.call(this, options);
  
    this.pair = pair;
    this._pending = null;
    this._pendingEncoding = '';
    this._pendingCallback = null;
    this._doneFlag = false;
    this._retryAfterPartial = false;
    this._halfRead = false;
    this._sslOutCb = null;
    this._resumingSession = false;
    this._reading = true;
    this._destroyed = false;
    this._ended = false;
    this._finished = false;
    this._opposite = null;
  
    if (util.isNull(slabBuffer)) slabBuffer = new SlabBuffer();
    this._buffer = slabBuffer;
  
    this.once('finish', onCryptoStreamFinish);
  
    // net.Socket calls .onend too
    this.once('end', onCryptoStreamEnd);
  }
  util.inherits(CryptoStream, stream.Duplex);
  
  
  function onCryptoStreamFinish() {
    this._finished = true;
  
    if (this === this.pair.cleartext) {
      debug('cleartext.onfinish');
      if (this.pair.ssl) {
        // Generate close notify
        // NOTE: first call checks if client has sent us shutdown,
        // second call enqueues shutdown into the BIO.
        if (this.pair.ssl.shutdown() !== 1) {
          if (this.pair.ssl && this.pair.ssl.error)
            return this.pair.error();
  
          this.pair.ssl.shutdown();
        }
  
        if (this.pair.ssl && this.pair.ssl.error)
          return this.pair.error();
      }
    } else {
      debug('encrypted.onfinish');
    }
  
    // Try to read just to get sure that we won't miss EOF
    if (this._opposite.readable) this._opposite.read(0);
  
    if (this._opposite._ended) {
      this._done();
  
      // No half-close, sorry
      if (this === this.pair.cleartext) this._opposite._done();
    }
  }
  
  
  function onCryptoStreamEnd() {
    this._ended = true;
    if (this === this.pair.cleartext) {
      debug('cleartext.onend');
    } else {
      debug('encrypted.onend');
    }
  }
  
  
  // NOTE: Called once `this._opposite` is set.
  CryptoStream.prototype.init = function init() {
    var self = this;
    this._opposite.on('sslOutEnd', function() {
      if (self._sslOutCb) {
        var cb = self._sslOutCb;
        self._sslOutCb = null;
        cb(null);
      }
    });
  };
  
  
  CryptoStream.prototype._write = function write(data, encoding, cb) {
    assert(util.isNull(this._pending));
  
    // Black-hole data
    if (!this.pair.ssl) return cb(null);
  
    // When resuming session don't accept any new data.
    // And do not put too much data into openssl, before writing it from encrypted
    // side.
    //
    // TODO(indutny): Remove magic number, use watermark based limits
    if (!this._resumingSession &&
        this._opposite._internallyPendingBytes() < 128 * 1024) {
      // Write current buffer now
      var written;
      if (this === this.pair.cleartext) {
        debug('cleartext.write called with %d bytes', data.length);
        written = this.pair.ssl.clearIn(data, 0, data.length);
      } else {
        debug('encrypted.write called with %d bytes', data.length);
        written = this.pair.ssl.encIn(data, 0, data.length);
      }
  
      // Handle and report errors
      if (this.pair.ssl && this.pair.ssl.error) {
        return cb(this.pair.error(true));
      }
  
      // Force SSL_read call to cycle some states/data inside OpenSSL
      this.pair.cleartext.read(0);
  
      // Cycle encrypted data
      if (this.pair.encrypted._internallyPendingBytes())
        this.pair.encrypted.read(0);
  
      // Get NPN and Server name when ready
      this.pair.maybeInitFinished();
  
      // Whole buffer was written
      if (written === data.length) {
        if (this === this.pair.cleartext) {
          debug('cleartext.write succeed with ' + written + ' bytes');
        } else {
          debug('encrypted.write succeed with ' + written + ' bytes');
        }
  
        // Invoke callback only when all data read from opposite stream
        if (this._opposite._halfRead) {
          assert(util.isNull(this._sslOutCb));
          this._sslOutCb = cb;
        } else {
          cb(null);
        }
        return;
      } else if (written !== 0 && written !== -1) {
        assert(!this._retryAfterPartial);
        this._retryAfterPartial = true;
        this._write(data.slice(written), encoding, cb);
        this._retryAfterPartial = false;
        return;
      }
    } else {
      debug('cleartext.write queue is full');
  
      // Force SSL_read call to cycle some states/data inside OpenSSL
      this.pair.cleartext.read(0);
    }
  
