text: /* v3_purp.c */
  /*
   * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
   * 2001.
   */
  /* ====================================================================
   * Copyright (c) 1999-2004 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 <stdio.h>
  
  #include <string.h>
  
  #include <openssl/err.h>
  #include <openssl/digest.h>
  #include <openssl/mem.h>
  #include <openssl/obj.h>
  #include <openssl/thread.h>
  #include <openssl/x509_vfy.h>
  #include <openssl/x509v3.h>
  
  #include "../internal.h"
  #include "../x509/internal.h"
  #include "internal.h"
  
  #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
  #define ku_reject(x, usage) \
          (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
  #define xku_reject(x, usage) \
          (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
  #define ns_reject(x, usage) \
          (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
  
  static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
                                      int ca);
  static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
                                      int ca);
  static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
                                         int ca);
  static int purpose_smime(const X509 *x, int ca);
  static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
                                      int ca);
  static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
                                         int ca);
  static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
                                    int ca);
  static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
                                          int ca);
  static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
  static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
  
  static int xp_cmp(const X509_PURPOSE **a, const X509_PURPOSE **b);
  static void xptable_free(X509_PURPOSE *p);
  
  static X509_PURPOSE xstandard[] = {
      {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
       check_purpose_ssl_client, (char *)"SSL client", (char *)"sslclient",
       NULL},
      {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
       check_purpose_ssl_server, (char *)"SSL server", (char *)"sslserver",
       NULL},
      {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
       check_purpose_ns_ssl_server, (char *)"Netscape SSL server",
       (char *)"nssslserver", NULL},
      {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
       (char *)"S/MIME signing", (char *)"smimesign", NULL},
      {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
       check_purpose_smime_encrypt, (char *)"S/MIME encryption",
       (char *)"smimeencrypt", NULL},
      {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
       (char *)"CRL signing", (char *)"crlsign", NULL},
      {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, (char *)"Any Purpose",
       (char *)"any", NULL},
      {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
       (char *)"OCSP helper", (char *)"ocsphelper", NULL},
      {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
       check_purpose_timestamp_sign, (char *)"Time Stamp signing",
       (char *)"timestampsign", NULL},
  };
  
  #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
  
  static STACK_OF(X509_PURPOSE) *xptable = NULL;
  
  static int xp_cmp(const X509_PURPOSE **a, const X509_PURPOSE **b)
  {
      return (*a)->purpose - (*b)->purpose;
  }
  
  /*
   * As much as I'd like to make X509_check_purpose use a "const" X509* I
   * really can't because it does recalculate hashes and do other non-const
   * things.
   */
  int X509_check_purpose(X509 *x, int id, int ca)
  {
      int idx;
      const X509_PURPOSE *pt;
      if (!x509v3_cache_extensions(x)) {
          return -1;
      }
  
      if (id == -1)
          return 1;
      idx = X509_PURPOSE_get_by_id(id);
      if (idx == -1)
          return -1;
      pt = X509_PURPOSE_get0(idx);
      return pt->check_purpose(pt, x, ca);
  }
  
  int X509_PURPOSE_set(int *p, int purpose)
  {
      if (X509_PURPOSE_get_by_id(purpose) == -1) {
          OPENSSL_PUT_ERROR(X509V3, X509V3_R_INVALID_PURPOSE);
          return 0;
      }
      *p = purpose;
      return 1;
  }
  
  int X509_PURPOSE_get_count(void)
  {
      if (!xptable)
          return X509_PURPOSE_COUNT;
      return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
  }
  
