/*
 * Copyright (C) 2011-2012 Free Software Foundation, Inc.
 * Copyright (C) 2016-2017 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/>
 *
 */

/* Online Certificate Status Protocol - RFC 2560
 */

#include "gnutls_int.h"
#include "global.h"
#include "errors.h"
#include <libtasn1.h>
#include "pk.h"
#include "common.h"
#include "verify-high.h"
#include "x509.h"
#include "ocsp.h"

#include <gnutls/ocsp.h>
#include "auth/cert.h"

#include <assert.h>
#include "intprops.h"

typedef struct gnutls_ocsp_req_int {
	asn1_node req;
	unsigned init;
} gnutls_ocsp_req_int;

typedef struct gnutls_ocsp_resp_int {
	asn1_node resp;
	gnutls_datum_t response_type_oid;
	asn1_node basicresp;
	gnutls_datum_t der;
	unsigned init;
} gnutls_ocsp_resp_int;

#define MAX_TIME 64

/**
 * gnutls_ocsp_req_init:
 * @req: A pointer to the type to be initialized
 *
 * This function will initialize an OCSP request structure.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_req_init(gnutls_ocsp_req_t *req)
{
	gnutls_ocsp_req_t tmp = gnutls_calloc(1, sizeof(gnutls_ocsp_req_int));
	int ret;

	*req = NULL;
	if (!tmp)
		return GNUTLS_E_MEMORY_ERROR;

	ret = asn1_create_element(_gnutls_get_pkix(), "PKIX1.OCSPRequest",
				  &tmp->req);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		gnutls_free(tmp);
		return _gnutls_asn2err(ret);
	}

	*req = tmp;

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_deinit:
 * @req: The data to be deinitialized
 *
 * This function will deinitialize a OCSP request structure.
 **/
void gnutls_ocsp_req_deinit(gnutls_ocsp_req_t req)
{
	if (!req)
		return;

	if (req->req)
		asn1_delete_structure(&req->req);

	req->req = NULL;
	gnutls_free(req);
}

/**
 * gnutls_ocsp_resp_init:
 * @resp: A pointer to the type to be initialized
 *
 * This function will initialize an OCSP response structure.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_init(gnutls_ocsp_resp_t *resp)
{
	gnutls_ocsp_resp_t tmp = gnutls_calloc(1, sizeof(gnutls_ocsp_resp_int));
	int ret;

	*resp = NULL;
	if (!tmp)
		return GNUTLS_E_MEMORY_ERROR;

	ret = asn1_create_element(_gnutls_get_pkix(), "PKIX1.OCSPResponse",
				  &tmp->resp);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		gnutls_free(tmp);
		return _gnutls_asn2err(ret);
	}

	ret = asn1_create_element(_gnutls_get_pkix(), "PKIX1.BasicOCSPResponse",
				  &tmp->basicresp);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&tmp->resp);
		gnutls_free(tmp);
		return _gnutls_asn2err(ret);
	}

	*resp = tmp;

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_deinit:
 * @resp: The data to be deinitialized
 *
 * This function will deinitialize a OCSP response structure.
 **/
void gnutls_ocsp_resp_deinit(gnutls_ocsp_resp_t resp)
{
	if (!resp)
		return;

	if (resp->resp)
		asn1_delete_structure(&resp->resp);
	gnutls_free(resp->response_type_oid.data);
	if (resp->basicresp)
		asn1_delete_structure(&resp->basicresp);

	resp->resp = NULL;
	resp->basicresp = NULL;

	gnutls_free(resp->der.data);
	gnutls_free(resp);
}

/**
 * gnutls_ocsp_req_import:
 * @req: The data to store the parsed request.
 * @data: DER encoded OCSP request.
 *
 * This function will convert the given DER encoded OCSP request to
 * the native #gnutls_ocsp_req_t format. The output will be stored in
 * @req.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_req_import(gnutls_ocsp_req_t req, const gnutls_datum_t *data)
{
	int ret = 0;

	if (req == NULL || data == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	if (req->init) {
		/* Any earlier _asn1_strict_der_decode will modify the ASN.1
		   structure, so we need to replace it with a fresh
		   structure. */
		asn1_delete_structure(&req->req);

		ret = asn1_create_element(_gnutls_get_pkix(),
					  "PKIX1.OCSPRequest", &req->req);
		if (ret != ASN1_SUCCESS) {
			gnutls_assert();
			return _gnutls_asn2err(ret);
		}
	}
	req->init = 1;

	ret = _asn1_strict_der_decode(&req->req, data->data, data->size, NULL);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(ret);
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_import:
 * @resp: The data to store the parsed response.
 * @data: DER encoded OCSP response.
 *
 * This function will convert the given DER encoded OCSP response to
 * the native #gnutls_ocsp_resp_t format.  It also decodes the Basic
 * OCSP Response part, if any.  The output will be stored in @resp.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_import(gnutls_ocsp_resp_t resp, const gnutls_datum_t *data)
{
	return gnutls_ocsp_resp_import2(resp, data, GNUTLS_X509_FMT_DER);
}

/**
 * gnutls_ocsp_resp_import2:
 * @resp: The data to store the parsed response.
 * @data: DER or PEM encoded OCSP response.
 * @fmt: DER or PEM
 *
 * This function will convert the given OCSP response to
 * the native #gnutls_ocsp_resp_t format.  It also decodes the Basic
 * OCSP Response part, if any.  The output will be stored in @resp.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.6.3
 **/
int gnutls_ocsp_resp_import2(gnutls_ocsp_resp_t resp,
			     const gnutls_datum_t *data,
			     gnutls_x509_crt_fmt_t fmt)
{
	int ret = 0;
	gnutls_datum_t der;

	if (resp == NULL || data == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	der.data = data->data;
	der.size = data->size;

	if (fmt == GNUTLS_X509_FMT_PEM) {
		ret = gnutls_pem_base64_decode2(BARE_PEM_OCSP_RESPONSE, data,
						&der);
		if (ret < 0) {
			return gnutls_assert_val(ret);
		}
	}

	if (resp->init != 0) {
		/* Any earlier _asn1_strict_der_decode will modify the ASN.1
		   structure, so we need to replace it with a fresh
		   structure. */
		asn1_delete_structure(&resp->resp);
		if (resp->basicresp)
			asn1_delete_structure(&resp->basicresp);

		ret = asn1_create_element(_gnutls_get_pkix(),
					  "PKIX1.OCSPResponse", &resp->resp);
		if (ret != ASN1_SUCCESS) {
			gnutls_assert();
			ret = _gnutls_asn2err(ret);
			goto cleanup;
		}

		ret = asn1_create_element(_gnutls_get_pkix(),
					  "PKIX1.BasicOCSPResponse",
					  &resp->basicresp);
		if (ret != ASN1_SUCCESS) {
			gnutls_assert();
			ret = _gnutls_asn2err(ret);
			goto cleanup;
		}

		gnutls_free(resp->der.data);
	}

	resp->init = 1;
	ret = _asn1_strict_der_decode(&resp->resp, der.data, der.size, NULL);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		ret = _gnutls_asn2err(ret);
		goto cleanup;
	}

	if (gnutls_ocsp_resp_get_status(resp) != GNUTLS_OCSP_RESP_SUCCESSFUL) {
		ret = GNUTLS_E_SUCCESS;
		goto cleanup;
	}

	ret = _gnutls_x509_read_value(resp->resp, "responseBytes.responseType",
				      &resp->response_type_oid);
	if (ret < 0) {
		gnutls_assert();
		goto cleanup;
	}
#define OCSP_BASIC "1.3.6.1.5.5.7.48.1.1"

	if (resp->response_type_oid.size == sizeof(OCSP_BASIC) - 1 &&
	    memcmp(resp->response_type_oid.data, OCSP_BASIC,
		   resp->response_type_oid.size) == 0) {
		ret = _gnutls_x509_read_value(
			resp->resp, "responseBytes.response", &resp->der);
		if (ret < 0) {
			gnutls_assert();
			goto cleanup;
		}

		ret = _asn1_strict_der_decode(&resp->basicresp, resp->der.data,
					      resp->der.size, NULL);
		if (ret != ASN1_SUCCESS) {
			gnutls_assert();
			ret = _gnutls_asn2err(ret);
			goto cleanup;
		}
	} else {
		asn1_delete_structure(&resp->basicresp);
		resp->basicresp = NULL;
	}

	ret = GNUTLS_E_SUCCESS;
cleanup:
	if (der.data != data->data)
		gnutls_free(der.data);
	return ret;
}

