/* $OpenBSD: x509_vfy.c,v 1.153 2026/06/26 06:03:32 tb Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * 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 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 acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS 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 AUTHOR OR 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.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <openssl/opensslconf.h>

#include <openssl/asn1.h>
#include <openssl/buffer.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/lhash.h>
#include <openssl/objects.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>

#include "asn1_local.h"
#include "err_local.h"
#include "x509_internal.h"
#include "x509_issuer_cache.h"
#include "x509_local.h"

/* CRL score values */

/* No unhandled critical extensions */

#define CRL_SCORE_NOCRITICAL    0x100

/* certificate is within CRL scope */

#define CRL_SCORE_SCOPE         0x080

/* CRL times valid */

#define CRL_SCORE_TIME          0x040

/* Issuer name matches certificate */

#define CRL_SCORE_ISSUER_NAME   0x020

/* If this score or above CRL is probably valid */

#define CRL_SCORE_VALID (CRL_SCORE_NOCRITICAL|CRL_SCORE_TIME|CRL_SCORE_SCOPE)

/* CRL issuer is certificate issuer */

#define CRL_SCORE_ISSUER_CERT   0x018

/* CRL issuer is on certificate path */

#define CRL_SCORE_SAME_PATH     0x008

/* CRL issuer matches CRL AKID */

#define CRL_SCORE_AKID          0x004

/* Have a delta CRL with valid times */

#define CRL_SCORE_TIME_DELTA    0x002

static int x509_vfy_check_crl(X509_STORE_CTX *ctx, X509_CRL *crl);
static int x509_vfy_cert_crl(X509_STORE_CTX *ctx, X509_CRL *crl, X509 *x);

static int null_callback(int ok, X509_STORE_CTX *e);
static int check_issued(X509_STORE_CTX *ctx, X509 *subject, X509 *issuer);
static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x,
    int allow_expired);
static int check_name_constraints(X509_STORE_CTX *ctx);
static int check_cert(X509_STORE_CTX *ctx, STACK_OF(X509) *chain, int depth);

static int get_crl_score(X509_STORE_CTX *ctx, X509 **pissuer,
    unsigned int *preasons, X509_CRL *crl, X509 *x);
static int get_crl_delta(X509_STORE_CTX *ctx,
    X509_CRL **pcrl, X509_CRL **pdcrl, X509 *x);
static void get_delta_sk(X509_STORE_CTX *ctx, X509_CRL **dcrl, int *pcrl_score,
    X509_CRL *base, STACK_OF(X509_CRL) *crls);
static void crl_akid_check(X509_STORE_CTX *ctx, X509_CRL *crl, X509 **pissuer,
    int *pcrl_score);
static int crl_crldp_check(X509 *x, X509_CRL *crl, int crl_score,
    unsigned int *preasons);
static int check_crl_path(X509_STORE_CTX *ctx, X509 *x);
static int check_crl_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *cert_path,
    STACK_OF(X509) *crl_path);
static int X509_cmp_time_internal(const ASN1_TIME *ctm, time_t *cmp_time,
    int clamp_notafter);

static int internal_verify(X509_STORE_CTX *ctx);
static int check_key_level(X509_STORE_CTX *ctx, X509 *cert);
static int verify_cb_cert(X509_STORE_CTX *ctx, X509 *x, int depth, int err);

static int
null_callback(int ok, X509_STORE_CTX *e)
{
        return ok;
}

/* Return 1 if a certificate is self signed */
static int
cert_self_signed(X509 *x)
{
        X509_check_purpose(x, -1, 0);
        if (x->ex_flags & EXFLAG_SS)
                return 1;
        else
                return 0;
}

static int
check_id_error(X509_STORE_CTX *ctx, int errcode)
{
        ctx->error = errcode;
        ctx->current_cert = ctx->cert;
        ctx->error_depth = 0;
        return ctx->verify_cb(0, ctx);
}

static int
x509_vfy_check_hosts(X509 *x, X509_VERIFY_PARAM *vpm)
{
        int i, n;
        char *name;

        n = sk_OPENSSL_STRING_num(vpm->hosts);
        free(vpm->peername);
        vpm->peername = NULL;

        for (i = 0; i < n; ++i) {
                name = sk_OPENSSL_STRING_value(vpm->hosts, i);
                if (X509_check_host(x, name, strlen(name), vpm->hostflags,
                    &vpm->peername) > 0)
                        return 1;
        }
        return n == 0;
}

int
x509_vfy_check_id(X509_STORE_CTX *ctx)
{
        X509_VERIFY_PARAM *vpm = ctx->param;
        X509 *x = ctx->cert;

        if (vpm->hosts && x509_vfy_check_hosts(x, vpm) <= 0) {
                if (!check_id_error(ctx, X509_V_ERR_HOSTNAME_MISMATCH))
                        return 0;
        }
        if (vpm->email != NULL && X509_check_email(x, vpm->email, vpm->emaillen, 0)
            <= 0) {
                if (!check_id_error(ctx, X509_V_ERR_EMAIL_MISMATCH))
                        return 0;
        }
        if (vpm->ip != NULL && X509_check_ip(x, vpm->ip, vpm->iplen, 0) <= 0) {
                if (!check_id_error(ctx, X509_V_ERR_IP_ADDRESS_MISMATCH))
                        return 0;
        }
        return 1;
}

/*
 * This is the effectively broken legacy OpenSSL chain builder. It
 * might find an unvalidated chain and leave it sitting in
 * ctx->chain. It does not correctly handle many cases where multiple
 * chains could exist.
 *
 * Oh no.. I know a dirty word...
 * Oooooooh..
 */
static int
X509_verify_cert_legacy_build_chain(X509_STORE_CTX *ctx, int *bad, int *out_ok)
{
        X509 *x, *xtmp, *xtmp2, *chain_ss = NULL;
        int bad_chain = 0;
        X509_VERIFY_PARAM *param = ctx->param;
        int ok = 0, ret = 0;
        int depth, i;
        int num, j, retry, trust;
        int (*cb) (int xok, X509_STORE_CTX *xctx);
        STACK_OF(X509) *sktmp = NULL;

        cb = ctx->verify_cb;

        /*
         * First we make sure the chain we are going to build is
         * present and that the first entry is in place.
         */
        ctx->chain = sk_X509_new_null();
        if (ctx->chain == NULL || !sk_X509_push(ctx->chain, ctx->cert)) {
                X509error(ERR_R_MALLOC_FAILURE);
                ctx->error = X509_V_ERR_OUT_OF_MEM;
                goto end;
        }
        X509_up_ref(ctx->cert);
        ctx->num_untrusted = 1;

        /* We use a temporary STACK so we can chop and hack at it */
        if (ctx->untrusted != NULL &&
            (sktmp = sk_X509_dup(ctx->untrusted)) == NULL) {
                X509error(ERR_R_MALLOC_FAILURE);
                ctx->error = X509_V_ERR_OUT_OF_MEM;
                goto end;
        }

        num = sk_X509_num(ctx->chain);
        x = sk_X509_value(ctx->chain, num - 1);
        depth = param->depth;

        for (;;) {
                /* If we have enough, we break */
                /* FIXME: If this happens, we should take
                 * note of it and, if appropriate, use the
                 * X509_V_ERR_CERT_CHAIN_TOO_LONG error code
                 * later.
                 */
                if (depth < num)
                        break;
                /* If we are self signed, we break */
                if (cert_self_signed(x))
                        break;
                /*
                 * If asked see if we can find issuer in trusted store first
                 */
                if (ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST) {
                        ok = ctx->get_issuer(&xtmp, ctx, x);
                        if (ok < 0) {
                                ctx->error = X509_V_ERR_STORE_LOOKUP;
                                goto end;
                        }
                        /*
                         * If successful for now free up cert so it
                         * will be picked up again later.
                         */
                        if (ok > 0) {
                                X509_free(xtmp);
                                break;
                        }
                }
                /* If we were passed a cert chain, use it first */
                if (ctx->untrusted != NULL) {
                        /*
                         * If we do not find a non-expired untrusted cert, peek
                         * ahead and see if we can satisfy this from the trusted
                         * store. If not, see if we have an expired untrusted cert.
                         */
                        xtmp = find_issuer(ctx, sktmp, x, 0);
                        if (xtmp == NULL &&
                            !(ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST)) {
                                ok = ctx->get_issuer(&xtmp, ctx, x);
                                if (ok < 0) {
                                        ctx->error = X509_V_ERR_STORE_LOOKUP;
                                        goto end;
                                }
                                if (ok > 0) {
                                        X509_free(xtmp);
                                        break;
                                }
                                xtmp = find_issuer(ctx, sktmp, x, 1);
                        }
                        if (xtmp != NULL) {
                                if (!sk_X509_push(ctx->chain, xtmp)) {
                                        X509error(ERR_R_MALLOC_FAILURE);
                                        ctx->error = X509_V_ERR_OUT_OF_MEM;
                                        ok = 0;
                                        goto end;
                                }
                                X509_up_ref(xtmp);
                                (void)sk_X509_delete_ptr(sktmp, xtmp);
                                ctx->num_untrusted++;
                                x = xtmp;
                                num++;
                                /*
                                 * reparse the full chain for the next one
                                 */
                                continue;
                        }
                }
                break;
        }
        /* Remember how many untrusted certs we have */
        j = num;

