text: /*
   * Copyright 1999-2018 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <stdio.h>
  #include "internal/cryptlib.h"
  #include "internal/numbers.h"
  #include <openssl/x509v3.h>
  #include <openssl/x509_vfy.h>
  #include "crypto/x509.h"
  #include "internal/tsan_assist.h"
  
  static void x509v3_cache_extensions(X509 *x);
  
  static int check_ssl_ca(const X509 *x);
  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 *const *a, const X509_PURPOSE *const *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, "SSL client", "sslclient", NULL},
      {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
       check_purpose_ssl_server, "SSL server", "sslserver", NULL},
      {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
       check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
      {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
       "S/MIME signing", "smimesign", NULL},
      {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
       check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
      {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
       "CRL signing", "crlsign", NULL},
      {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
       NULL},
      {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
       "OCSP helper", "ocsphelper", NULL},
      {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
       check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
       NULL},
  };
  
  #define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
  
  static STACK_OF(X509_PURPOSE) *xptable = NULL;
  
  static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *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;
  
      x509v3_cache_extensions(x);
  
      /* Return if side-effect only call */
      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) {
          X509V3err(X509V3_F_X509_PURPOSE_SET, 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(const 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) == 0)
              return i;
      }
      return -1;
  }
  
  int X509_PURPOSE_get_by_id(int purpose)
  {
      X509_PURPOSE tmp;
      int idx;
  
      if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
          return purpose - X509_PURPOSE_MIN;
      if (xptable == NULL)
          return -1;
      tmp.purpose = purpose;
      idx = sk_X509_PURPOSE_find(xptable, &tmp);
      if (idx < 0)
          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),
                       const char *name, const char *sname, void *arg)
  {
      int idx;
      X509_PURPOSE *ptmp;
      /*
       * 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(*ptmp))) == NULL) {
              X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
              return 0;
          }
          ptmp->flags = X509_PURPOSE_DYNAMIC;
      } else
          ptmp = X509_PURPOSE_get0(idx);
  
      /* 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 = OPENSSL_strdup(name);
      ptmp->sname = OPENSSL_strdup(sname);
      if (ptmp->name == NULL|| ptmp->sname == NULL) {
          X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      /* 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 == NULL
              && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
              X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
              goto err;
          }
          if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
              X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
              goto err;
          }
      }
      return 1;
   err:
      if (idx == -1) {
          OPENSSL_free(ptmp->name);
          OPENSSL_free(ptmp->sname);
          OPENSSL_free(ptmp);
      }
      return 0;
  }
  
  static void xptable_free(X509_PURPOSE *p)
  {
      if (p == NULL)
          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)
  {
      sk_X509_PURPOSE_pop_free(xptable, xptable_free);
      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 int *a, const int *b)
  {
      return *a - *b;
  }
  
  DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
  IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
  
  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_crl_distribution_points, /* 103 */
          NID_ext_key_usage,      /* 126 */
  #ifndef OPENSSL_NO_RFC3779
          NID_sbgp_ipAddrBlock,   /* 290 */
          NID_sbgp_autonomousSysNum, /* 291 */
  #endif
          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 (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
          return 1;
      return 0;
  }
  
  static void setup_dp(X509 *x, DIST_POINT *dp)
  {
      X509_NAME *iname = NULL;
      int 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;
      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);
  
      DIST_POINT_set_dpname(dp->distpoint, iname);
  
  }
  
  static void setup_crldp(X509 *x)
  {
      int i;
      x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
      for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
          setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
  }
  
  #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 void 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;
      int i;
  
  #ifdef tsan_ld_acq
      /* fast lock-free check, see end of the function for details. */
      if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
          return;
  #endif
  
      CRYPTO_THREAD_write_lock(x->lock);
      if (x->ex_flags & EXFLAG_SET) {
          CRYPTO_THREAD_unlock(x->lock);
          return;
      }
  
      X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
      /* V1 should mean no extensions ... */
      if (!X509_get_version(x))
          x->ex_flags |= EXFLAG_V1;
      /* Handle basic constraints */
      if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, 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
                  x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
          } else
              x->ex_pathlen = -1;
          BASIC_CONSTRAINTS_free(bs);
          x->ex_flags |= EXFLAG_BCONS;
      }
      /* Handle proxy certificates */
      if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, 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;
      }
      /* Handle key usage */
      if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, 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);
      }
      x->ex_xkusage = 0;
      if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, 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);
      }
  
      if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, 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);
      }
      x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
      x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
      /* 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, NULL, NULL);
      x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
      if (!x->nc && (i != -1))
          x->ex_flags |= EXFLAG_INVALID;
      setup_crldp(x);
  
  #ifndef OPENSSL_NO_RFC3779
      x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
      x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
                                         NULL, NULL);
  #endif
      for (i = 0; i < X509_get_ext_count(x); i++) {
          ex = X509_get_ext(x, i);
          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;
          }
      }
      x509_init_sig_info(x);
      x->ex_flags |= EXFLAG_SET;
  #ifdef tsan_st_rel
      tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
      /*
       * Above store triggers fast lock-free check in the beginning of the
       * function. But one has to ensure that the structure is "stable", i.e.
       * all stores are visible on all processors. Hence the release fence.
       */
  #endif
      CRYPTO_THREAD_unlock(x->lock);
  }
  
