/*

 * 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) TLS extension.  See RFC 6066 section 8:

  https://tools.ietf.org/html/rfc6066#section-8

*/

#include "gnutls_int.h"

#include "errors.h"

#include "hello_ext.h"

#include "ext/status_request.h"

#include "mbuffers.h"

#include "auth.h"

#include "auth/cert.h"

#include "handshake.h"

#ifdef ENABLE_OCSP

typedef struct {

  /* server response */

  gnutls_datum_t sresp;

  unsigned int expect_cstatus;

} status_request_ext_st;

/*

  From RFC 6066.  Client sends:

      struct {

    CertificateStatusType status_type;

    select (status_type) {

        case ocsp: OCSPStatusRequest;

    } request;

      } CertificateStatusRequest;

      enum { ocsp(1), (255) } CertificateStatusType;

      struct {

    ResponderID responder_id_list<0..2^16-1>;

    Extensions  request_extensions;

      } OCSPStatusRequest;

      opaque ResponderID<1..2^16-1>;

      opaque Extensions<0..2^16-1>;

*/

static int client_send(gnutls_session_t session, gnutls_buffer_st *extdata,

           status_request_ext_st *priv)

{

  const uint8_t data[5] = "\x01\x00\x00\x00\x00";

  const int len = 5;

  int ret;

  /* We do not support setting either ResponderID or Extensions */

  ret = _gnutls_buffer_append_data(extdata, data, len);

  if (ret < 0)

    return gnutls_assert_val(ret);

  session->internals.hsk_flags |= HSK_OCSP_REQUESTED;

  return len;

}

static int server_recv(gnutls_session_t session, const uint8_t *data,

           size_t data_size)

{

  unsigned rid_bytes = 0;

  /* minimum message is type (1) + responder_id_list (2) +

     request_extension (2) = 5 */

  if (data_size < 5)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  /* We ignore non-ocsp CertificateStatusType.  The spec is unclear

     what should be done. */

  if (data[0] != 0x01) {

    gnutls_assert();

    _gnutls_handshake_log("EXT[%p]: unknown status_type %d\n",

              session, data[0]);

    return 0;

  }

  DECR_LEN(data_size, 1);

  data++;

  rid_bytes = _gnutls_read_uint16(data);

  DECR_LEN(data_size, 2);

  /*data += 2; */

  /* sanity check only, we don't use any of the data below */

  if (data_size < rid_bytes)

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  _gnutls_handshake_log("EXT[%p]: OCSP status was requested\n", session);

  session->internals.hsk_flags |= HSK_OCSP_REQUESTED;

  return 0;

}

static int client_recv(gnutls_session_t session, status_request_ext_st *priv,

           const uint8_t *data, size_t size)

{

  if (size != 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  else {

    priv->expect_cstatus = 1;

    return 0;

  }

}

/*

 * Servers return a certificate response along with their certificate

 * by sending a "CertificateStatus" message immediately after the

 * "Certificate" message (and before any "ServerKeyExchange" or

 * "CertificateRequest" messages).  If a server returns a

 * "CertificateStatus" message, then the server MUST have included an

 * extension of type "status_request" with empty "extension_data" in

 * the extended server hello.

 *

 * According to the description above, as a server we could simply 

 * return GNUTLS_E_INT_RET_0 on this function. In that case we would

 * only need to use the callbacks at the time we need to send the data,

 * and skip the status response packet if no such data are there.

 * However, that behavior would break gnutls 3.3.x which expects the status 

 * response to be always send if the extension is present.

 *

 * Instead we ensure that this extension is parsed after the CS/certificate

 * are selected (with the _GNUTLS_EXT_TLS_POST_CS type), and we discover

 * (or not) the response to send early.

 */

static int server_send(gnutls_session_t session, gnutls_buffer_st *extdata,

           status_request_ext_st *priv)

{

  int ret;

  gnutls_certificate_credentials_t cred;

  gnutls_status_request_ocsp_func func;

  void *func_ptr;

  const version_entry_st *ver = get_version(session);

  cred = (gnutls_certificate_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_CERTIFICATE);

  if (cred == NULL) /* no certificate authentication */

    return 0;

  /* no need to set sresp; responses are send during certificate sending and

   * no response is required from server side. */

  if (ver && ver->multi_ocsp)

    return 0;

  /* Under TLS1.2 we obtain the response at this point in order to respond

   * appropriately (empty extension vs no response) */

  if (session->internals.selected_ocsp_length > 0) {

    if (session->internals.selected_ocsp[0].response.data) {

      if (session->internals.selected_ocsp[0].exptime != 0 &&

          (gnutls_time(0) >=

           session->internals.selected_ocsp[0].exptime)) {

        gnutls_assert();

        return 0;