        /*
         * At this point, chain should contain a list of untrusted
         * certificates.  We now need to add at least one trusted one,
         * if possible, otherwise we complain.
         */

        do {
                /*
                 * Examine last certificate in chain and see if it is
                 * self signed.
                 */
                i = sk_X509_num(ctx->chain);
                x = sk_X509_value(ctx->chain, i - 1);
                if (cert_self_signed(x)) {
                        /* we have a self signed certificate */
                        if (i == 1) {
                                /*
                                 * We have a single self signed
                                 * certificate: see if we can find it
                                 * in the store. We must have an exact
                                 * match to avoid possible
                                 * impersonation.
                                 */
                                ok = ctx->get_issuer(&xtmp, ctx, x);
                                if ((ok <= 0) || X509_cmp(x, xtmp)) {
                                        ctx->error = X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT;
                                        ctx->current_cert = x;
                                        ctx->error_depth = i - 1;
                                        if (ok == 1)
                                                X509_free(xtmp);
                                        bad_chain = 1;
                                        ok = cb(0, ctx);
                                        if (!ok)
                                                goto end;
                                } else {
                                        /*
                                         * We have a match: replace
                                         * certificate with store
                                         * version so we get any trust
                                         * settings.
                                         */
                                        X509_free(x);
                                        x = xtmp;
                                        (void)sk_X509_set(ctx->chain, i - 1, x);
                                        ctx->num_untrusted = 0;
                                }
                        } else {
                                /*
                                 * extract and save self signed
                                 * certificate for later use
                                 */
                                chain_ss = sk_X509_pop(ctx->chain);
                                ctx->num_untrusted--;
                                num--;
                                j--;
                                x = sk_X509_value(ctx->chain, num - 1);
                        }
                }
                /* We now lookup certs from the certificate store */
                for (;;) {
                        /* If we have enough, we break */
                        if (depth < num)
                                break;
                        /* If we are self signed, we break */
                        if (cert_self_signed(x))
                                break;
                        ok = ctx->get_issuer(&xtmp, ctx, x);

                        if (ok < 0) {
                                ctx->error = X509_V_ERR_STORE_LOOKUP;
                                goto end;
                        }
                        if (ok == 0)
                                break;
                        x = xtmp;
                        if (!sk_X509_push(ctx->chain, x)) {
                                X509_free(xtmp);
                                X509error(ERR_R_MALLOC_FAILURE);
                                ctx->error = X509_V_ERR_OUT_OF_MEM;
                                ok = 0;
                                goto end;
                        }
                        num++;
                }

                /* we now have our chain, lets check it... */
                trust = x509_vfy_check_trust(ctx);

                /* If explicitly rejected error */
                if (trust == X509_TRUST_REJECTED) {
                        ok = 0;
                        goto end;
                }
                /*
                 * If it's not explicitly trusted then check if there
                 * is an alternative chain that could be used. We only
                 * do this if we haven't already checked via
                 * TRUSTED_FIRST and the user hasn't switched off
                 * alternate chain checking
                 */
                retry = 0;
                if (trust != X509_TRUST_TRUSTED &&
                    !(ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST) &&
                    !(ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS)) {
                        while (j-- > 1) {
                                xtmp2 = sk_X509_value(ctx->chain, j - 1);
                                ok = ctx->get_issuer(&xtmp, ctx, xtmp2);
                                if (ok < 0)
                                        goto end;
                                /* Check if we found an alternate chain */
                                if (ok > 0) {
                                        /*
                                         * Free up the found cert
                                         * we'll add it again later
                                         */
                                        X509_free(xtmp);
                                        /*
                                         * Dump all the certs above
                                         * this point - we've found an
                                         * alternate chain
                                         */
                                        while (num > j) {
                                                xtmp = sk_X509_pop(ctx->chain);
                                                X509_free(xtmp);
                                                num--;
                                        }
                                        ctx->num_untrusted = sk_X509_num(ctx->chain);
                                        retry = 1;
                                        break;
                                }
                        }
                }
        } while (retry);

        /*
         * If not explicitly trusted then indicate error unless it's a single
         * self signed certificate in which case we've indicated an error already
         * and set bad_chain == 1
         */
        if (trust != X509_TRUST_TRUSTED && !bad_chain) {
                if ((chain_ss == NULL) || !ctx->check_issued(ctx, x, chain_ss)) {
                        if (ctx->num_untrusted >= num)
                                ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY;
                        else
                                ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT;
                        ctx->current_cert = x;
                } else {
                        if (!sk_X509_push(ctx->chain, chain_ss)) {
                                X509error(ERR_R_MALLOC_FAILURE);
                                ctx->error = X509_V_ERR_OUT_OF_MEM;
                                ok = 0;
                                goto end;
                        }
                        num++;
                        ctx->num_untrusted = num;
                        ctx->current_cert = chain_ss;
                        ctx->error = X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN;
                        chain_ss = NULL;
                }

                ctx->error_depth = num - 1;
                bad_chain = 1;
                ok = cb(0, ctx);
                if (!ok)
                        goto end;
        }

        ret = 1;
 end:
        sk_X509_free(sktmp);
        X509_free(chain_ss);
        *bad = bad_chain;
        *out_ok = ok;

        return ret;
}

static int
X509_verify_cert_legacy(X509_STORE_CTX *ctx)
{
        int ok = 0, bad_chain;

        ctx->error = X509_V_OK; /* Initialize to OK */

        if (!X509_verify_cert_legacy_build_chain(ctx, &bad_chain, &ok))
                goto end;

        /* We have the chain complete: now we need to check its purpose */
        ok = x509_vfy_check_chain_extensions(ctx);
        if (!ok)
                goto end;

        /* Check that the chain satisfies the security level. */
        ok = x509_vfy_check_security_level(ctx);
        if (!ok)
                goto end;

        /* Check name constraints */
        ok = check_name_constraints(ctx);
        if (!ok)
                goto end;

#ifndef OPENSSL_NO_RFC3779
        ok = X509v3_asid_validate_path(ctx);
        if (!ok)
                goto end;

        ok = X509v3_addr_validate_path(ctx);
        if (!ok)
                goto end;
#endif

        ok = x509_vfy_check_id(ctx);
        if (!ok)
                goto end;

        /*
         * Check revocation status: we do this after copying parameters because
         * they may be needed for CRL signature verification.
         */
        ok = x509_vfy_check_revocation(ctx);
        if (!ok)
                goto end;

        /* At this point, we have a chain and need to verify it */
        if (ctx->verify != NULL)
                ok = ctx->verify(ctx);
        else
                ok = internal_verify(ctx);
        if (!ok)
                goto end;

        /* If we get this far evaluate policies */
        if (!bad_chain)
                ok = x509_vfy_check_policy(ctx);

 end:
        /* Safety net, error returns must set ctx->error */
        if (ok <= 0 && ctx->error == X509_V_OK)
                ctx->error = X509_V_ERR_UNSPECIFIED;

        return ok;
}

int
X509_verify_cert(X509_STORE_CTX *ctx)
{
        struct x509_verify_ctx *vctx = NULL;
        int chain_count = 0;

        if (ctx->cert == NULL) {
                X509error(X509_R_NO_CERT_SET_FOR_US_TO_VERIFY);
                ctx->error = X509_V_ERR_INVALID_CALL;
                return -1;
        }
        if (ctx->chain != NULL) {
                /*
                 * This X509_STORE_CTX has already been used to verify
                 * a cert. We cannot do another one.
                 */
                X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
                ctx->error = X509_V_ERR_INVALID_CALL;
                return -1;
        }
        if (ctx->param->poisoned) {
                /*
                 * This X509_STORE_CTX had failures setting
                 * up verify parameters. We can not use it.
                 */
                X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
                ctx->error = X509_V_ERR_INVALID_CALL;
                return -1;
        }
        if (ctx->error != X509_V_ERR_INVALID_CALL) {
                /*
                 * This X509_STORE_CTX has not been properly initialized.
                 */
                X509error(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
                ctx->error = X509_V_ERR_INVALID_CALL;
                return -1;
        }

        /*
         * If the certificate's public key is too weak, don't bother
         * continuing.
         */
        if (!check_key_level(ctx, ctx->cert) &&
            !verify_cb_cert(ctx, ctx->cert, 0, X509_V_ERR_EE_KEY_TOO_SMALL))
                return 0;

        /*
         * If flags request legacy, use the legacy verifier. If we
         * requested "no alt chains" from the age of hammer pants, use
         * the legacy verifier because the multi chain verifier really
         * does find all the "alt chains".
         *
         * XXX deprecate the NO_ALT_CHAINS flag?
         */
        if ((ctx->param->flags & X509_V_FLAG_LEGACY_VERIFY) ||
            (ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS))
                return X509_verify_cert_legacy(ctx);

        /* Use the modern multi-chain verifier from x509_verify_cert */

        if ((vctx = x509_verify_ctx_new_from_xsc(ctx)) != NULL) {
                ctx->error = X509_V_OK; /* Initialize to OK */
                chain_count = x509_verify(vctx, NULL, NULL);
        }
        x509_verify_ctx_free(vctx);

        /* if we succeed we have a chain in ctx->chain */
        return chain_count > 0 && ctx->chain != NULL;
}
LCRYPTO_ALIAS(X509_verify_cert);

/* Given a STACK_OF(X509) find the issuer of cert (if any)
 */

static X509 *
find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x,
    int allow_expired)
{
        int i;
        X509 *issuer, *rv = NULL;

        for (i = 0; i < sk_X509_num(sk); i++) {
                issuer = sk_X509_value(sk, i);
                if (ctx->check_issued(ctx, x, issuer)) {
                        if (x509_check_cert_time(ctx, issuer, -1))
                                return issuer;
                        if (allow_expired)
                                rv = issuer;
                }
        }
        return rv;
}