    // No write has happened
    this._pending = data;
    this._pendingEncoding = encoding;
    this._pendingCallback = cb;
  
    if (this === this.pair.cleartext) {
      debug('cleartext.write queued with %d bytes', data.length);
    } else {
      debug('encrypted.write queued with %d bytes', data.length);
    }
  };
  
  
  CryptoStream.prototype._writePending = function writePending() {
    var data = this._pending,
        encoding = this._pendingEncoding,
        cb = this._pendingCallback;
  
    this._pending = null;
    this._pendingEncoding = '';
    this._pendingCallback = null;
    this._write(data, encoding, cb);
  };
  
  
  CryptoStream.prototype._read = function read(size) {
    // XXX: EOF?!
    if (!this.pair.ssl) return this.push(null);
  
    // Wait for session to be resumed
    // Mark that we're done reading, but don't provide data or EOF
    if (this._resumingSession || !this._reading) return this.push('');
  
    var out;
    if (this === this.pair.cleartext) {
      debug('cleartext.read called with %d bytes', size);
      out = this.pair.ssl.clearOut;
    } else {
      debug('encrypted.read called with %d bytes', size);
      out = this.pair.ssl.encOut;
    }
  
    var bytesRead = 0,
        start = this._buffer.offset,
        last = start;
    do {
      assert(last === this._buffer.offset);
      var read = this._buffer.use(this.pair.ssl, out, size - bytesRead);
      if (read > 0) {
        bytesRead += read;
      }
      last = this._buffer.offset;
  
      // Handle and report errors
      if (this.pair.ssl && this.pair.ssl.error) {
        this.pair.error();
        break;
      }
    } while (read > 0 &&
             !this._buffer.isFull &&
             bytesRead < size &&
             this.pair.ssl !== null);
  
    // Get NPN and Server name when ready
    this.pair.maybeInitFinished();
  
    // Create new buffer if previous was filled up
    var pool = this._buffer.pool;
    if (this._buffer.isFull) this._buffer.create();
  
    assert(bytesRead >= 0);
  
    if (this === this.pair.cleartext) {
      debug('cleartext.read succeed with %d bytes', bytesRead);
    } else {
      debug('encrypted.read succeed with %d bytes', bytesRead);
    }
  
    // Try writing pending data
    if (!util.isNull(this._pending)) this._writePending();
    if (!util.isNull(this._opposite._pending)) this._opposite._writePending();
  
    if (bytesRead === 0) {
      // EOF when cleartext has finished and we have nothing to read
      if (this._opposite._finished && this._internallyPendingBytes() === 0 ||
          this.pair.ssl && this.pair.ssl.receivedShutdown) {
        // Perform graceful shutdown
        this._done();
  
        // No half-open, sorry!
        if (this === this.pair.cleartext) {
          this._opposite._done();
  
          // EOF
          this.push(null);
        } else if (!this.pair.ssl || !this.pair.ssl.receivedShutdown) {
          // EOF
          this.push(null);
        }
      } else {
        // Bail out
        this.push('');
      }
    } else {
      // Give them requested data
      this.push(pool.slice(start, start + bytesRead));
    }
  
    // Let users know that we've some internal data to read
    var halfRead = this._internallyPendingBytes() !== 0;
  
    // Smart check to avoid invoking 'sslOutEnd' in the most of the cases
    if (this._halfRead !== halfRead) {
      this._halfRead = halfRead;
  
      // Notify listeners about internal data end
      if (!halfRead) {
        if (this === this.pair.cleartext) {
          debug('cleartext.sslOutEnd');
        } else {
          debug('encrypted.sslOutEnd');
        }
  
        this.emit('sslOutEnd');
      }
    }
  };
  
  
  CryptoStream.prototype.setTimeout = function(timeout, callback) {
    if (this.socket) this.socket.setTimeout(timeout, callback);
  };
  
  
  CryptoStream.prototype.setNoDelay = function(noDelay) {
    if (this.socket) this.socket.setNoDelay(noDelay);
  };
  
  
  CryptoStream.prototype.setKeepAlive = function(enable, initialDelay) {
    if (this.socket) this.socket.setKeepAlive(enable, initialDelay);
  };
  
  CryptoStream.prototype.__defineGetter__('bytesWritten', function() {
    return this.socket ? this.socket.bytesWritten : 0;
  });
  
