/*
 * Copyright (C) 2001-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS 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 program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_auth.h"
#include "gnutls_auth.h"
#include "algorithms.h"
#include <auth/cert.h>
#include <auth/psk.h>
#include <auth/anon.h>
#include <gnutls_datum.h>

/* The functions here are used in order for authentication algorithms
 * to be able to retrieve the needed credentials eg public and private
 * key etc.
 */

/**
 * gnutls_credentials_clear:
 * @session: is a #gnutls_session_t structure.
 *
 * Clears all the credentials previously set in this session.
 **/
void
gnutls_credentials_clear (gnutls_session_t session)
{
  if (session->key.cred)
    {                           /* beginning of the list */
      auth_cred_st *ccred, *ncred;
      ccred = session->key.cred;
      while (ccred != NULL)
        {
          ncred = ccred->next;
          gnutls_free (ccred);
          ccred = ncred;
        }
      session->key.cred = NULL;
    }
}

/* 
 * This creates a linked list of the form:
 * { algorithm, credentials, pointer to next }
 */
/**
 * gnutls_credentials_set:
 * @session: is a #gnutls_session_t structure.
 * @type: is the type of the credentials
 * @cred: is a pointer to a structure.
 *
 * Sets the needed credentials for the specified type.  Eg username,
 * password - or public and private keys etc.  The @cred parameter is
 * a structure that depends on the specified type and on the current
 * session (client or server).
 *
 * In order to minimize memory usage, and share credentials between
 * several threads gnutls keeps a pointer to cred, and not the whole
 * cred structure.  Thus you will have to keep the structure allocated
 * until you call gnutls_deinit().
 *
 * For %GNUTLS_CRD_ANON, @cred should be
 * #gnutls_anon_client_credentials_t in case of a client.  In case of
 * a server it should be #gnutls_anon_server_credentials_t.
 *
 * For %GNUTLS_CRD_SRP, @cred should be #gnutls_srp_client_credentials_t
 * in case of a client, and #gnutls_srp_server_credentials_t, in case
 * of a server.
 *
 * For %GNUTLS_CRD_CERTIFICATE, @cred should be
 * #gnutls_certificate_credentials_t.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned.
 **/
int
gnutls_credentials_set (gnutls_session_t session,
                        gnutls_credentials_type_t type, void *cred)
{
  auth_cred_st *ccred = NULL, *pcred = NULL;
  int exists = 0;

  if (session->key.cred == NULL)
    {                           /* beginning of the list */

      session->key.cred = gnutls_malloc (sizeof (auth_cred_st));
      if (session->key.cred == NULL)
        return GNUTLS_E_MEMORY_ERROR;

      /* copy credentials locally */
      session->key.cred->credentials = cred;

      session->key.cred->next = NULL;
      session->key.cred->algorithm = type;
    }
  else
    {
      ccred = session->key.cred;
      while (ccred != NULL)
        {
          if (ccred->algorithm == type)
            {
              exists = 1;
              break;
            }
          pcred = ccred;
          ccred = ccred->next;
        }
      /* After this, pcred is not null.
       */

      if (exists == 0)
        {                       /* new entry */
          pcred->next = gnutls_malloc (sizeof (auth_cred_st));
          if (pcred->next == NULL)
            return GNUTLS_E_MEMORY_ERROR;

          ccred = pcred->next;

          /* copy credentials locally */
          ccred->credentials = cred;

          ccred->next = NULL;
          ccred->algorithm = type;
        }
      else
        {                       /* modify existing entry */
          ccred->credentials = cred;
        }
    }

  return 0;
}

/**
 * gnutls_auth_get_type:
 * @session: is a #gnutls_session_t structure.
 *
 * Returns type of credentials for the current authentication schema.
 * The returned information is to be used to distinguish the function used
 * to access authentication data.
 *
 * Eg. for CERTIFICATE ciphersuites (key exchange algorithms:
 * %GNUTLS_KX_RSA, %GNUTLS_KX_DHE_RSA), the same function are to be
 * used to access the authentication data.
 *
 * Returns: The type of credentials for the current authentication
 *   schema, a #gnutls_credentials_type_t type.
 **/
gnutls_credentials_type_t
gnutls_auth_get_type (gnutls_session_t session)
{
/* This is not the credentials we must set, but the authentication data
 * we get by the peer, so it should be reversed.
 */
  int server = session->security_parameters.entity == GNUTLS_SERVER ? 0 : 1;

  return
    _gnutls_map_kx_get_cred (_gnutls_cipher_suite_get_kx_algo
                             (session->
                              security_parameters.cipher_suite),
                             server);
}

/**
 * gnutls_auth_server_get_type:
 * @session: is a #gnutls_session_t structure.
 *
 * Returns the type of credentials that were used for server authentication.
 * The returned information is to be used to distinguish the function used
 * to access authentication data.
 *
 * Returns: The type of credentials for the server authentication
 *   schema, a #gnutls_credentials_type_t type.
 **/
gnutls_credentials_type_t
gnutls_auth_server_get_type (gnutls_session_t session)
{
  return
    _gnutls_map_kx_get_cred (_gnutls_cipher_suite_get_kx_algo
                             (session->
                              security_parameters.cipher_suite), 1);
}

/**
 * gnutls_auth_client_get_type:
 * @session: is a #gnutls_session_t structure.
 *
 * Returns the type of credentials that were used for client authentication.
 * The returned information is to be used to distinguish the function used
 * to access authentication data.
 *
 * Returns: The type of credentials for the client authentication
 *   schema, a #gnutls_credentials_type_t type.
 **/
gnutls_credentials_type_t
gnutls_auth_client_get_type (gnutls_session_t session)
{
  return
    _gnutls_map_kx_get_cred (_gnutls_cipher_suite_get_kx_algo
                             (session->
                              security_parameters.cipher_suite), 0);
}


