doc/man3/X509_STORE_CTX_set_verify_cb.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 X509_STORE_CTX_get_cleanup,
 X509_STORE_CTX_get_lookup_crls,
 X509_STORE_CTX_get_lookup_certs,
 X509_STORE_CTX_get_check_policy,
 X509_STORE_CTX_get_cert_crl,
 X509_STORE_CTX_get_check_crl,
 X509_STORE_CTX_get_get_crl,
 X509_STORE_CTX_get_check_revocation,
 X509_STORE_CTX_get_check_issued,
 X509_STORE_CTX_get_get_issuer,
 X509_STORE_CTX_get_verify_cb,
 X509_STORE_CTX_set_verify_cb,
 X509_STORE_CTX_verify_cb,
 X509_STORE_CTX_print_verify_cb
 - get and set X509_STORE_CTX components such as verification callback

 =head1 SYNOPSIS

  #include <openssl/x509_vfy.h>

  typedef int (*X509_STORE_CTX_verify_cb)(int, X509_STORE_CTX *);
  int X509_STORE_CTX_print_verify_cb(int ok, X509_STORE_CTX *ctx);

  X509_STORE_CTX_verify_cb X509_STORE_CTX_get_verify_cb(X509_STORE_CTX *ctx);

  void X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
                                    X509_STORE_CTX_verify_cb verify_cb);

  X509_STORE_CTX_get_issuer_fn X509_STORE_CTX_get_get_issuer(X509_STORE_CTX *ctx);
  X509_STORE_CTX_check_issued_fn X509_STORE_CTX_get_check_issued(X509_STORE_CTX *ctx);
  X509_STORE_CTX_check_revocation_fn X509_STORE_CTX_get_check_revocation(X509_STORE_CTX *ctx);
  X509_STORE_CTX_get_crl_fn X509_STORE_CTX_get_get_crl(X509_STORE_CTX *ctx);
  X509_STORE_CTX_check_crl_fn X509_STORE_CTX_get_check_crl(X509_STORE_CTX *ctx);
  X509_STORE_CTX_cert_crl_fn X509_STORE_CTX_get_cert_crl(X509_STORE_CTX *ctx);
  X509_STORE_CTX_check_policy_fn X509_STORE_CTX_get_check_policy(X509_STORE_CTX *ctx);
  X509_STORE_CTX_lookup_certs_fn X509_STORE_CTX_get_lookup_certs(X509_STORE_CTX *ctx);
  X509_STORE_CTX_lookup_crls_fn X509_STORE_CTX_get_lookup_crls(X509_STORE_CTX *ctx);
  X509_STORE_CTX_cleanup_fn X509_STORE_CTX_get_cleanup(X509_STORE_CTX *ctx);

 =head1 DESCRIPTION

 X509_STORE_CTX_set_verify_cb() sets the verification callback of B<ctx> to
 B<verify_cb> overwriting any existing callback.

 The verification callback can be used to customise the operation of certificate
 verification, for instance by overriding error conditions or logging errors for
 debugging purposes.

 However, a verification callback is B<not> essential and the default operation
 is often sufficient.

 The B<ok> parameter to the callback indicates the value the callback should
 return to retain the default behaviour. If it is zero then an error condition
 is indicated. If it is 1 then no error occurred. If the flag
 B<X509_V_FLAG_NOTIFY_POLICY> is set then B<ok> is set to 2 to indicate the
 policy checking is complete.

 The B<ctx> parameter to the callback is the B<X509_STORE_CTX> structure that
 is performing the verification operation. A callback can examine this
 structure and receive additional information about the error, for example
 by calling X509_STORE_CTX_get_current_cert(). Additional application data can
 be passed to the callback via the B<ex_data> mechanism.

 X509_STORE_CTX_print_verify_cb() is a verification callback function that,
 when a certificate verification has failed, adds an entry to the error queue
 with code B<X509_R_CERTIFICATE_VERIFICATION_FAILED> and with diagnostic details,
 including the most relevant fields of the target certificate that failed to
 verify and, if appropriate, of the available untrusted and trusted certificates.

 X509_STORE_CTX_get_verify_cb() returns the value of the current callback
 for the specific B<ctx>.

 X509_STORE_CTX_get_get_issuer(),
 X509_STORE_CTX_get_check_issued(), X509_STORE_CTX_get_check_revocation(),
 X509_STORE_CTX_get_get_crl(), X509_STORE_CTX_get_check_crl(),
 X509_STORE_CTX_get_cert_crl(), X509_STORE_CTX_get_check_policy(),
 X509_STORE_CTX_get_lookup_certs(), X509_STORE_CTX_get_lookup_crls()
 and X509_STORE_CTX_get_cleanup() return the function pointers cached
 from the corresponding B<X509_STORE>, please see
 L<X509_STORE_set_verify(3)> for more information.