  CryptoStream.prototype.getPeerCertificate = function() {
    if (this.pair.ssl) {
      var c = this.pair.ssl.getPeerCertificate();
  
      if (c) {
        if (c.issuer) c.issuer = tls.parseCertString(c.issuer);
        if (c.subject) c.subject = tls.parseCertString(c.subject);
        return c;
      }
    }
  
    return null;
  };
  
  CryptoStream.prototype.getSession = function() {
    if (this.pair.ssl) {
      return this.pair.ssl.getSession();
    }
  
    return null;
  };
  
  CryptoStream.prototype.isSessionReused = function() {
    if (this.pair.ssl) {
      return this.pair.ssl.isSessionReused();
    }
  
    return null;
  };
  
  CryptoStream.prototype.getCipher = function(err) {
    if (this.pair.ssl) {
      return this.pair.ssl.getCurrentCipher();
    } else {
      return null;
    }
  };
  
  
  CryptoStream.prototype.end = function(chunk, encoding) {
    if (this === this.pair.cleartext) {
      debug('cleartext.end');
    } else {
      debug('encrypted.end');
    }
  
    // Write pending data first
    if (!util.isNull(this._pending)) this._writePending();
  
    this.writable = false;
  
    stream.Duplex.prototype.end.call(this, chunk, encoding);
  };
  
  
  CryptoStream.prototype.destroySoon = function(err) {
    if (this === this.pair.cleartext) {
      debug('cleartext.destroySoon');
    } else {
      debug('encrypted.destroySoon');
    }
  
    if (this.writable)
      this.end();
  
    if (this._writableState.finished && this._opposite._ended) {
      this.destroy();
    } else {
      // Wait for both `finish` and `end` events to ensure that all data that
      // was written on this side was read from the other side.
      var self = this;
      var waiting = 1;
      function finish() {
        if (--waiting === 0) self.destroy();
      }
      this._opposite.once('end', finish);
      if (!this._finished) {
        this.once('finish', finish);
        ++waiting;
      }
    }
  };
  
  
  CryptoStream.prototype.destroy = function(err) {
    if (this._destroyed) return;
    this._destroyed = true;
    this.readable = this.writable = false;
  
    // Destroy both ends
    if (this === this.pair.cleartext) {
      debug('cleartext.destroy');
    } else {
      debug('encrypted.destroy');
    }
    this._opposite.destroy();
  
    var self = this;
    process.nextTick(function() {
      // Force EOF
      self.push(null);
  
      // Emit 'close' event
      self.emit('close', err ? true : false);
    });
  };
  
  
  CryptoStream.prototype._done = function() {
    this._doneFlag = true;
  
    if (this === this.pair.encrypted && !this.pair._secureEstablished)
      return this.pair.error();
  
    if (this.pair.cleartext._doneFlag &&
        this.pair.encrypted._doneFlag &&
        !this.pair._doneFlag) {
      // If both streams are done:
      this.pair.destroy();
    }
  };
  
  
  // readyState is deprecated. Don't use it.
  Object.defineProperty(CryptoStream.prototype, 'readyState', {
    get: function() {
      if (this._connecting) {
        return 'opening';
      } else if (this.readable && this.writable) {
        return 'open';
      } else if (this.readable && !this.writable) {
        return 'readOnly';
      } else if (!this.readable && this.writable) {
        return 'writeOnly';
      } else {
        return 'closed';
      }
    }
  });
  
  
  function CleartextStream(pair, options) {
    CryptoStream.call(this, pair, options);
  
    // This is a fake kludge to support how the http impl sits
    // on top of net Sockets
    var self = this;
    this._handle = {
      readStop: function() {
        self._reading = false;
      },
      readStart: function() {
        if (self._reading && self._readableState.length > 0) return;
        self._reading = true;
        self.read(0);
        if (self._opposite.readable) self._opposite.read(0);
      }
    };
  }
  util.inherits(CleartextStream, CryptoStream);
  
  
  CleartextStream.prototype._internallyPendingBytes = function() {
    if (this.pair.ssl) {
      return this.pair.ssl.clearPending();
    } else {
      return 0;
    }
  };
  
  
  CleartextStream.prototype.address = function() {
    return this.socket && this.socket.address();
  };
  
  
  CleartextStream.prototype.__defineGetter__('remoteAddress', function() {
    return this.socket && this.socket.remoteAddress;
  });
  
  
  CleartextStream.prototype.__defineGetter__('remotePort', function() {
    return this.socket && this.socket.remotePort;
  });
  