      }

      ret = _gnutls_set_datum(

        &priv->sresp,

        session->internals.selected_ocsp[0]

          .response.data,

        session->internals.selected_ocsp[0]

          .response.size);

      if (ret < 0)

        return gnutls_assert_val(ret);

      return GNUTLS_E_INT_RET_0;

    } else {

      return 0;

    }

  } else if (session->internals.selected_ocsp_func) {

    func = session->internals.selected_ocsp_func;

    func_ptr = session->internals.selected_ocsp_func_ptr;

    if (func == NULL)

      return 0;

    ret = func(session, func_ptr, &priv->sresp);

    if (ret == GNUTLS_E_NO_CERTIFICATE_STATUS)

      return 0;

    else if (ret < 0)

      return gnutls_assert_val(ret);

  } else {

    return 0;

  }

  return GNUTLS_E_INT_RET_0;

}

static int _gnutls_status_request_send_params(gnutls_session_t session,

                gnutls_buffer_st *extdata)

{

  gnutls_ext_priv_data_t epriv;

  status_request_ext_st *priv;

  int ret;

  /* Do not bother sending the OCSP status request extension

   * if we are not using certificate authentication */

  if (_gnutls_get_cred(session, GNUTLS_CRD_CERTIFICATE) == NULL)

    return 0;

  if (session->security_parameters.entity == GNUTLS_CLIENT) {

    if (session->internals.flags & GNUTLS_NO_STATUS_REQUEST)

      return 0;

    ret = _gnutls_hello_ext_get_priv(

      session, GNUTLS_EXTENSION_STATUS_REQUEST, &epriv);

    if (ret < 0 || epriv == NULL) /* it is ok not to have it */

      return 0;

    priv = epriv;

    return client_send(session, extdata, priv);

  } else {

    epriv = priv = gnutls_calloc(1, sizeof(*priv));

    if (priv == NULL)

      return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

    _gnutls_hello_ext_set_priv(

      session, GNUTLS_EXTENSION_STATUS_REQUEST, epriv);

    return server_send(session, extdata, priv);

  }

}

static int _gnutls_status_request_recv_params(gnutls_session_t session,

                const uint8_t *data, size_t size)

{

  gnutls_ext_priv_data_t epriv;

  status_request_ext_st *priv;

  int ret;

  if (session->security_parameters.entity == GNUTLS_CLIENT) {

    ret = _gnutls_hello_ext_get_priv(

      session, GNUTLS_EXTENSION_STATUS_REQUEST, &epriv);

    if (ret < 0 || epriv == NULL) /* it is ok not to have it */

      return 0;

    priv = epriv;

    return client_recv(session, priv, data, size);

  } else {

    return server_recv(session, data, size);

  }

}

/**

 * gnutls_ocsp_status_request_enable_client:

 * @session: is a #gnutls_session_t type.

 * @responder_id: ignored, must be %NULL

 * @responder_id_size: ignored, must be zero

 * @extensions: ignored, must be %NULL

 *

 * This function is to be used by clients to request OCSP response

 * from the server, using the "status_request" TLS extension.  Only

 * OCSP status type is supported.

 *

 * Previous versions of GnuTLS supported setting @responder_id and

 * @extensions fields, but due to the difficult semantics of the

 * parameter usage, and other issues, this support was removed

 * since 3.6.0 and these parameters must be set to %NULL.

 *

 * 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_enable_client(gnutls_session_t session,

               gnutls_datum_t *responder_id,

               size_t responder_id_size,

               gnutls_datum_t *extensions)

{

  status_request_ext_st *priv;

  gnutls_ext_priv_data_t epriv;

  if (session->security_parameters.entity == GNUTLS_SERVER)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  epriv = priv = gnutls_calloc(1, sizeof(*priv));

  if (priv == NULL)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  _gnutls_hello_ext_set_priv(session, GNUTLS_EXTENSION_STATUS_REQUEST,

           epriv);

  session->internals.flags &= ~GNUTLS_NO_STATUS_REQUEST;

  if (session->internals.priorities)

    session->internals.priorities->no_status_request = 0;

  return 0;

}

static void _gnutls_status_request_deinit_data(gnutls_ext_priv_data_t epriv)

{

  status_request_ext_st *priv = epriv;

  if (priv == NULL)

    return;

  gnutls_free(priv->sresp.data);

  gnutls_free(priv);

