/**

 * @file

 * IMAP OAUTH authentication method

 *

 * @authors

 * Copyright (C) 1999-2001,2005 Brendan Cully <brendan@kublai.com>

 * Copyright (C) 2018 Brandon Long <blong@fiction.net>

 *

 * @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_oauth OAUTH authentication

 *

 * IMAP OAUTH authentication method

 */

#include "config.h"

#include <stdbool.h>

#include <stdio.h>

#include "private.h"

#include "mutt/lib.h"

#include "config/lib.h"

#include "core/lib.h"

#include "conn/lib.h"

#include "auth.h"

#include "adata.h"

#include "mutt_logging.h"

/**

 * imap_auth_oauth_xoauth2 - Authenticate an IMAP connection using OAUTHBEARER or XOAUTH2

 * @param adata   Imap Account data

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

 * @param xoauth2 Use xoauth2 token (if true) or oauthbearer token (if false)

 * @retval num ImapAuth::ImapAuthRes Result, e.g. IMAP_AUTH_SUCCESS

 */

static enum ImapAuthRes imap_auth_oauth_xoauth2(struct ImapAccountData *adata,

                                                const char *method, bool xoauth2)

{

  char *ibuf = NULL;

  char *oauthbearer = NULL;

  const char *authtype = xoauth2 ? "XOAUTH2" : "OAUTHBEARER";

  int ilen;

  int rc;

  /* For now, we only support SASL_IR also and over TLS */

  if ((xoauth2 && !(adata->capabilities & IMAP_CAP_AUTH_XOAUTH2)) ||

      (!xoauth2 && !(adata->capabilities & IMAP_CAP_AUTH_OAUTHBEARER)) ||

      !(adata->capabilities & IMAP_CAP_SASL_IR) || (adata->conn->ssf == 0))

  {

    return IMAP_AUTH_UNAVAIL;

  }

  /* If they did not explicitly request or configure oauth then fail quietly */

  const char *const c_imap_oauth_refresh_command = cs_subset_string(NeoMutt->sub, "imap_oauth_refresh_command");

  if (!method && !c_imap_oauth_refresh_command)

    return IMAP_AUTH_UNAVAIL;

  // L10N: (%s) is the method name, e.g. Anonymous, CRAM-MD5, GSSAPI, SASL

  mutt_message(_("Authenticating (%s)..."), authtype);

  /* We get the access token from the imap_oauth_refresh_command */

  oauthbearer = mutt_account_getoauthbearer(&adata->conn->account, xoauth2);

  if (!oauthbearer)

    return IMAP_AUTH_FAILURE;

  ilen = mutt_str_len(oauthbearer) + 30;

  ibuf = mutt_mem_malloc(ilen);

  snprintf(ibuf, ilen, "AUTHENTICATE %s %s", authtype, oauthbearer);

  /* This doesn't really contain a password, but the token is good for

   * an hour, so suppress it anyways.  */

  rc = imap_exec(adata, ibuf, IMAP_CMD_PASS);

  FREE(&oauthbearer);

  FREE(&ibuf);

  if (rc != IMAP_EXEC_SUCCESS)

  {

    /* The error response was in SASL continuation, so continue the SASL

     * to cause a failure and exit SASL input.  See RFC7628 3.2.3 */

    mutt_socket_send(adata->conn, "\001");

    rc = imap_exec(adata, ibuf, IMAP_CMD_NO_FLAGS);

  }

  if (rc == IMAP_EXEC_SUCCESS)

  {

    mutt_clear_error();

    return IMAP_AUTH_SUCCESS;

  }

  // L10N: %s is the method name, e.g. Anonymous, CRAM-MD5, GSSAPI, SASL

  mutt_error(_("%s authentication failed"), authtype);

  return IMAP_AUTH_FAILURE;

}

/**

 * imap_auth_oauth - Authenticate an IMAP connection using OAUTHBEARER - Implements ImapAuth::authenticate()

 */

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

{

  return imap_auth_oauth_xoauth2(adata, method, false);

}

/**

 * imap_auth_xoauth2 - Authenticate an IMAP connection using XOAUTH2 - Implements ImapAuth::authenticate()

 */

enum ImapAuthRes imap_auth_xoauth2(struct ImapAccountData *adata, const char *method)

{

  return imap_auth_oauth_xoauth2(adata, method, true);

}