1=pod 2 3=head1 NAME 4 5X509_ATTRIBUTE, X509at_get_attr, 6X509at_get_attr_count, X509at_get_attr_by_NID, X509at_get_attr_by_OBJ, 7X509at_delete_attr, 8X509at_add1_attr, 9X509at_add1_attr_by_OBJ, X509at_add1_attr_by_NID, X509at_add1_attr_by_txt, 10X509at_get0_data_by_OBJ, 11X509_ATTRIBUTE_create, X509_ATTRIBUTE_create_by_NID, 12X509_ATTRIBUTE_create_by_OBJ, X509_ATTRIBUTE_create_by_txt, 13X509_ATTRIBUTE_set1_object, X509_ATTRIBUTE_set1_data, 14X509_ATTRIBUTE_count, 15X509_ATTRIBUTE_get0_data, X509_ATTRIBUTE_get0_object, X509_ATTRIBUTE_get0_type 16- X509 attribute functions 17 18=head1 SYNOPSIS 19 20 #include <openssl/x509.h> 21 22 typedef struct x509_attributes_st X509_ATTRIBUTE; 23 24 int X509at_get_attr_count(const STACK_OF(X509_ATTRIBUTE) *x); 25 int X509at_get_attr_by_NID(const STACK_OF(X509_ATTRIBUTE) *x, int nid, 26 int lastpos); 27 int X509at_get_attr_by_OBJ(const STACK_OF(X509_ATTRIBUTE) *sk, 28 const ASN1_OBJECT *obj, int lastpos); 29 X509_ATTRIBUTE *X509at_get_attr(const STACK_OF(X509_ATTRIBUTE) *x, int loc); 30 X509_ATTRIBUTE *X509at_delete_attr(STACK_OF(X509_ATTRIBUTE) *x, int loc); 31 STACK_OF(X509_ATTRIBUTE) *X509at_add1_attr(STACK_OF(X509_ATTRIBUTE) **x, 32 X509_ATTRIBUTE *attr); 33 STACK_OF(X509_ATTRIBUTE) *X509at_add1_attr_by_OBJ(STACK_OF(X509_ATTRIBUTE) 34 **x, const ASN1_OBJECT *obj, 35 int type, 36 const unsigned char *bytes, 37 int len); 38 STACK_OF(X509_ATTRIBUTE) *X509at_add1_attr_by_NID(STACK_OF(X509_ATTRIBUTE) 39 **x, int nid, int type, 40 const unsigned char *bytes, 41 int len); 42 STACK_OF(X509_ATTRIBUTE) *X509at_add1_attr_by_txt(STACK_OF(X509_ATTRIBUTE) 43 **x, const char *attrname, 44 int type, 45 const unsigned char *bytes, 46 int len); 47 void *X509at_get0_data_by_OBJ(const STACK_OF(X509_ATTRIBUTE) *x, 48 const ASN1_OBJECT *obj, int lastpos, int type); 49 X509_ATTRIBUTE *X509_ATTRIBUTE_create(int nid, int atrtype, void *value); 50 X509_ATTRIBUTE *X509_ATTRIBUTE_create_by_NID(X509_ATTRIBUTE **attr, int nid, 51 int atrtype, const void *data, 52 int len); 53 X509_ATTRIBUTE *X509_ATTRIBUTE_create_by_OBJ(X509_ATTRIBUTE **attr, 54 const ASN1_OBJECT *obj, 55 int atrtype, const void *data, 56 int len); 57 X509_ATTRIBUTE *X509_ATTRIBUTE_create_by_txt(X509_ATTRIBUTE **attr, 58 const char *atrname, int type, 59 const unsigned char *bytes, 60 int len); 61 int X509_ATTRIBUTE_set1_object(X509_ATTRIBUTE *attr, const ASN1_OBJECT *obj); 62 int X509_ATTRIBUTE_set1_data(X509_ATTRIBUTE *attr, int attrtype, 63 const void *data, int len); 64 void *X509_ATTRIBUTE_get0_data(X509_ATTRIBUTE *attr, int idx, int atrtype, 65 void *data); 66 int X509_ATTRIBUTE_count(const X509_ATTRIBUTE *attr); 67 ASN1_OBJECT *X509_ATTRIBUTE_get0_object(X509_ATTRIBUTE *attr); 68 ASN1_TYPE *X509_ATTRIBUTE_get0_type(X509_ATTRIBUTE *attr, int idx); 69 70=head1 DESCRIPTION 71 72B<X509_ATTRIBUTE> objects are used by many standards including X509, X509_REQ, 73PKCS12, PKCS8, PKCS7 and CMS. 74 75The B<X509_ATTRIBUTE> object is used to represent the ASN.1 Attribute as defined 76in RFC 5280, i.e. 77 78 Attribute ::= SEQUENCE { 79 type AttributeType, 80 values SET OF AttributeValue } 81 82 AttributeType ::= OBJECT IDENTIFIER 83 AttributeValue ::= ANY -- DEFINED BY AttributeType 84 85For example CMS defines the signing-time attribute as: 86 87 id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2) 88 us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 } 89 90 SigningTime ::= Time 91 92 Time ::= CHOICE { 93 utcTime UTCTime, 94 generalizedTime GeneralizedTime } 95 96In OpenSSL B<AttributeType> maps to an B<ASN1_OBJECT> object 97and B<AttributeValue> maps to a list of B<ASN1_TYPE> objects. 98 99The following functions are used for B<X509_ATTRIBUTE> objects. 100 101X509at_get_attr_by_OBJ() finds the location of the first matching object I<obj> 102in a list of attributes I<sk>. The search starts at the position after I<lastpos>. 