  X509_PURPOSE *X509_PURPOSE_get0(int idx)
  {
      if (idx < 0)
          return NULL;
      if (idx < (int)X509_PURPOSE_COUNT)
          return xstandard + idx;
      return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
  }
  
  int X509_PURPOSE_get_by_sname(char *sname)
  {
      int i;
      X509_PURPOSE *xptmp;
      for (i = 0; i < X509_PURPOSE_get_count(); i++) {
          xptmp = X509_PURPOSE_get0(i);
          if (!strcmp(xptmp->sname, sname))
              return i;
      }
      return -1;
  }
  
  int X509_PURPOSE_get_by_id(int purpose)
  {
      X509_PURPOSE tmp;
      size_t idx;
  
      if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
          return purpose - X509_PURPOSE_MIN;
      tmp.purpose = purpose;
      if (!xptable)
          return -1;
  
      sk_X509_PURPOSE_sort(xptable);
      if (!sk_X509_PURPOSE_find(xptable, &idx, &tmp))
          return -1;
      return idx + X509_PURPOSE_COUNT;
  }
  
  int X509_PURPOSE_add(int id, int trust, int flags,
                       int (*ck) (const X509_PURPOSE *, const X509 *, int),
                       char *name, char *sname, void *arg)
  {
      int idx;
      X509_PURPOSE *ptmp;
      char *name_dup, *sname_dup;
  
      /*
       * This is set according to what we change: application can't set it
       */
      flags &= ~X509_PURPOSE_DYNAMIC;
      /* This will always be set for application modified trust entries */
      flags |= X509_PURPOSE_DYNAMIC_NAME;
      /* Get existing entry if any */
      idx = X509_PURPOSE_get_by_id(id);
      /* Need a new entry */
      if (idx == -1) {
          if (!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
              OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
              return 0;
          }
          ptmp->flags = X509_PURPOSE_DYNAMIC;
      } else
          ptmp = X509_PURPOSE_get0(idx);
  
      /* Duplicate the supplied names. */
      name_dup = OPENSSL_strdup(name);
      sname_dup = OPENSSL_strdup(sname);
      if (name_dup == NULL || sname_dup == NULL) {
          OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
          if (name_dup != NULL)
              OPENSSL_free(name_dup);
          if (sname_dup != NULL)
              OPENSSL_free(sname_dup);
          if (idx == -1)
              OPENSSL_free(ptmp);
          return 0;
      }
  
      /* OPENSSL_free existing name if dynamic */
      if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
          OPENSSL_free(ptmp->name);
          OPENSSL_free(ptmp->sname);
      }
      /* dup supplied name */
      ptmp->name = name_dup;
      ptmp->sname = sname_dup;
      /* Keep the dynamic flag of existing entry */
      ptmp->flags &= X509_PURPOSE_DYNAMIC;
      /* Set all other flags */
      ptmp->flags |= flags;
  
      ptmp->purpose = id;
      ptmp->trust = trust;
      ptmp->check_purpose = ck;
      ptmp->usr_data = arg;
  
      /* If its a new entry manage the dynamic table */
      if (idx == -1) {
          if (!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
              OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
              xptable_free(ptmp);
              return 0;
          }
          if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
              OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
              xptable_free(ptmp);
              return 0;
          }
      }
      return 1;
  }
  
  static void xptable_free(X509_PURPOSE *p)
  {
      if (!p)
          return;
      if (p->flags & X509_PURPOSE_DYNAMIC) {
          if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
              OPENSSL_free(p->name);
              OPENSSL_free(p->sname);
          }
          OPENSSL_free(p);
      }
  }
  
  void X509_PURPOSE_cleanup(void)
  {
      unsigned int i;
      sk_X509_PURPOSE_pop_free(xptable, xptable_free);
      for (i = 0; i < X509_PURPOSE_COUNT; i++)
          xptable_free(xstandard + i);
      xptable = NULL;
  }
  
  int X509_PURPOSE_get_id(const X509_PURPOSE *xp)
  {
      return xp->purpose;
  }
  
  char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
  {
      return xp->name;
  }
  
  char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
  {
      return xp->sname;
  }
  
  int X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
  {
      return xp->trust;
  }
  
  static int nid_cmp(const void *void_a, const void *void_b)
  {
      const int *a = void_a, *b = void_b;
  
      return *a - *b;
  }
  
  int X509_supported_extension(X509_EXTENSION *ex)
  {
      /*
       * This table is a list of the NIDs of supported extensions: that is
       * those which are used by the verify process. If an extension is
       * critical and doesn't appear in this list then the verify process will
       * normally reject the certificate. The list must be kept in numerical
       * order because it will be searched using bsearch.
       */
  