/* Given a possible certificate and issuer check them */

static int
check_issued(X509_STORE_CTX *ctx, X509 *subject, X509 *issuer)
{
        /*
         * Yes, the arguments of X509_STORE_CTX_check_issued_fn were exposed in
         * reverse order compared to the already public X509_check_issued()...
         */
        return X509_check_issued(issuer, subject) == X509_V_OK;
}

/* Alternative lookup method: look from a STACK stored in ctx->trusted */

static int
x509_vfy_get_trusted_issuer(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
{
        *issuer = find_issuer(ctx, ctx->trusted, x, 1);
        if (*issuer) {
                CRYPTO_add(&(*issuer)->references, 1, CRYPTO_LOCK_X509);
                return 1;
        } else
                return 0;
}

/* Check a certificate chains extensions for consistency
 * with the supplied purpose
 */

int
x509_vfy_check_chain_extensions(X509_STORE_CTX *ctx)
{
        int i, ok = 0, must_be_ca, plen = 0;
        X509 *x;
        int (*cb)(int xok, X509_STORE_CTX *xctx);
        int proxy_path_length = 0;
        int purpose;

        cb = ctx->verify_cb;

        /* must_be_ca can have 1 of 3 values:
           -1: we accept both CA and non-CA certificates, to allow direct
               use of self-signed certificates (which are marked as CA).
           0:  we only accept non-CA certificates.  This is currently not
               used, but the possibility is present for future extensions.
           1:  we only accept CA certificates.  This is currently used for
               all certificates in the chain except the leaf certificate.
        */
        must_be_ca = -1;

        /* CRL path validation */
        if (ctx->parent)
                purpose = X509_PURPOSE_CRL_SIGN;
        else
                purpose = ctx->param->purpose;

        /* Check all untrusted certificates */
        for (i = 0; i < ctx->num_untrusted; i++) {
                int ret;
                x = sk_X509_value(ctx->chain, i);
                if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL) &&
                    (x->ex_flags & EXFLAG_CRITICAL)) {
                        ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;
                        ctx->error_depth = i;
                        ctx->current_cert = x;
                        ok = cb(0, ctx);
                        if (!ok)
                                goto end;
                }
                ret = X509_check_ca(x);
                if (must_be_ca == -1) {
                        if ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
                            (ret != 1) && (ret != 0)) {
                                ret = 0;
                                ctx->error = X509_V_ERR_INVALID_CA;
                        } else
                                ret = 1;
                } else {
                        if ((ret == 0) ||
                            ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
                            (ret != 1))) {
                                ret = 0;
                                ctx->error = X509_V_ERR_INVALID_CA;
                        } else
                                ret = 1;
                }
                if (ret == 0) {
                        ctx->error_depth = i;
                        ctx->current_cert = x;
                        ok = cb(0, ctx);
                        if (!ok)
                                goto end;
                }
                if (ctx->param->purpose > 0) {
                        ret = X509_check_purpose(x, purpose, must_be_ca > 0);
                        if ((ret == 0) ||
                            ((ctx->param->flags & X509_V_FLAG_X509_STRICT) &&
                            (ret != 1))) {
                                ctx->error = X509_V_ERR_INVALID_PURPOSE;
                                ctx->error_depth = i;
                                ctx->current_cert = x;
                                ok = cb(0, ctx);
                                if (!ok)
                                        goto end;
                        }
                }
                /* Check pathlen if not self issued */
                if ((i > 1) && !(x->ex_flags & EXFLAG_SI) &&
                    (x->ex_pathlen != -1) &&
                    (plen > (x->ex_pathlen + proxy_path_length + 1))) {
                        ctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;
                        ctx->error_depth = i;
                        ctx->current_cert = x;
                        ok = cb(0, ctx);
                        if (!ok)
                                goto end;
                }
                /* Increment path length if not self issued */
                if (!(x->ex_flags & EXFLAG_SI))
                        plen++;
                must_be_ca = 1;
        }

        ok = 1;

 end:
        return ok;
}

static int
check_name_constraints(X509_STORE_CTX *ctx)
{
        if (!x509_constraints_chain(ctx->chain, &ctx->error,
            &ctx->error_depth)) {
                ctx->current_cert = sk_X509_value(ctx->chain, ctx->error_depth);
                if (!ctx->verify_cb(0, ctx))
                        return 0;
        }
        return 1;
}

/* Given a certificate try and find an exact match in the store */

static X509 *
lookup_cert_match(X509_STORE_CTX *ctx, X509 *x)
{
        STACK_OF(X509) *certs;
        X509 *xtmp = NULL;
        size_t i;

        /* Lookup all certs with matching subject name */
        certs = X509_STORE_CTX_get1_certs(ctx, X509_get_subject_name(x));
        if (certs == NULL)
                return NULL;

        /* Look for exact match */
        for (i = 0; i < sk_X509_num(certs); i++) {
                xtmp = sk_X509_value(certs, i);
                if (!X509_cmp(xtmp, x))
                        break;
        }

        if (i < sk_X509_num(certs))
                X509_up_ref(xtmp);
        else
                xtmp = NULL;

        sk_X509_pop_free(certs, X509_free);
        return xtmp;
}

X509 *
x509_vfy_lookup_cert_match(X509_STORE_CTX *ctx, X509 *x)
{
        if (ctx->store == NULL || ctx->store->objs == NULL)
                return NULL;
        return lookup_cert_match(ctx, x);
}

int
x509_vfy_check_trust(X509_STORE_CTX *ctx)
{
        size_t i;
        int ok;
        X509 *x = NULL;
        int (*cb) (int xok, X509_STORE_CTX *xctx);

        cb = ctx->verify_cb;
        /* Check all trusted certificates in chain */
        for (i = ctx->num_untrusted; i < sk_X509_num(ctx->chain); i++) {
                x = sk_X509_value(ctx->chain, i);
                ok = X509_check_trust(x, ctx->param->trust, 0);

                /* If explicitly trusted return trusted */
                if (ok == X509_TRUST_TRUSTED)
                        return X509_TRUST_TRUSTED;
                /*
                 * If explicitly rejected notify callback and reject if not
                 * overridden.
                 */
                if (ok == X509_TRUST_REJECTED) {
                        ctx->error_depth = i;
                        ctx->current_cert = x;
                        ctx->error = X509_V_ERR_CERT_REJECTED;
                        ok = cb(0, ctx);
                        if (!ok)
                                return X509_TRUST_REJECTED;
                }
        }
        /*
         * If we accept partial chains and have at least one trusted certificate
         * return success.
         */
        if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN) {
                X509 *mx;
                if (ctx->num_untrusted < (int)sk_X509_num(ctx->chain))
                        return X509_TRUST_TRUSTED;
                x = sk_X509_value(ctx->chain, 0);
                mx = lookup_cert_match(ctx, x);
                if (mx) {
                        (void)sk_X509_set(ctx->chain, 0, mx);
                        X509_free(x);
                        ctx->num_untrusted = 0;
                        return X509_TRUST_TRUSTED;
                }
        }

        /*
         * If no trusted certs in chain at all return untrusted and allow
         * standard (no issuer cert) etc errors to be indicated.
         */
        return X509_TRUST_UNTRUSTED;
}

int
x509_vfy_check_revocation(X509_STORE_CTX *ctx)
{
        int i, last, ok;

        if (!(ctx->param->flags & X509_V_FLAG_CRL_CHECK))
                return 1;
        if (ctx->param->flags & X509_V_FLAG_CRL_CHECK_ALL)
                last = sk_X509_num(ctx->chain) - 1;
        else {
                /* If checking CRL paths this isn't the EE certificate */
                if (ctx->parent)
                        return 1;
                last = 0;
        }
        for (i = 0; i <= last; i++) {
                ok = check_cert(ctx, ctx->chain, i);
                if (!ok)
                        return ok;
        }
        return 1;
}

static int
check_cert(X509_STORE_CTX *ctx, STACK_OF(X509) *chain, int depth)
{
        X509_CRL *crl = NULL, *dcrl = NULL;
        X509 *x;
        int ok = 0, cnum;
        unsigned int last_reasons;

        cnum = ctx->error_depth = depth;
        x = sk_X509_value(chain, cnum);
        ctx->current_cert = x;
        ctx->current_issuer = NULL;
        ctx->current_crl_score = 0;
        ctx->current_reasons = 0;
        while (ctx->current_reasons != CRLDP_ALL_REASONS) {
                last_reasons = ctx->current_reasons;
                /* Try to retrieve relevant CRL */
                ok = get_crl_delta(ctx, &crl, &dcrl, x);
                if (!ok) {
                        ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
                        ok = ctx->verify_cb(0, ctx);
                        goto err;
                }
                ctx->current_crl = crl;
                ok = x509_vfy_check_crl(ctx, crl);
                if (!ok)
                        goto err;

                if (dcrl) {
                        ok = x509_vfy_check_crl(ctx, dcrl);
                        if (!ok)
                                goto err;
                        ok = x509_vfy_cert_crl(ctx, dcrl, x);
                        if (!ok)
                                goto err;
                } else
                        ok = 1;

                /* Don't look in full CRL if delta reason is removefromCRL */
                if (ok != 2) {
                        ok = x509_vfy_cert_crl(ctx, crl, x);
                        if (!ok)
                                goto err;
                }

                ctx->current_crl = NULL;
                X509_CRL_free(crl);
                X509_CRL_free(dcrl);
                crl = NULL;
                dcrl = NULL;
                /* If reasons not updated we wont get anywhere by
                 * another iteration, so exit loop.
                 */
                if (last_reasons == ctx->current_reasons) {
                        ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
                        ok = ctx->verify_cb(0, ctx);
                        goto err;
                }
        }

err:
        ctx->current_crl = NULL;
        X509_CRL_free(crl);
        X509_CRL_free(dcrl);
        return ok;
}