103If the returned value is positive then it can be used on the next call to 104X509at_get_attr_by_OBJ() as the value of I<lastpos> in order to iterate through 105the remaining attributes. I<lastpos> can be set to any negative value on the 106first call, in order to start searching from the start of the list. 107 108X509at_get_attr_by_NID() is similar to X509at_get_attr_by_OBJ() except that it 109passes the numerical identifier (NID) I<nid> associated with the object. 110See <openssl/obj_mac.h> for a list of NID_*. 111 112X509at_get_attr() returns the B<X509_ATTRIBUTE> object at index I<loc> in the 113list of attributes I<x>. I<loc> should be in the range from 0 to 114X509at_get_attr_count() - 1. 115 116X509at_delete_attr() removes the B<X509_ATTRIBUTE> object at index I<loc> in 117the list of attributes I<x>. 118 119X509at_add1_attr() pushes a copy of the passed in B<X509_ATTRIBUTE> object 120to the list I<x>. 121Both I<x> and I<attr> must be non NULL or an error will occur. 122If I<*x> is NULL then a new list is created, otherwise it uses the 123passed in list. An error will occur if an existing attribute (with the same 124attribute type) already exists in the attribute list. 125 126X509at_add1_attr_by_OBJ() creates a new B<X509_ATTRIBUTE> using 127X509_ATTRIBUTE_set1_object() and X509_ATTRIBUTE_set1_data() to assign a new 128I<obj> with type I<type> and data I<bytes> of length I<len> and then pushes it 129to the attribute list I<x>. Both I<x> and I<attr> must be non NULL or an error 130will occur. If I<*x> is NULL then a new attribute list is created. If I<obj> 131already exists in the attribute list then an error occurs. 132 133X509at_add1_attr_by_NID() is similar to X509at_add1_attr_by_OBJ() except that it 134passes the numerical identifier (NID) I<nid> associated with the object. 135See <openssl/obj_mac.h> for a list of NID_*. 136 137X509at_add1_attr_by_txt() is similar to X509at_add1_attr_by_OBJ() except that it 138passes a name I<attrname> associated with the object. 139See <openssl/obj_mac.h> for a list of SN_* names. 140 141X509_ATTRIBUTE_set1_object() assigns a B<ASN1_OBJECT> I<obj> 142to the attribute I<attr>. If I<attr> contained an existing B<ASN1_OBJECT> then 143it is freed. An error occurs if either I<attr> or I<obj> are NULL, or if 144the passed in I<obj> cannot be duplicated. 145 146X509_ATTRIBUTE_set1_data() pushes a new B<ASN1_TYPE> object onto the I<attr> 147attributes list. The new object is assigned a copy of the data in I<data> of 148size I<len>. 149If I<attrtype> has flag I<MBSTRING_FLAG> set then a table lookup using the 150I<attr> attributes NID is used to set an B<ASN1_STRING> using 151ASN1_STRING_set_by_NID(), and the passed in I<data> must be in the format 152required for that object type or an error will occur. 153If I<len> is not -1 then internally ASN1_STRING_type_new() is 154used with the passed in I<attrtype>. 155If I<attrtype> is 0 the call does nothing except return 1. 156 157X509_ATTRIBUTE_create() creates a new B<X509_ATTRIBUTE> using the I<nid> 158to set the B<ASN1_OBJECT> OID and the I<atrtype> and I<value> to set the 159B<ASN1_TYPE>. 160 161X509_ATTRIBUTE_create_by_OBJ() uses X509_ATTRIBUTE_set1_object() and 162X509_ATTRIBUTE_set1_data() to assign a new I<obj> with type I<atrtype> and 163data I<data> of length I<len>. If the passed in attribute I<attr> OR I<*attr> is 164NULL then a new B<X509_ATTRIBUTE> will be returned, otherwise the passed in 165B<X509_ATTRIBUTE> is used. Note that the ASN1_OBJECT I<obj> is pushed onto the 166attributes existing list of objects, which could be an issue if the attributes 167<ASN1_OBJECT> was different. 168 169X509_ATTRIBUTE_create_by_NID() is similar to X509_ATTRIBUTE_create_by_OBJ() 170except that it passes the numerical identifier (NID) I<nid> associated with the 171object. See <openssl/obj_mac.h> for a list of NID_*. 