/**

 * @file

 * IMAP authenticator multiplexor

 *

 * @authors

 * Copyright (C) 1996-1998 Michael R. Elkins <me@mutt.org>

 * Copyright (C) 1996-1999 Brandon Long <blong@fiction.net>

 * Copyright (C) 1999-2001 Brendan Cully <brendan@kublai.com>

 *

 * @copyright

 * This program is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free Software

 * Foundation, either version 2 of the License, or (at your option) any later

 * version.

 *

 * 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 General Public License for more

 * details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program.  If not, see <http://www.gnu.org/licenses/>.

 */

/**

 * @page imap_auth Authenticator multiplexor

 *

 * IMAP authenticator multiplexor

 */

#include "config.h"

#include <string.h>

#include "private.h"

#include "mutt/lib.h"

#include "config/lib.h"

#include "core/lib.h"

#include "auth.h"

/**

 * struct ImapAuth - IMAP authentication multiplexor

 */

struct ImapAuth

{

  /**

   * authenticate - Authenticate an IMAP connection

   * @param adata Imap Account data

   * @param method Use this named method, or any available method if NULL

   * @retval #ImapAuthRes Result, e.g. #IMAP_AUTH_SUCCESS

   */

  enum ImapAuthRes (*authenticate)(struct ImapAccountData *adata, const char *method);

  const char *method; ///< Name of authentication method supported, NULL means variable.

      ///< If this is not null, authenticate may ignore the second parameter.

};

/**

 * ImapAuthenticators - Accepted authentication methods

 */

static const struct ImapAuth ImapAuthenticators[] = {

  // clang-format off

  { imap_auth_oauth, "oauthbearer" },

  { imap_auth_xoauth2, "xoauth2" },

  { imap_auth_plain, "plain" },

#if defined(USE_SASL_CYRUS)

  { imap_auth_sasl, NULL },

#elif defined(USE_SASL_GNU)

  { imap_auth_gsasl, NULL },

#else

  { imap_auth_anon, "anonymous" },

#endif

#ifdef USE_GSS

  { imap_auth_gss, "gssapi" },

#endif

/* SASL includes CRAM-MD5 (and GSSAPI, but that's not enabled by default) */

#ifndef HAVE_SASL

  { imap_auth_cram_md5, "cram-md5" },

#endif

  { imap_auth_login, "login" },

  // clang-format on

};

/**

 * imap_auth_is_valid - Check if string is a valid imap authentication method

 * @param authenticator Authenticator string to check

 * @retval true Argument is a valid auth method

 *

 * Validate whether an input string is an accepted imap authentication method as

 * defined by #ImapAuthenticators.

 */

bool imap_auth_is_valid(const char *authenticator)

{

  for (size_t i = 0; i < mutt_array_size(ImapAuthenticators); i++)

  {

    const struct ImapAuth *auth = &ImapAuthenticators[i];

    if (auth->method && mutt_istr_equal(auth->method, authenticator))

      return true;

  }

  return false;

}

/**

 * imap_authenticate - Authenticate to an IMAP server

 * @param adata Imap Account data

 * @retval enum ImapAuthRes, e.g. #IMAP_AUTH_SUCCESS

 *

 * Attempt to authenticate using either user-specified authentication method if

 * specified, or any.

 */

int imap_authenticate(struct ImapAccountData *adata)

{

  int rc = IMAP_AUTH_FAILURE;

  const struct Slist *c_imap_authenticators = cs_subset_slist(NeoMutt->sub, "imap_authenticators");

  if (c_imap_authenticators && (c_imap_authenticators->count > 0))

  {

    mutt_debug(LL_DEBUG2, "Trying user-defined imap_authenticators\n");

    /* Try user-specified list of authentication methods */

    struct ListNode *np = NULL;

    STAILQ_FOREACH(np, &c_imap_authenticators->head, entries)

    {

      mutt_debug(LL_DEBUG2, "Trying method %s\n", np->data);

      for (size_t i = 0; i < mutt_array_size(ImapAuthenticators); i++)

      {

        const struct ImapAuth *auth = &ImapAuthenticators[i];

        if (!auth->method || mutt_istr_equal(auth->method, np->data))

        {

          rc = auth->authenticate(adata, np->data);

          if (rc == IMAP_AUTH_SUCCESS)

          {

            return rc;

          }

        }

      }

    }

  }

  else

  {

    /* Fall back to default: any authenticator */

    mutt_debug(LL_DEBUG2, "Trying pre-defined imap_authenticators\n");

    for (size_t i = 0; i < mutt_array_size(ImapAuthenticators); i++)

    {

      rc = ImapAuthenticators[i].authenticate(adata, NULL);

      if (rc == IMAP_AUTH_SUCCESS)

        return rc;

    }

  }

  mutt_error(_("No authenticators available or wrong credentials"));

  return rc;

}