/* ocsp_vfy.c */

/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL

 * project 2000.

 */

/* ====================================================================

 * Copyright (c) 2000-2004 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer. 

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    licensing@OpenSSL.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com).

 *

 */

#include <openssl/ocsp.h>

#include <openssl/err.h>

#include <string.h>

static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs,

				X509_STORE *st, unsigned long flags);

static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id);

static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, unsigned long flags);

static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret);

static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid, STACK_OF(OCSP_SINGLERESP) *sresp);

static int ocsp_check_delegated(X509 *x, int flags);

static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, STACK_OF(X509) *certs,

				X509_STORE *st, unsigned long flags);

/* Verify a basic response message */

EXPORT_C int OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs,

				X509_STORE *st, unsigned long flags)

	{

	X509 *signer, *x;

	STACK_OF(X509) *chain = NULL;

	X509_STORE_CTX ctx;

	int i, ret = 0;

	ret = ocsp_find_signer(&signer, bs, certs, st, flags);

	if (!ret)

		{

		OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);

		goto end;

		}

	if ((ret == 2) && (flags & OCSP_TRUSTOTHER))

		flags |= OCSP_NOVERIFY;

	if (!(flags & OCSP_NOSIGS))

		{

		EVP_PKEY *skey;

		skey = X509_get_pubkey(signer);

		ret = OCSP_BASICRESP_verify(bs, skey, 0);

		EVP_PKEY_free(skey);

		if(ret <= 0)

			{

			OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, OCSP_R_SIGNATURE_FAILURE);

			goto end;

			}

		}

	if (!(flags & OCSP_NOVERIFY))

		{

		int init_res;

		if(flags & OCSP_NOCHAIN)

			init_res = X509_STORE_CTX_init(&ctx, st, signer, NULL);

		else

			init_res = X509_STORE_CTX_init(&ctx, st, signer, bs->certs);

		if(!init_res)

			{

			OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,ERR_R_X509_LIB);

			goto end;

			}

		X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);

		ret = X509_verify_cert(&ctx);

		chain = X509_STORE_CTX_get1_chain(&ctx);

		X509_STORE_CTX_cleanup(&ctx);

                if (ret <= 0)

			{

			i = X509_STORE_CTX_get_error(&ctx);	

			OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,OCSP_R_CERTIFICATE_VERIFY_ERROR);

			ERR_add_error_data(2, "Verify error:",

					X509_verify_cert_error_string(i));

                        goto end;

                	}

		if(flags & OCSP_NOCHECKS)

			{

			ret = 1;

			goto end;

			}

		/* At this point we have a valid certificate chain

		 * need to verify it against the OCSP issuer criteria.

		 */

		ret = ocsp_check_issuer(bs, chain, flags);

		/* If fatal error or valid match then finish */

		if (ret != 0) goto end;

		/* Easy case: explicitly trusted. Get root CA and

		 * check for explicit trust

		 */

		if(flags & OCSP_NOEXPLICIT) goto end;

		x = sk_X509_value(chain, sk_X509_num(chain) - 1);

		if(X509_check_trust(x, NID_OCSP_sign, 0) != X509_TRUST_TRUSTED)

			{

			OCSPerr(OCSP_F_OCSP_BASIC_VERIFY,OCSP_R_ROOT_CA_NOT_TRUSTED);

			goto end;

			}

		ret = 1;

		}

	end:

	if(chain) sk_X509_pop_free(chain, X509_free);

	return ret;

	}

static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs,

				X509_STORE *st, unsigned long flags)

	{

	X509 *signer;

	OCSP_RESPID *rid = bs->tbsResponseData->responderId;

	if ((signer = ocsp_find_signer_sk(certs, rid)))

		{

		*psigner = signer;

		return 2;

		}

	if(!(flags & OCSP_NOINTERN) &&

	    (signer = ocsp_find_signer_sk(bs->certs, rid)))

		{

		*psigner = signer;

		return 1;

