/*

 * Copyright (C) 2012-2017 Free Software Foundation, Inc.

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * Author: Simon Josefsson, 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 <https://www.gnu.org/licenses/>

 *

 */

/*

 *  Status Request (OCSP) API.

 */

#include "gnutls_int.h"

#include "errors.h"

#include "auth.h"

#include "auth/cert.h"

#include "handshake.h"

#include <minmax.h>

#ifdef ENABLE_OCSP

#include <gnutls/ocsp.h>

#include "x509/ocsp.h"

/**

 * gnutls_ocsp_status_request_get:

 * @session: is a #gnutls_session_t type.

 * @response: a #gnutls_datum_t with DER encoded OCSP response

 *

 * This function returns the OCSP status response received

 * from the TLS server. The @response should be treated as

 * constant. If no OCSP response is available then

 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.1.3

 **/

int gnutls_ocsp_status_request_get(gnutls_session_t session,

           gnutls_datum_t *response)

{

  return gnutls_ocsp_status_request_get2(session, 0, response);

}

/**

 * gnutls_ocsp_status_request_get2:

 * @session: is a #gnutls_session_t type.

 * @idx: the index of peer's certificate

 * @response: a #gnutls_datum_t with DER encoded OCSP response

 *

 * This function returns the OCSP status response received

 * from the TLS server for the certificate index provided.

 * The index corresponds to certificates as returned by

 * gnutls_certificate_get_peers. When index is zero this

 * function operates identically to gnutls_ocsp_status_request_get().

 *

 * The returned @response should be treated as

 * constant. If no OCSP response is available for the

 * given index then %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE

 * is returned.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.6.3

 **/

int gnutls_ocsp_status_request_get2(gnutls_session_t session, unsigned idx,

            gnutls_datum_t *response)

{

  const version_entry_st *ver = get_version(session);

  cert_auth_info_t info =

    _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);

  if (!ver->tls13_sem &&

      session->security_parameters.entity == GNUTLS_SERVER)

    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  if (info == NULL || info->raw_ocsp_list == NULL || info->nocsp <= idx ||

      info->raw_ocsp_list[idx].size == 0)

    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  response->data = info->raw_ocsp_list[idx].data;

  response->size = info->raw_ocsp_list[idx].size;

  return 0;

}

/**

 * gnutls_certificate_set_ocsp_status_request_function:

 * @sc: is a #gnutls_certificate_credentials_t type.

 * @ocsp_func: function pointer to OCSP status request callback.

 * @ptr: opaque pointer passed to callback function

 *

 * This function is to be used by server to register a callback to

 * handle OCSP status requests from the client.  The callback will be

 * invoked if the client supplied a status-request OCSP extension.

 * The callback function prototype is:

 *

 * typedef int (*gnutls_status_request_ocsp_func)

 *    (gnutls_session_t session, void *ptr, gnutls_datum_t *ocsp_response);

 *

 * The callback will be invoked if the client requests an OCSP certificate

 * status.  The callback may return %GNUTLS_E_NO_CERTIFICATE_STATUS, if

 * there is no recent OCSP response. If the callback returns %GNUTLS_E_SUCCESS,

 * it is expected to have the @ocsp_response field set with a valid (DER-encoded)

 * OCSP response. The response must be a value allocated using gnutls_malloc(),

 * and will be deinitialized by the caller.

 *

 * It is possible to set a specific callback for each provided certificate

 * using gnutls_certificate_set_ocsp_status_request_function2().

 *

 * Since: 3.1.3

 **/

void gnutls_certificate_set_ocsp_status_request_function(

  gnutls_certificate_credentials_t sc,

  gnutls_status_request_ocsp_func ocsp_func, void *ptr)

{

  sc->glob_ocsp_func = ocsp_func;

  sc->glob_ocsp_func_ptr = ptr;

}

/**

 * gnutls_certificate_set_ocsp_status_request_function2:

 * @sc: is a #gnutls_certificate_credentials_t type.

 * @idx: is a certificate index as returned by gnutls_certificate_set_key() and friends

 * @ocsp_func: function pointer to OCSP status request callback.