 =head1 WARNINGS

 In general a verification callback should B<NOT> unconditionally return 1 in
 all circumstances because this will allow verification to succeed no matter
 what the error. This effectively removes all security from the application
 because B<any> certificate (including untrusted generated ones) will be
 accepted.

 =head1 NOTES

 The verification callback can be set and inherited from the parent structure
 performing the operation. In some cases (such as S/MIME verification) the
 B<X509_STORE_CTX> structure is created and destroyed internally and the
 only way to set a custom verification callback is by inheriting it from the
 associated B<X509_STORE>.

 =head1 RETURN VALUES

 X509_STORE_CTX_set_verify_cb() does not return a value.

 =head1 EXAMPLES

 Default callback operation:

  int verify_callback(int ok, X509_STORE_CTX *ctx) {
      return ok;
  }

 Simple example, suppose a certificate in the chain is expired and we wish
 to continue after this error:

  int verify_callback(int ok, X509_STORE_CTX *ctx) {
      /* Tolerate certificate expiration */
      if (X509_STORE_CTX_get_error(ctx) == X509_V_ERR_CERT_HAS_EXPIRED)
          return 1;
      /* Otherwise don't override */
      return ok;
  }

 More complex example, we don't wish to continue after B<any> certificate has
 expired just one specific case:

  int verify_callback(int ok, X509_STORE_CTX *ctx)
  {
      int err = X509_STORE_CTX_get_error(ctx);
      X509 *err_cert = X509_STORE_CTX_get_current_cert(ctx);

      if (err == X509_V_ERR_CERT_HAS_EXPIRED) {
          if (check_is_acceptable_expired_cert(err_cert)
              return 1;
      }
      return ok;
  }

 Full featured logging callback. In this case the B<bio_err> is assumed to be
 a global logging B<BIO>, an alternative would to store a BIO in B<ctx> using
 B<ex_data>.

  int verify_callback(int ok, X509_STORE_CTX *ctx)
  {
      X509 *err_cert;
      int err, depth;

      err_cert = X509_STORE_CTX_get_current_cert(ctx);
      err = X509_STORE_CTX_get_error(ctx);
      depth = X509_STORE_CTX_get_error_depth(ctx);

      BIO_printf(bio_err, "depth=%d ", depth);
      if (err_cert) {
          X509_NAME_print_ex(bio_err, X509_get_subject_name(err_cert),
                             0, XN_FLAG_ONELINE);
          BIO_puts(bio_err, "\n");
      }
      else
          BIO_puts(bio_err, "<no cert>\n");
      if (!ok)
          BIO_printf(bio_err, "verify error:num=%d:%s\n", err,
                     X509_verify_cert_error_string(err));
      switch (err) {
      case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
          BIO_puts(bio_err, "issuer= ");
          X509_NAME_print_ex(bio_err, X509_get_issuer_name(err_cert),
                             0, XN_FLAG_ONELINE);
          BIO_puts(bio_err, "\n");
          break;
      case X509_V_ERR_CERT_NOT_YET_VALID:
      case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
          BIO_printf(bio_err, "notBefore=");
          ASN1_TIME_print(bio_err, X509_get_notBefore(err_cert));
          BIO_printf(bio_err, "\n");
          break;
      case X509_V_ERR_CERT_HAS_EXPIRED:
      case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
          BIO_printf(bio_err, "notAfter=");
          ASN1_TIME_print(bio_err, X509_get_notAfter(err_cert));
          BIO_printf(bio_err, "\n");
          break;
      case X509_V_ERR_NO_EXPLICIT_POLICY:
          policies_print(bio_err, ctx);
          break;
      }
      if (err == X509_V_OK && ok == 2)
          /* print out policies */

      BIO_printf(bio_err, "verify return:%d\n", ok);
      return(ok);
  }

 =head1 SEE ALSO

 L<X509_STORE_CTX_get_error(3)>
 L<X509_STORE_set_verify_cb_func(3)>
 L<X509_STORE_CTX_get_ex_new_index(3)>

 =head1 HISTORY

 The
 X509_STORE_CTX_get_get_issuer(),
 X509_STORE_CTX_get_check_issued(), X509_STORE_CTX_get_check_revocation(),
 X509_STORE_CTX_get_get_crl(), X509_STORE_CTX_get_check_crl(),
 X509_STORE_CTX_get_cert_crl(), X509_STORE_CTX_get_check_policy(),
 X509_STORE_CTX_get_lookup_certs(), X509_STORE_CTX_get_lookup_crls()
 and X509_STORE_CTX_get_cleanup() functions were added in OpenSSL 1.1.0.

 X509_STORE_CTX_print_verify_cb() was added in OpenSSL 3.0.

 =head1 COPYRIGHT

 Copyright 2009-2020 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
 L<https://www.openssl.org/source/license.html>.