}

const hello_ext_entry_st ext_mod_status_request = {

  .name = "OCSP Status Request",

  .tls_id = STATUS_REQUEST_TLS_ID,

  .gid = GNUTLS_EXTENSION_STATUS_REQUEST,

  .validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_DTLS |

        GNUTLS_EXT_FLAG_CLIENT_HELLO |

        GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO,

  .client_parse_point = _GNUTLS_EXT_TLS_POST_CS,

  .server_parse_point = _GNUTLS_EXT_TLS_POST_CS,

  .recv_func = _gnutls_status_request_recv_params,

  .send_func = _gnutls_status_request_send_params,

  .deinit_func = _gnutls_status_request_deinit_data,

  .cannot_be_overriden = 1

};

/* Functions to be called from handshake */

int _gnutls_send_server_certificate_status(gnutls_session_t session, int again)

{

  mbuffer_st *bufel = NULL;

  uint8_t *data;

  int data_size = 0;

  int ret;

  gnutls_ext_priv_data_t epriv;

  status_request_ext_st *priv;

  if (!(session->internals.hsk_flags & HSK_OCSP_REQUESTED))

    return 0;

  if (again == 0) {

    ret = _gnutls_hello_ext_get_priv(

      session, GNUTLS_EXTENSION_STATUS_REQUEST, &epriv);

    if (ret < 0)

      return 0;

    priv = epriv;

    if (!priv->sresp.size)

      return 0;

    data_size = priv->sresp.size + 4;

    bufel = _gnutls_handshake_alloc(session, data_size);

    if (!bufel) {

      _gnutls_free_datum(&priv->sresp);

      return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

    }

    data = _mbuffer_get_udata_ptr(bufel);

    data[0] = 0x01;

    _gnutls_write_uint24(priv->sresp.size, &data[1]);

    memcpy(&data[4], priv->sresp.data, priv->sresp.size);

    _gnutls_free_datum(&priv->sresp);

  }

  return _gnutls_send_handshake(session, data_size ? bufel : NULL,

              GNUTLS_HANDSHAKE_CERTIFICATE_STATUS);

}

int _gnutls_parse_ocsp_response(gnutls_session_t session, const uint8_t *data,

        ssize_t data_size, gnutls_datum_t *resp)

{

  int ret;

  ssize_t r_size;

  resp->data = 0;

  resp->size = 0;

  /* minimum message is type (1) + response (3) + data */

  if (data_size < 4)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (data[0] != 0x01) {

    gnutls_assert();

    _gnutls_handshake_log("EXT[%p]: unknown status_type %d\n",

              session, data[0]);

    return 0;

  }

  DECR_LENGTH_RET(data_size, 1, GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  data++;

  DECR_LENGTH_RET(data_size, 3, GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  r_size = _gnutls_read_uint24(data);

  data += 3;

  DECR_LENGTH_RET(data_size, r_size, GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (r_size < 1)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  ret = _gnutls_set_datum(resp, data, r_size);

  if (ret < 0)

    return gnutls_assert_val(ret);

  return 0;

}

int _gnutls_recv_server_certificate_status(gnutls_session_t session)

{

  uint8_t *data;

  ssize_t data_size;

  gnutls_buffer_st buf;

  int ret;

  gnutls_datum_t resp;

  status_request_ext_st *priv = NULL;

  gnutls_ext_priv_data_t epriv;

  cert_auth_info_t info =

    _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);

  if (info == NULL)

    return 0;

  ret = _gnutls_hello_ext_get_priv(

    session, GNUTLS_EXTENSION_STATUS_REQUEST, &epriv);

  if (ret < 0)

    return 0;

  priv = epriv;

  if (!priv->expect_cstatus)

    return 0;

  ret = _gnutls_recv_handshake(

    session, GNUTLS_HANDSHAKE_CERTIFICATE_STATUS, 1, &buf);

  if (ret < 0)

    return gnutls_assert_val_fatal(ret);

  priv->expect_cstatus = 0;

  data = buf.data;

  data_size = buf.length;

  if (data_size == 0) {

    ret = 0;

    goto error;

  }

  ret = _gnutls_parse_ocsp_response(session, data, data_size, &resp);

  if (ret < 0) {

    gnutls_assert();

    goto error;

  }

  if (resp.data && resp.size > 0) {

    for (unsigned int i = 0; i < info->nocsp; i++)

      gnutls_free(info->raw_ocsp_list[i].data);

    gnutls_free(info->raw_ocsp_list);

    info->raw_ocsp_list = gnutls_malloc(sizeof(gnutls_datum_t));

    if (info->raw_ocsp_list == NULL) {

      ret = GNUTLS_E_MEMORY_ERROR;

      goto error;

    }

    info->raw_ocsp_list[0].data = resp.data;

    info->raw_ocsp_list[0].size = resp.size;

    info->nocsp = 1;

  }

  ret = 0;

error:

  _gnutls_buffer_clear(&buf);

  return ret;

}

#endif