 * @ptr: opaque pointer passed to callback function

 *

 * This function is to be used by server to register a callback to

 * provide OCSP status requests that correspond to the indexed certificate chain

 * from the client.  The callback will be invoked if the client supplied a

 * status-request OCSP extension.

 *

 * The callback function prototype is:

 *

 * typedef int (*gnutls_status_request_ocsp_func)

 *    (gnutls_session_t session, void *ptr, gnutls_datum_t *ocsp_response);

 *

 * The callback will be invoked if the client requests an OCSP certificate

 * status.  The callback may return %GNUTLS_E_NO_CERTIFICATE_STATUS, if

 * there is no recent OCSP response. If the callback returns %GNUTLS_E_SUCCESS,

 * it is expected to have the @ocsp_response field set with a valid (DER-encoded)

 * OCSP response. The response must be a value allocated using gnutls_malloc(),

 * and will be deinitialized by the caller.

 *

 * Note: the ability to set multiple OCSP responses per credential

 * structure via the index @idx was added in version 3.5.6. To keep

 * backwards compatibility, it requires using gnutls_certificate_set_flags()

 * with the %GNUTLS_CERTIFICATE_API_V2 flag to make the set certificate

 * functions return an index usable by this function.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.5.5

 **/

int gnutls_certificate_set_ocsp_status_request_function2(

  gnutls_certificate_credentials_t sc, unsigned idx,

  gnutls_status_request_ocsp_func ocsp_func, void *ptr)

{

  if (idx >= sc->ncerts)

    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  sc->certs[idx].ocsp_func = ocsp_func;

  sc->certs[idx].ocsp_func_ptr = ptr;

  return 0;

}

static unsigned resp_matches_pcert(gnutls_ocsp_resp_t resp,

           const gnutls_pcert_st *cert)

{

  gnutls_x509_crt_t crt;

  int ret;

  unsigned retval;

  ret = gnutls_x509_crt_init(&crt);

  if (ret < 0)

    return 0;

  ret = gnutls_x509_crt_import(crt, &cert->cert, GNUTLS_X509_FMT_DER);

  if (ret < 0) {

    gnutls_assert();

    retval = 0;

    goto cleanup;

  }

  ret = gnutls_ocsp_resp_check_crt(resp, 0, crt);

  if (ret == 0)

    retval = 1;

  else

    retval = 0;

cleanup:

  gnutls_x509_crt_deinit(crt);

  return retval;

}

/**

 * gnutls_certificate_set_ocsp_status_request_file:

 * @sc: is a credentials structure.

 * @response_file: a filename of the OCSP response

 * @idx: is a certificate index as returned by gnutls_certificate_set_key() and friends

 *

 * This function loads the provided OCSP response. It will be

 * sent to the client if requests an OCSP certificate status for

 * the certificate chain specified by @idx.

 *

 * Note: the ability to set multiple OCSP responses per credential

 * structure via the index @idx was added in version 3.5.6. To keep

 * backwards compatibility, it requires using gnutls_certificate_set_flags()

 * with the %GNUTLS_CERTIFICATE_API_V2 flag to make the set certificate

 * functions return an index usable by this function.

 *

 * This function can be called multiple times since GnuTLS 3.6.3

 * when multiple responses which apply to the chain are available.

 * If the response provided does not match any certificates present

 * in the chain, the code %GNUTLS_E_OCSP_MISMATCH_WITH_CERTS is returned.

 * To revert to the previous behavior set the flag %GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK

 * in the certificate credentials structure. In that case, only the

 * end-certificate's OCSP response can be set.

 * If the response is already expired at the time of loading the code

 * %GNUTLS_E_EXPIRED is returned.

 *

 * To revert to the previous behavior of this function which does not return

 * any errors, set the flag %GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.1.3

 **/

int gnutls_certificate_set_ocsp_status_request_file(

  gnutls_certificate_credentials_t sc, const char *response_file,

  unsigned idx)

{

  int ret;

  ret = gnutls_certificate_set_ocsp_status_request_file2(

    sc, response_file, idx, GNUTLS_X509_FMT_DER);

  if (ret >= 0)

    return 0;

  else

    return ret;

}

static int append_response(gnutls_certificate_credentials_t sc, unsigned idx,

         gnutls_ocsp_resp_t resp, const gnutls_datum_t *der)

{

  int ret;

  unsigned i, found = 0;

  unsigned try_already_set = 0;

  time_t t;

retry:

  /* iterate through all certificates in chain, and add the response

   * to the certificate that it matches with.

