doc/man3/X509_VERIFY_PARAM_set_flags.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags,
 X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose,
 X509_VERIFY_PARAM_get_inh_flags, X509_VERIFY_PARAM_set_inh_flags,
 X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
 X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
 X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time,
 X509_VERIFY_PARAM_get_time,
 X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
 X509_VERIFY_PARAM_get0_host,
 X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
 X509_VERIFY_PARAM_set_hostflags,
 X509_VERIFY_PARAM_get_hostflags,
 X509_VERIFY_PARAM_get0_peername,
 X509_VERIFY_PARAM_get0_email, X509_VERIFY_PARAM_set1_email,
 X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_get1_ip_asc,
 X509_VERIFY_PARAM_set1_ip_asc
 - X509 verification parameters

 =head1 SYNOPSIS

  #include <openssl/x509_vfy.h>

  int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
                                  unsigned long flags);
  int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
                                    unsigned long flags);
  unsigned long X509_VERIFY_PARAM_get_flags(const X509_VERIFY_PARAM *param);

  int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
                                      uint32_t flags);
  uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);

  int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
  int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);

  void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
  time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);

  int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
                                    ASN1_OBJECT *policy);
  int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
                                      STACK_OF(ASN1_OBJECT) *policies);

  void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
  int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);

  void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
                                        int auth_level);
  int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);

  char *X509_VERIFY_PARAM_get0_host(X509_VERIFY_PARAM *param, int n);
  int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
                                  const char *name, size_t namelen);
  int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
                                  const char *name, size_t namelen);
  void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
                                       unsigned int flags);
  unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
  char *X509_VERIFY_PARAM_get0_peername(const X509_VERIFY_PARAM *param);
  char *X509_VERIFY_PARAM_get0_email(X509_VERIFY_PARAM *param);
  int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
                                   const char *email, size_t emaillen);
  char *X509_VERIFY_PARAM_get1_ip_asc(X509_VERIFY_PARAM *param);
  int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
                                const unsigned char *ip, size_t iplen);
  int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);

 =head1 DESCRIPTION

 These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
 a certificate verification operation.

 The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
 it with B<flags>. See L</VERIFICATION FLAGS> for a complete
 description of values the B<flags> parameter can take.

 X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.

 X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
 which specifies how verification flags are copied from one structure to
 another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
 See the B<INHERITANCE FLAGS> section for a description of these bits.

 X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.

 X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
 to B<purpose>. This determines the acceptable purpose of the certificate
 chain, for example B<X509_PURPOSE_SSL_CLIENT>.

 X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
 B<trust>.

 X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
 B<t>. Normally the current time is used.

 X509_VERIFY_PARAM_add0_policy() enables policy checking (it is disabled
 by default) and adds B<policy> to the acceptable policy set.

 X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
 by default) and sets the acceptable policy set to B<policies>. Any existing
 policy set is cleared. The B<policies> parameter can be B<NULL> to clear
 an existing policy set.

 X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
 That is the maximum number of intermediate CA certificates that can appear in a
 chain.
 A maximal depth chain contains 2 more certificates than the limit, since
 neither the end-entity certificate nor the trust-anchor count against this
 limit.
 Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
 directly by the trust anchor, while with a B<depth> limit of 1 there can be one
 intermediate CA certificate between the trust anchor and the end-entity
 certificate.

 X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
 B<auth_level>.
 The authentication security level determines the acceptable signature and public
 key strength when verifying certificate chains.
 For a certificate chain to validate, the public keys of all the certificates
 must meet the specified security level.
 The signature algorithm security level is not enforced for the chain's I<trust
 anchor> certificate, which is either directly trusted or validated by means other
 than its signature.
 See L<SSL_CTX_set_security_level(3)> for the definitions of the available
 levels.
 The default security level is -1, or "not set".
 At security level 0 or lower all algorithms are acceptable.
 Security level 1 requires at least 80-bit-equivalent security and is broadly
 interoperable, though it will, for example, reject MD5 signatures or RSA keys
 shorter than 1024 bits.

 X509_VERIFY_PARAM_get0_host() returns the B<n>th expected DNS hostname that has
 been set using X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host().
 To obtain all names start with B<n> = 0 and increment B<n> as long as no NULL
 pointer is returned.