      static const int supported_nids[] = {
          NID_netscape_cert_type, /* 71 */
          NID_key_usage,          /* 83 */
          NID_subject_alt_name,   /* 85 */
          NID_basic_constraints,  /* 87 */
          NID_certificate_policies, /* 89 */
          NID_ext_key_usage,      /* 126 */
          NID_policy_constraints, /* 401 */
          NID_proxyCertInfo,      /* 663 */
          NID_name_constraints,   /* 666 */
          NID_policy_mappings,    /* 747 */
          NID_inhibit_any_policy  /* 748 */
      };
  
      int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
  
      if (ex_nid == NID_undef)
          return 0;
  
      if (bsearch
          (&ex_nid, supported_nids, sizeof(supported_nids) / sizeof(int),
           sizeof(int), nid_cmp) != NULL)
          return 1;
      return 0;
  }
  
  static int setup_dp(X509 *x, DIST_POINT *dp)
  {
      X509_NAME *iname = NULL;
      size_t i;
      if (dp->reasons) {
          if (dp->reasons->length > 0)
              dp->dp_reasons = dp->reasons->data[0];
          if (dp->reasons->length > 1)
              dp->dp_reasons |= (dp->reasons->data[1] << 8);
          dp->dp_reasons &= CRLDP_ALL_REASONS;
      } else
          dp->dp_reasons = CRLDP_ALL_REASONS;
      if (!dp->distpoint || (dp->distpoint->type != 1))
          return 1;
      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) {
              iname = gen->d.directoryName;
              break;
          }
      }
      if (!iname)
          iname = X509_get_issuer_name(x);
  
      return DIST_POINT_set_dpname(dp->distpoint, iname);
  }
  
  static int setup_crldp(X509 *x)
  {
      int j;
      x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &j, NULL);
      if (x->crldp == NULL && j != -1) {
          return 0;
      }
      for (size_t i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
          if (!setup_dp(x, sk_DIST_POINT_value(x->crldp, i))) {
              return 0;
          }
      }
      return 1;
  }
  
  int x509v3_cache_extensions(X509 *x)
  {
      BASIC_CONSTRAINTS *bs;
      PROXY_CERT_INFO_EXTENSION *pci;
      ASN1_BIT_STRING *usage;
      ASN1_BIT_STRING *ns;
      EXTENDED_KEY_USAGE *extusage;
      X509_EXTENSION *ex;
      size_t i;
      int j;
  
      CRYPTO_MUTEX_lock_read(&x->lock);
      const int is_set = x->ex_flags & EXFLAG_SET;
      CRYPTO_MUTEX_unlock_read(&x->lock);
  
      if (is_set) {
          return (x->ex_flags & EXFLAG_INVALID) == 0;
      }
  
      CRYPTO_MUTEX_lock_write(&x->lock);
      if (x->ex_flags & EXFLAG_SET) {
          CRYPTO_MUTEX_unlock_write(&x->lock);
          return (x->ex_flags & EXFLAG_INVALID) == 0;
      }
  
      if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))
          x->ex_flags |= EXFLAG_INVALID;
      /* V1 should mean no extensions ... */
      if (X509_get_version(x) == X509_VERSION_1)
          x->ex_flags |= EXFLAG_V1;
      /* Handle basic constraints */
      if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &j, NULL))) {
          if (bs->ca)
              x->ex_flags |= EXFLAG_CA;
          if (bs->pathlen) {
              if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
                  || !bs->ca) {
                  x->ex_flags |= EXFLAG_INVALID;
                  x->ex_pathlen = 0;
              } else {
                  /* TODO(davidben): |ASN1_INTEGER_get| returns -1 on overflow,
                   * which currently acts as if the constraint isn't present. This
                   * works (an overflowing path length constraint may as well be
                   * infinity), but Chromium's verifier simply treats values above
                   * 255 as an error. */
                  x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
              }
          } else
              x->ex_pathlen = -1;
          BASIC_CONSTRAINTS_free(bs);
          x->ex_flags |= EXFLAG_BCONS;
      } else if (j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      /* Handle proxy certificates */
      if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &j, NULL))) {
          if (x->ex_flags & EXFLAG_CA
              || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
              || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
              x->ex_flags |= EXFLAG_INVALID;
          }
          if (pci->pcPathLengthConstraint) {
              x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
          } else
              x->ex_pcpathlen = -1;
          PROXY_CERT_INFO_EXTENSION_free(pci);
          x->ex_flags |= EXFLAG_PROXY;
      } else if (j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      /* Handle key usage */
      if ((usage = X509_get_ext_d2i(x, NID_key_usage, &j, NULL))) {
          if (usage->length > 0) {
              x->ex_kusage = usage->data[0];
              if (usage->length > 1)
                  x->ex_kusage |= usage->data[1] << 8;
          } else
              x->ex_kusage = 0;
          x->ex_flags |= EXFLAG_KUSAGE;
          ASN1_BIT_STRING_free(usage);
      } else if (j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      x->ex_xkusage = 0;
      if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &j, NULL))) {
          x->ex_flags |= EXFLAG_XKUSAGE;
          for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
              switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
              case NID_server_auth:
                  x->ex_xkusage |= XKU_SSL_SERVER;
                  break;
  
