1=pod
2
3=head1 NAME
4
5ASN1_TYPE_get, ASN1_TYPE_set, ASN1_TYPE_set1, ASN1_TYPE_cmp, ASN1_TYPE_unpack_sequence, ASN1_TYPE_pack_sequence - ASN1_TYPE utility
6functions
7
8=head1 SYNOPSIS
9
10 #include <openssl/asn1.h>
11
12 int ASN1_TYPE_get(const ASN1_TYPE *a);
13 void ASN1_TYPE_set(ASN1_TYPE *a, int type, void *value);
14 int ASN1_TYPE_set1(ASN1_TYPE *a, int type, const void *value);
15 int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b);
16
17 void *ASN1_TYPE_unpack_sequence(const ASN1_ITEM *it, const ASN1_TYPE *t);
18 ASN1_TYPE *ASN1_TYPE_pack_sequence(const ASN1_ITEM *it, void *s,
19                                    ASN1_TYPE **t);
20
21=head1 DESCRIPTION
22
23These functions allow an ASN1_TYPE structure to be manipulated. The
24ASN1_TYPE structure can contain any ASN.1 type or constructed type
25such as a SEQUENCE: it is effectively equivalent to the ASN.1 ANY type.
26
27ASN1_TYPE_get() returns the type of B<a>.
28
29ASN1_TYPE_set() sets the value of B<a> to B<type> and B<value>. This
30function uses the pointer B<value> internally so it must B<not> be freed
31up after the call.
32
33ASN1_TYPE_set1() sets the value of B<a> to B<type> a copy of B<value>.
34
35ASN1_TYPE_cmp() compares ASN.1 types B<a> and B<b> and returns 0 if
36they are identical and nonzero otherwise.
37
38ASN1_TYPE_unpack_sequence() attempts to parse the SEQUENCE present in
39B<t> using the ASN.1 structure B<it>. If successful it returns a pointer
40to the ASN.1 structure corresponding to B<it> which must be freed by the
41caller. If it fails it return NULL.
42
43ASN1_TYPE_pack_sequence() attempts to encode the ASN.1 structure B<s>
44corresponding to B<it> into an ASN1_TYPE. If successful the encoded
45ASN1_TYPE is returned. If B<t> and B<*t> are not NULL the encoded type
46is written to B<t> overwriting any existing data. If B<t> is not NULL
47but B<*t> is NULL the returned ASN1_TYPE is written to B<*t>.
48
49=head1 NOTES
50
51The type and meaning of the B<value> parameter for ASN1_TYPE_set() and
52ASN1_TYPE_set1() is determined by the B<type> parameter.
53If B<type> is V_ASN1_NULL B<value> is ignored. If B<type> is V_ASN1_BOOLEAN
54then the boolean is set to TRUE if B<value> is not NULL. If B<type> is
55V_ASN1_OBJECT then value is an ASN1_OBJECT structure. Otherwise B<type>
56is and ASN1_STRING structure. If B<type> corresponds to a primitive type
57(or a string type) then the contents of the ASN1_STRING contain the content
58octets of the type. If B<type> corresponds to a constructed type or
59a tagged type (V_ASN1_SEQUENCE, V_ASN1_SET or V_ASN1_OTHER) then the
60ASN1_STRING contains the entire ASN.1 encoding verbatim (including tag and
61length octets).
62
63ASN1_TYPE_cmp() may not return zero if two types are equivalent but have
64different encodings. For example the single content octet of the boolean TRUE
65value under BER can have any nonzero encoding but ASN1_TYPE_cmp() will
66only return zero if the values are the same.
67
68If either or both of the parameters passed to ASN1_TYPE_cmp() is NULL the
69return value is nonzero. Technically if both parameters are NULL the two
70types could be absent OPTIONAL fields and so should match, however, passing
71NULL values could also indicate a programming error (for example an
72unparsable type which returns NULL) for types which do B<not> match. So
73applications should handle the case of two absent values separately.
74
75=head1 RETURN VALUES
76
77ASN1_TYPE_get() returns the type of the ASN1_TYPE argument.
78
79ASN1_TYPE_set() does not return a value.
80
81ASN1_TYPE_set1() returns 1 for success and 0 for failure.
82
83ASN1_TYPE_cmp() returns 0 if the types are identical and nonzero otherwise.
84
85ASN1_TYPE_unpack_sequence() returns a pointer to an ASN.1 structure or
86NULL on failure.
87
88ASN1_TYPE_pack_sequence() return an ASN1_TYPE structure if it succeeds or
89NULL on failure.
90
91=head1 COPYRIGHT
92
93Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
94
95Licensed under the OpenSSL license (the "License").  You may not use
96this file except in compliance with the License.  You can obtain a copy
97in the file LICENSE in the source distribution or at
98L<https://www.openssl.org/source/license.html>.
99
100=cut
101