 X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
 B<name> clearing any previously specified hostname.  If
 B<name> is NULL, or empty the list of hostnames is cleared, and
 name checks are not performed on the peer certificate.  If B<name>
 is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
 must be set to the length of B<name>.

 When a hostname is specified,
 certificate verification automatically invokes L<X509_check_host(3)>
 with flags equal to the B<flags> argument given to
 X509_VERIFY_PARAM_set_hostflags() (default zero).  Applications
 are strongly advised to use this interface in preference to explicitly
 calling L<X509_check_host(3)>, hostname checks may be out of scope
 with the DANE-EE(3) certificate usage, and the internal check will
 be suppressed as appropriate when DANE verification is enabled.

 When the subject CommonName will not be ignored, whether as a result of the
 B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
 alternative names are present in the certificate, any DNS name constraints in
 issuer certificates apply to the subject CommonName as well as the subject
 alternative name extension.

 When the subject CommonName will be ignored, whether as a result of the
 B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
 alternative names are present in the certificate, DNS name constraints in
 issuer certificates will not be applied to the subject DN.
 As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
 flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.

 X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
 call to X509_VERIFY_PARAM_set_hostflags().

 X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
 identifier that can match the peer's certificate.  Any previous names
 set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
 are retained, no change is made if B<name> is NULL or empty.  When
 multiple names are configured, the peer is considered verified when
 any name matches.

 X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
 CommonName from the peer certificate that matched one of the reference
 identifiers.  When wildcard matching is not disabled, or when a
 reference identifier specifies a parent domain (starts with ".")
 rather than a hostname, the peer name may be a wildcard name or a
 sub-domain of the reference identifier respectively.  The return
 string is allocated by the library and is no longer valid once the
 associated B<param> argument is freed.  Applications must not free
 the return value.

 X509_VERIFY_PARAM_get0_email() returns the expected RFC822 email address.

 X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
 B<email>.  If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
 B<emaillen> must be set to the length of B<email>.  When an email address
 is specified, certificate verification automatically invokes
 L<X509_check_email(3)>.

 X509_VERIFY_PARAM_get1_ip_asc() returns the expected IP address as a string.
 The caller is responsible for freeing it.

 X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
 The B<ip> argument is in binary format, in network byte-order and
 B<iplen> must be set to 4 for IPv4 and 16 for IPv6.  When an IP
 address is specified, certificate verification automatically invokes
 L<X509_check_ip(3)>.

 X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
 B<ipasc>.  The B<ipasc> argument is a NUL-terminal ASCII string:
 dotted decimal quad for IPv4 and colon-separated hexadecimal for
 IPv6.  The condensed "::" notation is supported for IPv6 addresses.

 =head1 RETURN VALUES

 X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
 X509_VERIFY_PARAM_set_inh_flags(),
 X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
 X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
 X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
 X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
 X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
 failure.

 X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
 X509_VERIFY_PARAM_get1_ip_asc(), return the string pointers specified above
 or NULL if the respective value has not been set or on error.

 X509_VERIFY_PARAM_get_flags() returns the current verification flags.

 X509_VERIFY_PARAM_get_hostflags() returns any current host flags.

 X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.

 X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
 values.

 X509_VERIFY_PARAM_get_depth() returns the current verification depth.

 X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
 level.

 =head1 VERIFICATION FLAGS

 The verification flags consists of zero or more of the following flags
 ored together.

 B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
 certificate. An error occurs if a suitable CRL cannot be found.

 B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
 chain.

 B<X509_V_FLAG_IGNORE_CRITICAL> disabled critical extension checking. By default
 any unhandled critical extensions in certificates or (if checked) CRLs results
 in a fatal error. If this flag is set unhandled critical extensions are
 ignored. B<WARNING> setting this option for anything other than debugging
 purposes can be a security risk. Finer control over which extensions are
 supported can be performed in the verification callback.

 The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
 certificates and makes the verification strictly apply B<X509> rules.

 B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.

 B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
 no policy checking is performed. Additional information is sent to the
 verification callback relating to policy checking.

 B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
 B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
 policy> and B<inhibit policy mapping> flags respectively as defined in
 B<RFC3280>. Policy checking is automatically enabled if any of these flags
 are set.

