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.\" ========================================================================
.\"
.IX Title "X509_VERIFY_PARAM_set_flags 3"
.TH X509_VERIFY_PARAM_set_flags 3 "2017-01-26" "1.0.2k" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags, X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose, X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth, X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_time, X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies, X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host, X509_VERIFY_PARAM_set_hostflags, X509_VERIFY_PARAM_get0_peername, X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_set1_ip_asc \- X509 verification parameters
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #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(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);
\&
\& 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);
\&
\& 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);
\& char *X509_VERIFY_PARAM_get0_peername(X509_VERIFY_PARAM *param);
\& int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
\&                                 const char *email, size_t emaillen);
\& 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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
These functions manipulate the \fBX509_VERIFY_PARAM\fR structure associated with
a certificate verification operation.
.PP
The \fIX509_VERIFY_PARAM_set_flags()\fR function sets the flags in \fBparam\fR by oring
it with \fBflags\fR. See the \fB\s-1VERIFICATION FLAGS\s0\fR section for a complete
description of values the \fBflags\fR parameter can take.
.PP
\&\fIX509_VERIFY_PARAM_get_flags()\fR returns the flags in \fBparam\fR.
.PP
\&\fIX509_VERIFY_PARAM_clear_flags()\fR clears the flags \fBflags\fR in \fBparam\fR.
.PP
\&\fIX509_VERIFY_PARAM_set_purpose()\fR sets the verification purpose in \fBparam\fR
to \fBpurpose\fR. This determines the acceptable purpose of the certificate
chain, for example \s-1SSL\s0 client or \s-1SSL\s0 server.
.PP
\&\fIX509_VERIFY_PARAM_set_trust()\fR sets the trust setting in \fBparam\fR to 
\&\fBtrust\fR.
.PP
\&\fIX509_VERIFY_PARAM_set_time()\fR sets the verification time in \fBparam\fR to
\&\fBt\fR. Normally the current time is used.
.PP
\&\fIX509_VERIFY_PARAM_add0_policy()\fR enables policy checking (it is disabled
by default) and adds \fBpolicy\fR to the acceptable policy set.
.PP
\&\fIX509_VERIFY_PARAM_set1_policies()\fR enables policy checking (it is disabled
by default) and sets the acceptable policy set to \fBpolicies\fR. Any existing
policy set is cleared. The \fBpolicies\fR parameter can be \fB\s-1NULL\s0\fR to clear
an existing policy set.
.PP
\&\fIX509_VERIFY_PARAM_set_depth()\fR sets the maximum verification depth to \fBdepth\fR.
That is the maximum number of untrusted \s-1CA\s0 certificates that can appear in a
chain.
.PP
\&\fIX509_VERIFY_PARAM_set1_host()\fR sets the expected \s-1DNS\s0 hostname to
\&\fBname\fR clearing any previously specified host name or names.  If
\&\fBname\fR is \s-1NULL,\s0 or empty the list of hostnames is cleared, and
name checks are not performed on the peer certificate.  If \fBname\fR
is NUL-terminated, \fBnamelen\fR may be zero, otherwise \fBnamelen\fR
must be set to the length of \fBname\fR.  When a hostname is specified,
certificate verification automatically invokes \fIX509_check_host\fR\|(3)
with flags equal to the \fBflags\fR argument given to
\&\fB\f(BIX509_VERIFY_PARAM_set_hostflags()\fB\fR (default zero).  Applications
are strongly advised to use this interface in preference to explicitly
calling \fIX509_check_host\fR\|(3), hostname checks are out of scope
with the \s-1\fIDANE\-EE\s0\fR\|(3) certificate usage, and the internal check will
be suppressed as appropriate when \s-1DANE\s0 support is added to OpenSSL.
.PP
\&\fIX509_VERIFY_PARAM_add1_host()\fR adds \fBname\fR as an additional reference
identifer that can match the peer's certificate.  Any previous names
set via \fIX509_VERIFY_PARAM_set1_host()\fR or \fIX509_VERIFY_PARAM_add1_host()\fR
are retained, no change is made if \fBname\fR is \s-1NULL\s0 or empty.  When
multiple names are configured, the peer is considered verified when
any name matches.
.PP
\&\fIX509_VERIFY_PARAM_get0_peername()\fR returns the \s-1DNS\s0 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 \*(L".\*(R")
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 \fBparam\fR argument is freed.  Applications must not free
the return value.
.PP
\&\fIX509_VERIFY_PARAM_set1_email()\fR sets the expected \s-1RFC822\s0 email address to
\&\fBemail\fR.  If \fBemail\fR is NUL-terminated, \fBemaillen\fR may be zero, otherwise
\&\fBemaillen\fR must be set to the length of \fBemail\fR.  When an email address
is specified, certificate verification automatically invokes
\&\fIX509_check_email\fR\|(3).
.PP
\&\fIX509_VERIFY_PARAM_set1_ip()\fR sets the expected \s-1IP\s0 address to \fBip\fR.
The \fBip\fR argument is in binary format, in network byte-order and
\&\fBiplen\fR must be set to 4 for IPv4 and 16 for IPv6.  When an \s-1IP\s0
address is specified, certificate verification automatically invokes
\&\fIX509_check_ip\fR\|(3).
