/* ocsp_vfy.c */

/*

 * Written by Dr Stephen N Henson (steve@openssl.org) 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 */

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;

    STACK_OF(X509) *untrusted = 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);

        if (skey) {

            ret = OCSP_BASICRESP_verify(bs, skey, 0);

            EVP_PKEY_free(skey);

        }

        if (!skey || 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) {

            untrusted = NULL;

        } else if (bs->certs && certs) {

            untrusted = sk_X509_dup(bs->certs);

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

                if (!sk_X509_push(untrusted, sk_X509_value(certs, i))) {

                    OCSPerr(OCSP_F_OCSP_BASIC_VERIFY, ERR_R_MALLOC_FAILURE);

                    goto end;

                }

            }

        } else if (certs != NULL) {

            untrusted = certs;

        } else {

            untrusted = bs->certs;

        }

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

        if (!init_res) {

            ret = -1;

            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);

    if (bs->certs && certs)

        sk_X509_free(untrusted);

    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 (mdlen < 0)

            return -1;

        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, dgst, 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.

 */

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);

        if (signer) {

            *psigner = signer;

            return 1;

        }

    }

    signer = X509_find_by_subject(certs, nm);

    if (signer) {

        *psigner = signer;

        return 2;

    }

    return 0;

}