/* Check CRL times against values in X509_STORE_CTX */

static int
check_crl_time(X509_STORE_CTX *ctx, X509_CRL *crl, int notify)
{
        time_t *ptime;
        int i;

        if (notify)
                ctx->current_crl = crl;
        if (ctx->param->flags & X509_V_FLAG_USE_CHECK_TIME)
                ptime = &ctx->param->check_time;
        else if (ctx->param->flags & X509_V_FLAG_NO_CHECK_TIME)
                return 1;
        else
                ptime = NULL;

        i = X509_cmp_time(X509_CRL_get_lastUpdate(crl), ptime);
        if (i == 0) {
                if (!notify)
                        return 0;
                ctx->error = X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD;
                if (!ctx->verify_cb(0, ctx))
                        return 0;
        }

        if (i > 0) {
                if (!notify)
                        return 0;
                ctx->error = X509_V_ERR_CRL_NOT_YET_VALID;
                if (!ctx->verify_cb(0, ctx))
                        return 0;
        }

        if (X509_CRL_get_nextUpdate(crl)) {
                i = X509_cmp_time(X509_CRL_get_nextUpdate(crl), ptime);

                if (i == 0) {
                        if (!notify)
                                return 0;
                        ctx->error = X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD;
                        if (!ctx->verify_cb(0, ctx))
                                return 0;
                }
                /* Ignore expiry of base CRL is delta is valid */
                if ((i < 0) &&
                    !(ctx->current_crl_score & CRL_SCORE_TIME_DELTA)) {
                        if (!notify)
                                return 0;
                        ctx->error = X509_V_ERR_CRL_HAS_EXPIRED;
                        if (!ctx->verify_cb(0, ctx))
                                return 0;
                }
        }

        if (notify)
                ctx->current_crl = NULL;

        return 1;
}

static int
get_crl_sk(X509_STORE_CTX *ctx, X509_CRL **pcrl, X509_CRL **pdcrl,
    X509 **pissuer, int *pscore, unsigned int *preasons,
    STACK_OF(X509_CRL) *crls)
{
        int i, crl_score, best_score = *pscore;
        unsigned int reasons, best_reasons = 0;
        X509 *x = ctx->current_cert;
        X509_CRL *crl, *best_crl = NULL;
        X509 *crl_issuer = NULL, *best_crl_issuer = NULL;

        for (i = 0; i < sk_X509_CRL_num(crls); i++) {
                crl = sk_X509_CRL_value(crls, i);
                reasons = *preasons;
                crl_score = get_crl_score(ctx, &crl_issuer, &reasons, crl, x);

                if (crl_score < best_score || crl_score == 0)
                        continue;

                if (crl_score == best_score && best_crl != NULL) {
                        int day, sec;

                        if (!ASN1_TIME_diff(&day, &sec, best_crl->crl->lastUpdate,
                            crl->crl->lastUpdate))
                                continue;

                        if (day <= 0 && sec <= 0)
                                continue;
                }

                best_crl = crl;
                best_crl_issuer = crl_issuer;
                best_score = crl_score;
                best_reasons = reasons;
        }

        if (best_crl != NULL) {
                X509_CRL_free(*pcrl);
                *pcrl = best_crl;
                *pissuer = best_crl_issuer;
                *pscore = best_score;
                *preasons = best_reasons;
                CRYPTO_add(&best_crl->references, 1, CRYPTO_LOCK_X509_CRL);
                X509_CRL_free(*pdcrl);
                *pdcrl = NULL;
                get_delta_sk(ctx, pdcrl, pscore, best_crl, crls);
        }

        if (best_score >= CRL_SCORE_VALID)
                return 1;

        return 0;
}

/* Compare two CRL extensions for delta checking purposes. They should be
 * both present or both absent. If both present all fields must be identical.
 */

static int
crl_extension_match(X509_CRL *a, X509_CRL *b, int nid)
{
        ASN1_OCTET_STRING *exta, *extb;
        int i;

        i = X509_CRL_get_ext_by_NID(a, nid, -1);
        if (i >= 0) {
                /* Can't have multiple occurrences */
                if (X509_CRL_get_ext_by_NID(a, nid, i) != -1)
                        return 0;
                exta = X509_EXTENSION_get_data(X509_CRL_get_ext(a, i));
        } else
                exta = NULL;

        i = X509_CRL_get_ext_by_NID(b, nid, -1);

        if (i >= 0) {
                if (X509_CRL_get_ext_by_NID(b, nid, i) != -1)
                        return 0;
                extb = X509_EXTENSION_get_data(X509_CRL_get_ext(b, i));
        } else
                extb = NULL;

        if (!exta && !extb)
                return 1;

        if (!exta || !extb)
                return 0;

        if (ASN1_OCTET_STRING_cmp(exta, extb))
                return 0;

        return 1;
}

/* See if a base and delta are compatible */

static int
check_delta_base(X509_CRL *delta, X509_CRL *base)
{
        /*
         * Delta CRL must be a delta and have a CRL number.
         * XXX - This means EXFLAG_INVALID was set by crl_cb(),
         * which we should check somewhere and bail out.
         */
        if (delta->base_crl_number == NULL || delta->crl_number == NULL)
                return 0;
        /* Base must have a CRL number */
        if (base->crl_number == NULL)
                return 0;
        /* Issuer names must match */
        if (X509_NAME_cmp(X509_CRL_get_issuer(base),
            X509_CRL_get_issuer(delta)))
                return 0;
        /* AKID and IDP must match */
        if (!crl_extension_match(delta, base, NID_authority_key_identifier))
                return 0;
        if (!crl_extension_match(delta, base, NID_issuing_distribution_point))
                return 0;
        /* Delta CRL base number must not exceed Full CRL number. */
        if (ASN1_INTEGER_cmp(delta->base_crl_number, base->crl_number) > 0)
                return 0;
        /* Delta CRL number must exceed full CRL number */
        if (ASN1_INTEGER_cmp(delta->crl_number, base->crl_number) > 0)
                return 1;
        return 0;
}

/* For a given base CRL find a delta... maybe extend to delta scoring
 * or retrieve a chain of deltas...
 */

static void
get_delta_sk(X509_STORE_CTX *ctx, X509_CRL **dcrl, int *pscore, X509_CRL *base,
    STACK_OF(X509_CRL) *crls)
{
        X509_CRL *delta;
        int i;

        if (!(ctx->param->flags & X509_V_FLAG_USE_DELTAS))
                return;
        if (!((ctx->current_cert->ex_flags | base->flags) & EXFLAG_FRESHEST))
                return;
        for (i = 0; i < sk_X509_CRL_num(crls); i++) {
                delta = sk_X509_CRL_value(crls, i);
                if (check_delta_base(delta, base)) {
                        if (check_crl_time(ctx, delta, 0))
                                *pscore |= CRL_SCORE_TIME_DELTA;
                        CRYPTO_add(&delta->references, 1, CRYPTO_LOCK_X509_CRL);
                        *dcrl = delta;
                        return;
                }
        }
        *dcrl = NULL;
}

/* For a given CRL return how suitable it is for the supplied certificate 'x'.
 * The return value is a mask of several criteria.
 * If the issuer is not the certificate issuer this is returned in *pissuer.
 * The reasons mask is also used to determine if the CRL is suitable: if
 * no new reasons the CRL is rejected, otherwise reasons is updated.
 */

static int
get_crl_score(X509_STORE_CTX *ctx, X509 **pissuer, unsigned int *preasons,
    X509_CRL *crl, X509 *x)
{
        int crl_score = 0;
        unsigned int tmp_reasons = *preasons, crl_reasons;

        /* First see if we can reject CRL straight away */

        /* Invalid IDP cannot be processed */
        if (crl->idp_flags & IDP_INVALID)
                return 0;
        /* Reason codes or indirect CRLs need extended CRL support */
        if (!(ctx->param->flags & X509_V_FLAG_EXTENDED_CRL_SUPPORT)) {
                if (crl->idp_flags & (IDP_INDIRECT | IDP_REASONS))
                        return 0;
        } else if (crl->idp_flags & IDP_REASONS) {
                /* If no new reasons reject */
                if (!(crl->idp_reasons & ~tmp_reasons))
                        return 0;
        }
        /* Don't process deltas at this stage */
        else if (crl->base_crl_number)
                return 0;
        /* If issuer name doesn't match certificate need indirect CRL */
        if (X509_NAME_cmp(X509_get_issuer_name(x), X509_CRL_get_issuer(crl))) {
                if (!(crl->idp_flags & IDP_INDIRECT))
                        return 0;
        } else
                crl_score |= CRL_SCORE_ISSUER_NAME;

        if (!(crl->flags & EXFLAG_CRITICAL))
                crl_score |= CRL_SCORE_NOCRITICAL;

        /* Check expiry */
        if (check_crl_time(ctx, crl, 0))
                crl_score |= CRL_SCORE_TIME;

        /* Check authority key ID and locate certificate issuer */
        crl_akid_check(ctx, crl, pissuer, &crl_score);

        /* If we can't locate certificate issuer at this point forget it */

        if (!(crl_score & CRL_SCORE_AKID))
                return 0;

        /* Check cert for matching CRL distribution points */

        if (crl_crldp_check(x, crl, crl_score, &crl_reasons)) {
                /* If no new reasons reject */
                if (!(crl_reasons & ~tmp_reasons))
                        return 0;
                tmp_reasons |= crl_reasons;
                crl_score |= CRL_SCORE_SCOPE;
        }