              case NID_client_auth:
                  x->ex_xkusage |= XKU_SSL_CLIENT;
                  break;
  
              case NID_email_protect:
                  x->ex_xkusage |= XKU_SMIME;
                  break;
  
              case NID_code_sign:
                  x->ex_xkusage |= XKU_CODE_SIGN;
                  break;
  
              case NID_ms_sgc:
              case NID_ns_sgc:
                  x->ex_xkusage |= XKU_SGC;
                  break;
  
              case NID_OCSP_sign:
                  x->ex_xkusage |= XKU_OCSP_SIGN;
                  break;
  
              case NID_time_stamp:
                  x->ex_xkusage |= XKU_TIMESTAMP;
                  break;
  
              case NID_dvcs:
                  x->ex_xkusage |= XKU_DVCS;
                  break;
  
              case NID_anyExtendedKeyUsage:
                  x->ex_xkusage |= XKU_ANYEKU;
                  break;
              }
          }
          sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
      } else if (j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
  
      if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &j, NULL))) {
          if (ns->length > 0)
              x->ex_nscert = ns->data[0];
          else
              x->ex_nscert = 0;
          x->ex_flags |= EXFLAG_NSCERT;
          ASN1_BIT_STRING_free(ns);
      } else if (j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &j, NULL);
      if (x->skid == NULL && j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &j, NULL);
      if (x->akid == NULL && j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      /* Does subject name match issuer ? */
      if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
          x->ex_flags |= EXFLAG_SI;
          /* If SKID matches AKID also indicate self signed */
          if (X509_check_akid(x, x->akid) == X509_V_OK &&
              !ku_reject(x, KU_KEY_CERT_SIGN))
              x->ex_flags |= EXFLAG_SS;
      }
      x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &j, NULL);
      if (x->altname == NULL && j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      x->nc = X509_get_ext_d2i(x, NID_name_constraints, &j, NULL);
      if (x->nc == NULL && j != -1) {
          x->ex_flags |= EXFLAG_INVALID;
      }
      if (!setup_crldp(x)) {
          x->ex_flags |= EXFLAG_INVALID;
      }
  
      for (j = 0; j < X509_get_ext_count(x); j++) {
          ex = X509_get_ext(x, j);
          if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
              == NID_freshest_crl)
              x->ex_flags |= EXFLAG_FRESHEST;
          if (!X509_EXTENSION_get_critical(ex))
              continue;
          if (!X509_supported_extension(ex)) {
              x->ex_flags |= EXFLAG_CRITICAL;
              break;
          }
      }
      x->ex_flags |= EXFLAG_SET;
  
      CRYPTO_MUTEX_unlock_write(&x->lock);
      return (x->ex_flags & EXFLAG_INVALID) == 0;
  }
  