.PP
\&\fIX509_VERIFY_PARAM_set1_ip_asc()\fR sets the expected \s-1IP\s0 address to
\&\fBipasc\fR.  The \fBipasc\fR argument is a NUL-terminal \s-1ASCII\s0 string:
dotted decimal quad for IPv4 and colon-separated hexadecimal for
IPv6.  The condensed \*(L"::\*(R" notation is supported for IPv6 addresses.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIX509_VERIFY_PARAM_set_flags()\fR, \fIX509_VERIFY_PARAM_clear_flags()\fR,
\&\fIX509_VERIFY_PARAM_set_purpose()\fR, \fIX509_VERIFY_PARAM_set_trust()\fR,
\&\fIX509_VERIFY_PARAM_add0_policy()\fR \fIX509_VERIFY_PARAM_set1_policies()\fR,
\&\fIX509_VERIFY_PARAM_set1_host()\fR, \fIX509_VERIFY_PARAM_set_hostflags()\fR,
\&\fIX509_VERIFY_PARAM_set1_email()\fR, \fIX509_VERIFY_PARAM_set1_ip()\fR and
\&\fIX509_VERIFY_PARAM_set1_ip_asc()\fR return 1 for success and 0 for
failure.
.PP
\&\fIX509_VERIFY_PARAM_get_flags()\fR returns the current verification flags.
.PP
\&\fIX509_VERIFY_PARAM_set_time()\fR and \fIX509_VERIFY_PARAM_set_depth()\fR do not return
values.
.PP
\&\fIX509_VERIFY_PARAM_get_depth()\fR returns the current verification depth.
.SH "VERIFICATION FLAGS"
.IX Header "VERIFICATION FLAGS"
The verification flags consists of zero or more of the following flags
ored together.
.PP
\&\fBX509_V_FLAG_CRL_CHECK\fR enables \s-1CRL\s0 checking for the certificate chain leaf
certificate. An error occurs if a suitable \s-1CRL\s0 cannot be found.
.PP
\&\fBX509_V_FLAG_CRL_CHECK_ALL\fR enables \s-1CRL\s0 checking for the entire certificate
chain.
.PP
\&\fBX509_V_FLAG_IGNORE_CRITICAL\fR 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. \fB\s-1WARNING\s0\fR 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.
.PP
THe \fBX509_V_FLAG_X509_STRICT\fR flag disables workarounds for some broken
certificates and makes the verification strictly apply \fBX509\fR rules.
.PP
\&\fBX509_V_FLAG_ALLOW_PROXY_CERTS\fR enables proxy certificate verification.
.PP
\&\fBX509_V_FLAG_POLICY_CHECK\fR enables certificate policy checking, by default
no policy checking is peformed. Additional information is sent to the 
verification callback relating to policy checking.
.PP
\&\fBX509_V_FLAG_EXPLICIT_POLICY\fR, \fBX509_V_FLAG_INHIBIT_ANY\fR and
\&\fBX509_V_FLAG_INHIBIT_MAP\fR set the \fBrequire explicit policy\fR, \fBinhibit any
policy\fR and \fBinhibit policy mapping\fR flags respectively as defined in
\&\fB\s-1RFC3280\s0\fR. Policy checking is automatically enabled if any of these flags
are set.
.PP
If \fBX509_V_FLAG_NOTIFY_POLICY\fR 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.
.PP
By default some additional features such as indirect CRLs and CRLs signed by
different keys are disabled. If \fBX509_V_FLAG_EXTENDED_CRL_SUPPORT\fR is set
they are enabled.
.PP
If \fBX509_V_FLAG_USE_DELTAS\fR ise set delta CRLs (if present) are used to
determine certificate status. If not set deltas are ignored.
.PP
\&\fBX509_V_FLAG_CHECK_SS_SIGNATURE\fR enables checking of the root \s-1CA\s0 self signed
cerificate signature. 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 root \s-1CA\s0
signature is that disabled or unsupported message digests on the root \s-1CA\s0
are not treated as fatal errors.
.PP
The \fBX509_V_FLAG_CB_ISSUER_CHECK\fR flag enables debugging of certificate
issuer checks. It is \fBnot\fR needed unless you are logging certificate
verification. If this flag is set then additional status codes will be sent
to the verification callback and it \fBmust\fR be prepared to handle such cases
without assuming they are hard errors.
.PP
The \fBX509_V_FLAG_NO_ALT_CHAINS\fR flag suppresses checking for alternative
chains. By default, when building a certificate chain, if the first certificate
chain found is not trusted, then OpenSSL will continue to check to see if an
alternative chain can be found that is trusted. With this flag set the behaviour
will match that of OpenSSL versions prior to 1.0.2b.
.SH "NOTES"
.IX Header "NOTES"
The above functions should be used to manipulate verification parameters
instead of legacy functions which work in specific structures such as
\&\fIX509_STORE_CTX_set_flags()\fR.
.SH "BUGS"
.IX Header "BUGS"
Delta \s-1CRL\s0 checking is currently primitive. Only a single delta can be used and
(partly due to limitations of \fBX509_STORE\fR) constructed CRLs are not 
maintained.
.PP
If CRLs checking is enable CRLs are expected to be available in the
corresponding \fBX509_STORE\fR structure. No attempt is made to download
CRLs from the \s-1CRL\s0 distribution points extension.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Enable \s-1CRL\s0 checking when performing certificate verification during \s-1SSL \s0
connections associated with an \fB\s-1SSL_CTX\s0\fR structure \fBctx\fR:
.PP
.Vb 5
\&  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);
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIX509_verify_cert\fR\|(3),
\&\fIX509_check_host\fR\|(3),
\&\fIX509_check_email\fR\|(3),
\&\fIX509_check_ip\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The \fBX509_V_FLAG_NO_ALT_CHAINS\fR flag was added in OpenSSL 1.0.2b