  
  CleartextStream.prototype.__defineGetter__('localAddress', function() {
    return this.socket && this.socket.localAddress;
  });
  
  
  CleartextStream.prototype.__defineGetter__('localPort', function() {
    return this.socket && this.socket.localPort;
  });
  
  
  function EncryptedStream(pair, options) {
    CryptoStream.call(this, pair, options);
  }
  util.inherits(EncryptedStream, CryptoStream);
  
  
  EncryptedStream.prototype._internallyPendingBytes = function() {
    if (this.pair.ssl) {
      return this.pair.ssl.encPending();
    } else {
      return 0;
    }
  };
  
  
  function onhandshakestart() {
    debug('onhandshakestart');
  
    var self = this;
    var ssl = self.ssl;
    var now = Timer.now();
  
    assert(now >= ssl.lastHandshakeTime);
  
    if ((now - ssl.lastHandshakeTime) >= tls.CLIENT_RENEG_WINDOW * 1000) {
      ssl.handshakes = 0;
    }
  
    var first = (ssl.lastHandshakeTime === 0);
    ssl.lastHandshakeTime = now;
    if (first) return;
  
    if (++ssl.handshakes > tls.CLIENT_RENEG_LIMIT) {
      // Defer the error event to the next tick. We're being called from OpenSSL's
      // state machine and OpenSSL is not re-entrant. We cannot allow the user's
      // callback to destroy the connection right now, it would crash and burn.
      setImmediate(function() {
        var err = new Error('TLS session renegotiation attack detected.');
        if (self.cleartext) self.cleartext.emit('error', err);
      });
    }
  }
  
  
  function onhandshakedone() {
    // for future use
    debug('onhandshakedone');
  }
  
  
  function onclienthello(hello) {
    var self = this,
        once = false;
  
    this._resumingSession = true;
    function callback(err, session) {
      if (once) return;
      once = true;
  
      if (err) return self.socket.destroy(err);
  
      self.ssl.loadSession(session);
      self.ssl.endParser();
  
      // Cycle data
      self._resumingSession = false;
      self.cleartext.read(0);
      self.encrypted.read(0);
    }
  
    if (hello.sessionId.length <= 0 ||
        !this.server ||
        !this.server.emit('resumeSession', hello.sessionId, callback)) {
      callback(null, null);
    }
  }
  
  
  function onnewsession(key, session) {
    if (!this.server) return;
    this.server.emit('newSession', key, session);
  }
  
  
  /**
   * Provides a pair of streams to do encrypted communication.
   */
  
  function SecurePair(credentials, isServer, requestCert, rejectUnauthorized,
                      options) {
    if (!(this instanceof SecurePair)) {
      return new SecurePair(credentials,
                            isServer,
                            requestCert,
                            rejectUnauthorized,
                            options);
    }
  
    var self = this;
  
    options || (options = {});
  
    events.EventEmitter.call(this);
  
    this.server = options.server;
    this._secureEstablished = false;
    this._isServer = isServer ? true : false;
    this._encWriteState = true;
    this._clearWriteState = true;
    this._doneFlag = false;
    this._destroying = false;
  
    if (!credentials) {
      this.credentials = crypto.createCredentials();
    } else {
      this.credentials = credentials;
    }
  
    if (!this._isServer) {
      // For clients, we will always have either a given ca list or be using
      // default one
      requestCert = true;
    }
  
    this._rejectUnauthorized = rejectUnauthorized ? true : false;
    this._requestCert = requestCert ? true : false;
  
    this.ssl = new Connection(this.credentials.context,
                              this._isServer ? true : false,
                              this._isServer ? this._requestCert :
                                               options.servername,
                              this._rejectUnauthorized);
  
    if (this._isServer) {
      this.ssl.onhandshakestart = onhandshakestart.bind(this);
      this.ssl.onhandshakedone = onhandshakedone.bind(this);
      this.ssl.onclienthello = onclienthello.bind(this);
      this.ssl.onnewsession = onnewsession.bind(this);
      this.ssl.lastHandshakeTime = 0;
      this.ssl.handshakes = 0;
    }
  
    if (process.features.tls_sni) {
      if (this._isServer && options.SNICallback) {
        this.ssl.setSNICallback(options.SNICallback);
      }
      this.servername = null;
    }
  
    if (process.features.tls_npn && options.NPNProtocols) {
      this.ssl.setNPNProtocols(options.NPNProtocols);
      this.npnProtocol = null;
    }
  
