1=pod
2
3=head1 NAME
4
5X509v3_get_ext_count, X509v3_get_ext, X509v3_get_ext_by_NID,
6X509v3_get_ext_by_OBJ, X509v3_get_ext_by_critical, X509v3_delete_ext,
7X509v3_add_ext, X509v3_add_extensions, X509_get_ext_count, X509_get_ext,
8X509_get_ext_by_NID, X509_get_ext_by_OBJ, X509_get_ext_by_critical,
9X509_delete_ext, X509_add_ext, X509_CRL_get_ext_count, X509_CRL_get_ext,
10X509_CRL_get_ext_by_NID, X509_CRL_get_ext_by_OBJ, X509_CRL_get_ext_by_critical,
11X509_CRL_delete_ext, X509_CRL_add_ext, X509_REVOKED_get_ext_count,
12X509_REVOKED_get_ext, X509_REVOKED_get_ext_by_NID, X509_REVOKED_get_ext_by_OBJ,
13X509_REVOKED_get_ext_by_critical, X509_REVOKED_delete_ext,
14X509_REVOKED_add_ext - extension stack utility functions
15
16=head1 SYNOPSIS
17
18 #include <openssl/x509.h>
19
20 int X509v3_get_ext_count(const STACK_OF(X509_EXTENSION) *x);
21 X509_EXTENSION *X509v3_get_ext(const STACK_OF(X509_EXTENSION) *x, int loc);
22
23 int X509v3_get_ext_by_NID(const STACK_OF(X509_EXTENSION) *x,
24                           int nid, int lastpos);
25 int X509v3_get_ext_by_OBJ(const STACK_OF(X509_EXTENSION) *x,
26                           const ASN1_OBJECT *obj, int lastpos);
27 int X509v3_get_ext_by_critical(const STACK_OF(X509_EXTENSION) *x,
28                                int crit, int lastpos);
29 X509_EXTENSION *X509v3_delete_ext(STACK_OF(X509_EXTENSION) *x, int loc);
30 STACK_OF(X509_EXTENSION) *X509v3_add_ext(STACK_OF(X509_EXTENSION) **x,
31                                          X509_EXTENSION *ex, int loc);
32 STACK_OF(X509_EXTENSION)
33      *X509v3_add_extensions(STACK_OF(X509_EXTENSION) **target,
34                             const STACK_OF(X509_EXTENSION) *exts);
35
36 int X509_get_ext_count(const X509 *x);
37 X509_EXTENSION *X509_get_ext(const X509 *x, int loc);
38 int X509_get_ext_by_NID(const X509 *x, int nid, int lastpos);
39 int X509_get_ext_by_OBJ(const X509 *x, const ASN1_OBJECT *obj, int lastpos);
40 int X509_get_ext_by_critical(const X509 *x, int crit, int lastpos);
41 X509_EXTENSION *X509_delete_ext(X509 *x, int loc);
42 int X509_add_ext(X509 *x, X509_EXTENSION *ex, int loc);
43
44 int X509_CRL_get_ext_count(const X509_CRL *x);
45 X509_EXTENSION *X509_CRL_get_ext(const X509_CRL *x, int loc);
46 int X509_CRL_get_ext_by_NID(const X509_CRL *x, int nid, int lastpos);
47 int X509_CRL_get_ext_by_OBJ(const X509_CRL *x, const ASN1_OBJECT *obj,
48                             int lastpos);
49 int X509_CRL_get_ext_by_critical(const X509_CRL *x, int crit, int lastpos);
50 X509_EXTENSION *X509_CRL_delete_ext(X509_CRL *x, int loc);
51 int X509_CRL_add_ext(X509_CRL *x, X509_EXTENSION *ex, int loc);
52
53 int X509_REVOKED_get_ext_count(const X509_REVOKED *x);
54 X509_EXTENSION *X509_REVOKED_get_ext(const X509_REVOKED *x, int loc);
55 int X509_REVOKED_get_ext_by_NID(const X509_REVOKED *x, int nid, int lastpos);
56 int X509_REVOKED_get_ext_by_OBJ(const X509_REVOKED *x, const ASN1_OBJECT *obj,
57                                 int lastpos);
58 int X509_REVOKED_get_ext_by_critical(const X509_REVOKED *x, int crit, int lastpos);
59 X509_EXTENSION *X509_REVOKED_delete_ext(X509_REVOKED *x, int loc);
60 int X509_REVOKED_add_ext(X509_REVOKED *x, X509_EXTENSION *ex, int loc);
61
62=head1 DESCRIPTION
63
64X509v3_get_ext_count() retrieves the number of extensions in I<x>.
65
66X509v3_get_ext() retrieves extension I<loc> from I<x>. The index I<loc>
67can take any value from 0 to X509_get_ext_count(I<x>) - 1. The returned
68extension is an internal pointer which B<MUST NOT> be freed by the
69application.
