/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#ifndef _THRIFT_TRANSPORT_TSSLSOCKET_H_
#define _THRIFT_TRANSPORT_TSSLSOCKET_H_ 1

#include <string>
#include <boost/shared_ptr.hpp>
#include <openssl/ssl.h>
#include <sys/socket.h>
#include "concurrency/Mutex.h"
#include "TSocket.h"

namespace apache { namespace thrift { namespace transport {

class AccessManager;
class SSLContext;

/**
 * OpenSSL implementation for SSL socket interface.
 */
class TSSLSocket: public TSocket {
 public:
 ~TSSLSocket();
  /**
   * TTransport interface.
   */
  bool     isOpen();
  bool     peek();
  void     open();
  void     close();
  uint32_t read(uint8_t* buf, uint32_t len);
  void     write(const uint8_t* buf, uint32_t len);
  void     flush();
   /**
   * Set whether to use client or server side SSL handshake protocol.
   *
   * @param flag  Use server side handshake protocol if true.
   */
  void server(bool flag) { server_ = flag; }
  /**
   * Determine whether the SSL socket is server or client mode.
   */
  bool server() const { return server_; }
  /**
   * Set AccessManager.
   *
   * @param manager  Instance of AccessManager
   */
  virtual void access(boost::shared_ptr<AccessManager> manager) {
    access_ = manager;
  }
protected:
  /**
   * Constructor.
   */
  TSSLSocket(boost::shared_ptr<SSLContext> ctx);
  /**
   * Constructor, create an instance of TSSLSocket given an existing socket.
   *
   * @param socket An existing socket
   */
  TSSLSocket(boost::shared_ptr<SSLContext> ctx, int socket);
  /**
   * Constructor.
   *
   * @param host  Remote host name
   * @param port  Remote port number
   */
  TSSLSocket(boost::shared_ptr<SSLContext> ctx,
                               std::string host,
                                       int port);
  /**
   * Authorize peer access after SSL handshake completes.
   */
  virtual void authorize();
  /**
   * Initiate SSL handshake if not already initiated.
   */
  void checkHandshake();

  bool server_;
  SSL* ssl_;
  boost::shared_ptr<SSLContext> ctx_;
  boost::shared_ptr<AccessManager> access_;
  friend class TSSLSocketFactory;
};

/**
 * SSL socket factory. SSL sockets should be created via SSL factory.
 */
class TSSLSocketFactory {
 public:
  /**
   * Constructor/Destructor
   */
  TSSLSocketFactory();
  virtual ~TSSLSocketFactory();
  /**
   * Create an instance of TSSLSocket with a fresh new socket.
   */
  virtual boost::shared_ptr<TSSLSocket> createSocket();
  /**
   * Create an instance of TSSLSocket with the given socket.
   *
   * @param socket An existing socket.
   */
  virtual boost::shared_ptr<TSSLSocket> createSocket(int socket);
   /**
   * Create an instance of TSSLSocket.
   *
   * @param host  Remote host to be connected to
   * @param port  Remote port to be connected to
   */
  virtual boost::shared_ptr<TSSLSocket> createSocket(const std::string& host,
                                                     int port);
  /**
   * Set ciphers to be used in SSL handshake process.
   *
   * @param ciphers  A list of ciphers
   */
  virtual void ciphers(const std::string& enable);
  /**
   * Enable/Disable authentication.
   *
   * @param required Require peer to present valid certificate if true
   */
  virtual void authenticate(bool required);
  /**
   * Load server certificate.
   *
   * @param path   Path to the certificate file
   * @param format Certificate file format
   */
  virtual void loadCertificate(const char* path, const char* format = "PEM");
  /**
   * Load private key.
   *
   * @param path   Path to the private key file
   * @param format Private key file format
   */
  virtual void loadPrivateKey(const char* path, const char* format = "PEM");
  /**
   * Load trusted certificates from specified file.
   *
   * @param path Path to trusted certificate file
   */
  virtual void loadTrustedCertificates(const char* path);
  /**
   * Default randomize method.
   */
  virtual void randomize();
  /**
   * Override default OpenSSL password callback with getPassword().
   */
  void overrideDefaultPasswordCallback();
  /**
   * Set/Unset server mode.
   *
   * @param flag  Server mode if true
   */
  virtual void server(bool flag) { server_ = flag; }
  /**
   * Determine whether the socket is in server or client mode.
   *
   * @return true, if server mode, or, false, if client mode
   */
  virtual bool server() const { return server_; }
  /**
   * Set AccessManager.
   *
   * @param manager  The AccessManager instance
   */
  virtual void access(boost::shared_ptr<AccessManager> manager) {
    access_ = manager;
  }
 protected:
  boost::shared_ptr<SSLContext> ctx_;