        *preasons = tmp_reasons;

        return crl_score;
}

static void
crl_akid_check(X509_STORE_CTX *ctx, X509_CRL *crl, X509 **pissuer,
    int *pcrl_score)
{
        X509 *crl_issuer = NULL;
        X509_NAME *cnm = X509_CRL_get_issuer(crl);
        int cidx = ctx->error_depth;
        int i;

        if (cidx != sk_X509_num(ctx->chain) - 1)
                cidx++;

        crl_issuer = sk_X509_value(ctx->chain, cidx);

        if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
                if (*pcrl_score & CRL_SCORE_ISSUER_NAME) {
                        *pcrl_score |= CRL_SCORE_AKID|CRL_SCORE_ISSUER_CERT;
                        *pissuer = crl_issuer;
                        return;
                }
        }

        for (cidx++; cidx < sk_X509_num(ctx->chain); cidx++) {
                crl_issuer = sk_X509_value(ctx->chain, cidx);
                if (X509_NAME_cmp(X509_get_subject_name(crl_issuer), cnm))
                        continue;
                if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
                        *pcrl_score |= CRL_SCORE_AKID|CRL_SCORE_SAME_PATH;
                        *pissuer = crl_issuer;
                        return;
                }
        }

        /* Anything else needs extended CRL support */

        if (!(ctx->param->flags & X509_V_FLAG_EXTENDED_CRL_SUPPORT))
                return;

        /* Otherwise the CRL issuer is not on the path. Look for it in the
         * set of untrusted certificates.
         */
        for (i = 0; i < sk_X509_num(ctx->untrusted); i++) {
                crl_issuer = sk_X509_value(ctx->untrusted, i);
                if (X509_NAME_cmp(X509_get_subject_name(crl_issuer), cnm))
                        continue;
                if (X509_check_akid(crl_issuer, crl->akid) == X509_V_OK) {
                        *pissuer = crl_issuer;
                        *pcrl_score |= CRL_SCORE_AKID;
                        return;
                }
        }
}

/* Check the path of a CRL issuer certificate. This creates a new
 * X509_STORE_CTX and populates it with most of the parameters from the
 * parent. This could be optimised somewhat since a lot of path checking
 * will be duplicated by the parent, but this will rarely be used in
 * practice.
 */

static int
check_crl_path(X509_STORE_CTX *ctx, X509 *x)
{
        X509_STORE_CTX crl_ctx;
        int ret;

        /* Don't allow recursive CRL path validation */
        if (ctx->parent)
                return 0;
        if (!X509_STORE_CTX_init(&crl_ctx, ctx->store, x, ctx->untrusted)) {
                ret = -1;
                goto err;
        }

        crl_ctx.crls = ctx->crls;
        /* Copy verify params across */
        X509_STORE_CTX_set0_param(&crl_ctx, ctx->param);

        crl_ctx.parent = ctx;
        crl_ctx.verify_cb = ctx->verify_cb;

        /* Verify CRL issuer */
        ret = X509_verify_cert(&crl_ctx);

        if (ret <= 0)
                goto err;

        /* Check chain is acceptable */
        ret = check_crl_chain(ctx, ctx->chain, crl_ctx.chain);

err:
        X509_STORE_CTX_cleanup(&crl_ctx);
        return ret;
}

/* RFC3280 says nothing about the relationship between CRL path
 * and certificate path, which could lead to situations where a
 * certificate could be revoked or validated by a CA not authorised
 * to do so. RFC5280 is more strict and states that the two paths must
 * end in the same trust anchor, though some discussions remain...
 * until this is resolved we use the RFC5280 version
 */

static int
check_crl_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *cert_path,
    STACK_OF(X509) *crl_path)
{
        X509 *cert_ta, *crl_ta;

        cert_ta = sk_X509_value(cert_path, sk_X509_num(cert_path) - 1);
        crl_ta = sk_X509_value(crl_path, sk_X509_num(crl_path) - 1);
        if (!X509_cmp(cert_ta, crl_ta))
                return 1;
        return 0;
}

/* Check for match between two dist point names: three separate cases.
 * 1. Both are relative names and compare X509_NAME types.
 * 2. One full, one relative. Compare X509_NAME to GENERAL_NAMES.
 * 3. Both are full names and compare two GENERAL_NAMES.
 * 4. One is NULL: automatic match.
 */

static int
idp_check_dp(DIST_POINT_NAME *a, DIST_POINT_NAME *b)
{
        X509_NAME *nm = NULL;
        GENERAL_NAMES *gens = NULL;
        GENERAL_NAME *gena, *genb;
        int i, j;

        if (!a || !b)
                return 1;
        if (a->type == 1) {
                if (!a->dpname)
                        return 0;
                /* Case 1: two X509_NAME */
                if (b->type == 1) {
                        if (!b->dpname)
                                return 0;
                        if (!X509_NAME_cmp(a->dpname, b->dpname))
                                return 1;
                        else
                                return 0;
                }
                /* Case 2: set name and GENERAL_NAMES appropriately */
                nm = a->dpname;
                gens = b->name.fullname;
        } else if (b->type == 1) {
                if (!b->dpname)
                        return 0;
                /* Case 2: set name and GENERAL_NAMES appropriately */
                gens = a->name.fullname;
                nm = b->dpname;
        }

        /* Handle case 2 with one GENERAL_NAMES and one X509_NAME */
        if (nm) {
                for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
                        gena = sk_GENERAL_NAME_value(gens, i);
                        if (gena->type != GEN_DIRNAME)
                                continue;
                        if (!X509_NAME_cmp(nm, gena->d.directoryName))
                                return 1;
                }
                return 0;
        }

        /* Else case 3: two GENERAL_NAMES */

        for (i = 0; i < sk_GENERAL_NAME_num(a->name.fullname); i++) {
                gena = sk_GENERAL_NAME_value(a->name.fullname, i);
                for (j = 0; j < sk_GENERAL_NAME_num(b->name.fullname); j++) {
                        genb = sk_GENERAL_NAME_value(b->name.fullname, j);
                        if (!GENERAL_NAME_cmp(gena, genb))
                                return 1;
                }
        }

        return 0;
}

static int
crldp_check_crlissuer(DIST_POINT *dp, X509_CRL *crl, int crl_score)
{
        int i;
        X509_NAME *nm = X509_CRL_get_issuer(crl);

        /* If no CRLissuer return is successful iff don't need a match */
        if (!dp->CRLissuer)
                return !!(crl_score & CRL_SCORE_ISSUER_NAME);
        for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
                GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
                if (gen->type != GEN_DIRNAME)
                        continue;
                if (!X509_NAME_cmp(gen->d.directoryName, nm))
                        return 1;
        }
        return 0;
}

/* Check CRLDP and IDP */

static int
crl_crldp_check(X509 *x, X509_CRL *crl, int crl_score, unsigned int *preasons)
{
        int i;

        if (crl->idp_flags & IDP_ONLYATTR)
                return 0;
        if (x->ex_flags & EXFLAG_CA) {
                if (crl->idp_flags & IDP_ONLYUSER)
                        return 0;
        } else {
                if (crl->idp_flags & IDP_ONLYCA)
                        return 0;
        }
        *preasons = crl->idp_reasons;
        for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
                DIST_POINT *dp = sk_DIST_POINT_value(x->crldp, i);
                if (crldp_check_crlissuer(dp, crl, crl_score)) {
                        if (!crl->idp ||
                            idp_check_dp(dp->distpoint, crl->idp->distpoint)) {
                                *preasons &= dp->dp_reasons;
                                return 1;
                        }
                }
        }
        if ((!crl->idp || !crl->idp->distpoint) &&
            (crl_score & CRL_SCORE_ISSUER_NAME))
                return 1;
        return 0;
}

/* Retrieve CRL corresponding to current certificate.
 * If deltas enabled try to find a delta CRL too
 */

static int
get_crl_delta(X509_STORE_CTX *ctx, X509_CRL **pcrl, X509_CRL **pdcrl, X509 *x)
{
        int ok;
        X509 *issuer = NULL;
        int crl_score = 0;
        unsigned int reasons;
        X509_CRL *crl = NULL, *dcrl = NULL;
        STACK_OF(X509_CRL) *skcrl;
        X509_NAME *nm = X509_get_issuer_name(x);

        reasons = ctx->current_reasons;
        ok = get_crl_sk(ctx, &crl, &dcrl, &issuer, &crl_score, &reasons,
            ctx->crls);
        if (ok)
                goto done;

        /* Lookup CRLs from store */
        skcrl = X509_STORE_CTX_get1_crls(ctx, nm);

        /* If no CRLs found and a near match from get_crl_sk use that */
        if (!skcrl && crl)
                goto done;

        get_crl_sk(ctx, &crl, &dcrl, &issuer, &crl_score, &reasons, skcrl);

        sk_X509_CRL_pop_free(skcrl, X509_CRL_free);

done:

        /* If we got any kind of CRL use it and return success */
        if (crl) {
                ctx->current_issuer = issuer;
                ctx->current_crl_score = crl_score;
                ctx->current_reasons = reasons;
                *pcrl = crl;
                *pdcrl = dcrl;
                return 1;
        }

        return 0;
}

/* Matches x509_verify_parent_signature() */
static int
x509_crl_verify_parent_signature(X509 *parent, X509_CRL *crl, int *error)
{
        EVP_PKEY *pkey;
        int cached;
        int ret = 0;

        /* Use cached value if we have it */
        if ((cached = x509_issuer_cache_find(parent->hash, crl->hash)) >= 0) {
                if (cached == 0)
                        *error = X509_V_ERR_CRL_SIGNATURE_FAILURE;
                return cached;
        }