		}

	/* Maybe lookup from store if by subject name */

	*psigner = NULL;

	return 0;

	}

static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id)

	{

	int i;

	unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;

	X509 *x;

	/* Easy if lookup by name */

	if (id->type == V_OCSP_RESPID_NAME)

		return X509_find_by_subject(certs, id->value.byName);

	/* Lookup by key hash */

	/* If key hash isn't SHA1 length then forget it */

	if (id->value.byKey->length != SHA_DIGEST_LENGTH) return NULL;

	keyhash = id->value.byKey->data;

	/* Calculate hash of each key and compare */

	for (i = 0; i < sk_X509_num(certs); i++)

		{

		x = sk_X509_value(certs, i);

		X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);

		if(!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH))

			return x;

		}

	return NULL;

	}

static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain, unsigned long flags)

	{

	STACK_OF(OCSP_SINGLERESP) *sresp;

	X509 *signer, *sca;

	OCSP_CERTID *caid = NULL;

	int i;

	sresp = bs->tbsResponseData->responses;

	if (sk_X509_num(chain) <= 0)

		{

		OCSPerr(OCSP_F_OCSP_CHECK_ISSUER, OCSP_R_NO_CERTIFICATES_IN_CHAIN);

		return -1;

		}

	/* See if the issuer IDs match. */

	i = ocsp_check_ids(sresp, &caid);

	/* If ID mismatch or other error then return */

	if (i <= 0) return i;

	signer = sk_X509_value(chain, 0);

	/* Check to see if OCSP responder CA matches request CA */

	if (sk_X509_num(chain) > 1)

		{

		sca = sk_X509_value(chain, 1);

		i = ocsp_match_issuerid(sca, caid, sresp);

		if (i < 0) return i;

		if (i)

			{

			/* We have a match, if extensions OK then success */

			if (ocsp_check_delegated(signer, flags)) return 1;

			return 0;

			}

		}

	/* Otherwise check if OCSP request signed directly by request CA */

	return ocsp_match_issuerid(signer, caid, sresp);

	}

/* Check the issuer certificate IDs for equality. If there is a mismatch with the same

 * algorithm then there's no point trying to match any certificates against the issuer.

 * If the issuer IDs all match then we just need to check equality against one of them.

 */

static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret)

	{

	OCSP_CERTID *tmpid, *cid;

	int i, idcount;

	idcount = sk_OCSP_SINGLERESP_num(sresp);

	if (idcount <= 0)

		{

		OCSPerr(OCSP_F_OCSP_CHECK_IDS, OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA);

		return -1;

		}

	cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId;

	*ret = NULL;

	for (i = 1; i < idcount; i++)

		{

		tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;

		/* Check to see if IDs match */

		if (OCSP_id_issuer_cmp(cid, tmpid))

			{

			/* If algoritm mismatch let caller deal with it */

			if (OBJ_cmp(tmpid->hashAlgorithm->algorithm,

					cid->hashAlgorithm->algorithm))

					return 2;

			/* Else mismatch */

			return 0;

			}

		}

	/* All IDs match: only need to check one ID */

	*ret = cid;

	return 1;

	}

static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,

			STACK_OF(OCSP_SINGLERESP) *sresp)

	{

	/* If only one ID to match then do it */

	if(cid)

		{

		const EVP_MD *dgst;

		X509_NAME *iname;

		int mdlen;

		unsigned char md[EVP_MAX_MD_SIZE];

		if (!(dgst = EVP_get_digestbyobj(cid->hashAlgorithm->algorithm)))

			{

			OCSPerr(OCSP_F_OCSP_MATCH_ISSUERID, OCSP_R_UNKNOWN_MESSAGE_DIGEST);

			return -1;

			}

		mdlen = EVP_MD_size(dgst);

		if ((cid->issuerNameHash->length != mdlen) ||

		   (cid->issuerKeyHash->length != mdlen))

			return 0;

		iname = X509_get_subject_name(cert);

		if (!X509_NAME_digest(iname, dgst, md, NULL))

			return -1;

		if (memcmp(md, cid->issuerNameHash->data, mdlen))

			return 0;