  static void initializeOpenSSL();
  static void cleanupOpenSSL();
  /**
   * Override this method for custom password callback. It may be called
   * multiple times at any time during a session as necessary.
   *
   * @param password Pass collected password to OpenSSL
   * @param size     Maximum length of password including NULL character
   */
  virtual void getPassword(std::string& /* password */, int /* size */) {}
 private:
  bool server_;
  boost::shared_ptr<AccessManager> access_;
  static bool initialized;
  static concurrency::Mutex mutex_;
  static uint64_t count_;
  void setup(boost::shared_ptr<TSSLSocket> ssl);
  static int passwordCallback(char* password, int size, int, void* data);
};

/**
 * SSL exception.
 */
class TSSLException: public TTransportException {
 public:
  TSSLException(const std::string& message):
    TTransportException(TTransportException::INTERNAL_ERROR, message) {}

  virtual const char* what() const throw() {
    if (message_.empty()) {
      return "TSSLException";
    } else {
      return message_.c_str();
    }
  }
};

/**
 * Wrap OpenSSL SSL_CTX into a class.
 */
class SSLContext {
 public:
  SSLContext();
  virtual ~SSLContext();
  SSL* createSSL();
  SSL_CTX* get() { return ctx_; }
 private:
  SSL_CTX* ctx_;
};

/**
 * Callback interface for access control. It's meant to verify the remote host.
 * It's constructed when application starts and set to TSSLSocketFactory
 * instance. It's passed onto all TSSLSocket instances created by this factory
 * object.
 */
class AccessManager {
 public:
  enum Decision {
    DENY   = -1,    // deny access
    SKIP   =  0,    // cannot make decision, move on to next (if any)
    ALLOW  =  1     // allow access
  };
 /**
  * Destructor
  */
 virtual ~AccessManager() {}
 /**
  * Determine whether the peer should be granted access or not. It's called
  * once after the SSL handshake completes successfully, before peer certificate
  * is examined.
  *
  * If a valid decision (ALLOW or DENY) is returned, the peer certificate is
  * not to be verified.
  *
  * @param  sa Peer IP address
  * @return True if the peer is trusted, false otherwise
  */
 virtual Decision verify(const sockaddr_storage& /* sa */ ) throw() { return DENY; }
 /**
  * Determine whether the peer should be granted access or not. It's called
  * every time a DNS subjectAltName/common name is extracted from peer's
  * certificate.
  *
  * @param  host Client mode: host name returned by TSocket::getHost()
  *              Server mode: host name returned by TSocket::getPeerHost()
  * @param  name SubjectAltName or common name extracted from peer certificate
  * @param  size Length of name
  * @return True if the peer is trusted, false otherwise
  *
  * Note: The "name" parameter may be UTF8 encoded.
  */
 virtual Decision verify(const std::string& /* host */, const char* /* name */, int /* size */)
   throw() { return DENY; }
 /**
  * Determine whether the peer should be granted access or not. It's called
  * every time an IP subjectAltName is extracted from peer's certificate.
  *
  * @param  sa   Peer IP address retrieved from the underlying socket
  * @param  data IP address extracted from certificate
  * @param  size Length of the IP address
  * @return True if the peer is trusted, false otherwise
  */
 virtual Decision verify(const sockaddr_storage& /* sa */, const char* /* data */, int /* size */)
   throw() { return DENY; }
};

typedef AccessManager::Decision Decision;

class DefaultClientAccessManager: public AccessManager {
 public:
  // AccessManager interface
  Decision verify(const sockaddr_storage& sa) throw();
  Decision verify(const std::string& host, const char* name, int size) throw();
  Decision verify(const sockaddr_storage& sa, const char* data, int size) throw();
};


}}}

#endif