/**
 * gnutls_ocsp_req_export:
 * @req: Holds the OCSP request
 * @data: newly allocate buffer holding DER encoded OCSP request
 *
 * This function will export the OCSP request to DER format.
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 **/
int gnutls_ocsp_req_export(gnutls_ocsp_req_const_t req, gnutls_datum_t *data)
{
	int ret;

	if (req == NULL || data == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	/* XXX remove when we support these fields */
	(void)asn1_write_value(req->req, "tbsRequest.requestorName", NULL, 0);
	(void)asn1_write_value(req->req, "optionalSignature", NULL, 0);

	/* prune extension field if we don't have any extension */
	ret = gnutls_ocsp_req_get_extension(req, 0, NULL, NULL, NULL);
	if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
		(void)asn1_write_value(req->req, "tbsRequest.requestExtensions",
				       NULL, 0);

	return _gnutls_x509_get_raw_field(req->req, "", data);
}

/**
 * gnutls_ocsp_resp_export:
 * @resp: Holds the OCSP response
 * @data: newly allocate buffer holding DER encoded OCSP response
 *
 * This function will export the OCSP response to DER format.
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 **/
int gnutls_ocsp_resp_export(gnutls_ocsp_resp_const_t resp, gnutls_datum_t *data)
{
	return gnutls_ocsp_resp_export2(resp, data, GNUTLS_X509_FMT_DER);
}

/**
 * gnutls_ocsp_resp_export2:
 * @resp: Holds the OCSP response
 * @data: newly allocate buffer holding DER or PEM encoded OCSP response
 * @fmt: DER or PEM
 *
 * This function will export the OCSP response to DER or PEM format.
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 *
 * Since: 3.6.3
 **/
int gnutls_ocsp_resp_export2(gnutls_ocsp_resp_const_t resp,
			     gnutls_datum_t *data, gnutls_x509_crt_fmt_t fmt)
{
	int ret;
	gnutls_datum_t der;

	if (resp == NULL || data == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	ret = _gnutls_x509_get_raw_field(resp->resp, "", &der);
	if (ret < 0)
		return gnutls_assert_val(ret);

	if (fmt == GNUTLS_X509_FMT_DER) {
		data->data = der.data;
		data->size = der.size;
		return ret;
	} else {
		ret = gnutls_pem_base64_encode2("OCSP RESPONSE", &der, data);
		gnutls_free(der.data);
		if (ret < 0)
			return gnutls_assert_val(ret);

		return 0;
	}
}

/**
 * gnutls_ocsp_req_get_version:
 * @req: should contain a #gnutls_ocsp_req_t type
 *
 * This function will return the version of the OCSP request.
 * Typically this is always 1 indicating version 1.
 *
 * Returns: version of OCSP request, or a negative error code on error.
 **/
int gnutls_ocsp_req_get_version(gnutls_ocsp_req_const_t req)
{
	if (req == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	return _gnutls_x509_get_version(req->req, "tbsRequest.version");
}

/**
 * gnutls_ocsp_req_get_cert_id:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @indx: Specifies which extension OID to get. Use (0) to get the first one.
 * @digest: output variable with #gnutls_digest_algorithm_t hash algorithm
 * @issuer_name_hash: output buffer with hash of issuer's DN
 * @issuer_key_hash: output buffer with hash of issuer's public key
 * @serial_number: output buffer with serial number of certificate to check
 *
 * This function will return the certificate information of the
 * @indx'ed request in the OCSP request.  The information returned
 * corresponds to the CertID structure:
 *
 * <informalexample><programlisting>
 *    CertID	  ::=     SEQUENCE {
 *	hashAlgorithm       AlgorithmIdentifier,
 *	issuerNameHash      OCTET STRING, -- Hash of Issuer's DN
 *	issuerKeyHash       OCTET STRING, -- Hash of Issuers public key
 *	serialNumber	CertificateSerialNumber }
 * </programlisting></informalexample>
 *
 * Each of the pointers to output variables may be NULL to indicate
 * that the caller is not interested in that value.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.  If you have reached the last
 *   CertID available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be
 *   returned.
 **/
int gnutls_ocsp_req_get_cert_id(gnutls_ocsp_req_const_t req, unsigned indx,
				gnutls_digest_algorithm_t *digest,
				gnutls_datum_t *issuer_name_hash,
				gnutls_datum_t *issuer_key_hash,
				gnutls_datum_t *serial_number)
{
	gnutls_datum_t sa;
	char name[MAX_NAME_SIZE];
	int ret;

	if (req == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	snprintf(name, sizeof(name),
		 "tbsRequest.requestList.?%u.reqCert.hashAlgorithm.algorithm",
		 indx + 1);
	ret = _gnutls_x509_read_value(req->req, name, &sa);
	if (ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND)
		return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
	else if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_oid_to_digest((char *)sa.data);
	_gnutls_free_datum(&sa);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	if (digest)
		*digest = ret;

	if (issuer_name_hash) {
		snprintf(name, sizeof(name),
			 "tbsRequest.requestList.?%u.reqCert.issuerNameHash",
			 indx + 1);
		ret = _gnutls_x509_read_value(req->req, name, issuer_name_hash);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			return ret;
		}
	}

	if (issuer_key_hash) {
		snprintf(name, sizeof(name),
			 "tbsRequest.requestList.?%u.reqCert.issuerKeyHash",
			 indx + 1);
		ret = _gnutls_x509_read_value(req->req, name, issuer_key_hash);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			if (issuer_name_hash)
				gnutls_free(issuer_name_hash->data);
			return ret;
		}
	}

	if (serial_number) {
		snprintf(name, sizeof(name),
			 "tbsRequest.requestList.?%u.reqCert.serialNumber",
			 indx + 1);
		ret = _gnutls_x509_read_value(req->req, name, serial_number);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			if (issuer_name_hash)
				gnutls_free(issuer_name_hash->data);
			if (issuer_key_hash)
				gnutls_free(issuer_key_hash->data);
			return ret;
		}
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_add_cert_id:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @digest: hash algorithm, a #gnutls_digest_algorithm_t value
 * @issuer_name_hash: hash of issuer's DN
 * @issuer_key_hash: hash of issuer's public key
 * @serial_number: serial number of certificate to check
 *
 * This function will add another request to the OCSP request for a
 * particular certificate having the issuer name hash of
 * @issuer_name_hash and issuer key hash of @issuer_key_hash (both
 * hashed using @digest) and serial number @serial_number.
 *
 * The information needed corresponds to the CertID structure:
 *
 * <informalexample><programlisting>
 *    CertID	  ::=     SEQUENCE {
 *	hashAlgorithm       AlgorithmIdentifier,
 *	issuerNameHash      OCTET STRING, -- Hash of Issuer's DN
 *	issuerKeyHash       OCTET STRING, -- Hash of Issuers public key
 *	serialNumber	CertificateSerialNumber }
 * </programlisting></informalexample>
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_add_cert_id(gnutls_ocsp_req_t req,
				gnutls_digest_algorithm_t digest,
				const gnutls_datum_t *issuer_name_hash,
				const gnutls_datum_t *issuer_key_hash,
				const gnutls_datum_t *serial_number)
{
	int result;
	const char *oid;

	if (req == NULL || issuer_name_hash == NULL ||
	    issuer_key_hash == NULL || serial_number == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	oid = _gnutls_x509_digest_to_oid(hash_to_entry(digest));
	if (oid == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	result = asn1_write_value(req->req, "tbsRequest.requestList", "NEW", 1);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(
		req->req,
		"tbsRequest.requestList.?LAST.reqCert.hashAlgorithm.algorithm",
		oid, 1);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	/* XXX we don't support any algorithm with parameters */
	result = asn1_write_value(
		req->req,
		"tbsRequest.requestList.?LAST.reqCert.hashAlgorithm.parameters",
		ASN1_NULL, ASN1_NULL_SIZE);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(
		req->req, "tbsRequest.requestList.?LAST.reqCert.issuerNameHash",
		issuer_name_hash->data, issuer_name_hash->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(
		req->req, "tbsRequest.requestList.?LAST.reqCert.issuerKeyHash",
		issuer_key_hash->data, issuer_key_hash->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(
		req->req, "tbsRequest.requestList.?LAST.reqCert.serialNumber",
		serial_number->data, serial_number->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	/* XXX add separate function that can add extensions too */
	result = asn1_write_value(
		req->req,
		"tbsRequest.requestList.?LAST.singleRequestExtensions", NULL,
		0);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_add_cert:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @digest: hash algorithm, a #gnutls_digest_algorithm_t value
 * @issuer: issuer of @subject certificate
 * @cert: certificate to request status for
 *
 * This function will add another request to the OCSP request for a
 * particular certificate.  The issuer name hash, issuer key hash, and
 * serial number fields is populated as follows.  The issuer name and
 * the serial number is taken from @cert.  The issuer key is taken
 * from @issuer.  The hashed values will be hashed using the @digest
 * algorithm, normally %GNUTLS_DIG_SHA1.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_add_cert(gnutls_ocsp_req_t req,
			     gnutls_digest_algorithm_t digest,
			     gnutls_x509_crt_t issuer, gnutls_x509_crt_t cert)
{
	int ret;
	gnutls_datum_t sn, tmp, inh, ikh;
	uint8_t inh_buf[MAX_HASH_SIZE];
	uint8_t ikh_buf[MAX_HASH_SIZE];
	size_t inhlen = MAX_HASH_SIZE;
	size_t ikhlen = MAX_HASH_SIZE;

