//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2017 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

// This code implements an OpenSSL BIO object for streams based on the
// MemQ buffer queue object.

#pragma once

#include <cstring> // for std::strlen and others

#include <openssl/err.h>
#include <openssl/bio.h>

#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/frame/frame.hpp>
#include <openvpn/frame/memq_stream.hpp>

#include <openvpn/openssl/compat.hpp>

namespace openvpn {
  namespace bmq_stream {

    class MemQ : public MemQStream {
    public:
      MemQ() {}

      long ctrl (BIO *b, int cmd, long num, void *ptr)
      {
	long ret = 1;

	switch (cmd)
	  {
	  case BIO_CTRL_RESET:
	    clear();
	    break;
	  case BIO_CTRL_EOF:
	    ret = (long)empty();
	    break;
	  case BIO_C_SET_BUF_MEM_EOF_RETURN:
	    return_eof_on_empty = (num == 0);
	    break;
	  case BIO_CTRL_GET_CLOSE:
	    ret = BIO_get_shutdown(b);
	    break;
	  case BIO_CTRL_SET_CLOSE:
	    BIO_set_shutdown(b, (int) num);
	    break;
	  case BIO_CTRL_WPENDING:
	    ret = 0L;
	    break;
	  case BIO_CTRL_PENDING:
	    ret = (long)pending();
	    break;
	  case BIO_CTRL_DUP:
	  case BIO_CTRL_FLUSH:
	    ret = 1;
	    break;
	  default:
	    //OPENVPN_LOG("*** MemQ-stream unimplemented ctrl method=" << cmd);
	    ret = 0;
	    break;
	  }
	return (ret);
      }

       bool return_eof_on_empty = false;
    };

    class bio_memq_internal {
    public:
      static int memq_method_type;
      static BIO_METHOD* memq_method;


      static inline int memq_new (BIO *b)
      {
	MemQ *bmq = new(std::nothrow) MemQ();
	if (!bmq)
	  return 0;
	BIO_set_shutdown(b, 1);
	BIO_set_init(b, 1);
	BIO_set_data(b, (void *)bmq);
	return 1;
      }

      static inline int memq_free (BIO *b)
      {
	if (b == nullptr)
	  return (0);
	if (BIO_get_shutdown (b))
	  {
            MemQ *bmq = (MemQ*) (BIO_get_data (b));
            if (BIO_get_init (b) && (bmq != nullptr))
	      {
		delete bmq;
		BIO_set_data (b, nullptr);
	      }
	  }
	return 1;
      }

      static inline int memq_write (BIO *b, const char *in, int len)
      {
	MemQ *bmq = (MemQ*)(BIO_get_data(b));
	if (in)
	  {
	    BIO_clear_retry_flags (b);
	    try {
	      if (len)
		bmq->write((const unsigned char *)in, (size_t)len);
	      return len;
	    }
	    catch (...)
	      {
		BIOerr(BIO_F_MEM_WRITE, BIO_R_INVALID_ARGUMENT);
		return -1;
	      }
	  }
	else
	  {
	    BIOerr(BIO_F_MEM_WRITE, BIO_R_NULL_PARAMETER);
	    return -1;
	  }
      }

      static inline int memq_read (BIO *b, char *out, int size)
      {
	MemQ *bmq = (MemQ*)(BIO_get_data(b));
	int ret = -1;
	BIO_clear_retry_flags (b);
	if (!bmq->empty())
	  {
	    try {
	      ret = (int)bmq->read((unsigned char *)out, (size_t)size);
	    }
	    catch (...)
	      {
		BIOerr(memq_method_type, BIO_R_INVALID_ARGUMENT);
		return -1;
	      }
	  }
	else
	  {
	    if (!bmq->return_eof_on_empty)
		BIO_set_retry_read (b);
	  }
	return ret;
      }

      static inline long memq_ctrl (BIO *b, int cmd, long arg1, void *arg2)
      {
	MemQ *bmq = (MemQ*)(BIO_get_data(b));
	return bmq->ctrl(b, cmd, arg1, arg2);
      }

      static inline int memq_puts (BIO *b, const char *str)
      {
	const int len = std::strlen (str);
	const int ret = memq_write (b, str, len);
	return ret;
      }

      static inline void init_static ()
      {
	memq_method_type = BIO_get_new_index ();
	memq_method = BIO_meth_new (memq_method_type, "stream memory queue");
	BIO_meth_set_write (memq_method, memq_write);
	BIO_meth_set_read (memq_method, memq_read);
	BIO_meth_set_puts (memq_method, memq_puts);
	BIO_meth_set_create (memq_method, memq_new);
	BIO_meth_set_destroy (memq_method, memq_free);
	BIO_meth_set_gets (memq_method, nullptr);
	BIO_meth_set_ctrl (memq_method, memq_ctrl);
      }

      static inline void free_bio_method()
      {
	BIO_meth_free (memq_method);
	memq_method = nullptr;
      }
    }; // class bio_memq_internal

#if defined(OPENVPN_NO_EXTERN)
    int bio_memq_internal::memq_method_type = -1;
    BIO_METHOD* bio_memq_internal::memq_method = nullptr;
#endif

    inline void init_static()
    {
      bio_memq_internal::init_static();
    }

    inline BIO_METHOD *BIO_s_memq(void)
    {
      return (bio_memq_internal::memq_method);
    }

    inline MemQ *memq_from_bio(BIO *b)
    {
      if (BIO_method_type(b) == bio_memq_internal::memq_method_type)
	return (MemQ *)(BIO_get_data (b));
      else
	return nullptr;
    }

    inline const MemQ *const_memq_from_bio(const BIO *b)
    {
      if (BIO_method_type(b) == bio_memq_internal::memq_method_type)
	return (const MemQ *)(BIO_get_data (const_cast<BIO*>(b)));
      else
	return nullptr;
    }
  } // namespace bmq_dgram
} // namespace openvpn