172 173X509_ATTRIBUTE_create_by_txt() is similar to X509_ATTRIBUTE_create_by_OBJ() 174except that it passes a name I<atrname> associated with the 175object. See <openssl/obj_mac.h> for a list of SN_* names. 176 177X509_ATTRIBUTE_count() returns the number of B<ASN1_TYPE> objects in an 178attribute I<attr>. 179 180X509_ATTRIBUTE_get0_type() returns the B<ASN1_TYPE> object at index I<idx> in 181the attribute list I<attr>. I<idx> should be in the 182range of 0 to X509_ATTRIBUTE_count() - 1 or an error will occur. 183 184X509_ATTRIBUTE_get0_data() returns the data of an B<ASN1_TYPE> object at 185index I<idx> in the attribute I<attr>. I<data> is unused and can be set to NULL. 186An error will occur if the attribute type I<atrtype> does not match the type of 187the B<ASN1_TYPE> object at index I<idx> OR if I<atrtype> is either 188B<V_ASN1_BOOLEAN> or B<V_ASN1_NULL> OR if the I<idx> is not in the 189range 0 to X509_ATTRIBUTE_count() - 1. 190 191X509at_get0_data_by_OBJ() finds the first attribute in an attribute list I<x> 192that matches the I<obj> starting at index I<lastpos> and returns the data 193retrieved from the found attributes first B<ASN1_TYPE> object. An error will 194occur if the attribute type I<type> does not match the type of the B<ASN1_TYPE> 195object OR if I<type> is either B<V_ASN1_BOOLEAN> or B<V_ASN1_NULL> OR the 196attribute is not found. 197If I<lastpos> is less than -1 then an error will occur if there are multiple 198objects in the list I<x> that match I<obj>. 199If I<lastpos> is less than -2 then an error will occur if there is more than 200one B<ASN1_TYPE> object in the found attribute. 201 202=head1 RETURN VALUES 203 204X509at_get_attr_count() returns the number of attributes in the list I<x> or -1 205if I<x> is NULL. 206 207X509at_get_attr_by_OBJ() returns -1 if either the list is empty OR the object 208is not found, otherwise it returns the location of the object in the list. 209 210X509at_get_attr_by_NID() is similar to X509at_get_attr_by_OBJ(), except that 211it returns -2 if the I<nid> is not known by OpenSSL. 212 213X509at_get_attr() returns either an B<X509_ATTRIBUTE> or NULL if there is a error. 214 215X509at_delete_attr() returns either the removed B<X509_ATTRIBUTE> or NULL if 216there is a error. 217 218X509_ATTRIBUTE_count() returns -1 on error, otherwise it returns the number 219of B<ASN1_TYPE> elements. 220 221X509_ATTRIBUTE_get0_type() returns NULL on error, otherwise it returns a 222B<ASN1_TYPE> object. 223 224X509_ATTRIBUTE_get0_data() returns NULL if an error occurs, 225otherwise it returns the data associated with an B<ASN1_TYPE> object. 226 227X509_ATTRIBUTE_set1_object() and X509_ATTRIBUTE_set1_data() returns 1 on 228success, or 0 otherwise. 229 230X509_ATTRIBUTE_create(), X509_ATTRIBUTE_create_by_OBJ(), 231X509_ATTRIBUTE_create_by_NID() and X509_ATTRIBUTE_create_by_txt() return either 232a B<X509_ATTRIBUTE> on success, or NULL if there is a error. 233 234X509at_add1_attr(), X509at_add1_attr_by_OBJ(), X509at_add1_attr_by_NID() and 235X509at_add1_attr_by_txt() return NULL on error, otherwise they return a list 236of B<X509_ATTRIBUTE>. 237 238X509at_get0_data_by_OBJ() returns the data retrieved from the found attributes 239first B<ASN1_TYPE> object, or NULL if an error occurs. 240 241=head1 SEE ALSO 242 243L<ASN1_TYPE_get(3)>, 244L<ASN1_INTEGER_get(3)>, 245L<ASN1_ENUMERATED_get(3)>, 246L<ASN1_STRING_get0_data(3)>, 247L<ASN1_STRING_length(3)>, 248L<ASN1_STRING_type(3)>, 249L<X509_REQ_get_attr(3)>, 250L<EVP_PKEY_get_attr(3)>, 251L<CMS_signed_get_attr(3)>, 252L<PKCS8_pkey_get0_attrs(3)>, 253 254=head1 COPYRIGHT 255 256Copyright 2023-2024 The OpenSSL Project Authors. All Rights Reserved. 257 258Licensed under the Apache License 2.0 (the "License"). You may not use 259this file except in compliance with the License. You can obtain a copy 260in the file LICENSE in the source distribution or at 261L<https://www.openssl.org/source/license.html>. 262 263=cut 264