	if (req == NULL || issuer == NULL || cert == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	ret = _gnutls_x509_der_encode(
		cert->cert, "tbsCertificate.issuer.rdnSequence", &tmp, 0);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_fingerprint(digest, &tmp, inh_buf, &inhlen);
	gnutls_free(tmp.data);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}
	inh.size = inhlen;
	inh.data = inh_buf;

	ret = _gnutls_x509_read_value(
		issuer->cert,
		"tbsCertificate.subjectPublicKeyInfo.subjectPublicKey", &tmp);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_fingerprint(digest, &tmp, ikh_buf, &ikhlen);
	gnutls_free(tmp.data);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}
	ikh.size = ikhlen;
	ikh.data = ikh_buf;

	ret = _gnutls_x509_read_value(cert->cert, "tbsCertificate.serialNumber",
				      &sn);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_ocsp_req_add_cert_id(req, digest, &inh, &ikh, &sn);
	gnutls_free(sn.data);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_get_extension:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @indx: Specifies which extension OID to get. Use (0) to get the first one.
 * @oid: will hold newly allocated buffer with OID of extension, may be NULL
 * @critical: output variable with critical flag, may be NULL.
 * @data: will hold newly allocated buffer with extension data, may be NULL
 *
 * This function will return all information about the requested
 * extension in the OCSP request.  The information returned is the
 * OID, the critical flag, and the data itself.  The extension OID
 * will be stored as a string.  Any of @oid, @critical, and @data may
 * be NULL which means that the caller is not interested in getting
 * that information back.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @oid->data and @data->data.
 *
 * Since 3.7.0 @oid->size does not account for the terminating null byte.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.  If you have reached the last
 *   extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will
 *   be returned.
 **/
int gnutls_ocsp_req_get_extension(gnutls_ocsp_req_const_t req, unsigned indx,
				  gnutls_datum_t *oid, unsigned int *critical,
				  gnutls_datum_t *data)
{
	int ret;
	char str_critical[10];
	char name[MAX_NAME_SIZE];
	int len;

	if (!req) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	snprintf(name, sizeof(name),
		 "tbsRequest.requestExtensions.?%u.critical", indx + 1);
	len = sizeof(str_critical);
	ret = asn1_read_value(req->req, name, str_critical, &len);
	if (ret == ASN1_ELEMENT_NOT_FOUND)
		return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
	else if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(ret);
	}

	if (critical) {
		if (str_critical[0] == 'T')
			*critical = 1;
		else
			*critical = 0;
	}

	if (oid) {
		snprintf(name, sizeof(name),
			 "tbsRequest.requestExtensions.?%u.extnID", indx + 1);
		ret = _gnutls_x509_read_value(req->req, name, oid);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			return ret;
		}
	}

	if (data) {
		snprintf(name, sizeof(name),
			 "tbsRequest.requestExtensions.?%u.extnValue",
			 indx + 1);
		ret = _gnutls_x509_read_value(req->req, name, data);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			if (oid)
				gnutls_free(oid->data);
			return ret;
		}
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_set_extension:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @oid: buffer with OID of extension as a string.
 * @critical: critical flag, normally false.
 * @data: the extension data
 *
 * This function will add an extension to the OCSP request.  Calling
 * this function multiple times for the same OID will overwrite values
 * from earlier calls.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_set_extension(gnutls_ocsp_req_t req, const char *oid,
				  unsigned int critical,
				  const gnutls_datum_t *data)
{
	if (req == NULL || oid == NULL || data == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	return _gnutls_set_extension(req->req, "tbsRequest.requestExtensions",
				     oid, data, critical);
}

/**
 * gnutls_ocsp_req_get_nonce:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @critical: whether nonce extension is marked critical, or NULL
 * @nonce: will hold newly allocated buffer with nonce data
 *
 * This function will return the OCSP request nonce extension data.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @nonce->data.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_get_nonce(gnutls_ocsp_req_const_t req,
			      unsigned int *critical, gnutls_datum_t *nonce)
{
	int ret;
	gnutls_datum_t tmp;

	if (req == NULL || nonce == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	ret = _gnutls_get_extension(req->req, "tbsRequest.requestExtensions",
				    GNUTLS_OCSP_NONCE, 0, &tmp, critical);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = _gnutls_x509_decode_string(ASN1_ETYPE_OCTET_STRING, tmp.data,
					 (size_t)tmp.size, nonce, 0);
	if (ret < 0) {
		gnutls_assert();
		gnutls_free(tmp.data);
		return ret;
	}

	gnutls_free(tmp.data);

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_req_set_nonce:
 * @req: should contain a #gnutls_ocsp_req_t type
 * @critical: critical flag, normally false.
 * @nonce: the nonce data
 *
 * This function will add an nonce extension to the OCSP request.
 * Calling this function multiple times will overwrite values from
 * earlier calls.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_set_nonce(gnutls_ocsp_req_t req, unsigned int critical,
			      const gnutls_datum_t *nonce)
{
	int ret;
	gnutls_datum_t dernonce;
	unsigned char temp[SIZEOF_UNSIGNED_LONG_INT + 1];
	int len;

	if (req == NULL || nonce == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	asn1_length_der(nonce->size, temp, &len);

	dernonce.size = 1 + len + nonce->size;
	dernonce.data = gnutls_malloc(dernonce.size);
	if (dernonce.data == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	dernonce.data[0] = '\x04';
	memcpy(dernonce.data + 1, temp, len);
	memcpy(dernonce.data + 1 + len, nonce->data, nonce->size);

	ret = _gnutls_set_extension(req->req, "tbsRequest.requestExtensions",
				    GNUTLS_OCSP_NONCE, &dernonce, critical);
	gnutls_free(dernonce.data);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	return ret;
}

/**
 * gnutls_ocsp_req_randomize_nonce:
 * @req: should contain a #gnutls_ocsp_req_t type
 *
 * This function will add or update an nonce extension to the OCSP
 * request with a newly generated random value.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_req_randomize_nonce(gnutls_ocsp_req_t req)
{
	int ret;
	uint8_t rndbuf[23];
	gnutls_datum_t nonce = { rndbuf, sizeof(rndbuf) };

	if (req == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	ret = gnutls_rnd(GNUTLS_RND_NONCE, rndbuf, sizeof(rndbuf));
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_ocsp_req_set_nonce(req, 0, &nonce);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_get_status:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 *
 * This function will return the status of a OCSP response, an
 * #gnutls_ocsp_resp_status_t enumeration.
 *
 * Returns: status of OCSP request as a #gnutls_ocsp_resp_status_t, or
 *   a negative error code on error.
 **/
int gnutls_ocsp_resp_get_status(gnutls_ocsp_resp_const_t resp)
{
	uint8_t str[1];
	int len, ret;

	if (resp == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	len = sizeof(str);
	ret = asn1_read_value(resp->resp, "responseStatus", str, &len);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(ret);
	}

	if (len != 1)
		return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);

	switch (str[0]) {
	case GNUTLS_OCSP_RESP_SUCCESSFUL:
	case GNUTLS_OCSP_RESP_MALFORMEDREQUEST:
	case GNUTLS_OCSP_RESP_INTERNALERROR:
	case GNUTLS_OCSP_RESP_TRYLATER:
	case GNUTLS_OCSP_RESP_SIGREQUIRED:
	case GNUTLS_OCSP_RESP_UNAUTHORIZED:
		break;
	default:
		return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);
	}

	return (int)str[0];
}

/**
 * gnutls_ocsp_resp_get_response:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @response_type_oid: newly allocated output buffer with response type OID
 * @response: newly allocated output buffer with DER encoded response
 *
 * This function will extract the response type OID in and the
 * response data from an OCSP response.  Normally the
 * @response_type_oid is always "1.3.6.1.5.5.7.48.1.1" which means the
 * @response should be decoded as a Basic OCSP Response, but
 * technically other response types could be used.
 *
 * This function is typically only useful when you want to extract the
 * response type OID of an response for diagnostic purposes.
 * Otherwise gnutls_ocsp_resp_import() will decode the basic OCSP
 * response part and the caller need not worry about that aspect.
 *
 * Since 3.7.0 @response_type_oid->size does not account for the terminating
 * null byte.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_get_response(gnutls_ocsp_resp_const_t resp,
				  gnutls_datum_t *response_type_oid,
				  gnutls_datum_t *response)
{
	int ret;

	if (resp == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	if (response_type_oid != NULL) {
		ret = _gnutls_x509_read_value(resp->resp,
					      "responseBytes.responseType",
					      response_type_oid);
		if (ret < 0) {
			gnutls_assert();
			return ret;
		}
	}

	if (response != NULL) {
		ret = _gnutls_x509_read_value(
			resp->resp, "responseBytes.response", response);
		if (ret < 0) {
			gnutls_assert();
			return ret;
		}
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_get_version:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 *
 * This function will return the version of the Basic OCSP Response.
 * Typically this is always 1 indicating version 1.
 *
 * Returns: version of Basic OCSP response, or a negative error code
 *   on error.
 **/
int gnutls_ocsp_resp_get_version(gnutls_ocsp_resp_const_t resp)
{
	if (resp == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	return _gnutls_x509_get_version(resp->resp, "tbsResponseData.version");
}