   */

  for (i = 0;

       i < MIN(sc->certs[idx].cert_list_length, MAX_OCSP_RESPONSES);

       i++) {

    if (!try_already_set &&

        sc->certs[idx].ocsp_data[i].response.data)

      continue;

    if (!resp_matches_pcert(resp, &sc->certs[idx].cert_list[i]))

      continue;

    t = _gnutls_ocsp_get_validity(resp);

    /* if already invalid */

    if (t == (time_t)-1) {

      _gnutls_debug_log(

        "the OCSP response associated with chain %d on pos %d, is invalid/expired\n",

        idx, i);

      return GNUTLS_E_EXPIRED;

    } else if (t == (time_t)-2) {

      _gnutls_debug_log(

        "the OCSP response associated with chain %d on pos %d, is too old (ignoring)\n",

        idx, i);

      return 0;

    }

    if (t >= 0)

      sc->certs[idx].ocsp_data[i].exptime = t;

    else

      sc->certs[idx].ocsp_data[i].exptime = 0;

    _gnutls_debug_log(

      "associating OCSP response with chain %d on pos %d\n",

      idx, i);

    gnutls_free(sc->certs[idx].ocsp_data[i].response.data);

    ret = _gnutls_set_datum(&sc->certs[idx].ocsp_data[i].response,

          der->data, der->size);

    if (ret < 0) {

      gnutls_assert();

      sc->certs[idx].ocsp_data[i].response.data = NULL;

      sc->certs[idx].ocsp_data[i].response.size = 0;

      return ret;

    }

    if (sc->certs[idx].ocsp_data_length <= i)

      sc->certs[idx].ocsp_data_length = i + 1;

    found = 1;

    break;

  }

  if (!found) {

    /* slow path; if we found no matching certificate for the OCSP

     * response, try all the existing, even if a response is already

     * given. */

    if (!try_already_set) {

      try_already_set = 1;

      goto retry;

    }

    ret = GNUTLS_E_OCSP_MISMATCH_WITH_CERTS;

  } else {

    ret = 0;

  }

  return ret;

}

/**

 * gnutls_certificate_set_ocsp_status_request_file2:

 * @sc: is a credentials structure.

 * @response_file: a filename of the OCSP response

 * @idx: is a certificate index as returned by gnutls_certificate_set_key() and friends

 * @fmt: is PEM or DER

 *

 * This function loads the OCSP responses to be sent to the

 * peer for the certificate chain specified by @idx. When @fmt is

 * set to PEM, multiple responses can be loaded.

 *

 * This function must be called after setting any certificates, and

 * cannot be used for certificates that are provided via a callback --

 * that is when gnutls_certificate_set_retrieve_function() is used. In

 * that case consider using gnutls_certificate_set_retrieve_function3().

 *

 * This function can be called multiple times when multiple responses

 * applicable to the certificate chain are available.

 * If the response provided does not match any certificates present

 * in the chain, the code %GNUTLS_E_OCSP_MISMATCH_WITH_CERTS is returned.

 * If the response is already expired at the time of loading the code

 * %GNUTLS_E_EXPIRED is returned.

 *

 * Returns: On success, the number of loaded responses is returned,

 *   otherwise a negative error code.

 *

 * Since: 3.1.3

 **/

int gnutls_certificate_set_ocsp_status_request_file2(

  gnutls_certificate_credentials_t sc, const char *response_file,

  unsigned idx, gnutls_x509_crt_fmt_t fmt)

{

  gnutls_datum_t raw = { NULL, 0 };

  int ret;

  if (idx >= sc->ncerts)

    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  ret = gnutls_load_file(response_file, &raw);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_FILE_ERROR);

  ret = gnutls_certificate_set_ocsp_status_request_mem(sc, &raw, idx,

                   fmt);

  gnutls_free(raw.data);

  return ret;

}

#define PEM_OCSP_RESPONSE "OCSP RESPONSE"

#define FULL_PEM_OCSP_RESPONSE "-----BEGIN OCSP RESPONSE"

/**

 * gnutls_certificate_set_ocsp_status_request_mem:

 * @sc: is a credentials structure.