 If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
 a special status code is set to the verification callback. This permits it
 to examine the valid policy tree and perform additional checks or simply
 log it for debugging purposes.

 By default some additional features such as indirect CRLs and CRLs signed by
 different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
 they are enabled.

 If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
 determine certificate status. If not set deltas are ignored.

 B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of
 the last certificate in a chain if the certificate is supposedly self-signed.
 This is prohibited and will result in an error if it is a non-conforming CA
 certificate with key usage restrictions not including the I<keyCertSign> bit.
 By default this check is disabled because it doesn't
 add any additional security but in some cases applications might want to
 check the signature anyway. A side effect of not checking the self-signature
 of such a certificate is that disabled or unsupported message digests used for
 the signature are not treated as fatal errors.

 When B<X509_V_FLAG_TRUSTED_FIRST> is set, which is always the case since
 OpenSSL 1.1.0, construction of the certificate chain
 in L<X509_verify_cert(3)> searches the trust store for issuer certificates
 before searching the provided untrusted certificates.
 Local issuer certificates are often more likely to satisfy local security
 requirements and lead to a locally trusted root.
 This is especially important when some certificates in the trust store have
 explicit trust settings (see "TRUST SETTINGS" in L<openssl-x509(1)>).

 The B<X509_V_FLAG_NO_ALT_CHAINS> flag could have been used before OpenSSL 1.1.0
 to suppress checking for alternative chains.
 By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
 certificate chain, if the first certificate chain found is not trusted, then
 OpenSSL will attempt to replace untrusted certificates supplied by the peer
 with certificates from the trust store to see if an alternative chain can be
 found that is trusted.
 As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
 has no effect.

 The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes non-self-signed certificates in the
 trust store to be treated as trust anchors, in the same way as self-signed
 root CA certificates.
 This makes it possible to trust self-issued certificates as well as certificates
 issued by an intermediate CA without having to trust their ancestor root CA.
 With OpenSSL 1.1.0 and later and B<X509_V_FLAG_PARTIAL_CHAIN> set, chain
 construction stops as soon as the first certificate contained in the trust store
 is added to the chain, whether that certificate is a self-signed "root"
 certificate or a not self-signed "intermediate" or self-issued certificate.
 Thus, when an intermediate certificate is found in the trust store, the
 verified chain passed to callbacks may be shorter than it otherwise would
 be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.

 The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
 of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
 is used to specify a verification time, the check is not suppressed.

 =head1 INHERITANCE FLAGS

 These flags specify how parameters are "inherited" from one structure to
 another.

 If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
 after the next call.

 If B<X509_VP_FLAG_LOCKED> is set then no values are copied.  This overrides
 all of the following flags.

 If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
 to the destination. Effectively the values in "to" become default values
 which will be used only if nothing new is set in "from".  This is the
 default.

 If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
 they are set or not. Flags is still Ored though.

 If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
 of ORed.

 =head1 NOTES

 The above functions should be used to manipulate verification parameters
 instead of functions which work in specific structures such as
 X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
 release.

 =head1 BUGS

 Delta CRL checking is currently primitive. Only a single delta can be used and
 (partly due to limitations of B<X509_STORE>) constructed CRLs are not
 maintained.

 If CRLs checking is enable CRLs are expected to be available in the
 corresponding B<X509_STORE> structure. No attempt is made to download
 CRLs from the CRL distribution points extension.

 =head1 EXAMPLES

 Enable CRL checking when performing certificate verification during SSL
 connections associated with an B<SSL_CTX> structure B<ctx>:

  X509_VERIFY_PARAM *param;

  param = X509_VERIFY_PARAM_new();
  X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
  SSL_CTX_set1_param(ctx, param);
  X509_VERIFY_PARAM_free(param);

 =head1 SEE ALSO

 L<X509_verify_cert(3)>,
 L<X509_check_host(3)>,
 L<X509_check_email(3)>,
 L<X509_check_ip(3)>,
 L<openssl-x509(1)>

 =head1 HISTORY

 The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
 The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
 and has no effect.

 The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.

 The X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(),
 and X509_VERIFY_PARAM_get1_ip_asc() functions were added in OpenSSL 3.0.