 =cut
	=pod

	=head1 NAME

	X509_STORE_CTX_get_cleanup,
	X509_STORE_CTX_get_lookup_crls,
	X509_STORE_CTX_get_lookup_certs,
	X509_STORE_CTX_get_check_policy,
	X509_STORE_CTX_get_cert_crl,
	X509_STORE_CTX_get_check_crl,
	X509_STORE_CTX_get_get_crl,
	X509_STORE_CTX_get_check_revocation,
	X509_STORE_CTX_get_check_issued,
	X509_STORE_CTX_get_get_issuer,
	X509_STORE_CTX_get_verify_cb,
	X509_STORE_CTX_set_verify_cb,
	X509_STORE_CTX_verify_cb,
	X509_STORE_CTX_print_verify_cb
	- get and set X509_STORE_CTX components such as verification callback

	=head1 SYNOPSIS

	#include <openssl/x509_vfy.h>

	typedef int (X509_STORE_CTX_verify_cb)(int, X509_STORE_CTX );
	int X509_STORE_CTX_print_verify_cb(int ok, X509_STORE_CTX *ctx);

	X509_STORE_CTX_verify_cb X509_STORE_CTX_get_verify_cb(X509_STORE_CTX *ctx);

	void X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
	X509_STORE_CTX_verify_cb verify_cb);

	X509_STORE_CTX_get_issuer_fn X509_STORE_CTX_get_get_issuer(X509_STORE_CTX *ctx);
	X509_STORE_CTX_check_issued_fn X509_STORE_CTX_get_check_issued(X509_STORE_CTX *ctx);
	X509_STORE_CTX_check_revocation_fn X509_STORE_CTX_get_check_revocation(X509_STORE_CTX *ctx);
	X509_STORE_CTX_get_crl_fn X509_STORE_CTX_get_get_crl(X509_STORE_CTX *ctx);
	X509_STORE_CTX_check_crl_fn X509_STORE_CTX_get_check_crl(X509_STORE_CTX *ctx);
	X509_STORE_CTX_cert_crl_fn X509_STORE_CTX_get_cert_crl(X509_STORE_CTX *ctx);
	X509_STORE_CTX_check_policy_fn X509_STORE_CTX_get_check_policy(X509_STORE_CTX *ctx);
	X509_STORE_CTX_lookup_certs_fn X509_STORE_CTX_get_lookup_certs(X509_STORE_CTX *ctx);
	X509_STORE_CTX_lookup_crls_fn X509_STORE_CTX_get_lookup_crls(X509_STORE_CTX *ctx);
	X509_STORE_CTX_cleanup_fn X509_STORE_CTX_get_cleanup(X509_STORE_CTX *ctx);

	=head1 DESCRIPTION

	X509_STORE_CTX_set_verify_cb() sets the verification callback of B<ctx> to
	B<verify_cb> overwriting any existing callback.

	The verification callback can be used to customise the operation of certificate
	verification, for instance by overriding error conditions or logging errors for
	debugging purposes.

	However, a verification callback is B<not> essential and the default operation
	is often sufficient.

	The B<ok> parameter to the callback indicates the value the callback should
	return to retain the default behaviour. If it is zero then an error condition
	is indicated. If it is 1 then no error occurred. If the flag
	B<X509_V_FLAG_NOTIFY_POLICY> is set then B<ok> is set to 2 to indicate the
	policy checking is complete.

	The B<ctx> parameter to the callback is the B<X509_STORE_CTX> structure that
	is performing the verification operation. A callback can examine this
	structure and receive additional information about the error, for example
	by calling X509_STORE_CTX_get_current_cert(). Additional application data can
	be passed to the callback via the B<ex_data> mechanism.

	X509_STORE_CTX_print_verify_cb() is a verification callback function that,
	when a certificate verification has failed, adds an entry to the error queue
	with code B<X509_R_CERTIFICATE_VERIFICATION_FAILED> and with diagnostic details,
	including the most relevant fields of the target certificate that failed to
	verify and, if appropriate, of the available untrusted and trusted certificates.

	X509_STORE_CTX_get_verify_cb() returns the value of the current callback
	for the specific B<ctx>.

	X509_STORE_CTX_get_get_issuer(),
	X509_STORE_CTX_get_check_issued(), X509_STORE_CTX_get_check_revocation(),
	X509_STORE_CTX_get_get_crl(), X509_STORE_CTX_get_check_crl(),
	X509_STORE_CTX_get_cert_crl(), X509_STORE_CTX_get_check_policy(),
	X509_STORE_CTX_get_lookup_certs(), X509_STORE_CTX_get_lookup_crls()
	and X509_STORE_CTX_get_cleanup() return the function pointers cached
	from the corresponding B<X509_STORE>, please see
	L<X509_STORE_set_verify(3)> for more information.


