.\" $OpenBSD: X509V3_get_d2i.3,v 1.19 2021/07/12 14:54:00 schwarze Exp $
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.Dd $Mdocdate: July 12 2021 $
.Dt X509V3_GET_D2I 3
.Os
.Sh NAME
.Nm X509V3_get_d2i ,
.Nm X509V3_add1_i2d ,
.Nm X509V3_EXT_d2i ,
.Nm X509V3_EXT_i2d ,
.Nm X509_get_ext_d2i ,
.Nm X509_add1_ext_i2d ,
.Nm X509_CRL_get_ext_d2i ,
.Nm X509_CRL_add1_ext_i2d ,
.Nm X509_REVOKED_get_ext_d2i ,
.Nm X509_REVOKED_add1_ext_i2d ,
.Nm X509_get0_extensions ,
.Nm X509_CRL_get0_extensions ,
.Nm X509_REVOKED_get0_extensions
.Nd X509 extension decode and encode functions
.Sh SYNOPSIS
.In openssl/x509v3.h
.Ft void *
.Fo X509V3_get_d2i
.Fa "const STACK_OF(X509_EXTENSION) *x"
.Fa "int nid"
.Fa "int *crit"
.Fa "int *idx"
.Fc
.Ft int
.Fo X509V3_add1_i2d
.Fa "STACK_OF(X509_EXTENSION) **x"
.Fa "int nid"
.Fa "void *value"
.Fa "int crit"
.Fa "unsigned long flags"
.Fc
.Ft void *
.Fo X509V3_EXT_d2i
.Fa "X509_EXTENSION *ext"
.Fc
.Ft X509_EXTENSION *
.Fo X509V3_EXT_i2d
.Fa "int ext_nid"
.Fa "int crit"
.Fa "void *ext"
.Fc
.Ft void *
.Fo X509_get_ext_d2i
.Fa "const X509 *x"
.Fa "int nid"
.Fa "int *crit"
.Fa "int *idx"
.Fc
.Ft int
.Fo X509_add1_ext_i2d
.Fa "X509 *x"
.Fa "int nid"
.Fa "void *value"
.Fa "int crit"
.Fa "unsigned long flags"
.Fc
.Ft void *
.Fo X509_CRL_get_ext_d2i
.Fa "const X509_CRL *crl"
.Fa "int nid"
.Fa "int *crit"
.Fa "int *idx"
.Fc
.Ft int
.Fo X509_CRL_add1_ext_i2d
.Fa "X509_CRL *crl"
.Fa "int nid"
.Fa "void *value"
.Fa "int crit"
.Fa "unsigned long flags"
.Fc
.Ft void *
.Fo X509_REVOKED_get_ext_d2i
.Fa "const X509_REVOKED *r"
.Fa "int nid"
.Fa "int *crit"
.Fa "int *idx"
.Fc
.Ft int
.Fo X509_REVOKED_add1_ext_i2d
.Fa "X509_REVOKED *r"
.Fa "int nid"
.Fa "void *value"
.Fa "int crit"
.Fa "unsigned long flags"
.Fc
.Ft const STACK_OF(X509_EXTENSION) *
.Fo X509_get0_extensions
.Fa "const X509 *x"
.Fc
.Ft const STACK_OF(X509_EXTENSION) *
.Fo X509_CRL_get0_extensions
.Fa "const X509_CRL *crl"
.Fc
.Ft const STACK_OF(X509_EXTENSION) *
.Fo X509_REVOKED_get0_extensions
.Fa "const X509_REVOKED *r"
.Fc
.Sh DESCRIPTION
.Fn X509V3_get_d2i
looks for an extension with OID
.Fa nid
in the extensions
.Fa x
and, if found, decodes it.
If
.Fa idx
is
.Dv NULL ,
then only one occurrence of an extension is permissible.
Otherwise the first extension after index
.Pf * Fa idx
is returned and
.Pf * Fa idx
is updated to the location of the extension.
If
.Fa crit
is not
.Dv NULL ,
then
.Pf * Fa crit
is set to a status value: -2 if the extension occurs multiple times
(this is only returned if
.Fa idx
is
.Dv NULL ) ,
-1 if the extension could not be found, 0 if the extension is found
and is not critical, and 1 if it is critical.
A pointer to an extension specific structure or
.Dv NULL
is returned.
.Pp
.Fn X509V3_add1_i2d
adds extension
.Fa value
to STACK
.Pf * Fa x
(allocating a new STACK if necessary) using OID
.Fa nid
and criticality
.Fa crit
according to
.Fa flags .
.Pp
.Fn X509V3_EXT_d2i
attempts to decode the ASN.1 data contained in extension
.Fa ext
and returns a pointer to an extension specific structure or
.Dv NULL
if the extension could not be decoded (invalid syntax or not supported).