 =head1 COPYRIGHT

 Copyright 2009-2021 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_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags,
	X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose,
	X509_VERIFY_PARAM_get_inh_flags, X509_VERIFY_PARAM_set_inh_flags,
	X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
	X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
	X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time,
	X509_VERIFY_PARAM_get_time,
	X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
	X509_VERIFY_PARAM_get0_host,
	X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
	X509_VERIFY_PARAM_set_hostflags,
	X509_VERIFY_PARAM_get_hostflags,
	X509_VERIFY_PARAM_get0_peername,
	X509_VERIFY_PARAM_get0_email, X509_VERIFY_PARAM_set1_email,
	X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_get1_ip_asc,
	X509_VERIFY_PARAM_set1_ip_asc
	- X509 verification parameters

	=head1 SYNOPSIS

	#include <openssl/x509_vfy.h>

	int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
	unsigned long flags);
	int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
	unsigned long flags);
	unsigned long X509_VERIFY_PARAM_get_flags(const X509_VERIFY_PARAM *param);

	int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
	uint32_t flags);
	uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);

	int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
	int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);

	void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
	time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);

	int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
	ASN1_OBJECT *policy);
	int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
	STACK_OF(ASN1_OBJECT) *policies);

	void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
	int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);

	void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
	int auth_level);
	int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);

	char X509_VERIFY_PARAM_get0_host(X509_VERIFY_PARAM param, int n);
	int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
	const char *name, size_t namelen);
	int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
	const char *name, size_t namelen);
	void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
	unsigned int flags);
	unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
	char X509_VERIFY_PARAM_get0_peername(const X509_VERIFY_PARAM param);
	char X509_VERIFY_PARAM_get0_email(X509_VERIFY_PARAM param);
	int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
	const char *email, size_t emaillen);
	char X509_VERIFY_PARAM_get1_ip_asc(X509_VERIFY_PARAM param);
	int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
	const unsigned char *ip, size_t iplen);
	int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM param, const char ipasc);

	=head1 DESCRIPTION

	These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
	a certificate verification operation.

	The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
	it with B<flags>. See L</VERIFICATION FLAGS> for a complete
	description of values the B<flags> parameter can take.

	X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.

	X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
	which specifies how verification flags are copied from one structure to
	another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
	See the B<INHERITANCE FLAGS> section for a description of these bits.

	X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.

	X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
	to B<purpose>. This determines the acceptable purpose of the certificate
	chain, for example B<X509_PURPOSE_SSL_CLIENT>.

	X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
	B<trust>.

	X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
	B<t>. Normally the current time is used.

	X509_VERIFY_PARAM_add0_policy() enables policy checking (it is disabled
	by default) and adds B<policy> to the acceptable policy set.

	X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
	by default) and sets the acceptable policy set to B<policies>. Any existing
	policy set is cleared. The B<policies> parameter can be B<NULL> to clear
	an existing policy set.

	X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
	That is the maximum number of intermediate CA certificates that can appear in a
	chain.
	A maximal depth chain contains 2 more certificates than the limit, since
	neither the end-entity certificate nor the trust-anchor count against this
	limit.
	Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
	directly by the trust anchor, while with a B<depth> limit of 1 there can be one
	intermediate CA certificate between the trust anchor and the end-entity
	certificate.

	X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
	B<auth_level>.
	The authentication security level determines the acceptable signature and public
	key strength when verifying certificate chains.
	For a certificate chain to validate, the public keys of all the certificates
	must meet the specified security level.
	The signature algorithm security level is not enforced for the chain's I<trust
	anchor> certificate, which is either directly trusted or validated by means other
	than its signature.
	See L<SSL_CTX_set_security_level(3)> for the definitions of the available
	levels.
	The default security level is -1, or "not set".
	At security level 0 or lower all algorithms are acceptable.
	Security level 1 requires at least 80-bit-equivalent security and is broadly
	interoperable, though it will, for example, reject MD5 signatures or RSA keys
	shorter than 1024 bits.

	X509_VERIFY_PARAM_get0_host() returns the B<n>th expected DNS hostname that has
	been set using X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host().
	To obtain all names start with B<n> = 0 and increment B<n> as long as no NULL
	pointer is returned.