  /* check_ca returns one if |x| should be considered a CA certificate and zero
   * otherwise. */
  static int check_ca(const X509 *x)
  {
      /* keyUsage if present should allow cert signing */
      if (ku_reject(x, KU_KEY_CERT_SIGN))
          return 0;
      /* Version 1 certificates are considered CAs and don't have extensions. */
      if ((x->ex_flags & V1_ROOT) == V1_ROOT) {
          return 1;
      }
      /* Otherwise, it's only a CA if basicConstraints says so. */
      return ((x->ex_flags & EXFLAG_BCONS) &&
              (x->ex_flags & EXFLAG_CA));
  }
  
  int X509_check_ca(X509 *x)
  {
      if (!x509v3_cache_extensions(x)) {
          return 0;
      }
      return check_ca(x);
  }
  
  static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
                                      int ca)
  {
      if (xku_reject(x, XKU_SSL_CLIENT))
          return 0;
      if (ca)
          return check_ca(x);
      /* We need to do digital signatures or key agreement */
      if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
          return 0;
      /* nsCertType if present should allow SSL client use */
      if (ns_reject(x, NS_SSL_CLIENT))
          return 0;
      return 1;
  }
  
  /*
   * Key usage needed for TLS/SSL server: digital signature, encipherment or
   * key agreement. The ssl code can check this more thoroughly for individual
   * key types.
   */
  #define KU_TLS \
          (KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT)
  
  static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
                                      int ca)
  {
      if (xku_reject(x, XKU_SSL_SERVER))
          return 0;
      if (ca)
          return check_ca(x);
  
      if (ns_reject(x, NS_SSL_SERVER))
          return 0;
      if (ku_reject(x, KU_TLS))
          return 0;
  
      return 1;
  
  }
  
  static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
                                         int ca)
  {
      int ret;
      ret = check_purpose_ssl_server(xp, x, ca);
      if (!ret || ca)
          return ret;
      /* We need to encipher or Netscape complains */
      if (ku_reject(x, KU_KEY_ENCIPHERMENT))
          return 0;
      return ret;
  }
  
  /* purpose_smime returns one if |x| is a valid S/MIME leaf (|ca| is zero) or CA
   * (|ca| is one) certificate, and zero otherwise. */
  static int purpose_smime(const X509 *x, int ca)
  {
      if (xku_reject(x, XKU_SMIME))
          return 0;
      if (ca) {
          /* check nsCertType if present */
          if ((x->ex_flags & EXFLAG_NSCERT) &&
              (x->ex_nscert & NS_SMIME_CA) == 0) {
            return 0;
          }
  
          return check_ca(x);
      }
      if (x->ex_flags & EXFLAG_NSCERT) {
          return (x->ex_nscert & NS_SMIME) == NS_SMIME;
      }
      return 1;
  }
  
  static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
                                      int ca)
  {
      int ret;
      ret = purpose_smime(x, ca);
      if (!ret || ca)
          return ret;
      if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
          return 0;
      return ret;
  }
  
  static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
                                         int ca)
  {
      int ret;
      ret = purpose_smime(x, ca);
      if (!ret || ca)
          return ret;
      if (ku_reject(x, KU_KEY_ENCIPHERMENT))
          return 0;
      return ret;
  }
  
  static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
                                    int ca)
  {
      if (ca) {
          return check_ca(x);
      }
      if (ku_reject(x, KU_CRL_SIGN))
          return 0;
      return 1;
  }
  
  /*
   * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
   * is valid. Additional checks must be made on the chain.
   */
  
  static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
  {
      if (ca)
          return check_ca(x);
      /* leaf certificate is checked in OCSP_verify() */
      return 1;
  }
  
  static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
                                          int ca)
  {
      int i_ext;
  
      /* If ca is true we must return if this is a valid CA certificate. */
      if (ca)
          return check_ca(x);
  
      /*
       * Check the optional key usage field:
       * if Key Usage is present, it must be one of digitalSignature
       * and/or nonRepudiation (other values are not consistent and shall
       * be rejected).
       */
      if ((x->ex_flags & EXFLAG_KUSAGE)
          && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
              !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
          return 0;
  
      /* Only time stamp key usage is permitted and it's required. */
      if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
          return 0;
  
      /* Extended Key Usage MUST be critical */
      i_ext = X509_get_ext_by_NID((X509 *)x, NID_ext_key_usage, -1);
      if (i_ext >= 0) {
          X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
          if (!X509_EXTENSION_get_critical(ext))
              return 0;
      }
  
      return 1;
  }
  
  static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
  {
      return 1;
  }
  