/**
 * gnutls_ocsp_resp_get_responder:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @dn: newly allocated buffer with name
 *
 * This function will extract the name of the Basic OCSP Response in
 * the provided buffer. The name will be in the form
 * "C=xxxx,O=yyyy,CN=zzzz" as described in RFC2253. The output string
 * will be ASCII or UTF-8 encoded, depending on the certificate data.
 *
 * If the responder ID is not a name but a hash, this function
 * will return zero and the @dn elements will be set to %NULL.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @dn->data.
 *
 * This function does not output a fully RFC4514 compliant string, if
 * that is required see gnutls_ocsp_resp_get_responder2().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned. When no data exist it will
 *   return success and set @dn elements to zero.
 **/
int gnutls_ocsp_resp_get_responder(gnutls_ocsp_resp_const_t resp,
				   gnutls_datum_t *dn)
{
	int ret;

	ret = gnutls_ocsp_resp_get_responder2(resp, dn,
					      GNUTLS_X509_DN_FLAG_COMPAT);
	if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
		dn->data = NULL;
		dn->size = 0;
		return 0; /* for backwards compatibility */
	}

	return ret;
}

/**
 * gnutls_ocsp_resp_get_responder2:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @dn: newly allocated buffer with name
 * @flags: zero or %GNUTLS_X509_DN_FLAG_COMPAT
 *
 * This function will extract the name of the Basic OCSP Response in
 * the provided buffer. The name will be in the form
 * "C=xxxx,O=yyyy,CN=zzzz" as described in RFC2253. The output string
 * will be ASCII or UTF-8 encoded, depending on the certificate data.
 *
 * If the responder ID is not a name but a hash, this function
 * will return zero and the @dn elements will be set to %NULL.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @dn->data.
 *
 * When the flag %GNUTLS_X509_DN_FLAG_COMPAT is specified, the output
 * format will match the format output by previous to 3.5.6 versions of GnuTLS
 * which was not not fully RFC4514-compliant.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned. When no data exist it will return
 *   %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE.
 **/
int gnutls_ocsp_resp_get_responder2(gnutls_ocsp_resp_const_t resp,
				    gnutls_datum_t *dn, unsigned flags)
{
	if (resp == NULL || dn == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	dn->data = NULL;
	dn->size = 0;

	return _gnutls_x509_get_dn(resp->basicresp,
				   "tbsResponseData.responderID.byName", dn,
				   flags);
}

/**
 * gnutls_ocsp_resp_get_responder_by_key:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @type: should be %GNUTLS_OCSP_RESP_ID_KEY or %GNUTLS_OCSP_RESP_ID_DN
 * @raw: newly allocated buffer with the raw ID
 *
 * This function will extract the raw key (or DN) ID of the Basic OCSP Response in
 * the provided buffer. If the responder ID is not a key ID then
 * this function will return %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @dn->data.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_resp_get_responder_raw_id(gnutls_ocsp_resp_const_t resp,
					  unsigned type, gnutls_datum_t *raw)
{
	int ret;

	if (resp == NULL || raw == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	if (type == GNUTLS_OCSP_RESP_ID_KEY)
		ret = _gnutls_x509_read_value(
			resp->basicresp, "tbsResponseData.responderID.byKey",
			raw);
	else {
		gnutls_datum_t tmp;

		/* simply reading a CHOICE of CHOICE value doesn't work in libtasn1 */
		ret = _gnutls_x509_get_raw_field2(
			resp->basicresp, &resp->der,
			"tbsResponseData.responderID.byName", &tmp);
		if (ret >= 0) {
			int real;
			/* skip the tag */
			if (tmp.size < 2) {
				gnutls_assert();
				ret = GNUTLS_E_ASN1_GENERIC_ERROR;
				goto fail;
			}

			tmp.data++;
			tmp.size--;

			ret = asn1_get_length_der(tmp.data, tmp.size, &real);
			if (ret < 0) {
				gnutls_assert();
				ret = GNUTLS_E_ASN1_GENERIC_ERROR;
				goto fail;
			}

			if (tmp.size < (unsigned)real) {
				gnutls_assert();
				ret = GNUTLS_E_ASN1_GENERIC_ERROR;
				goto fail;
			}

			tmp.data += real;
			tmp.size -= real;

			ret = _gnutls_set_datum(raw, tmp.data, tmp.size);
		}
	}

	if (ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND ||
	    ret == GNUTLS_E_ASN1_VALUE_NOT_FOUND)
		return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;

fail:
	return ret;
}

/**
 * gnutls_ocsp_resp_get_produced:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 *
 * This function will return the time when the OCSP response was
 * signed.
 *
 * Returns: signing time, or (time_t)-1 on error.
 **/
time_t gnutls_ocsp_resp_get_produced(gnutls_ocsp_resp_const_t resp)
{
	char ttime[MAX_TIME];
	int len, ret;
	time_t c_time;

	if (resp == NULL || resp->basicresp == NULL) {
		gnutls_assert();
		return (time_t)(-1);
	}

	len = sizeof(ttime) - 1;
	ret = asn1_read_value(resp->basicresp, "tbsResponseData.producedAt",
			      ttime, &len);
	if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		return (time_t)(-1);
	}

	c_time = _gnutls_x509_generalTime2gtime(ttime);

	return c_time;
}

/**
 * gnutls_ocsp_resp_check_crt:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @indx: Specifies response number to get. Use (0) to get the first one.
 * @crt: The certificate to check
 *
 * This function will check whether the OCSP response
 * is about the provided certificate.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.  
 * 
 * Since: 3.1.3
 **/
int gnutls_ocsp_resp_check_crt(gnutls_ocsp_resp_const_t resp, unsigned int indx,
			       gnutls_x509_crt_t crt)
{
	int ret;
	gnutls_digest_algorithm_t digest;
	gnutls_datum_t rdn_hash = { NULL, 0 }, rserial = { NULL, 0 };
	gnutls_datum_t cserial = { NULL, 0 };
	gnutls_datum_t dn = { NULL, 0 };
	uint8_t cdn_hash[MAX_HASH_SIZE];
	size_t t, hash_len;

	if (resp == NULL)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	ret = gnutls_ocsp_resp_get_single(resp, indx, &digest, &rdn_hash, NULL,
					  &rserial, NULL, NULL, NULL, NULL,
					  NULL);
	if (ret < 0)
		return gnutls_assert_val(ret);

	if (rserial.size == 0 || digest == GNUTLS_DIG_UNKNOWN) {
		ret = gnutls_assert_val(GNUTLS_E_OCSP_RESPONSE_ERROR);
		goto cleanup;
	}

	hash_len = _gnutls_hash_get_algo_len(hash_to_entry(digest));
	if (hash_len != rdn_hash.size) {
		ret = gnutls_assert_val(GNUTLS_E_OCSP_RESPONSE_ERROR);
		goto cleanup;
	}

	cserial.size = rserial.size;
	cserial.data = gnutls_malloc(cserial.size);
	if (cserial.data == NULL) {
		ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
		goto cleanup;
	}

	t = cserial.size;
	ret = gnutls_x509_crt_get_serial(crt, cserial.data, &t);
	if (ret < 0) {
		gnutls_assert();
		goto cleanup;
	}
	cserial.size = t;

	if (rserial.size != cserial.size ||
	    memcmp(cserial.data, rserial.data, rserial.size) != 0) {
		ret = GNUTLS_E_OCSP_RESPONSE_ERROR;
		gnutls_assert();
		goto cleanup;
	}

	ret = gnutls_x509_crt_get_raw_issuer_dn(crt, &dn);
	if (ret < 0) {
		gnutls_assert();
		goto cleanup;
	}

	ret = _gnutls_hash_fast(digest, dn.data, dn.size, cdn_hash);
	if (ret < 0) {
		gnutls_assert();
		goto cleanup;
	}