	X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
	B<name> clearing any previously specified hostname. If
	B<name> is NULL, or empty the list of hostnames is cleared, and
	name checks are not performed on the peer certificate. If B<name>
	is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
	must be set to the length of B<name>.

	When a hostname is specified,
	certificate verification automatically invokes L<X509_check_host(3)>
	with flags equal to the B<flags> argument given to
	X509_VERIFY_PARAM_set_hostflags() (default zero). Applications
	are strongly advised to use this interface in preference to explicitly
	calling L<X509_check_host(3)>, hostname checks may be out of scope
	with the DANE-EE(3) certificate usage, and the internal check will
	be suppressed as appropriate when DANE verification is enabled.

	When the subject CommonName will not be ignored, whether as a result of the
	B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
	alternative names are present in the certificate, any DNS name constraints in
	issuer certificates apply to the subject CommonName as well as the subject
	alternative name extension.

	When the subject CommonName will be ignored, whether as a result of the
	B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
	alternative names are present in the certificate, DNS name constraints in
	issuer certificates will not be applied to the subject DN.
	As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
	flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.

	X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
	call to X509_VERIFY_PARAM_set_hostflags().

	X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
	identifier that can match the peer's certificate. Any previous names
	set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
	are retained, no change is made if B<name> is NULL or empty. When
	multiple names are configured, the peer is considered verified when
	any name matches.

	X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
	CommonName from the peer certificate that matched one of the reference
	identifiers. When wildcard matching is not disabled, or when a
	reference identifier specifies a parent domain (starts with ".")
	rather than a hostname, the peer name may be a wildcard name or a
	sub-domain of the reference identifier respectively. The return
	string is allocated by the library and is no longer valid once the
	associated B<param> argument is freed. Applications must not free
	the return value.

	X509_VERIFY_PARAM_get0_email() returns the expected RFC822 email address.

	X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
	B<email>. If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
	B<emaillen> must be set to the length of B<email>. When an email address
	is specified, certificate verification automatically invokes
	L<X509_check_email(3)>.

	X509_VERIFY_PARAM_get1_ip_asc() returns the expected IP address as a string.
	The caller is responsible for freeing it.

	X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
	The B<ip> argument is in binary format, in network byte-order and
	B<iplen> must be set to 4 for IPv4 and 16 for IPv6. When an IP
	address is specified, certificate verification automatically invokes
	L<X509_check_ip(3)>.

	X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
	B<ipasc>. The B<ipasc> argument is a NUL-terminal ASCII string:
	dotted decimal quad for IPv4 and colon-separated hexadecimal for
	IPv6. The condensed "::" notation is supported for IPv6 addresses.

	=head1 RETURN VALUES

	X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
	X509_VERIFY_PARAM_set_inh_flags(),
	X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
	X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
	X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
	X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
	X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
	failure.

	X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
	X509_VERIFY_PARAM_get1_ip_asc(), return the string pointers specified above
	or NULL if the respective value has not been set or on error.

	X509_VERIFY_PARAM_get_flags() returns the current verification flags.

	X509_VERIFY_PARAM_get_hostflags() returns any current host flags.

	X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.

	X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
	values.

	X509_VERIFY_PARAM_get_depth() returns the current verification depth.

	X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
	level.

	=head1 VERIFICATION FLAGS

	The verification flags consists of zero or more of the following flags
	ored together.

	B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
	certificate. An error occurs if a suitable CRL cannot be found.

	B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
	chain.

	B<X509_V_FLAG_IGNORE_CRITICAL> disabled critical extension checking. By default
	any unhandled critical extensions in certificates or (if checked) CRLs results
	in a fatal error. If this flag is set unhandled critical extensions are
	ignored. B<WARNING> setting this option for anything other than debugging
	purposes can be a security risk. Finer control over which extensions are
	supported can be performed in the verification callback.

	The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
	certificates and makes the verification strictly apply B<X509> rules.

	B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.

	B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
	no policy checking is performed. Additional information is sent to the
	verification callback relating to policy checking.

	B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
	B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
	policy> and B<inhibit policy mapping> flags respectively as defined in
	B<RFC3280>. Policy checking is automatically enabled if any of these flags
	are set.

