/*
 * Copyright (C) 2005 Free Software Foundation
 *
 * Author: Nikos Mavroyanopoulos
 *
 * This file is part of GNUTLS.
 *
 * The GNUTLS library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA
 *
 */

/* Functions for manipulating the PSK credentials. */

#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <auth_psk.h>
#include <gnutls_state.h>

#ifdef ENABLE_PSK

#include <auth_psk_passwd.h>
#include <gnutls_num.h>
#include <gnutls_helper.h>
#include <gnutls_datum.h>
#include "debug.h"

/**
  * gnutls_psk_free_client_credentials - Used to free an allocated gnutls_psk_client_credentials_t structure
  * @sc: is an #gnutls_psk_client_credentials_t structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to free (deallocate) it.
  *
  **/
void
gnutls_psk_free_client_credentials (gnutls_psk_client_credentials_t sc)
{
  _gnutls_free_datum (&sc->username);
  _gnutls_free_datum (&sc->key);
  gnutls_free (sc);
}

/**
  * gnutls_psk_allocate_client_credentials - Used to allocate an gnutls_psk_server_credentials_t structure
  * @sc: is a pointer to an #gnutls_psk_server_credentials_t structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to allocate it.
  *
  * Returns 0 on success.
  **/
int
gnutls_psk_allocate_client_credentials (gnutls_psk_client_credentials_t * sc)
{
  *sc = gnutls_calloc (1, sizeof (psk_client_credentials_st));

  if (*sc == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  return 0;
}

/**
  * gnutls_psk_set_client_credentials - Used to set the username/password, in a gnutls_psk_client_credentials_t structure
  * @res: is an #gnutls_psk_client_credentials_t structure.
  * @username: is the user's zero-terminated userid
  * @key: is the user's key
  *
  * This function sets the username and password, in a
  * gnutls_psk_client_credentials_t structure.  Those will be used in
  * PSK authentication. @username should be an ASCII
  * string or UTF-8 strings prepared using the "SASLprep" profile of
  * "stringprep". The key can be either in raw byte format or in Hex
  * (not with the '0x' prefix).
  *
  * Returns 0 on success.
  **/
int
gnutls_psk_set_client_credentials (gnutls_psk_client_credentials_t res,
				   const char *username,
				   const gnutls_datum * key,
				   unsigned int flags)
{
  int ret;

  if (username == NULL || key == NULL || key->data == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  ret = _gnutls_set_datum (&res->username, username, strlen (username));
  if (ret < 0)
    return ret;

  if (flags == GNUTLS_PSK_KEY_RAW)
    {
      if (_gnutls_set_datum (&res->key, key->data, key->size) < 0)
	{
	  gnutls_assert ();
	  ret = GNUTLS_E_MEMORY_ERROR;
	  goto error;
	}
    }
  else
    {				/* HEX key */
      res->key.size = key->size / 2;
      res->key.data = gnutls_malloc (res->key.size);
      if (res->key.data == NULL)
	{
	  gnutls_assert ();
	  ret = GNUTLS_E_MEMORY_ERROR;
	  goto error;
	}

      ret = gnutls_hex_decode (key, (char *) res->key.data, &res->key.size);
      if (ret < 0)
	{
	  gnutls_assert ();
	  goto error;
	}

    }

  return 0;

error:
  _gnutls_free_datum (&res->username);

  return ret;
}

/**
  * gnutls_psk_free_server_credentials - Used to free an allocated gnutls_psk_server_credentials_t structure
  * @sc: is an #gnutls_psk_server_credentials_t structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to free (deallocate) it.
  *
  **/
void
gnutls_psk_free_server_credentials (gnutls_psk_server_credentials_t sc)
{
  gnutls_free (sc->password_file);
  gnutls_free (sc);
}

/**
  * gnutls_psk_allocate_server_credentials - Used to allocate an gnutls_psk_server_credentials_t structure
  * @sc: is a pointer to an #gnutls_psk_server_credentials_t structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to allocate it.
  * 
  * Returns 0 on success.
  **/
int
gnutls_psk_allocate_server_credentials (gnutls_psk_server_credentials_t * sc)
{
  *sc = gnutls_calloc (1, sizeof (psk_server_cred_st));

  if (*sc == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  return 0;
}


/**
  * gnutls_psk_set_server_credentials_file - Used to set the password files, in a gnutls_psk_server_credentials_t structure
  * @res: is an #gnutls_psk_server_credentials_t structure.
  * @password_file: is the PSK password file (passwd.psk)
  *
  * This function sets the password file, in a gnutls_psk_server_credentials_t structure.
  * This password file holds usernames and keys and will be used for PSK authentication.
  *
  * Returns 0 on success.
  *
  **/
int
gnutls_psk_set_server_credentials_file (gnutls_psk_server_credentials_t
					res, const char *password_file)
{

  if (password_file == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  /* Check if the files can be opened */
  if (_gnutls_file_exists (password_file) != 0)
    {
      gnutls_assert ();
      return GNUTLS_E_FILE_ERROR;
    }

  res->password_file = gnutls_strdup (password_file);
  if (res->password_file == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  return 0;
}