	if (memcmp(cdn_hash, rdn_hash.data, hash_len) != 0) {
		ret = GNUTLS_E_OCSP_RESPONSE_ERROR;
		gnutls_assert();
		goto cleanup;
	}

	ret = 0;

cleanup:
	gnutls_free(rdn_hash.data);
	gnutls_free(rserial.data);
	gnutls_free(cserial.data);
	gnutls_free(dn.data);

	return ret;
}

/**
 * gnutls_ocsp_resp_get_single:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @indx: Specifies response number to get. Use (0) to get the first one.
 * @digest: output variable with #gnutls_digest_algorithm_t hash algorithm
 * @issuer_name_hash: output buffer with hash of issuer's DN
 * @issuer_key_hash: output buffer with hash of issuer's public key
 * @serial_number: output buffer with serial number of certificate to check
 * @cert_status: a certificate status, a #gnutls_ocsp_cert_status_t enum.
 * @this_update: time at which the status is known to be correct.
 * @next_update: when newer information will be available, or (time_t)-1 if unspecified
 * @revocation_time: when @cert_status is %GNUTLS_OCSP_CERT_REVOKED, holds time of revocation.
 * @revocation_reason: revocation reason, a #gnutls_x509_crl_reason_t enum.
 *
 * This function will return the certificate information of the
 * @indx'ed response in the Basic OCSP Response @resp.  The
 * information returned corresponds to the OCSP SingleResponse structure
 * except the final singleExtensions.
 *
 * Each of the pointers to output variables may be NULL to indicate
 * that the caller is not interested in that value.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.  If you have reached the last
 *   CertID available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be
 *   returned.
 **/
int gnutls_ocsp_resp_get_single(gnutls_ocsp_resp_const_t resp, unsigned indx,
				gnutls_digest_algorithm_t *digest,
				gnutls_datum_t *issuer_name_hash,
				gnutls_datum_t *issuer_key_hash,
				gnutls_datum_t *serial_number,
				unsigned int *cert_status, time_t *this_update,
				time_t *next_update, time_t *revocation_time,
				unsigned int *revocation_reason)
{
	char name[MAX_NAME_SIZE];
	int ret, result;
	char oidtmp[MAX_OID_SIZE];
	int len;
	char ttime[MAX_TIME];

	/* initialize any allocated values to NULL, to allow deallocation
	 * on error. */
	if (issuer_name_hash)
		issuer_name_hash->data = NULL;
	if (issuer_key_hash)
		issuer_key_hash->data = NULL;
	if (serial_number)
		serial_number->data = NULL;

	if (digest) {
		snprintf(
			name, sizeof(name),
			"tbsResponseData.responses.?%u.certID.hashAlgorithm.algorithm",
			indx + 1);
		len = sizeof(oidtmp);
		result = asn1_read_value(resp->basicresp, name, oidtmp, &len);
		if (result == ASN1_ELEMENT_NOT_FOUND) {
			return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
		} else if (result != ASN1_SUCCESS) {
			gnutls_assert();
			return _gnutls_asn2err(result);
		}

		ret = gnutls_oid_to_digest(oidtmp);
		if (ret < 0) {
			gnutls_assert();
			return ret;
		}

		*digest = ret;
	}

	if (issuer_name_hash) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certID.issuerNameHash",
			 indx + 1);
		ret = _gnutls_x509_read_value(resp->basicresp, name,
					      issuer_name_hash);
		if (ret < 0) {
			gnutls_assert();
			return ret;
		}
	}

	if (issuer_key_hash) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certID.issuerKeyHash",
			 indx + 1);
		ret = _gnutls_x509_read_value(resp->basicresp, name,
					      issuer_key_hash);
		if (ret < 0) {
			gnutls_assert();
			goto fail;
		}
	}

	if (serial_number) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certID.serialNumber",
			 indx + 1);
		ret = _gnutls_x509_read_value(resp->basicresp, name,
					      serial_number);
		if (ret < 0) {
			gnutls_assert();
			goto fail;
		}
	}

	if (cert_status) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certStatus", indx + 1);

		len = sizeof(oidtmp);
		result = asn1_read_value(resp->basicresp, name, oidtmp, &len);
		if (result == ASN1_ELEMENT_NOT_FOUND) {
			gnutls_assert();
			ret = GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
			goto fail;
		} else if (result != ASN1_SUCCESS) {
			gnutls_assert();
			ret = _gnutls_asn2err(result);
			goto fail;
		}

		if (len == 5 && memcmp(oidtmp, "good", len) == 0)
			*cert_status = GNUTLS_OCSP_CERT_GOOD;
		else if (len == 8 && memcmp(oidtmp, "revoked", len) == 0)
			*cert_status = GNUTLS_OCSP_CERT_REVOKED;
		else if (len == 8 && memcmp(oidtmp, "unknown", len) == 0)
			*cert_status = GNUTLS_OCSP_CERT_UNKNOWN;
		else {
			gnutls_assert();
			ret = GNUTLS_E_ASN1_DER_ERROR;
			goto fail;
		}
	}

	if (this_update) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.thisUpdate", indx + 1);
		len = sizeof(ttime) - 1;
		result = asn1_read_value(resp->basicresp, name, ttime, &len);
		if (result != ASN1_SUCCESS) {
			gnutls_assert();
			ret = GNUTLS_E_ASN1_DER_ERROR;
			goto fail;
		} else {
			*this_update = _gnutls_x509_generalTime2gtime(ttime);
		}
	}

	if (next_update) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.nextUpdate", indx + 1);
		len = sizeof(ttime) - 1;
		result = asn1_read_value(resp->basicresp, name, ttime, &len);
		if (result != ASN1_SUCCESS) {
			gnutls_assert();
			*next_update = (time_t)(-1);
		} else
			*next_update = _gnutls_x509_generalTime2gtime(ttime);
	}

	if (revocation_time) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certStatus."
			 "revoked.revocationTime",
			 indx + 1);
		len = sizeof(ttime) - 1;
		result = asn1_read_value(resp->basicresp, name, ttime, &len);
		if (result != ASN1_SUCCESS) {
			gnutls_assert();
			*revocation_time = (time_t)(-1);
		} else
			*revocation_time =
				_gnutls_x509_generalTime2gtime(ttime);
	}

	/* revocation_reason */
	if (revocation_reason) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responses.?%u.certStatus."
			 "revoked.revocationReason",
			 indx + 1);

		ret = _gnutls_x509_read_uint(resp->basicresp, name,
					     revocation_reason);
		if (ret < 0)
			*revocation_reason = GNUTLS_X509_CRLREASON_UNSPECIFIED;
	}

	return GNUTLS_E_SUCCESS;
fail:
	if (issuer_name_hash)
		gnutls_free(issuer_name_hash->data);
	if (issuer_key_hash)
		gnutls_free(issuer_key_hash->data);
	if (serial_number)
		gnutls_free(serial_number->data);
	return ret;
}

/**
 * gnutls_ocsp_resp_get_extension:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @indx: Specifies which extension OID to get. Use (0) to get the first one.
 * @oid: will hold newly allocated buffer with OID of extension, may be NULL
 * @critical: output variable with critical flag, may be NULL.
 * @data: will hold newly allocated buffer with extension data, may be NULL
 *
 * This function will return all information about the requested
 * extension in the OCSP response.  The information returned is the
 * OID, the critical flag, and the data itself.  The extension OID
 * will be stored as a string.  Any of @oid, @critical, and @data may
 * be NULL which means that the caller is not interested in getting
 * that information back.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @oid->data and @data->data.
 *
 * Since 3.7.0 @oid->size does not account for the terminating null byte.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.  If you have reached the last
 *   extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will
 *   be returned.
 **/
int gnutls_ocsp_resp_get_extension(gnutls_ocsp_resp_const_t resp, unsigned indx,
				   gnutls_datum_t *oid, unsigned int *critical,
				   gnutls_datum_t *data)
{
	int ret;
	char str_critical[10];
	char name[MAX_NAME_SIZE];
	int len;

	if (!resp) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	snprintf(name, sizeof(name),
		 "tbsResponseData.responseExtensions.?%u.critical", indx + 1);
	len = sizeof(str_critical);
	ret = asn1_read_value(resp->basicresp, name, str_critical, &len);
	if (ret == ASN1_ELEMENT_NOT_FOUND)
		return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
	else if (ret != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(ret);
	}

	if (critical) {
		if (str_critical[0] == 'T')
			*critical = 1;
		else
			*critical = 0;
	}

	if (oid) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responseExtensions.?%u.extnID",
			 indx + 1);
		ret = _gnutls_x509_read_value(resp->basicresp, name, oid);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			return ret;
		}
	}

	if (data) {
		snprintf(name, sizeof(name),
			 "tbsResponseData.responseExtensions.?%u.extnValue",
			 indx + 1);
		ret = _gnutls_x509_read_value(resp->basicresp, name, data);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			if (oid)
				gnutls_free(oid->data);
			return ret;
		}
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_get_nonce:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @critical: whether nonce extension is marked critical
 * @nonce: will hold newly allocated buffer with nonce data
 *
 * This function will return the Basic OCSP Response nonce extension
 * data.
 *
 * The caller needs to deallocate memory by calling gnutls_free() on
 * @nonce->data.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code is returned.
 **/
int gnutls_ocsp_resp_get_nonce(gnutls_ocsp_resp_const_t resp,
			       unsigned int *critical, gnutls_datum_t *nonce)
{
	int ret;
	gnutls_datum_t tmp;

	ret = _gnutls_get_extension(resp->basicresp,
				    "tbsResponseData.responseExtensions",
				    GNUTLS_OCSP_NONCE, 0, &tmp, critical);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	ret = _gnutls_x509_decode_string(ASN1_ETYPE_OCTET_STRING, tmp.data,
					 (size_t)tmp.size, nonce, 0);
	if (ret < 0) {
		gnutls_assert();
		gnutls_free(tmp.data);
		return ret;
	}

	gnutls_free(tmp.data);