 * @resp_data: a memory buffer holding an OCSP response

 * @idx: is a certificate index as returned by gnutls_certificate_set_key() and friends

 * @fmt: is PEM or DER

 *

 * This function sets the OCSP responses to be sent to the

 * peer for the certificate chain specified by @idx. When @fmt is set

 * to PEM, multiple responses can be loaded.

 *

 * Note: the ability to set multiple OCSP responses per credential

 * structure via the index @idx was added in version 3.5.6. To keep

 * backwards compatibility, it requires using gnutls_certificate_set_flags()

 * with the %GNUTLS_CERTIFICATE_API_V2 flag to make the set certificate

 * functions return an index usable by this function.

 *

 * This function must be called after setting any certificates, and

 * cannot be used for certificates that are provided via a callback --

 * that is when gnutls_certificate_set_retrieve_function() is used.

 *

 * This function can be called multiple times when multiple responses which

 * apply to the certificate chain are available.

 * If the response provided does not match any certificates present

 * in the chain, the code %GNUTLS_E_OCSP_MISMATCH_WITH_CERTS is returned.

 * If the response is already expired at the time of loading the code

 * %GNUTLS_E_EXPIRED is returned.

 *

 * Returns: On success, the number of loaded responses is returned,

 *   otherwise a negative error code.

 *

 * Since: 3.6.3

 **/

int gnutls_certificate_set_ocsp_status_request_mem(

  gnutls_certificate_credentials_t sc, const gnutls_datum_t *resp_data,

  unsigned idx, gnutls_x509_crt_fmt_t fmt)

{

  gnutls_datum_t der = { NULL, 0 };

  gnutls_ocsp_resp_t resp = NULL;

  int ret;

  unsigned int nresp = 0;

  ret = gnutls_ocsp_resp_init(&resp);

  if (ret < 0) {

    return gnutls_assert_val(ret);

  }

  if (fmt == GNUTLS_X509_FMT_PEM) {

    /* load multiple responses */

    gnutls_datum_t p = { resp_data->data, resp_data->size };

    p.data = memmem(p.data, p.size, FULL_PEM_OCSP_RESPONSE,

        sizeof(FULL_PEM_OCSP_RESPONSE) - 1);

    if (p.data == NULL) {

      ret = gnutls_assert_val(

        GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

      goto cleanup;

    }

    p.size -= p.data - resp_data->data;

    if (p.size <= 0) {

      ret = gnutls_assert_val(

        GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

      goto cleanup;

    }

    do {

      ret = gnutls_pem_base64_decode2(PEM_OCSP_RESPONSE, &p,

              &der);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

      ret = gnutls_certificate_set_ocsp_status_request_mem(

        sc, &der, idx, GNUTLS_X509_FMT_DER);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

      nresp++;

      gnutls_free(der.data);

      p.data++;

      p.size--;

      p.data = memmem(p.data, p.size, FULL_PEM_OCSP_RESPONSE,

          sizeof(FULL_PEM_OCSP_RESPONSE) - 1);

      if (p.data == NULL)

        break;

      p.size = resp_data->size - (p.data - resp_data->data);

    } while (p.size > 0);

    ret = nresp;

  } else {

    /* DER: load a single response */

    if (sc->flags & GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK) {

      ret = gnutls_ocsp_resp_import2(resp, resp_data,

                   GNUTLS_X509_FMT_DER);

      if (ret >= 0) {

        sc->certs[idx].ocsp_data[0].exptime =

          _gnutls_ocsp_get_validity(resp);

        if (sc->certs[idx].ocsp_data[0].exptime <= 0)

          sc->certs[idx].ocsp_data[0].exptime = 0;

      }

      /* quick load of first response */

      gnutls_free(sc->certs[idx].ocsp_data[0].response.data);

      ret = _gnutls_set_datum(

        &sc->certs[idx].ocsp_data[0].response,

        resp_data->data, resp_data->size);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

      sc->certs[idx].ocsp_data_length = 1;

      goto cleanup;

    }

    ret = gnutls_ocsp_resp_import2(resp, resp_data,

                 GNUTLS_X509_FMT_DER);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    ret = append_response(sc, idx, resp, resp_data);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    ret = 1;

  }

cleanup:

  gnutls_free(der.data);

  if (resp)

    gnutls_ocsp_resp_deinit(resp);

  return ret;

}

/**

 * gnutls_certificate_get_ocsp_expiration:

 * @sc: is a credentials structure.