	If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
	a special status code is set to the verification callback. This permits it
	to examine the valid policy tree and perform additional checks or simply
	log it for debugging purposes.

	By default some additional features such as indirect CRLs and CRLs signed by
	different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
	they are enabled.

	If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
	determine certificate status. If not set deltas are ignored.

	B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of
	the last certificate in a chain if the certificate is supposedly self-signed.
	This is prohibited and will result in an error if it is a non-conforming CA
	certificate with key usage restrictions not including the I<keyCertSign> bit.
	By default this check is disabled because it doesn't
	add any additional security but in some cases applications might want to
	check the signature anyway. A side effect of not checking the self-signature
	of such a certificate is that disabled or unsupported message digests used for
	the signature are not treated as fatal errors.

	When B<X509_V_FLAG_TRUSTED_FIRST> is set, which is always the case since
	OpenSSL 1.1.0, construction of the certificate chain
	in L<X509_verify_cert(3)> searches the trust store for issuer certificates
	before searching the provided untrusted certificates.
	Local issuer certificates are often more likely to satisfy local security
	requirements and lead to a locally trusted root.
	This is especially important when some certificates in the trust store have
	explicit trust settings (see "TRUST SETTINGS" in L<openssl-x509(1)>).

	The B<X509_V_FLAG_NO_ALT_CHAINS> flag could have been used before OpenSSL 1.1.0
	to suppress checking for alternative chains.
	By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
	certificate chain, if the first certificate chain found is not trusted, then
	OpenSSL will attempt to replace untrusted certificates supplied by the peer
	with certificates from the trust store to see if an alternative chain can be
	found that is trusted.
	As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
	has no effect.

	The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes non-self-signed certificates in the
	trust store to be treated as trust anchors, in the same way as self-signed
	root CA certificates.
	This makes it possible to trust self-issued certificates as well as certificates
	issued by an intermediate CA without having to trust their ancestor root CA.
	With OpenSSL 1.1.0 and later and B<X509_V_FLAG_PARTIAL_CHAIN> set, chain
	construction stops as soon as the first certificate contained in the trust store
	is added to the chain, whether that certificate is a self-signed "root"
	certificate or a not self-signed "intermediate" or self-issued certificate.
	Thus, when an intermediate certificate is found in the trust store, the
	verified chain passed to callbacks may be shorter than it otherwise would
	be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.

	The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
	of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
	is used to specify a verification time, the check is not suppressed.

	=head1 INHERITANCE FLAGS

	These flags specify how parameters are "inherited" from one structure to
	another.

	If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
	after the next call.

	If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides
	all of the following flags.

	If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
	to the destination. Effectively the values in "to" become default values
	which will be used only if nothing new is set in "from". This is the
	default.

	If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
	they are set or not. Flags is still Ored though.

	If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
	of ORed.

	=head1 NOTES

	The above functions should be used to manipulate verification parameters
	instead of functions which work in specific structures such as
	X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
	release.

	=head1 BUGS

	Delta CRL checking is currently primitive. Only a single delta can be used and
	(partly due to limitations of B<X509_STORE>) constructed CRLs are not
	maintained.

	If CRLs checking is enable CRLs are expected to be available in the
	corresponding B<X509_STORE> structure. No attempt is made to download
	CRLs from the CRL distribution points extension.

	=head1 EXAMPLES

	Enable CRL checking when performing certificate verification during SSL
	connections associated with an B<SSL_CTX> structure B<ctx>:

	X509_VERIFY_PARAM *param;

	param = X509_VERIFY_PARAM_new();
	X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
	SSL_CTX_set1_param(ctx, param);
	X509_VERIFY_PARAM_free(param);

	=head1 SEE ALSO

	L<X509_verify_cert(3)>,
	L<X509_check_host(3)>,
	L<X509_check_email(3)>,
	L<X509_check_ip(3)>,
	L<openssl-x509(1)>

	=head1 HISTORY

	The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
	The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
	and has no effect.

	The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.

	The X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(),
	and X509_VERIFY_PARAM_get1_ip_asc() functions were added in OpenSSL 3.0.

	=head1 COPYRIGHT

	Copyright 2009-2021 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