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_get_signature_algorithm:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 *
 * This function will return a value of the #gnutls_sign_algorithm_t
 * enumeration that is the signature algorithm that has been used to
 * sign the OCSP response.
 *
 * Returns: a #gnutls_sign_algorithm_t value, or a negative error code
 *   on error.
 **/
int gnutls_ocsp_resp_get_signature_algorithm(gnutls_ocsp_resp_const_t resp)
{
	int ret;
	gnutls_datum_t sa;

	ret = _gnutls_x509_read_value(resp->basicresp,
				      "signatureAlgorithm.algorithm", &sa);
	if (ret < 0) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_oid_to_sign((char *)sa.data);

	_gnutls_free_datum(&sa);

	return ret;
}

/**
 * gnutls_ocsp_resp_get_signature:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @sig: newly allocated output buffer with signature data
 *
 * This function will extract the signature field of a OCSP response.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_get_signature(gnutls_ocsp_resp_const_t resp,
				   gnutls_datum_t *sig)
{
	int ret;

	if (resp == NULL || sig == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	ret = _gnutls_x509_read_value(resp->basicresp, "signature", sig);
	if (ret != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return ret;
	}

	return GNUTLS_E_SUCCESS;
}

/**
 * gnutls_ocsp_resp_get_certs:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @certs: newly allocated array with #gnutls_x509_crt_t certificates
 * @ncerts: output variable with number of allocated certs.
 *
 * This function will extract the X.509 certificates found in the
 * Basic OCSP Response.  The @certs output variable will hold a newly
 * allocated zero-terminated array with X.509 certificates.
 *
 * Every certificate in the array needs to be de-allocated with
 * gnutls_x509_crt_deinit() and the array itself must be freed using
 * gnutls_free().
 *
 * Both the @certs and @ncerts variables may be NULL.  Then the
 * function will work as normal but will not return the NULL:d
 * information.  This can be used to get the number of certificates
 * only, or to just get the certificate array without its size.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_get_certs(gnutls_ocsp_resp_const_t resp,
			       gnutls_x509_crt_t **certs, size_t *ncerts)
{
	int ret;
	size_t ctr = 0, i;
	gnutls_x509_crt_t *tmpcerts = NULL, *tmpcerts2;
	gnutls_datum_t c = { NULL, 0 };

	if (resp == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	tmpcerts = gnutls_malloc(sizeof(*tmpcerts));
	if (tmpcerts == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	for (;;) {
		char name[MAX_NAME_SIZE];

		snprintf(name, sizeof(name), "certs.?%u",
			 (unsigned int)(ctr + 1));
		ret = _gnutls_x509_der_encode(resp->basicresp, name, &c, 0);
		if (ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND)
			break;
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			goto error;
		}

		if (unlikely(INT_ADD_OVERFLOW(ctr, 2))) {
			ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
			goto error;
		}

		tmpcerts2 = _gnutls_reallocarray_fast(tmpcerts, ctr + 2,
						      sizeof(*tmpcerts));
		if (tmpcerts2 == NULL) {
			gnutls_assert();
			ret = GNUTLS_E_MEMORY_ERROR;
			goto error;
		}
		tmpcerts = tmpcerts2;

		ret = gnutls_x509_crt_init(&tmpcerts[ctr]);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			goto error;
		}
		ctr++;

		ret = gnutls_x509_crt_import(tmpcerts[ctr - 1], &c,
					     GNUTLS_X509_FMT_DER);
		if (ret != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			goto error;
		}

		gnutls_free(c.data);
	}

	tmpcerts[ctr] = NULL;

	if (ncerts)
		*ncerts = ctr;
	if (certs)
		*certs = tmpcerts;
	else {
		/* clean up memory */
		ret = GNUTLS_E_SUCCESS;
		goto error;
	}

	return GNUTLS_E_SUCCESS;

error:
	gnutls_free(c.data);
	for (i = 0; i < ctr; i++)
		gnutls_x509_crt_deinit(tmpcerts[i]);
	gnutls_free(tmpcerts);
	return ret;
}

/* Search the OCSP response for a certificate matching the responderId
   mentioned in the OCSP response. */
static gnutls_x509_crt_t find_signercert(gnutls_ocsp_resp_const_t resp)
{
	int rc;
	gnutls_x509_crt_t *certs = NULL;
	size_t ncerts = 0, i;
	gnutls_datum_t riddn = { NULL, 0 };
	gnutls_datum_t keyid = { NULL, 0 };
	gnutls_x509_crt_t signercert = NULL;

	rc = gnutls_ocsp_resp_get_responder_raw_id(resp, GNUTLS_OCSP_RESP_ID_DN,
						   &riddn);
	if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
		gnutls_assert();
		rc = gnutls_ocsp_resp_get_responder_raw_id(
			resp, GNUTLS_OCSP_RESP_ID_KEY, &keyid);
	}
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		return NULL;
	}

	rc = gnutls_ocsp_resp_get_certs(resp, &certs, &ncerts);
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		signercert = NULL;
		goto quit;
	}

	for (i = 0; i < ncerts; i++) {
		assert(certs[i] != NULL);
		_gnutls_cert_log("checking whether signed against", certs[i]);
		if (keyid.data != NULL) {
			uint8_t digest[64]; /* to support longer key IDs */
			gnutls_datum_t spki;
			size_t digest_size = sizeof(digest);
			int len;

			_gnutls_debug_log(
				"checking key ID against SPK identifier\n");

			/* check subject key identifier as well, some certificates
			 * match that, but not the hash */
			rc = gnutls_x509_crt_get_subject_key_id(
				certs[i], digest, &digest_size, NULL);
			if (rc >= 0 && digest_size == keyid.size &&
			    memcmp(keyid.data, digest, digest_size) == 0) {
				signercert = certs[i];
				goto quit;
			}

			_gnutls_debug_log(
				"checking key ID against SPKI hash\n");

			/* continue with checking the hash */
			rc = _gnutls_x509_get_raw_field2(
				certs[i]->cert, &certs[i]->der,
				"tbsCertificate.subjectPublicKeyInfo.subjectPublicKey",
				&spki);
			if (rc < 0 || spki.size < 6) {
				gnutls_assert();
				signercert = NULL;
				continue;
			}

			/* For some reason the protocol requires we skip the
			 * tag, length and number of unused bits.
			 */
			if (spki.data[0] != 0x03) { /* bit string */
				gnutls_assert();
				signercert = NULL;
				continue;
			}

			rc = asn1_get_length_der(spki.data + 1, spki.size - 1,
						 &len);
			if (rc <= 0) {
				gnutls_assert();
				signercert = NULL;
				continue;
			}
			len += 1 + 1; /* skip unused bits as well */
			if (len >= (int)spki.size) {
				gnutls_assert();
				signercert = NULL;
				continue;
			}

			rc = gnutls_hash_fast(GNUTLS_DIG_SHA1, spki.data + len,
					      spki.size - len, digest);
			if (rc < 0) {
				gnutls_assert();
				signercert = NULL;
				continue;
			}

			if ((20 == keyid.size) &&
			    memcmp(keyid.data, digest, 20) == 0) {
				signercert = certs[i];
				goto quit;
			}
			gnutls_assert();
		} else {
			_gnutls_debug_log("checking issuer DN\n");

			assert(riddn.data != NULL);
			if ((certs[i]->raw_dn.size == riddn.size) &&
			    memcmp(riddn.data, certs[i]->raw_dn.data,
				   riddn.size) == 0) {
				signercert = certs[i];
				goto quit;
			}
			gnutls_assert();
		}
	}

	gnutls_assert();
	signercert = NULL;

quit:
	gnutls_free(riddn.data);
	gnutls_free(keyid.data);
	for (i = 0; i < ncerts; i++)
		if (certs[i] != signercert)
			gnutls_x509_crt_deinit(certs[i]);
	gnutls_free(certs);
	return signercert;
}

static int _ocsp_resp_verify_direct(gnutls_ocsp_resp_const_t resp,
				    gnutls_x509_crt_t signercert,
				    unsigned int *verify, unsigned int flags)
{
	gnutls_datum_t sig = { NULL };
	gnutls_datum_t data = { NULL };
	gnutls_pubkey_t pubkey = NULL;
	int sigalg;
	int rc;

	if (resp == NULL || signercert == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	rc = gnutls_ocsp_resp_get_signature_algorithm(resp);
	if (rc < 0) {
		gnutls_assert();
		goto done;
	}
	sigalg = rc;

	rc = _gnutls_x509_get_raw_field2(resp->basicresp, &resp->der,
					 "tbsResponseData", &data);
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		goto done;
	}

	rc = gnutls_pubkey_init(&pubkey);
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		goto done;
	}