  /*-
   * CA checks common to all purposes
   * return codes:
   * 0 not a CA
   * 1 is a CA
   * 2 Only possible in older versions of openSSL when basicConstraints are absent
   *   new versions will not return this value. May be a CA
   * 3 basicConstraints absent but self signed V1.
   * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
   * 5 Netscape specific CA Flags present
   */
  
  static int check_ca(const X509 *x)
  {
      /* keyUsage if present should allow cert signing */
      if (ku_reject(x, KU_KEY_CERT_SIGN))
          return 0;
      if (x->ex_flags & EXFLAG_BCONS) {
          if (x->ex_flags & EXFLAG_CA)
              return 1;
          /* If basicConstraints says not a CA then say so */
          else
              return 0;
      } else {
          /* we support V1 roots for...  uh, I don't really know why. */
          if ((x->ex_flags & V1_ROOT) == V1_ROOT)
              return 3;
          /*
           * If key usage present it must have certSign so tolerate it
           */
          else if (x->ex_flags & EXFLAG_KUSAGE)
              return 4;
          /* Older certificates could have Netscape-specific CA types */
          else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
              return 5;
          /* can this still be regarded a CA certificate?  I doubt it */
          return 0;
      }
  }
  
  void X509_set_proxy_flag(X509 *x)
  {
      x->ex_flags |= EXFLAG_PROXY;
  }
  
  void X509_set_proxy_pathlen(X509 *x, long l)
  {
      x->ex_pcpathlen = l;
  }
  
  int X509_check_ca(X509 *x)
  {
      x509v3_cache_extensions(x);
  
      return check_ca(x);
  }
  
  /* Check SSL CA: common checks for SSL client and server */
  static int check_ssl_ca(const X509 *x)
  {
      int ca_ret;
      ca_ret = check_ca(x);
      if (!ca_ret)
          return 0;
      /* check nsCertType if present */
      if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
          return ca_ret;
      else
          return 0;
  }
  
  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_ssl_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 | XKU_SGC))
          return 0;
      if (ca)
          return check_ssl_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;
  }
  
  /* common S/MIME checks */
  static int purpose_smime(const X509 *x, int ca)
  {
      if (xku_reject(x, XKU_SMIME))
          return 0;
      if (ca) {
          int ca_ret;
          ca_ret = check_ca(x);
          if (!ca_ret)
              return 0;
          /* check nsCertType if present */
          if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
              return ca_ret;
          else
              return 0;
      }
      if (x->ex_flags & EXFLAG_NSCERT) {
          if (x->ex_nscert & NS_SMIME)
              return 1;
          /* Workaround for some buggy certificates */
          if (x->ex_nscert & NS_SSL_CLIENT)
              return 2;
          return 0;
      }
      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) {
          int ca_ret;
          if ((ca_ret = check_ca(x)) != 2)
              return ca_ret;
          else
              return 0;
      }
      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)
  {
      /*
       * Must be a valid CA.  Should we really support the "I don't know" value
       * (2)?
       */
      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(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 that it matches issuer
   * 3. Check that issuer public key algorithm matches subject signature algorithm
   * 4. If key_usage(issuer) exists, check that 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;
  
      x509v3_cache_extensions(issuer);
      x509v3_cache_extensions(subject);
  
      if (subject->akid) {
          int ret = X509_check_akid(issuer, subject->akid);
          if (ret != X509_V_OK)
              return ret;
      }
  
      {
          /*
           * Check if the subject signature algorithm matches the issuer's PUBKEY
           * algorithm
           */
          EVP_PKEY *i_pkey = X509_get0_pubkey(issuer);
          X509_ALGOR *s_algor = &subject->cert_info.signature;
          int s_pknid = NID_undef, s_mdnid = NID_undef;
  
          if (i_pkey == NULL)
              return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
  
          if (!OBJ_find_sigid_algs(OBJ_obj2nid(s_algor->algorithm),
                                   &s_mdnid, &s_pknid)
              || EVP_PKEY_type(s_pknid) != EVP_PKEY_base_id(i_pkey))
              return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
      }
  
      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;
          int 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)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      return x->ex_flags;
  }
  
  uint32_t X509_get_key_usage(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      if (x->ex_flags & EXFLAG_KUSAGE)
          return x->ex_kusage;
      return UINT32_MAX;
  }
  
  uint32_t X509_get_extended_key_usage(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      if (x->ex_flags & EXFLAG_XKUSAGE)
          return x->ex_xkusage;
      return UINT32_MAX;
  }
  
  const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      return x->skid;
  }
  
  const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      return (x->akid != NULL ? x->akid->keyid : NULL);
  }
  
  const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      return (x->akid != NULL ? x->akid->issuer : NULL);
  }
  
  const ASN1_INTEGER *X509_get0_authority_serial(X509 *x)
  {
      /* Call for side-effect of computing hash and caching extensions */
      X509_check_purpose(x, -1, -1);
      return (x->akid != NULL ? x->akid->serial : NULL);
  }
  
  long X509_get_pathlen(X509 *x)
  {
      /* Called for side effect of caching extensions */
      if (X509_check_purpose(x, -1, -1) != 1
              || (x->ex_flags & EXFLAG_BCONS) == 0)
          return -1;
      return x->ex_pathlen;
  }
  
  long X509_get_proxy_pathlen(X509 *x)
  {
      /* Called for side effect of caching extensions */
      if (X509_check_purpose(x, -1, -1) != 1
              || (x->ex_flags & EXFLAG_PROXY) == 0)
          return -1;
      return x->ex_pcpathlen;
  }
  