/**
  * gnutls_psk_set_server_credentials_function - Used to set a callback to retrieve the user's PSK credentials
  * @cred: is a #gnutls_psk_server_credentials_t structure.
  * @func: is the callback function
  *
  * This function can be used to set a callback to retrieve the user's PSK credentials.
  * The callback's function form is:
  * int (*callback)(gnutls_session_t, const char* username,
  *  gnutls_datum_t* key);
  *
  * @username contains the actual username. 
  * The @key must be filled in using the gnutls_malloc(). 
  *
  * In case the callback returned a negative number then gnutls will
  * assume that the username does not exist.
  *
  * The callback function will only be called once per handshake.
  * The callback function should return 0 on success, while
  * -1 indicates an error.
  *
  **/
void
gnutls_psk_set_server_credentials_function (gnutls_psk_server_credentials_t
					    cred,
					    gnutls_psk_server_credentials_function
					    * func)
{
  cred->pwd_callback = func;
}

/**
  * gnutls_psk_set_client_credentials_function - Used to set a callback to retrieve the username and key
  * @cred: is a #gnutls_psk_server_credentials_t structure.
  * @func: is the callback function
  *
  * This function can be used to set a callback to retrieve the username and
  * password for client PSK authentication.
  * The callback's function form is:
  * int (*callback)(gnutls_session_t, char** username,
  *  gnutls_datum* key);
  *
  * The @username and @key must be allocated using gnutls_malloc().
  * @username should be ASCII strings or UTF-8 strings 
  * prepared using the "SASLprep" profile of "stringprep".
  *
  * The callback function will be called once per handshake.
  * 
  * The callback function should return 0 on success.
  * -1 indicates an error.
  *
  **/
void
gnutls_psk_set_client_credentials_function (gnutls_psk_client_credentials_t
					    cred,
					    gnutls_psk_client_credentials_function
					    * func)
{
  cred->get_function = func;
}


/**
  * gnutls_psk_server_get_username - This function returns the username of the peer
  * @session: is a gnutls session
  *
  * This function will return the username of the peer. This should only be
  * called in case of PSK authentication and in case of a server.
  * Returns NULL in case of an error.
  *
  **/
const char *
gnutls_psk_server_get_username (gnutls_session_t session)
{
  psk_auth_info_t info;

  CHECK_AUTH (GNUTLS_CRD_PSK, NULL);

  info = _gnutls_get_auth_info (session);
  if (info == NULL)
    return NULL;

  if (info->username[0] != 0)
    return info->username;

  return NULL;
}

/**
  * gnutls_hex_decode - This function will decode hex encoded data
  * @hex_data: contain the encoded data
  * @result: the place where decoded data will be copied
  * @result_size: holds the size of the result
  *
  * This function will decode the given encoded data, using the hex encoding
  * used by PSK password files.
  *
  * Note that hex_data should be null terminated.
  * 
  * Returns GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough,
  * or 0 on success.
  **/
int
gnutls_hex_decode (const gnutls_datum_t * hex_data, char *result,
		   size_t * result_size)
{
  int ret;

  ret =
    _gnutls_hex2bin (hex_data->data, hex_data->size, (opaque *) result,
		     result_size);
  if (ret < 0)
    return ret;

  return 0;
}

/**
  * gnutls_hex_encode - This function will convert raw data to hex encoded
  * @data: contain the raw data
  * @result: the place where hex data will be copied
  * @result_size: holds the size of the result
  *
  * This function will convert the given data to printable data, using the hex 
  * encoding, as used in the PSK password files.
  * 
  * Returns GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not long enough,
  * or 0 on success.
  **/
int
gnutls_hex_encode (const gnutls_datum_t * data, char *result,
		   size_t * result_size)
{
  if (*result_size < data->size + data->size + 1)
    {
      gnutls_assert ();
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }

  _gnutls_bin2hex (data->data, data->size, result, *result_size);

  return 0;
}

/**
  * gnutls_psk_set_server_dh_params - This function will set the DH parameters for a server to use
  * @res: is a gnutls_psk_server_credentials_t structure
  * @dh_params: is a structure that holds diffie hellman parameters.
  *
  * This function will set the diffie hellman parameters for an anonymous
  * server to use. These parameters will be used in Diffie Hellman with PSK
  * cipher suites.
  *
  **/
void
gnutls_psk_set_server_dh_params (gnutls_psk_server_credentials_t res,
				 gnutls_dh_params_t dh_params)
{
  res->dh_params = dh_params;
}

/**
  * gnutls_psk_set_server_params_function - This function will set the DH parameters callback
  * @res: is a gnutls_certificate_credentials_t structure
  * @func: is the function to be called
  *
  * This function will set a callback in order for the server to get the 
  * diffie hellman parameters for PSK authentication. The callback should
  * return zero on success.
  *
  **/
void
gnutls_psk_set_server_params_function (gnutls_psk_server_credentials_t res,
				       gnutls_params_function * func)
{
  res->params_func = func;
}

#endif /* ENABLE_PSK */