    /* Acts as a r/w stream to the cleartext side of the stream. */
    this.cleartext = new CleartextStream(this, options.cleartext);
  
    /* Acts as a r/w stream to the encrypted side of the stream. */
    this.encrypted = new EncryptedStream(this, options.encrypted);
  
    /* Let streams know about each other */
    this.cleartext._opposite = this.encrypted;
    this.encrypted._opposite = this.cleartext;
    this.cleartext.init();
    this.encrypted.init();
  
    process.nextTick(function() {
      /* The Connection may be destroyed by an abort call */
      if (self.ssl) {
        self.ssl.start();
  
        /* In case of cipher suite failures - SSL_accept/SSL_connect may fail */
        if (self.ssl && self.ssl.error)
          self.error();
      }
    });
  }
  
  util.inherits(SecurePair, events.EventEmitter);
  
  
  exports.createSecurePair = function(credentials,
                                      isServer,
                                      requestCert,
                                      rejectUnauthorized) {
    var pair = new SecurePair(credentials,
                              isServer,
                              requestCert,
                              rejectUnauthorized);
    return pair;
  };
  
  
  SecurePair.prototype.maybeInitFinished = function() {
    if (this.ssl && !this._secureEstablished && this.ssl.isInitFinished()) {
      if (process.features.tls_npn) {
        this.npnProtocol = this.ssl.getNegotiatedProtocol();
      }
  
      if (process.features.tls_sni) {
        this.servername = this.ssl.getServername();
      }
  
      this._secureEstablished = true;
      debug('secure established');
      this.emit('secure');
    }
  };
  
  
  SecurePair.prototype.destroy = function() {
    if (this._destroying) return;
  
    if (!this._doneFlag) {
      debug('SecurePair.destroy');
      this._destroying = true;
  
      // SecurePair should be destroyed only after it's streams
      this.cleartext.destroy();
      this.encrypted.destroy();
  
      this._doneFlag = true;
      this.ssl.error = null;
      this.ssl.close();
      this.ssl = null;
    }
  };
  
  
  SecurePair.prototype.error = function(returnOnly) {
    var err = this.ssl.error;
    this.ssl.error = null;
  
    if (!this._secureEstablished) {
      // Emit ECONNRESET instead of zero return
      if (!err || err.message === 'ZERO_RETURN') {
        var connReset = new Error('socket hang up');
        connReset.code = 'ECONNRESET';
        connReset.sslError = err && err.message;
  
        err = connReset;
      }
      this.destroy();
      if (!returnOnly) this.emit('error', err);
    } else if (this._isServer &&
               this._rejectUnauthorized &&
               /peer did not return a certificate/.test(err.message)) {
      // Not really an error.
      this.destroy();
    } else {
      if (!returnOnly) this.cleartext.emit('error', err);
    }
    return err;
  };
  
  
  exports.pipe = function pipe(pair, socket) {
    pair.encrypted.pipe(socket);
    socket.pipe(pair.encrypted);
  
    pair.encrypted.on('close', function() {
      process.nextTick(function() {
        // Encrypted should be unpiped from socket to prevent possible
        // write after destroy.
        pair.encrypted.unpipe(socket);
        socket.destroySoon();
      });
    });
  
    pair.fd = socket.fd;
    var cleartext = pair.cleartext;
    cleartext.socket = socket;
    cleartext.encrypted = pair.encrypted;
    cleartext.authorized = false;
  
    // cycle the data whenever the socket drains, so that
    // we can pull some more into it.  normally this would
    // be handled by the fact that pipe() triggers read() calls
    // on writable.drain, but CryptoStreams are a bit more
    // complicated.  Since the encrypted side actually gets
    // its data from the cleartext side, we have to give it a
    // light kick to get in motion again.
    socket.on('drain', function() {
      if (pair.encrypted._pending)
        pair.encrypted._writePending();
      if (pair.cleartext._pending)
        pair.cleartext._writePending();
      pair.encrypted.read(0);
      pair.cleartext.read(0);
    });
  
    function onerror(e) {
      if (cleartext._controlReleased) {
        cleartext.emit('error', e);
      }
    }
  
    function onclose() {
      socket.removeListener('error', onerror);
      socket.removeListener('timeout', ontimeout);
    }
  
    function ontimeout() {
      cleartext.emit('timeout');
    }
  
    socket.on('error', onerror);
    socket.on('close', onclose);
    socket.on('timeout', ontimeout);
  
    return cleartext;
  };
  