        /* Check signature. Did parent sign crl? */
        if ((pkey = X509_get0_pubkey(parent)) == NULL) {
                *error = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
                return 0;
        }
        if (X509_CRL_verify(crl, pkey) <= 0)
                *error = X509_V_ERR_CRL_SIGNATURE_FAILURE;
        else
                ret = 1;

        /* Add result to cache */
        x509_issuer_cache_add(parent->hash, crl->hash, ret);

        return ret;
}

/* Check CRL validity */
static int
x509_vfy_check_crl(X509_STORE_CTX *ctx, X509_CRL *crl)
{
        X509 *issuer = NULL;
        int ok = 0, chnum, cnum;

        cnum = ctx->error_depth;
        chnum = sk_X509_num(ctx->chain) - 1;
        /* if we have an alternative CRL issuer cert use that */
        if (ctx->current_issuer) {
                issuer = ctx->current_issuer;
        } else if (cnum < chnum) {
                /*
                 * Else find CRL issuer: if not last certificate then issuer
                 * is next certificate in chain.
                 */
                issuer = sk_X509_value(ctx->chain, cnum + 1);
        } else {
                issuer = sk_X509_value(ctx->chain, chnum);
                /* If not self signed, can't check signature */
                if (!ctx->check_issued(ctx, issuer, issuer)) {
                        ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER;
                        ok = ctx->verify_cb(0, ctx);
                        if (!ok)
                                goto err;
                }
        }

        if (issuer) {
                /* Skip most tests for deltas because they have already
                 * been done
                 */
                if (!crl->base_crl_number) {
                        /* Check for cRLSign bit if keyUsage present */
                        if ((issuer->ex_flags & EXFLAG_KUSAGE) &&
                            !(issuer->ex_kusage & KU_CRL_SIGN)) {
                                ctx->error = X509_V_ERR_KEYUSAGE_NO_CRL_SIGN;
                                ok = ctx->verify_cb(0, ctx);
                                if (!ok)
                                        goto err;
                        }

                        if (!(ctx->current_crl_score & CRL_SCORE_SCOPE)) {
                                ctx->error = X509_V_ERR_DIFFERENT_CRL_SCOPE;
                                ok = ctx->verify_cb(0, ctx);
                                if (!ok)
                                        goto err;
                        }

                        if (!(ctx->current_crl_score & CRL_SCORE_SAME_PATH)) {
                                if (check_crl_path(ctx,
                                    ctx->current_issuer) <= 0) {
                                        ctx->error = X509_V_ERR_CRL_PATH_VALIDATION_ERROR;
                                        ok = ctx->verify_cb(0, ctx);
                                        if (!ok)
                                                goto err;
                                }
                        }

                        if (crl->idp_flags & IDP_INVALID) {
                                ctx->error = X509_V_ERR_INVALID_EXTENSION;
                                ok = ctx->verify_cb(0, ctx);
                                if (!ok)
                                        goto err;
                        }


                }

                if (!(ctx->current_crl_score & CRL_SCORE_TIME)) {
                        ok = check_crl_time(ctx, crl, 1);
                        if (!ok)
                                goto err;
                }

                if (!x509_crl_verify_parent_signature(issuer, crl, &ctx->error)) {
                        ok = ctx->verify_cb(0, ctx);
                        if (!ok)
                                goto err;
                }
        }

        ok = 1;

 err:
        return ok;
}

/* Check certificate against CRL */
static int
x509_vfy_cert_crl(X509_STORE_CTX *ctx, X509_CRL *crl, X509 *x)
{
        int ok;
        X509_REVOKED *rev;

        /* The rules changed for this... previously if a CRL contained
         * unhandled critical extensions it could still be used to indicate
         * a certificate was revoked. This has since been changed since
         * critical extension can change the meaning of CRL entries.
         */
        if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL) &&
            (crl->flags & EXFLAG_CRITICAL)) {
                ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                        return 0;
        }
        /* Look for serial number of certificate in CRL
         * If found make sure reason is not removeFromCRL.
         */
        if (X509_CRL_get0_by_cert(crl, &rev, x)) {
                if (rev->reason == CRL_REASON_REMOVE_FROM_CRL)
                        return 2;
                ctx->error = X509_V_ERR_CERT_REVOKED;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                        return 0;
        }

        return 1;
}

int
x509_vfy_check_policy(X509_STORE_CTX *ctx)
{
        X509 *current_cert = NULL;
        int ret;

        if (ctx->parent != NULL)
                return 1;

        ret = X509_policy_check(ctx->chain, ctx->param->policies,
            ctx->param->flags, &current_cert);
        if (ret != X509_V_OK) {
                ctx->current_cert = current_cert;
                ctx->error = ret;
                if (ret == X509_V_ERR_OUT_OF_MEM)
                        return 0;
                return ctx->verify_cb(0, ctx);
        }

        if (ctx->param->flags & X509_V_FLAG_NOTIFY_POLICY) {
                ctx->current_cert = NULL;
                /*
                 * Verification errors need to be "sticky", a callback may have
                 * allowed an SSL handshake to continue despite an error, and
                 * we must then remain in an error state.  Therefore, we MUST
                 * NOT clear earlier verification errors by setting the error
                 * to X509_V_OK.
                 */
                if (!ctx->verify_cb(2, ctx))
                        return 0;
        }

        return 1;
}

/*
 * Inform the verify callback of an error.
 *
 * If x is not NULL it is the error cert, otherwise use the chain cert
 * at depth.
 *
 * If err is not X509_V_OK, that's the error value, otherwise leave
 * unchanged (presumably set by the caller).
 *
 * Returns 0 to abort verification with an error, non-zero to continue.
 */
static int
verify_cb_cert(X509_STORE_CTX *ctx, X509 *x, int depth, int err)
{
        ctx->error_depth = depth;
        ctx->current_cert = (x != NULL) ? x : sk_X509_value(ctx->chain, depth);
        if (err != X509_V_OK)
                ctx->error = err;
        return ctx->verify_cb(0, ctx);
}

/*
 * Check certificate validity times.
 *
 * If depth >= 0, invoke verification callbacks on error, otherwise just return
 * the validation status.
 *
 * Return 1 on success, 0 otherwise.
 */
int
x509_check_cert_time(X509_STORE_CTX *ctx, X509 *x, int depth)
{
        time_t ptime;
        int i;

        if (ctx->param->flags & X509_V_FLAG_USE_CHECK_TIME)
                ptime = ctx->param->check_time;
        else if (ctx->param->flags & X509_V_FLAG_NO_CHECK_TIME)
                return 1;
        else
                ptime = time(NULL);

        i = X509_cmp_time(X509_get_notBefore(x), &ptime);

        if (i >= 0 && depth < 0)
                return 0;
        if (i == 0 && !verify_cb_cert(ctx, x, depth,
            X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD))
                return 0;
        if (i > 0 && !verify_cb_cert(ctx, x, depth,
            X509_V_ERR_CERT_NOT_YET_VALID))
                return 0;

        i = X509_cmp_time_internal(X509_get_notAfter(x), &ptime, 1);

        if (i <= 0 && depth < 0)
                return 0;
        if (i == 0 && !verify_cb_cert(ctx, x, depth,
            X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD))
                return 0;
        if (i < 0 && !verify_cb_cert(ctx, x, depth,
            X509_V_ERR_CERT_HAS_EXPIRED))
                return 0;

        return 1;
}

static int
x509_vfy_internal_verify(X509_STORE_CTX *ctx, int chain_verified)
{
        int n = sk_X509_num(ctx->chain) - 1;
        X509 *xi = sk_X509_value(ctx->chain, n);
        X509 *xs;

        if (ctx->check_issued(ctx, xi, xi))
                xs = xi;
        else {
                if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN) {
                        xs = xi;
                        goto check_cert;
                }
                if (n <= 0)
                        return verify_cb_cert(ctx, xi, 0,
                            X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE);
                n--;
                ctx->error_depth = n;
                xs = sk_X509_value(ctx->chain, n);
        }

        /*
         * Do not clear ctx->error=0, it must be "sticky", only the
         * user's callback is allowed to reset errors (at its own
         * peril).
         */
        while (n >= 0) {

                /*
                 * Skip signature check for self signed certificates
                 * unless explicitly asked for.  It doesn't add any
                 * security and just wastes time.  If the issuer's
                 * public key is unusable, report the issuer
                 * certificate and its depth (rather than the depth of
                 * the subject).
                 */
                if (!chain_verified && ( xs != xi ||
                    (ctx->param->flags & X509_V_FLAG_CHECK_SS_SIGNATURE))) {
                        EVP_PKEY *pkey;
                        if ((pkey = X509_get_pubkey(xi)) == NULL) {
                                if (!verify_cb_cert(ctx, xi, xi != xs ? n+1 : n,
                                    X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY))
                                        return 0;
                        } else if (X509_verify(xs, pkey) <= 0) {
                                if (!verify_cb_cert(ctx, xs, n,
                                    X509_V_ERR_CERT_SIGNATURE_FAILURE)) {
                                        EVP_PKEY_free(pkey);
                                        return 0;
                                }
                        }
                        EVP_PKEY_free(pkey);
                }
check_cert:
                /* Calls verify callback as needed */
                if (!chain_verified && !x509_check_cert_time(ctx, xs, n))
                        return 0;