 * @idx: is a certificate chain index as returned by gnutls_certificate_set_key() and friends

 * @oidx: is an OCSP response index

 * @flags: should be zero

 *

 * This function returns the validity of the loaded OCSP responses,

 * to provide information on when to reload/refresh them.

 *

 * Note that the credentials structure should be read-only when in

 * use, thus when reloading, either the credentials structure must not

 * be in use by any sessions, or a new credentials structure should be

 * allocated for new sessions.

 *

 * When @oidx is (-1) then the minimum refresh time for all responses

 * is returned. Otherwise the index specifies the response corresponding

 * to the @odix certificate in the certificate chain.

 *

 * Returns: On success, the expiration time of the OCSP response. Otherwise

 *   (time_t)(-1) on error, or (time_t)-2 on out of bounds.

 *

 * Since: 3.6.3

 **/

time_t

gnutls_certificate_get_ocsp_expiration(gnutls_certificate_credentials_t sc,

               unsigned idx, int oidx, unsigned flags)

{

  unsigned j;

  if (idx >= sc->ncerts)

    return (time_t)-2;

  if (oidx == -1) {

    time_t min = 0;

    for (j = 0; j < MIN(sc->certs[idx].cert_list_length,

            MAX_OCSP_RESPONSES);

         j++) {

      if (min <= 0)

        min = sc->certs[idx].ocsp_data[j].exptime;

      else if (sc->certs[idx].ocsp_data[j].exptime > 0 &&

         min >= sc->certs[idx].ocsp_data[j].exptime)

        min = sc->certs[idx].ocsp_data[j].exptime;

    }

    return min;

  }

  if (oidx >= MAX_OCSP_RESPONSES ||

      (unsigned)oidx >= sc->certs[idx].cert_list_length)

    return (time_t)-2;

  if (sc->certs[idx].ocsp_data[oidx].response.data == NULL)

    return (time_t)-1;

  return sc->certs[idx].ocsp_data[oidx].exptime;

}

/**

 * gnutls_ocsp_status_request_is_checked:

 * @session: is a gnutls session

 * @flags: should be zero or %GNUTLS_OCSP_SR_IS_AVAIL

 *

 * When flags are zero this function returns non-zero if a valid OCSP status

 * response was included in the TLS handshake. That is, an OCSP status response

 * which is not too old, superseded or marks the certificate as revoked.

 * It returns zero otherwise.

 *

 * When the flag %GNUTLS_OCSP_SR_IS_AVAIL is specified, the function

 * returns non-zero if an OCSP status response was included in the handshake

 * even if it was invalid. Otherwise, if no OCSP status response was included,

 * it returns zero. The %GNUTLS_OCSP_SR_IS_AVAIL flag was introduced in GnuTLS 3.4.0.

 *

 * This is a helper function when needing to decide whether to perform an

 * explicit OCSP validity check on the peer's certificate. Should be called after

 * any of gnutls_certificate_verify_peers*() are called.

 *

 * This function is always usable on client side, but on server side only

 * under TLS 1.3, which is the first version of TLS that allows cliend-side OCSP

 * responses.

 *

 * Returns: Non-zero if the response was valid, or a zero if it wasn't sent,

 * or sent and was invalid.

 *

 * Since: 3.1.4

 **/

unsigned gnutls_ocsp_status_request_is_checked(gnutls_session_t session,

                 unsigned int flags)

{

  int ret;

  gnutls_datum_t data;

  if (flags & GNUTLS_OCSP_SR_IS_AVAIL) {

    ret = gnutls_ocsp_status_request_get(session, &data);

    if (ret < 0)

      return gnutls_assert_val(0);

    if (data.data == NULL)

      return gnutls_assert_val(0);

    return 1;

  }

  return session->internals.ocsp_check_ok;

}

#endif