.Pp
.Fn X509V3_EXT_i2d
encodes the extension specific structure
.Fa ext
with OID
.Fa ext_nid
and criticality
.Fa crit .
.Pp
.Fn X509_get_ext_d2i
and
.Fn X509_add1_ext_i2d
operate on the extensions of certificate
.Fa x ,
and are otherwise identical to
.Fn X509V3_get_d2i
and
.Fn X509V3_add1_i2d .
.Pp
.Fn X509_CRL_get_ext_d2i
and
.Fn X509_CRL_add1_ext_i2d
operate on the extensions of CRL
.Fa crl ,
and are otherwise identical to
.Fn X509V3_get_d2i
and
.Fn X509V3_add1_i2d .
.Pp
.Fn X509_REVOKED_get_ext_d2i
and
.Fn X509_REVOKED_add1_ext_i2d
operate on the extensions of the
.Vt X509_REVOKED
structure
.Fa r
(i.e. for CRL entry extensions), and are otherwise identical to
.Fn X509V3_get_d2i
and
.Fn X509V3_add1_i2d .
.Pp
.Fn X509_get0_extensions ,
.Fn X509_CRL_get0_extensions ,
and
.Fn X509_REVOKED_get0_extensions
return a stack of all the extensions of a certificate, a CRL,
or a CRL entry, respectively.
.Pp
In almost all cases an extension can occur at most once and multiple
occurrences is an error.
Therefore the
.Fa idx
parameter is usually
.Dv NULL .
.Pp
The
.Fa flags
parameter may be one of the following values.
.Pp
.Dv X509V3_ADD_DEFAULT
appends a new extension only if the extension does not already exist.
An error is returned if the extension does already exist.
.Pp
.Dv X509V3_ADD_APPEND
appends a new extension, ignoring whether the extension already exists.
.Pp
.Dv X509V3_ADD_REPLACE
replaces an extension if it exists otherwise appends a new extension.
.Pp
.Dv X509V3_ADD_REPLACE_EXISTING
replaces an existing extension if it exists otherwise returns an error.
.Pp
.Dv X509V3_ADD_KEEP_EXISTING
appends a new extension only if the extension does not already exist.
An error
.Sy is not
returned if the extension does already exist.
.Pp
.Dv X509V3_ADD_DELETE
deletes extension
.Fa nid .
No new extension is added.
.Pp
If
.Dv X509V3_ADD_SILENT
is OR'd with
.Fa flags ,
any error returned will not be added to the error queue.
.Pp
The function
.Fn X509V3_get_d2i
will return
.Dv NULL
if the extension is not found, occurs multiple times or cannot be
decoded.
It is possible to determine the precise reason by checking the value of
.Pf * Fa crit .
.Sh SUPPORTED EXTENSIONS
The following sections contain a list of all supported extensions
including their name and NID.
.Ss PKIX Certificate Extensions
The following certificate extensions are defined in PKIX standards such
as RFC 5280.
.Bl -column 30n 30n
.It Basic Constraints             Ta Dv NID_basic_constraints
.It Key Usage                     Ta Dv NID_key_usage
.It Extended Key Usage            Ta Dv NID_ext_key_usage
.It Subject Key Identifier        Ta Dv NID_subject_key_identifier
.It Authority Key Identifier      Ta Dv NID_authority_key_identifier
.It Private Key Usage Period      Ta Dv NID_private_key_usage_period
.It Subject Alternative Name      Ta Dv NID_subject_alt_name
.It Issuer Alternative Name       Ta Dv NID_issuer_alt_name
.It Authority Information Access  Ta Dv NID_info_access
.It Subject Information Access    Ta Dv NID_sinfo_access
.It Name Constraints              Ta Dv NID_name_constraints
.It Certificate Policies          Ta Dv NID_certificate_policies
.It Policy Mappings               Ta Dv NID_policy_mappings
.It Policy Constraints            Ta Dv NID_policy_constraints
.It Inhibit Any Policy            Ta Dv NID_inhibit_any_policy
.El
.Ss Netscape Certificate Extensions
The following are (largely obsolete) Netscape certificate extensions.
.Bl -column 30n 30n
.It Netscape Cert Type            Ta Dv NID_netscape_cert_type
.It Netscape Base Url             Ta Dv NID_netscape_base_url
.It Netscape Revocation Url       Ta Dv NID_netscape_revocation_url
.It Netscape CA Revocation Url    Ta Dv NID_netscape_ca_revocation_url
.It Netscape Renewal Url          Ta Dv NID_netscape_renewal_url
.It Netscape CA Policy Url        Ta Dv NID_netscape_ca_policy_url
.It Netscape SSL Server Name      Ta Dv NID_netscape_ssl_server_name
.It Netscape Comment              Ta Dv NID_netscape_comment
.El
.Ss Miscellaneous Certificate Extensions
.Bl -column 30n 30n
.It Strong Extranet ID            Ta Dv NID_sxnet
.It Proxy Certificate Information Ta Dv NID_proxyCertInfo
.El
.Ss PKIX CRL Extensions
The following are CRL extensions from PKIX standards such as RFC 5280.