	_gnutls_cert_log("ocsp signer", signercert);

	rc = gnutls_pubkey_import_x509(pubkey, signercert, 0);
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		goto done;
	}

	rc = gnutls_ocsp_resp_get_signature(resp, &sig);
	if (rc != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		goto done;
	}

	rc = gnutls_pubkey_verify_data2(pubkey, sigalg, flags, &data, &sig);
	if (rc == GNUTLS_E_PK_SIG_VERIFY_FAILED) {
		gnutls_assert();
		*verify = GNUTLS_OCSP_VERIFY_SIGNATURE_FAILURE;
	} else if (rc < 0) {
		gnutls_assert();
		goto done;
	} else
		*verify = 0;

	rc = GNUTLS_E_SUCCESS;

done:
	gnutls_free(sig.data);
	gnutls_pubkey_deinit(pubkey);

	return rc;
}

static inline unsigned int vstatus_to_ocsp_status(unsigned int status)
{
	unsigned int ostatus;

	if (status & GNUTLS_CERT_INSECURE_ALGORITHM)
		ostatus = GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM;
	else if (status & GNUTLS_CERT_NOT_ACTIVATED)
		ostatus = GNUTLS_OCSP_VERIFY_CERT_NOT_ACTIVATED;
	else if (status & GNUTLS_CERT_EXPIRED)
		ostatus = GNUTLS_OCSP_VERIFY_CERT_EXPIRED;
	else
		ostatus = GNUTLS_OCSP_VERIFY_UNTRUSTED_SIGNER;

	return ostatus;
}

static int check_ocsp_purpose(gnutls_x509_crt_t signercert)
{
	char oidtmp[MAX_OID_SIZE];
	size_t oidsize;
	int indx, rc;

	for (indx = 0;; indx++) {
		oidsize = sizeof(oidtmp);
		rc = gnutls_x509_crt_get_key_purpose_oid(
			signercert, indx, oidtmp, &oidsize, NULL);

		if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
			gnutls_assert();
			return rc;
		} else if (rc == GNUTLS_E_SHORT_MEMORY_BUFFER) {
			gnutls_assert();
			continue;
		} else if (rc != GNUTLS_E_SUCCESS) {
			return gnutls_assert_val(rc);
		}

		if (memcmp(oidtmp, GNUTLS_KP_OCSP_SIGNING, oidsize) != 0) {
			gnutls_assert();
			continue;
		}
		break;
	}

	return 0;
}

/**
 * gnutls_ocsp_resp_verify_direct:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @issuer: certificate believed to have signed the response
 * @verify: output variable with verification status, an #gnutls_ocsp_verify_reason_t
 * @flags: verification flags from #gnutls_certificate_verify_flags
 *
 * Verify signature of the Basic OCSP Response against the public key
 * in the @issuer certificate.
 *
 * The output @verify variable will hold verification status codes
 * (e.g., %GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND,
 * %GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM) which are only valid if the
 * function returned %GNUTLS_E_SUCCESS.
 *
 * Note that the function returns %GNUTLS_E_SUCCESS even when
 * verification failed.  The caller must always inspect the @verify
 * variable to find out the verification status.
 *
 * The @flags variable should be 0 for now.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_verify_direct(gnutls_ocsp_resp_const_t resp,
				   gnutls_x509_crt_t issuer,
				   unsigned int *verify, unsigned int flags)
{
	gnutls_x509_crt_t signercert;
	int rc;

	if (resp == NULL || issuer == NULL) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	signercert = find_signercert(resp);
	if (!signercert) {
		signercert = issuer;
	} else if (!gnutls_x509_crt_equals(signercert, issuer)) {
		/* response contains a signer. Verify him */

		unsigned int vtmp;

		rc = gnutls_x509_crt_verify(signercert, &issuer, 1, flags,
					    &vtmp);
		if (rc != GNUTLS_E_SUCCESS) {
			gnutls_assert();
			goto done;
		}

		if (vtmp != 0) {
			_gnutls_reason_log("cert verification", vtmp);
			*verify = vstatus_to_ocsp_status(vtmp);
			gnutls_assert();
			rc = GNUTLS_E_SUCCESS;
			goto done;
		}

		rc = check_ocsp_purpose(signercert);
		if (rc < 0) {
			gnutls_assert();
			*verify = GNUTLS_OCSP_VERIFY_SIGNER_KEYUSAGE_ERROR;
			rc = GNUTLS_E_SUCCESS;
			goto done;
		}
	}

	rc = _ocsp_resp_verify_direct(resp, signercert, verify, flags);

done:
	if (signercert != issuer)
		gnutls_x509_crt_deinit(signercert);

	return rc;
}

/**
 * gnutls_ocsp_resp_verify:
 * @resp: should contain a #gnutls_ocsp_resp_t type
 * @trustlist: trust anchors as a #gnutls_x509_trust_list_t type
 * @verify: output variable with verification status, an #gnutls_ocsp_verify_reason_t
 * @flags: verification flags from #gnutls_certificate_verify_flags
 *
 * Verify signature of the Basic OCSP Response against the public key
 * in the certificate of a trusted signer.  The @trustlist should be
 * populated with trust anchors.  The function will extract the signer
 * certificate from the Basic OCSP Response and will verify it against
 * the @trustlist.  A trusted signer is a certificate that is either
 * in @trustlist, or it is signed directly by a certificate in
 * @trustlist and has the id-ad-ocspSigning Extended Key Usage bit
 * set.
 *
 * The output @verify variable will hold verification status codes
 * (e.g., %GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND,
 * %GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM) which are only valid if the
 * function returned %GNUTLS_E_SUCCESS.
 *
 * Note that the function returns %GNUTLS_E_SUCCESS even when
 * verification failed.  The caller must always inspect the @verify
 * variable to find out the verification status.
 *
 * The @flags variable should be 0 for now.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_ocsp_resp_verify(gnutls_ocsp_resp_const_t resp,
			    gnutls_x509_trust_list_t trustlist,
			    unsigned int *verify, unsigned int flags)
{
	gnutls_x509_crt_t signercert = NULL;
	int rc;

	/* Algorithm:
	   1. Find signer cert.
	   1a. Search in OCSP response Certificate field for responderID.
	   1b. Verify that signer cert is trusted.
	   2a. It is in trustlist?
	   2b. It has OCSP key usage and directly signed by a CA in trustlist?
	   3. Verify signature of Basic Response using public key from signer cert.
	 */

	signercert = find_signercert(resp);
	if (!signercert) {
		gnutls_datum_t dn;

		rc = gnutls_ocsp_resp_get_responder_raw_id(
			resp, GNUTLS_OCSP_RESP_ID_DN, &dn);
		if (rc < 0) {
			gnutls_assert();
			*verify = GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND;
			rc = GNUTLS_E_SUCCESS;
			goto done;
		}

		rc = gnutls_x509_trust_list_get_issuer_by_dn(trustlist, &dn,
							     &signercert, 0);
		gnutls_free(dn.data);

		if (rc < 0) {
			gnutls_assert();
			*verify = GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND;
			rc = GNUTLS_E_SUCCESS;
			goto done;
		}
	} else {
		/* Either the signer is directly trusted (i.e., in trustlist) or it
		   is directly signed by something in trustlist and has proper OCSP
		   extkeyusage. */
		rc = _gnutls_trustlist_inlist(trustlist, signercert);
		if (rc == 0) {
			/* not in trustlist, need to verify signature and bits */
			unsigned vtmp;
			gnutls_typed_vdata_st vdata;