                /*
                 * Signal success at this depth.  However, the
                 * previous error (if any) is retained.
                 */
                ctx->current_issuer = xi;
                ctx->current_cert = xs;
                ctx->error_depth = n;
                if (!ctx->verify_cb(1, ctx))
                        return 0;

                if (--n >= 0) {
                        xi = xs;
                        xs = sk_X509_value(ctx->chain, n);
                }
        }
        return 1;
}

static int
internal_verify(X509_STORE_CTX *ctx)
{
        return x509_vfy_internal_verify(ctx, 0);
}

/*
 * Internal verify, but with a chain where the verification
 * math has already been performed.
 */
int
x509_vfy_callback_indicate_completion(X509_STORE_CTX *ctx)
{
        return x509_vfy_internal_verify(ctx, 1);
}

int
X509_cmp_current_time(const ASN1_TIME *ctm)
{
        return X509_cmp_time(ctm, NULL);
}
LCRYPTO_ALIAS(X509_cmp_current_time);

/*
 * Compare a possibly unvalidated ASN1_TIME string against a time_t
 * using RFC 5280 rules for the time string. If *cmp_time is NULL
 * the current system time is used.
 *
 * XXX NOTE that unlike what you expect a "cmp" function to do in C,
 * XXX this one is "special", and returns 0 for error.
 *
 * Returns:
 * -1 if the ASN1_time is earlier than OR the same as *cmp_time.
 * 1 if the ASN1_time is later than *cmp_time.
 * 0 on error.
 */
static int
X509_cmp_time_internal(const ASN1_TIME *ctm, time_t *cmp_time, int is_notafter)
{
        time_t compare, cert_time;

        if (cmp_time == NULL)
                compare = time(NULL);
        else
                compare = *cmp_time;

        if (!x509_verify_asn1_time_to_time_t(ctm, is_notafter, &cert_time))
                return 0; /* invalid time */

        if (cert_time <= compare)
                return -1; /* 0 is used for error, so map same to less than */

        return 1;
}

int
X509_cmp_time(const ASN1_TIME *ctm, time_t *cmp_time)
{
        return X509_cmp_time_internal(ctm, cmp_time, 0);
}
LCRYPTO_ALIAS(X509_cmp_time);


ASN1_TIME *
X509_gmtime_adj(ASN1_TIME *s, long adj)
{
        return X509_time_adj(s, adj, NULL);
}
LCRYPTO_ALIAS(X509_gmtime_adj);

ASN1_TIME *
X509_time_adj(ASN1_TIME *s, long offset_sec, time_t *in_time)
{
        return X509_time_adj_ex(s, 0, offset_sec, in_time);
}
LCRYPTO_ALIAS(X509_time_adj);

ASN1_TIME *
X509_time_adj_ex(ASN1_TIME *s, int offset_day, long offset_sec, time_t *in_time)
{
        time_t t;
        if (in_time == NULL)
                t = time(NULL);
        else
                t = *in_time;

        return ASN1_TIME_adj(s, t, offset_day, offset_sec);
}
LCRYPTO_ALIAS(X509_time_adj_ex);

int
X509_get_pubkey_parameters(EVP_PKEY *pkey, STACK_OF(X509) *chain)
{
        EVP_PKEY *ktmp = NULL, *ktmp2;
        int i, j;

        if ((pkey != NULL) && !EVP_PKEY_missing_parameters(pkey))
                return 1;

        for (i = 0; i < sk_X509_num(chain); i++) {
                ktmp = X509_get0_pubkey(sk_X509_value(chain, i));
                if (ktmp == NULL) {
                        X509error(X509_R_UNABLE_TO_GET_CERTS_PUBLIC_KEY);
                        return 0;
                }
                if (!EVP_PKEY_missing_parameters(ktmp))
                        break;
                else
                        ktmp = NULL;
        }
        if (ktmp == NULL) {
                X509error(X509_R_UNABLE_TO_FIND_PARAMETERS_IN_CHAIN);
                return 0;
        }

        /* first, populate the other certs */
        for (j = i - 1; j >= 0; j--) {
                if ((ktmp2 = X509_get0_pubkey(sk_X509_value(chain, j))) == NULL)
                        return 0;
                if (!EVP_PKEY_copy_parameters(ktmp2, ktmp))
                        return 0;
        }

        if (pkey != NULL)
                if (!EVP_PKEY_copy_parameters(pkey, ktmp))
                        return 0;
        return 1;
}
LCRYPTO_ALIAS(X509_get_pubkey_parameters);

int
X509_STORE_CTX_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
    CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
{
        /* This function is (usually) called only once, by
         * SSL_get_ex_data_X509_STORE_CTX_idx (ssl/ssl_cert.c). */
        return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_X509_STORE_CTX,
            argl, argp, new_func, dup_func, free_func);
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_ex_new_index);

int
X509_STORE_CTX_set_ex_data(X509_STORE_CTX *ctx, int idx, void *data)
{
        return CRYPTO_set_ex_data(&ctx->ex_data, idx, data);
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_ex_data);

void *
X509_STORE_CTX_get_ex_data(X509_STORE_CTX *ctx, int idx)
{
        return CRYPTO_get_ex_data(&ctx->ex_data, idx);
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_ex_data);

int
X509_STORE_CTX_get_error(X509_STORE_CTX *ctx)
{
        return ctx->error;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_error);

void
X509_STORE_CTX_set_error(X509_STORE_CTX *ctx, int err)
{
        ctx->error = err;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_error);

int
X509_STORE_CTX_get_error_depth(X509_STORE_CTX *ctx)
{
        return ctx->error_depth;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_error_depth);

void
X509_STORE_CTX_set_error_depth(X509_STORE_CTX *ctx, int depth)
{
        ctx->error_depth = depth;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_error_depth);

X509 *
X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx)
{
        return ctx->current_cert;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_current_cert);

void
X509_STORE_CTX_set_current_cert(X509_STORE_CTX *ctx, X509 *x)
{
        ctx->current_cert = x;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_current_cert);

STACK_OF(X509) *
X509_STORE_CTX_get_chain(X509_STORE_CTX *ctx)
{
        return ctx->chain;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_chain);

STACK_OF(X509) *
X509_STORE_CTX_get0_chain(X509_STORE_CTX *xs)
{
        return xs->chain;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_chain);

STACK_OF(X509) *
X509_STORE_CTX_get1_chain(X509_STORE_CTX *ctx)
{
        int i;
        X509 *x;
        STACK_OF(X509) *chain;

        if (!ctx->chain || !(chain = sk_X509_dup(ctx->chain)))
                return NULL;
        for (i = 0; i < sk_X509_num(chain); i++) {
                x = sk_X509_value(chain, i);
                CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
        }
        return chain;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get1_chain);

X509 *
X509_STORE_CTX_get0_current_issuer(X509_STORE_CTX *ctx)
{
        return ctx->current_issuer;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_current_issuer);

X509_CRL *
X509_STORE_CTX_get0_current_crl(X509_STORE_CTX *ctx)
{
        return ctx->current_crl;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_current_crl);

X509_STORE_CTX *
X509_STORE_CTX_get0_parent_ctx(X509_STORE_CTX *ctx)
{
        return ctx->parent;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_parent_ctx);

X509_STORE *
X509_STORE_CTX_get0_store(X509_STORE_CTX *xs)
{
        return xs->store;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_store);

void
X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *x)
{
        ctx->cert = x;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_cert);

void
X509_STORE_CTX_set_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
        ctx->untrusted = sk;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_chain);

void
X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk)
{
        ctx->crls = sk;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set0_crls);

/*
 * This function is used to set the X509_STORE_CTX purpose and trust
 * values. This is intended to be used when another structure has its
 * own trust and purpose values which (if set) will be inherited by
 * the ctx. If they aren't set then we will usually have a default
 * purpose in mind which should then be used to set the trust value.
 * An example of this is SSL use: an SSL structure will have its own
 * purpose and trust settings which the application can set: if they
 * aren't set then we use the default of SSL client/server.
 */
int
X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose_id)
{
        const X509_PURPOSE *purpose;
        int idx;

        /* XXX - Match wacky/documented behavior. Do we need to keep this? */
        if (purpose_id == 0)
                return 1;

        if (purpose_id < X509_PURPOSE_MIN || purpose_id > X509_PURPOSE_MAX) {
                X509error(X509_R_UNKNOWN_PURPOSE_ID);
                return 0;
        }
        idx = purpose_id - X509_PURPOSE_MIN;
        if ((purpose = X509_PURPOSE_get0(idx)) == NULL) {
                X509error(X509_R_UNKNOWN_PURPOSE_ID);
                return 0;
        }

        /* XXX - Succeeding while ignoring purpose_id and trust is awful. */
        if (ctx->param->purpose == 0)
                ctx->param->purpose = purpose_id;
        if (ctx->param->trust == 0)
                ctx->param->trust = X509_PURPOSE_get_trust(purpose);

        return 1;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_purpose);

int
X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust_id)
{
        /* XXX - Match wacky/documented behavior. Do we need to keep this? */
        if (trust_id == 0)
                return 1;

        if (trust_id < X509_TRUST_MIN || trust_id > X509_TRUST_MAX) {
                X509error(X509_R_UNKNOWN_TRUST_ID);
                return 0;
        }

        /* XXX - Succeeding while ignoring the trust_id is awful. */
        if (ctx->param->trust == 0)
                ctx->param->trust = trust_id;

        return 1;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_trust);

X509_STORE_CTX *
X509_STORE_CTX_new(void)
{
        X509_STORE_CTX *ctx;

        ctx = calloc(1, sizeof(X509_STORE_CTX));
        if (!ctx) {
                X509error(ERR_R_MALLOC_FAILURE);
                return NULL;
        }
        return ctx;
}
LCRYPTO_ALIAS(X509_STORE_CTX_new);

void
X509_STORE_CTX_free(X509_STORE_CTX *ctx)
{
        if (ctx == NULL)
                return;