.Bl -column 30n 30n
.It CRL Number                    Ta Dv NID_crl_number
.It CRL Distribution Points       Ta Dv NID_crl_distribution_points
.It Delta CRL Indicator           Ta Dv NID_delta_crl
.It Freshest CRL                  Ta Dv NID_freshest_crl
.It Invalidity Date               Ta Dv NID_invalidity_date
.It Issuing Distribution Point    Ta Dv NID_issuing_distribution_point
.El
.Pp
The following are CRL entry extensions from PKIX standards such as
RFC 5280.
.Bl -column 30n 30n
.It CRL Reason Code               Ta Dv NID_crl_reason
.It Certificate Issuer            Ta Dv NID_certificate_issuer
.El
.Ss OCSP Extensions
.Bl -column 30n 30n
.It OCSP Nonce                    Ta Dv NID_id_pkix_OCSP_Nonce
.It OCSP CRL ID                   Ta Dv NID_id_pkix_OCSP_CrlID
.It Acceptable OCSP Responses     Ta Dv NID_id_pkix_OCSP_acceptableResponses
.It OCSP No Check                 Ta Dv NID_id_pkix_OCSP_noCheck
.It OCSP Archive Cutoff           Ta Dv NID_id_pkix_OCSP_archiveCutoff
.It OCSP Service Locator          Ta Dv NID_id_pkix_OCSP_serviceLocator
.It Hold Instruction Code         Ta Dv NID_hold_instruction_code
.El
.Sh RETURN VALUES
.Fn X509V3_get_d2i ,
.Fn X509V3_EXT_d2i ,
.Fn X509_get_ext_d2i ,
.Fn X509_CRL_get_ext_d2i ,
and
.Fn X509_REVOKED_get_ext_d2i
return a pointer to an extension specific structure or
.Dv NULL
if an error occurs.
.Pp
.Fn X509V3_add1_i2d ,
.Fn X509_add1_ext_i2d ,
.Fn X509_CRL_add1_ext_i2d ,
and
.Fn X509_REVOKED_add1_ext_i2d
return 1 if the operation is successful, 0 if it fails due to a
non-fatal error (extension not found, already exists, cannot be encoded),
or -1 due to a fatal error such as a memory allocation failure.
In some cases of failure, the reason can be determined with
.Xr ERR_get_error 3 .
.Pp
The
.Fn X509V3_EXT_i2d
function returns a pointer to an
.Vt X509_EXTENSION
structure if successful; otherwise
.Dv NULL
is returned and an error code can be retrieved with
.Xr ERR_get_error 3 .
.Pp
.Fn X509_get0_extensions ,
.Fn X509_CRL_get0_extensions ,
and
.Fn X509_REVOKED_get0_extensions
return a stack of extensions, or
.Dv NULL
if no extensions are present.
.Sh SEE ALSO
.Xr d2i_X509 3 ,
.Xr d2i_X509_EXTENSION 3 ,
.Xr X509_check_purpose 3 ,
.Xr X509_CRL_get0_by_serial 3 ,
.Xr X509_CRL_new 3 ,
.Xr X509_EXTENSION_new 3 ,
.Xr X509_get_pubkey 3 ,
.Xr X509_get_subject_name 3 ,
.Xr X509_get_version 3 ,
.Xr X509_new 3 ,
.Xr X509_REVOKED_new 3 ,
.Xr X509V3_EXT_print 3 ,
.Xr X509V3_extensions_print 3
.Sh HISTORY
.Fn X509V3_EXT_d2i
first appeared in OpenSSL 0.9.2b.
.Fn X509V3_EXT_i2d
first appeared in OpenSSL 0.9.3.
Both functions have been available since
.Ox 2.6 .
.Pp
.Fn X509V3_get_d2i ,
.Fn X509_get_ext_d2i ,
.Fn X509_CRL_get_ext_d2i ,
and
.Fn X509_REVOKED_get_ext_d2i
first appeared in OpenSSL 0.9.5 and have been available since
.Ox 2.7 .
.Pp
.Fn X509V3_add1_i2d ,
.Fn X509_add1_ext_i2d ,
.Fn X509_CRL_add1_ext_i2d ,
and
.Fn X509_REVOKED_add1_ext_i2d
first appeared in OpenSSL 0.9.7 and have been available since
.Ox 3.2 .
.Pp
.Fn X509_get0_extensions ,
.Fn X509_CRL_get0_extensions ,
and
.Fn X509_REVOKED_get0_extensions
first appeared in OpenSSL 1.1.0 and have been available since
.Ox 6.3 .