			vdata.type = GNUTLS_DT_KEY_PURPOSE_OID;
			vdata.data = (void *)GNUTLS_KP_OCSP_SIGNING;
			vdata.size = 0;

			gnutls_assert();

			rc = gnutls_x509_trust_list_verify_crt2(
				trustlist, &signercert, 1, &vdata, 1, flags,
				&vtmp, NULL);
			if (rc != GNUTLS_E_SUCCESS) {
				gnutls_assert();
				goto done;
			}

			if (vtmp != 0) {
				*verify = vstatus_to_ocsp_status(vtmp);
				gnutls_assert();
				rc = GNUTLS_E_SUCCESS;
				goto done;
			}

			rc = check_ocsp_purpose(signercert);
			if (rc < 0) {
				gnutls_assert();
				*verify =
					GNUTLS_OCSP_VERIFY_SIGNER_KEYUSAGE_ERROR;
				rc = GNUTLS_E_SUCCESS;
				goto done;
			}
		}
	}

	rc = _ocsp_resp_verify_direct(resp, signercert, verify, flags);

done:
	gnutls_x509_crt_deinit(signercert);

	return rc;
}

/**
 * gnutls_x509_ocsp_resp_list_import2:
 * @ocsps: Will hold the parsed OCSP response list.
 * @size: It will contain the size of the list.
 * @resp_data: The PEM encoded OCSP list.
 * @format: One of %GNUTLS_X509_FMT_PEM or %GNUTLS_X509_FMT_DER
 * @flags: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.
 *
 * This function will convert the given PEM encoded OCSP response list
 * to the native gnutls_ocsp_resp_t format. The output will be stored
 * in @ocsps which will be allocated and initialized.
 *
 * The OCSP responses should have a header of "OCSP RESPONSE".
 *
 * To deinitialize responses, you need to deinitialize each %gnutls_ocsp_resp_t
 * structure independently, and use gnutls_free() at @ocsps.
 *
 * In PEM files, when no OCSP responses are detected
 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
 *
 * Returns: the number of responses read or a negative error value.
 *
 * Since: 3.6.3
 **/
int gnutls_ocsp_resp_list_import2(gnutls_ocsp_resp_t **ocsps,
				  unsigned int *size,
				  const gnutls_datum_t *resp_data,
				  gnutls_x509_crt_fmt_t format,
				  unsigned int flags)
{
	gnutls_ocsp_resp_t resp = NULL;
	gnutls_ocsp_resp_t *new_ocsps;
	int ret;
	unsigned i;

	if (format == GNUTLS_X509_FMT_PEM) {
		/* load multiple responses */
		gnutls_datum_t p = { resp_data->data, resp_data->size };

		*size = 0;
		*ocsps = NULL;

		p.data = memmem(p.data, p.size, PEM_OCSP_RESPONSE,
				sizeof(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_ocsp_resp_init(&resp);
			if (ret < 0) {
				gnutls_assert();
				goto fail;
			}

			ret = gnutls_ocsp_resp_import2(resp, &p,
						       GNUTLS_X509_FMT_PEM);
			if (ret < 0) {
				gnutls_assert();
				goto fail;
			}

			if (unlikely(INT_ADD_OVERFLOW(*size, 1))) {
				ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
				goto fail;
			}

			new_ocsps = _gnutls_reallocarray(
				*ocsps, *size + 1, sizeof(gnutls_ocsp_resp_t));
			if (new_ocsps == NULL) {
				resp = NULL;
				gnutls_assert();
				goto fail;
			}

			new_ocsps[*size] = resp;
			resp = NULL;
			(*size)++;
			*ocsps = new_ocsps;

			p.data++;
			p.size--;

			p.data = memmem(p.data, p.size, PEM_OCSP_RESPONSE,
					sizeof(PEM_OCSP_RESPONSE) - 1);
			if (p.data == NULL)
				break;
			p.size = resp_data->size - (p.data - resp_data->data);
		} while (p.size > 0);
	} else {
		/* DER: load a single response */
		ret = gnutls_ocsp_resp_init(&resp);
		if (ret < 0) {
			return gnutls_assert_val(ret);
		}

		ret = gnutls_ocsp_resp_import2(resp, resp_data,
					       GNUTLS_X509_FMT_DER);
		if (ret < 0) {
			gnutls_assert();
			goto cleanup;
		}

		*ocsps = gnutls_malloc(sizeof(gnutls_ocsp_resp_t));
		if (*ocsps == NULL) {
			gnutls_assert();
			ret = GNUTLS_E_MEMORY_ERROR;
			goto cleanup;
		}

		(*ocsps)[0] = resp;
		resp = NULL;
		*size = 1;
	}

	ret = 0;
	goto cleanup;

fail:
	for (i = 0; i < *size; i++) {
		gnutls_ocsp_resp_deinit((*ocsps)[i]);
	}
	gnutls_free(*ocsps);

cleanup:
	if (resp)
		gnutls_ocsp_resp_deinit(resp);
	return ret;
}

/* This returns -1 if the OCSP response is invalid (revoked) or its
 * data are too old. It returns -2 if it cannot determine the expiration
 * time, and would otherwise treat it as too old.
 * Otherwise it returns the time after which that data  is invalid.
 */
time_t _gnutls_ocsp_get_validity(gnutls_ocsp_resp_const_t resp)
{
	unsigned int cert_status;
	time_t rtime, vtime, ntime, now;
	int ret;

	ret = gnutls_ocsp_resp_get_single(resp, 0, NULL, NULL, NULL, NULL,
					  &cert_status, &vtime, &ntime, &rtime,
					  NULL);
	if (ret < 0) {
		_gnutls_debug_log(
			"There was an error parsing the OCSP response: %s\n",
			gnutls_strerror(ret));
		return gnutls_assert_val(-1);
	}

	if (cert_status != GNUTLS_OCSP_CERT_GOOD &&
	    cert_status != GNUTLS_OCSP_CERT_UNKNOWN) {
		_gnutls_debug_log("The OCSP response status (%d) is invalid\n",
				  cert_status);
		return gnutls_assert_val(-1);
	}

	now = gnutls_time(0);

	if (ntime == -1) {
		/* This is a problematic case, and there is no consensus on how
		 * to treat these responses. It doesn't contain the time after which
		 * the response is invalid, thus it is an OCSP response effectively
		 * valid forever defeating the purpose of OCSP. We set here the same
		 * limit we apply when verifying responses. */
		if (now - vtime > MAX_OCSP_VALIDITY_SECS) {
			_gnutls_debug_log("The OCSP response is old\n");
			return gnutls_assert_val(-2);
		}

		return now + MAX_OCSP_VALIDITY_SECS;
	} else {
		/* there is a newer OCSP answer, don't trust this one */
		if (ntime < now) {
			_gnutls_debug_log("There is a newer OCSP response\n");
			return gnutls_assert_val(-1);
		}

		return ntime;
	}
}

const char *_gnutls_ocsp_verify_status_to_str(gnutls_ocsp_verify_reason_t r,
					      char out[MAX_OCSP_MSG_SIZE])
{
	gnutls_buffer_st str;
	gnutls_datum_t buf;
	int ret;

	_gnutls_buffer_init(&str);

	if (r == 0)
		_gnutls_buffer_append_str(&str,
					  _("The OCSP response is trusted. "));

	if (r & GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND)
		_gnutls_buffer_append_str(
			&str,
			_("The OCSP response's signer could not be found. "));

	if (r & GNUTLS_OCSP_VERIFY_SIGNER_KEYUSAGE_ERROR)
		_gnutls_buffer_append_str(
			&str, _("Error in the signer's key usageflags. "));

	if (r & GNUTLS_OCSP_VERIFY_UNTRUSTED_SIGNER)
		_gnutls_buffer_append_str(
			&str, _("The OCSP response's signer is not trusted. "));

	if (r & GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM)
		_gnutls_buffer_append_str(
			&str,
			_("The OCSP response depends on insecure algorithms. "));

	if (r & GNUTLS_OCSP_VERIFY_SIGNATURE_FAILURE)
		_gnutls_buffer_append_str(
			&str,
			_("The OCSP response's signature cannot be validated. "));

	if (r & GNUTLS_OCSP_VERIFY_CERT_NOT_ACTIVATED)
		_gnutls_buffer_append_str(
			&str,
			_("The OCSP response's signer's certificate is not activated. "));

	if (r & GNUTLS_OCSP_VERIFY_CERT_EXPIRED)
		_gnutls_buffer_append_str(
			&str,
			_("The OCSP response's signer's certificate is expired. "));

	ret = _gnutls_buffer_to_datum(&str, &buf, 1);
	if (ret < 0)
		return _("Memory error");

	snprintf(out, MAX_OCSP_MSG_SIZE, "%s", buf.data);
	gnutls_free(buf.data);

	return out;
}