	=head1 WARNINGS

	In general a verification callback should B<NOT> unconditionally return 1 in
	all circumstances because this will allow verification to succeed no matter
	what the error. This effectively removes all security from the application
	because B<any> certificate (including untrusted generated ones) will be
	accepted.

	=head1 NOTES

	The verification callback can be set and inherited from the parent structure
	performing the operation. In some cases (such as S/MIME verification) the
	B<X509_STORE_CTX> structure is created and destroyed internally and the
	only way to set a custom verification callback is by inheriting it from the
	associated B<X509_STORE>.

	=head1 RETURN VALUES

	X509_STORE_CTX_set_verify_cb() does not return a value.

	=head1 EXAMPLES

	Default callback operation:

	int verify_callback(int ok, X509_STORE_CTX *ctx) {
	return ok;
	}

	Simple example, suppose a certificate in the chain is expired and we wish
	to continue after this error:

	int verify_callback(int ok, X509_STORE_CTX *ctx) {
	/* Tolerate certificate expiration */
	if (X509_STORE_CTX_get_error(ctx) == X509_V_ERR_CERT_HAS_EXPIRED)
	return 1;
	/* Otherwise don't override */
	return ok;
	}

	More complex example, we don't wish to continue after B<any> certificate has
	expired just one specific case:

	int verify_callback(int ok, X509_STORE_CTX *ctx)
	{
	int err = X509_STORE_CTX_get_error(ctx);
	X509 *err_cert = X509_STORE_CTX_get_current_cert(ctx);

	if (err == X509_V_ERR_CERT_HAS_EXPIRED) {
	if (check_is_acceptable_expired_cert(err_cert)
	return 1;
	}
	return ok;
	}

	Full featured logging callback. In this case the B<bio_err> is assumed to be
	a global logging B<BIO>, an alternative would to store a BIO in B<ctx> using
	B<ex_data>.

	int verify_callback(int ok, X509_STORE_CTX *ctx)
	{
	X509 *err_cert;
	int err, depth;

	err_cert = X509_STORE_CTX_get_current_cert(ctx);
	err = X509_STORE_CTX_get_error(ctx);
	depth = X509_STORE_CTX_get_error_depth(ctx);

	BIO_printf(bio_err, "depth=%d ", depth);
	if (err_cert) {
	X509_NAME_print_ex(bio_err, X509_get_subject_name(err_cert),
	0, XN_FLAG_ONELINE);
	BIO_puts(bio_err, "\n");
	}
	else
	BIO_puts(bio_err, "<no cert>\n");
	if (!ok)
	BIO_printf(bio_err, "verify error:num=%d:%s\n", err,
	X509_verify_cert_error_string(err));
	switch (err) {
	case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
	BIO_puts(bio_err, "issuer= ");
	X509_NAME_print_ex(bio_err, X509_get_issuer_name(err_cert),
	0, XN_FLAG_ONELINE);
	BIO_puts(bio_err, "\n");
	break;
	case X509_V_ERR_CERT_NOT_YET_VALID:
	case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
	BIO_printf(bio_err, "notBefore=");
	ASN1_TIME_print(bio_err, X509_get_notBefore(err_cert));
	BIO_printf(bio_err, "\n");
	break;
	case X509_V_ERR_CERT_HAS_EXPIRED:
	case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
	BIO_printf(bio_err, "notAfter=");
	ASN1_TIME_print(bio_err, X509_get_notAfter(err_cert));
	BIO_printf(bio_err, "\n");
	break;
	case X509_V_ERR_NO_EXPLICIT_POLICY:
	policies_print(bio_err, ctx);
	break;
	}
	if (err == X509_V_OK && ok == 2)
	/* print out policies */

	BIO_printf(bio_err, "verify return:%d\n", ok);
	return(ok);
	}

	=head1 SEE ALSO

	L<X509_STORE_CTX_get_error(3)>
	L<X509_STORE_set_verify_cb_func(3)>
	L<X509_STORE_CTX_get_ex_new_index(3)>

	=head1 HISTORY

	The
	X509_STORE_CTX_get_get_issuer(),
	X509_STORE_CTX_get_check_issued(), X509_STORE_CTX_get_check_revocation(),
	X509_STORE_CTX_get_get_crl(), X509_STORE_CTX_get_check_crl(),
	X509_STORE_CTX_get_cert_crl(), X509_STORE_CTX_get_check_policy(),
	X509_STORE_CTX_get_lookup_certs(), X509_STORE_CTX_get_lookup_crls()
	and X509_STORE_CTX_get_cleanup() functions were added in OpenSSL 1.1.0.

	X509_STORE_CTX_print_verify_cb() was added in OpenSSL 3.0.

	=head1 COPYRIGHT

	Copyright 2009-2020 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
	L<https://www.openssl.org/source/license.html>.

	=cut