  /*
   * Various checks to see if one certificate issued the second. This can be
   * used to prune a set of possible issuer certificates which have been looked
   * up using some simple method such as by subject name. These are: 1. Check
   * issuer_name(subject) == subject_name(issuer) 2. If akid(subject) exists
   * check it matches issuer 3. If key_usage(issuer) exists check it supports
   * certificate signing returns 0 for OK, positive for reason for mismatch,
   * reasons match codes for X509_verify_cert()
   */
  
  int X509_check_issued(X509 *issuer, X509 *subject)
  {
      if (X509_NAME_cmp(X509_get_subject_name(issuer),
                        X509_get_issuer_name(subject)))
          return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
      if (!x509v3_cache_extensions(issuer) ||
          !x509v3_cache_extensions(subject)) {
          return X509_V_ERR_UNSPECIFIED;
      }
  
      if (subject->akid) {
          int ret = X509_check_akid(issuer, subject->akid);
          if (ret != X509_V_OK)
              return ret;
      }
  
      if (subject->ex_flags & EXFLAG_PROXY) {
          if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
              return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
      } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
          return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
      return X509_V_OK;
  }
  
  int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
  {
  
      if (!akid)
          return X509_V_OK;
  
      /* Check key ids (if present) */
      if (akid->keyid && issuer->skid &&
          ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
          return X509_V_ERR_AKID_SKID_MISMATCH;
      /* Check serial number */
      if (akid->serial &&
          ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
          return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
      /* Check issuer name */
      if (akid->issuer) {
          /*
           * Ugh, for some peculiar reason AKID includes SEQUENCE OF
           * GeneralName. So look for a DirName. There may be more than one but
           * we only take any notice of the first.
           */
          GENERAL_NAMES *gens;
          GENERAL_NAME *gen;
          X509_NAME *nm = NULL;
          size_t i;
          gens = akid->issuer;
          for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
              gen = sk_GENERAL_NAME_value(gens, i);
              if (gen->type == GEN_DIRNAME) {
                  nm = gen->d.dirn;
                  break;
              }
          }
          if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
              return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
      }
      return X509_V_OK;
  }
  
  uint32_t X509_get_extension_flags(X509 *x)
  {
      /* Ignore the return value. On failure, |x->ex_flags| will include
       * |EXFLAG_INVALID|. */
      x509v3_cache_extensions(x);
      return x->ex_flags;
  }
  
  uint32_t X509_get_key_usage(X509 *x)
  {
      if (!x509v3_cache_extensions(x)) {
          return 0;
      }
      if (x->ex_flags & EXFLAG_KUSAGE)
          return x->ex_kusage;
      return UINT32_MAX;
  }
  
  uint32_t X509_get_extended_key_usage(X509 *x)
  {
      if (!x509v3_cache_extensions(x)) {
          return 0;
      }
      if (x->ex_flags & EXFLAG_XKUSAGE)
          return x->ex_xkusage;
      return UINT32_MAX;
  }
  
  const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x509)
  {
      if (!x509v3_cache_extensions(x509)) {
          return NULL;
      }
      return x509->skid;
  }
  
  const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x509)
  {
      if (!x509v3_cache_extensions(x509)) {
          return NULL;
      }
      return x509->akid != NULL ? x509->akid->keyid : NULL;
  }
  
  const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x509)
  {
      if (!x509v3_cache_extensions(x509)) {
          return NULL;
      }
      return x509->akid != NULL ? x509->akid->issuer : NULL;
  }
  
  const ASN1_INTEGER *X509_get0_authority_serial(X509 *x509)
  {
      if (!x509v3_cache_extensions(x509)) {
          return NULL;
      }
      return x509->akid != NULL ? x509->akid->serial : NULL;
  }
  
  long X509_get_pathlen(X509 *x509)
  {
      if (!x509v3_cache_extensions(x509) ||
          (x509->ex_flags & EXFLAG_BCONS) == 0) {
          return -1;
      }
      return x509->ex_pathlen;
  }
  