/* 
 * This returns a pointer to the linked list. Don't
 * free that!!!
 */
const void *
_gnutls_get_kx_cred (gnutls_session_t session,
                     gnutls_kx_algorithm_t algo, int *err)
{
  int server = session->security_parameters.entity == GNUTLS_SERVER ? 1 : 0;

  return _gnutls_get_cred (session,
                           _gnutls_map_kx_get_cred (algo, server), err);
}

const void *
_gnutls_get_cred (gnutls_session_t session, gnutls_credentials_type_t type, int *err)
{
  const void *retval = NULL;
  int _err = -1;
  auth_cred_st *ccred;
  gnutls_key_st * key = &session->key;

  ccred = key->cred;
  while (ccred != NULL)
    {
      if (ccred->algorithm == type)
        {
          break;
        }
      ccred = ccred->next;
    }
  if (ccred == NULL)
    goto out;

  _err = 0;
  retval = ccred->credentials;

out:
  if (err != NULL)
    *err = _err;
  return retval;
}

/*-
 * _gnutls_get_auth_info - Returns a pointer to authentication information.
 * @session: is a #gnutls_session_t structure.
 *
 * This function must be called after a successful gnutls_handshake().
 * Returns a pointer to authentication information. That information
 * is data obtained by the handshake protocol, the key exchange algorithm,
 * and the TLS extensions messages.
 *
 * In case of GNUTLS_CRD_ANON returns a type of &anon_(server/client)_auth_info_t;
 * In case of GNUTLS_CRD_CERTIFICATE returns a type of &cert_auth_info_t;
 * In case of GNUTLS_CRD_SRP returns a type of &srp_(server/client)_auth_info_t;
 -*/
void *
_gnutls_get_auth_info (gnutls_session_t session)
{
  return session->key.auth_info;
}

/*-
 * _gnutls_free_auth_info - Frees the auth info structure
 * @session: is a #gnutls_session_t structure.
 *
 * This function frees the auth info structure and sets it to
 * null. It must be called since some structures contain malloced
 * elements.
 -*/
void
_gnutls_free_auth_info (gnutls_session_t session)
{
  dh_info_st *dh_info;
  rsa_info_st *rsa_info;

  if (session == NULL)
    {
      gnutls_assert ();
      return;
    }

  switch (session->key.auth_info_type)
    {
    case GNUTLS_CRD_SRP:
      break;
    case GNUTLS_CRD_ANON:
      {
        anon_auth_info_t info = _gnutls_get_auth_info (session);

        if (info == NULL)
          break;

        dh_info = &info->dh;
        _gnutls_free_dh_info (dh_info);
      }
      break;
    case GNUTLS_CRD_PSK:
      {
        psk_auth_info_t info = _gnutls_get_auth_info (session);

        if (info == NULL)
          break;

        dh_info = &info->dh;
        _gnutls_free_dh_info (dh_info);
      }
      break;
    case GNUTLS_CRD_CERTIFICATE:
      {
        unsigned int i;
        cert_auth_info_t info = _gnutls_get_auth_info (session);

        if (info == NULL)
          break;

        dh_info = &info->dh;
        rsa_info = &info->rsa_export;
        for (i = 0; i < info->ncerts; i++)
          {
            _gnutls_free_datum (&info->raw_certificate_list[i]);
          }

        gnutls_free (info->raw_certificate_list);
        info->raw_certificate_list = NULL;
        info->ncerts = 0;

        _gnutls_free_dh_info (dh_info);
        _gnutls_free_rsa_info (rsa_info);
      }


      break;
    default:
      return;

    }

  gnutls_free (session->key.auth_info);
  session->key.auth_info = NULL;
  session->key.auth_info_size = 0;
  session->key.auth_info_type = 0;

}

/* This function will set the auth info structure in the key
 * structure.
 * If allow change is !=0 then this will allow changing the auth
 * info structure to a different type.
 */
int
_gnutls_auth_info_set (gnutls_session_t session,
                       gnutls_credentials_type_t type, int size,
                       int allow_change)
{
  if (session->key.auth_info == NULL)
    {
      session->key.auth_info = gnutls_calloc (1, size);
      if (session->key.auth_info == NULL)
        {
          gnutls_assert ();
          return GNUTLS_E_MEMORY_ERROR;
        }
      session->key.auth_info_type = type;
      session->key.auth_info_size = size;
    }
  else
    {
      if (allow_change == 0)
        {
          /* If the credentials for the current authentication scheme,
           * are not the one we want to set, then it's an error.
           * This may happen if a rehandshake is performed an the
           * ciphersuite which is negotiated has different authentication
           * schema.
           */
          if (gnutls_auth_get_type (session) != session->key.auth_info_type)
            {
              gnutls_assert ();
              return GNUTLS_E_INVALID_REQUEST;
            }
        }
      else
        {
          /* The new behaviour: Here we reallocate the auth info structure
           * in order to be able to negotiate different authentication
           * types. Ie. perform an auth_anon and then authenticate again using a
           * certificate (in order to prevent revealing the certificate's contents,
           * to passive eavesdropers.
           */
          if (gnutls_auth_get_type (session) != session->key.auth_info_type)
            {

              _gnutls_free_auth_info (session);

              session->key.auth_info = calloc (1, size);
              if (session->key.auth_info == NULL)
                {
                  gnutls_assert ();
                  return GNUTLS_E_MEMORY_ERROR;
                }

              session->key.auth_info_type = type;
              session->key.auth_info_size = size;
            }
        }
    }
  return 0;
}