        X509_STORE_CTX_cleanup(ctx);
        free(ctx);
}
LCRYPTO_ALIAS(X509_STORE_CTX_free);

int
X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *store, X509 *leaf,
    STACK_OF(X509) *untrusted)
{
        int param_ret = 1;

        /*
         * Make sure everything is initialized properly even in case of an
         * early return due to an error.
         *
         * While this 'ctx' can be reused, X509_STORE_CTX_cleanup() will have
         * freed everything and memset ex_data anyway.  This also allows us
         * to safely use X509_STORE_CTX variables from the stack which will
         * have uninitialized data.
         */
        memset(ctx, 0, sizeof(*ctx));

        /*
         * Start with this set to not valid - it will be set to valid
         * in X509_verify_cert.
         */
        ctx->error = X509_V_ERR_INVALID_CALL;

        /*
         * Set values other than 0.  Keep this in the same order as
         * X509_STORE_CTX except for values that may fail.  All fields that
         * may fail should go last to make sure 'ctx' is as consistent as
         * possible even on early exits.
         */
        ctx->store = store;
        ctx->cert = leaf;
        ctx->untrusted = untrusted;

        if (store && store->verify)
                ctx->verify = store->verify;
        else
                ctx->verify = internal_verify;

        if (store && store->verify_cb)
                ctx->verify_cb = store->verify_cb;
        else
                ctx->verify_cb = null_callback;

        ctx->get_issuer = X509_STORE_CTX_get1_issuer;
        ctx->check_issued = check_issued;

        ctx->param = X509_VERIFY_PARAM_new();
        if (!ctx->param) {
                X509error(ERR_R_MALLOC_FAILURE);
                return 0;
        }

        /* Inherit callbacks and flags from X509_STORE if not set
         * use defaults.
         */
        if (store)
                param_ret = X509_VERIFY_PARAM_inherit(ctx->param, store->param);
        else
                ctx->param->inh_flags |= X509_VP_FLAG_DEFAULT|X509_VP_FLAG_ONCE;

        if (param_ret)
                param_ret = X509_VERIFY_PARAM_inherit(ctx->param,
                    X509_VERIFY_PARAM_lookup("default"));

        if (param_ret == 0) {
                X509error(ERR_R_MALLOC_FAILURE);
                return 0;
        }

        if (CRYPTO_new_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX, ctx,
            &ctx->ex_data) == 0) {
                X509error(ERR_R_MALLOC_FAILURE);
                return 0;
        }
        return 1;
}
LCRYPTO_ALIAS(X509_STORE_CTX_init);

/* Set alternative lookup method: just a STACK of trusted certificates.
 * This avoids X509_STORE nastiness where it isn't needed.
 */

void
X509_STORE_CTX_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *trusted)
{
        X509_STORE_CTX_set0_trusted_stack(ctx, trusted);
}
LCRYPTO_ALIAS(X509_STORE_CTX_trusted_stack);

void
X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *trusted)
{
        ctx->trusted = trusted;
        ctx->get_issuer = x509_vfy_get_trusted_issuer;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set0_trusted_stack);

void
X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx)
{
        if (ctx->param != NULL) {
                if (ctx->parent == NULL)
                        X509_VERIFY_PARAM_free(ctx->param);
                ctx->param = NULL;
        }
        if (ctx->chain != NULL) {
                sk_X509_pop_free(ctx->chain, X509_free);
                ctx->chain = NULL;
        }
        CRYPTO_free_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX, ctx, &ctx->ex_data);
        memset(&ctx->ex_data, 0, sizeof(CRYPTO_EX_DATA));
}
LCRYPTO_ALIAS(X509_STORE_CTX_cleanup);

void
X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth)
{
        X509_VERIFY_PARAM_set_depth(ctx->param, depth);
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_depth);

void
X509_STORE_CTX_set_flags(X509_STORE_CTX *ctx, unsigned long flags)
{
        X509_VERIFY_PARAM_set_flags(ctx->param, flags);
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_flags);

void
X509_STORE_CTX_set_time(X509_STORE_CTX *ctx, unsigned long flags, time_t t)
{
        X509_VERIFY_PARAM_set_time(ctx->param, t);
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_time);

int
(*X509_STORE_CTX_get_verify_cb(X509_STORE_CTX *ctx))(int, X509_STORE_CTX *)
{
        return ctx->verify_cb;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_verify_cb);

void
X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
    int (*verify_cb)(int, X509_STORE_CTX *))
{
        ctx->verify_cb = verify_cb;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_verify_cb);

int
(*X509_STORE_CTX_get_verify(X509_STORE_CTX *ctx))(X509_STORE_CTX *)
{
        return ctx->verify;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_verify);

void
X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, int (*verify)(X509_STORE_CTX *))
{
        ctx->verify = verify;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_verify);

X509_STORE_CTX_check_issued_fn
X509_STORE_get_check_issued(X509_STORE *store)
{
        return store->check_issued;
}
LCRYPTO_ALIAS(X509_STORE_get_check_issued);

void
X509_STORE_set_check_issued(X509_STORE *store,
    X509_STORE_CTX_check_issued_fn check_issued_fn)
{
        store->check_issued = check_issued_fn;
}
LCRYPTO_ALIAS(X509_STORE_set_check_issued);

X509_STORE_CTX_check_issued_fn
X509_STORE_CTX_get_check_issued(X509_STORE_CTX *ctx)
{
        return ctx->check_issued;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_check_issued);

X509 *
X509_STORE_CTX_get0_cert(X509_STORE_CTX *ctx)
{
        return ctx->cert;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_cert);

STACK_OF(X509) *
X509_STORE_CTX_get0_untrusted(X509_STORE_CTX *ctx)
{
        return ctx->untrusted;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_untrusted);

void
X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
        ctx->untrusted = sk;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set0_untrusted);

void
X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
        sk_X509_pop_free(ctx->chain, X509_free);
        ctx->chain = sk;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set0_verified_chain);

int
X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx)
{
        return ctx->num_untrusted;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get_num_untrusted);

int
X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name)
{
        const X509_VERIFY_PARAM *param;
        param = X509_VERIFY_PARAM_lookup(name);
        if (!param)
                return 0;
        return X509_VERIFY_PARAM_inherit(ctx->param, param);
}
LCRYPTO_ALIAS(X509_STORE_CTX_set_default);

X509_VERIFY_PARAM *
X509_STORE_CTX_get0_param(X509_STORE_CTX *ctx)
{
        return ctx->param;
}
LCRYPTO_ALIAS(X509_STORE_CTX_get0_param);

void
X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param)
{
        if (ctx->param)
                X509_VERIFY_PARAM_free(ctx->param);
        ctx->param = param;
}
LCRYPTO_ALIAS(X509_STORE_CTX_set0_param);

/*
 * Check if |bits| are adequate for |security level|.
 * Returns 1 if ok, 0 otherwise.
 */
static int
enough_bits_for_security_level(int bits, int level)
{
        /*
         * Sigh. OpenSSL does this silly squashing, so we will
         * too. Derp for Derp compatibility being important.
         */
        if (level < 0)
                level = 0;
        if (level > 5)
                level = 5;

        switch (level) {
        case 0:
                return 1;
        case 1:
                return bits >= 80;
        case 2:
                return bits >= 112;
        case 3:
                return bits >= 128;
        case 4:
                return bits >= 192;
        case 5:
                return bits >= 256;
        default:
                return 0;
        }
}

/*
 * Check whether the public key of |cert| meets the security level of |ctx|.
 *
 * Returns 1 on success, 0 otherwise.
 */
static int
check_key_level(X509_STORE_CTX *ctx, X509 *cert)
{
        EVP_PKEY *pkey;
        int bits;

        /* Unsupported or malformed keys are not secure */
        if ((pkey = X509_get0_pubkey(cert)) == NULL)
                return 0;

        if ((bits = EVP_PKEY_security_bits(pkey)) <= 0)
                return 0;

        return enough_bits_for_security_level(bits, ctx->param->security_level);
}

/*
 * Check whether the signature digest algorithm of |cert| meets the security
 * level of |ctx|.  Do not check trust anchors (self-signed or not).
 *
 * Returns 1 on success, 0 otherwise.
 */
static int
check_sig_level(X509_STORE_CTX *ctx, X509 *cert)
{
        int bits;

        if (!X509_get_signature_info(cert, NULL, NULL, &bits, NULL))
                return 0;

        return enough_bits_for_security_level(bits, ctx->param->security_level);
}

int
x509_vfy_check_security_level(X509_STORE_CTX *ctx)
{
        int num = sk_X509_num(ctx->chain);
        int i;

        if (ctx->param->security_level <= 0)
                return 1;

        for (i = 0; i < num; i++) {
                X509 *cert = sk_X509_value(ctx->chain, i);

                /*
                 * We've already checked the security of the leaf key, so here
                 * we only check the security of issuer keys.
                 */
                if (i > 0) {
                        if (!check_key_level(ctx, cert) &&
                            !verify_cb_cert(ctx, cert, i,
                            X509_V_ERR_CA_KEY_TOO_SMALL))
                                return 0;
                }

                /*
                 * We also check the signature algorithm security of all certs
                 * except those of the trust anchor at index num - 1.
                 */
                if (i == num - 1)
                        break;

                if (!check_sig_level(ctx, cert) &&
                    !verify_cb_cert(ctx, cert, i, X509_V_ERR_CA_MD_TOO_WEAK))
                        return 0;
        }
        return 1;
}