70
71X509v3_get_ext_by_NID() and X509v3_get_ext_by_OBJ() look for an extension
72with I<nid> or I<obj> from extension STACK I<x>. The search starts from the
73extension after I<lastpos> or from the beginning if I<lastpos> is -1. If
74the extension is found, its index is returned, otherwise -1 is returned.
75
76X509v3_get_ext_by_critical() is similar to X509v3_get_ext_by_NID() except it
77looks for an extension of criticality I<crit>. A zero value for I<crit>
78looks for a non-critical extension. A nonzero value looks for a critical
79extension.
80
81X509v3_delete_ext() deletes the extension with index I<loc> from I<x>.
82The deleted extension is returned and must be freed by the caller.
83If I<loc> is an invalid index value, NULL is returned.
84
85X509v3_add_ext() inserts extension I<ex> to STACK I<*x> at position I<loc>.
86If I<loc> is -1, the new extension is added to the end.
87A new STACK is allocated if I<*x> is NULL.
88The passed extension I<ex> is duplicated so it must be freed after use.
89
90X509v3_add_extensions() adds the list of extensions I<exts> to STACK I<*target>.
91The STACK I<*target> is returned unchanged if I<exts> is NULL or an empty list.
92Otherwise a new stack is allocated if I<*target> is NULL.
93An extension to be added
94that has the same OID as a pre-existing one replaces this earlier one.
95
96X509_get_ext_count(), X509_get_ext(), X509_get_ext_by_NID(),
97X509_get_ext_by_OBJ(), X509_get_ext_by_critical(), X509_delete_ext()
98and X509_add_ext() operate on the extensions of certificate I<x>. They are
99otherwise identical to the X509v3 functions.
100
101X509_CRL_get_ext_count(), X509_CRL_get_ext(), X509_CRL_get_ext_by_NID(),
102X509_CRL_get_ext_by_OBJ(), X509_CRL_get_ext_by_critical(),
103X509_CRL_delete_ext() and X509_CRL_add_ext() operate on the extensions of
104CRL I<x>. They are otherwise identical to the X509v3 functions.
105
106X509_REVOKED_get_ext_count(), X509_REVOKED_get_ext(),
107X509_REVOKED_get_ext_by_NID(), X509_REVOKED_get_ext_by_OBJ(),
108X509_REVOKED_get_ext_by_critical(), X509_REVOKED_delete_ext() and
109X509_REVOKED_add_ext() operate on the extensions of CRL entry I<x>.
110They are otherwise identical to the X509v3 functions.
111
112=head1 NOTES
113
114These functions are used to examine stacks of extensions directly.
115Applications that want to parse or encode and add an extension should
116use the extension encode and decode functions instead, such as
117X509_add1_ext_i2d() and X509_get_ext_d2i().
118
119For X509v3_get_ext_by_NID(), X509v3_get_ext_by_OBJ(),
120X509v3_get_ext_by_critical() and its variants, a zero index return value
121is not an error since extension STACK I<x> indices start from zero.
122These search functions start from the extension B<after> the I<lastpos> parameter
123so it should initially be set to -1. If it is set to zero, the initial extension
124will not be checked.
125
126X509v3_delete_ext() and its variants are a bit counter-intuitive
127because these functions do not free the extension they delete.
128They return an B<X509_EXTENSION> object which must be explicitly freed
129using X509_EXTENSION_free().
130
131=head1 RETURN VALUES
132
133X509v3_get_ext_count() returns the extension count or 0 for failure.
134
135X509v3_get_ext(), X509v3_delete_ext() and X509_delete_ext() return an
136B<X509_EXTENSION> structure or NULL if an error occurs.
137
138X509v3_get_ext_by_OBJ() and X509v3_get_ext_by_critical() return
139the extension index or -1 if an error occurs.
140
141X509v3_get_ext_by_NID() returns the extension index or negative values if an
142error occurs.
143
144X509v3_add_ext() returns a STACK of extensions or NULL on error.
145
146X509v3_add_extensions() returns a STACK of extensions
147or NULL on error or if I<*target> is NULL and I<exts> is NULL or an empty list.
148
149X509_add_ext() returns 1 on success and 0 on error.
150
151=head1 SEE ALSO
152
153L<X509V3_get_d2i(3)>
154
155=head1 HISTORY
156
157X509v3_add_extensions() was added in OpenSSL 3.4.
158
159=head1 COPYRIGHT
160
161Copyright 2015-2024 The OpenSSL Project Authors. All Rights Reserved.
162
163Licensed under the Apache License 2.0 (the "License").  You may not use
164this file except in compliance with the License.  You can obtain a copy
165in the file LICENSE in the source distribution or at
166L<https://www.openssl.org/source/license.html>.
167
168=cut
169