		X509_pubkey_digest(cert, EVP_sha1(), md, NULL);

		if (memcmp(md, cid->issuerKeyHash->data, mdlen))

			return 0;

		return 1;

		}

	else

		{

		/* We have to match the whole lot */

		int i, ret;

		OCSP_CERTID *tmpid;

		for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++)

			{

			tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;

			ret = ocsp_match_issuerid(cert, tmpid, NULL);

			if (ret <= 0) return ret;

			}

		return 1;

		}

	}

static int ocsp_check_delegated(X509 *x, int flags)

	{

	X509_check_purpose(x, -1, 0);

	if ((x->ex_flags & EXFLAG_XKUSAGE) &&

	    (x->ex_xkusage & XKU_OCSP_SIGN))

		return 1;

	OCSPerr(OCSP_F_OCSP_CHECK_DELEGATED, OCSP_R_MISSING_OCSPSIGNING_USAGE);

	return 0;

	}

/* Verify an OCSP request. This is fortunately much easier than OCSP

 * response verify. Just find the signers certificate and verify it

 * against a given trust value.

 */

EXPORT_C int OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs, X509_STORE *store, unsigned long flags)

        {

	X509 *signer;

	X509_NAME *nm;

	GENERAL_NAME *gen;

	int ret;

	X509_STORE_CTX ctx;

	if (!req->optionalSignature) 

		{

		OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_REQUEST_NOT_SIGNED);

		return 0;

		}

	gen = req->tbsRequest->requestorName;

	if (!gen || gen->type != GEN_DIRNAME)

		{

		OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);

		return 0;

		}

	nm = gen->d.directoryName;

	ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags);

	if (ret <= 0)

		{

		OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);

		return 0;

		}

	if ((ret == 2) && (flags & OCSP_TRUSTOTHER))

		flags |= OCSP_NOVERIFY;

	if (!(flags & OCSP_NOSIGS))

		{

		EVP_PKEY *skey;

		skey = X509_get_pubkey(signer);

		ret = OCSP_REQUEST_verify(req, skey);

		EVP_PKEY_free(skey);

		if(ret <= 0)

			{

			OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY, OCSP_R_SIGNATURE_FAILURE);

			return 0;

			}

		}

	if (!(flags & OCSP_NOVERIFY))

		{

		int init_res;

		if(flags & OCSP_NOCHAIN)

			init_res = X509_STORE_CTX_init(&ctx, store, signer, NULL);

		else

			init_res = X509_STORE_CTX_init(&ctx, store, signer,

					req->optionalSignature->certs);

		if(!init_res)

			{

			OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,ERR_R_X509_LIB);

			return 0;

			}

		X509_STORE_CTX_set_purpose(&ctx, X509_PURPOSE_OCSP_HELPER);

		X509_STORE_CTX_set_trust(&ctx, X509_TRUST_OCSP_REQUEST);

		ret = X509_verify_cert(&ctx);

		X509_STORE_CTX_cleanup(&ctx);

                if (ret <= 0)

			{

			ret = X509_STORE_CTX_get_error(&ctx);	

			OCSPerr(OCSP_F_OCSP_REQUEST_VERIFY,OCSP_R_CERTIFICATE_VERIFY_ERROR);

			ERR_add_error_data(2, "Verify error:",

					X509_verify_cert_error_string(ret));

                        return 0;

                	}

		}

	return 1;

        }

static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm, STACK_OF(X509) *certs,

				X509_STORE *st, unsigned long flags)

	{

	X509 *signer;

	if(!(flags & OCSP_NOINTERN))

		{

		signer = X509_find_by_subject(req->optionalSignature->certs, nm);

		*psigner = signer;

		return 1;

		}

	signer = X509_find_by_subject(certs, nm);

	if (signer)

		{

		*psigner = signer;

		return 2;

		}

	return 0;

	}