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 B<ASN1_TYPE> structure to be manipulated. The
24B<ASN1_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 I<a>.
28
29ASN1_TYPE_set() sets the value of I<a> to I<type> and I<value>. This
30function uses the pointer I<value> internally so it must B<not> be freed
31up after the call.
32
33ASN1_TYPE_set1() sets the value of I<a> to I<type> a copy of I<value>.
34
35ASN1_TYPE_cmp() compares ASN.1 types I<a> and I<b> and returns 0 if
36they are identical and nonzero otherwise.
37
38ASN1_TYPE_unpack_sequence() attempts to parse the SEQUENCE present in
39I<t> using the ASN.1 structure I<it>. If successful it returns a pointer
40to the ASN.1 structure corresponding to I<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 I<s>
44corresponding to I<it> into an B<ASN1_TYPE>. If successful the encoded
45B<ASN1_TYPE> is returned. If I<t> and I<*t> are not NULL the encoded type
46is written to I<t> overwriting any existing data. If I<t> is not NULL
47but I<*t> is NULL the returned B<ASN1_TYPE> is written to I<*t>.
48
49=head1 NOTES
50
51The type and meaning of the I<value> parameter for ASN1_TYPE_set() and
52ASN1_TYPE_set1() is determined by the I<type> parameter.
53If I<type> is B<V_ASN1_NULL> I<value> is ignored. If I<type> is
54B<V_ASN1_BOOLEAN>
55then the boolean is set to TRUE if I<value> is not NULL. If I<type> is
56B<V_ASN1_OBJECT> then value is an B<ASN1_OBJECT> structure. Otherwise I<type>
57is and B<ASN1_STRING> structure. If I<type> corresponds to a primitive type
58(or a string type) then the contents of the B<ASN1_STRING> contain the content
59octets of the type. If I<type> corresponds to a constructed type or
60a tagged type (B<V_ASN1_SEQUENCE>, B<V_ASN1_SET> or B<V_ASN1_OTHER>) then the
61B<ASN1_STRING> contains the entire ASN.1 encoding verbatim (including tag and
62length octets).
63
64ASN1_TYPE_cmp() may not return zero if two types are equivalent but have
65different encodings. For example the single content octet of the boolean TRUE
66value under BER can have any nonzero encoding but ASN1_TYPE_cmp() will
67only return zero if the values are the same.
68
69If either or both of the parameters passed to ASN1_TYPE_cmp() is NULL the
70return value is nonzero. Technically if both parameters are NULL the two
71types could be absent OPTIONAL fields and so should match, however, passing
72NULL values could also indicate a programming error (for example an
73unparsable type which returns NULL) for types which do B<not> match. So
74applications should handle the case of two absent values separately.
75
76=head1 RETURN VALUES
77
78ASN1_TYPE_get() returns the type of the B<ASN1_TYPE> argument.
79
80ASN1_TYPE_set() does not return a value.
81
82ASN1_TYPE_set1() returns 1 for success and 0 for failure.
83
84ASN1_TYPE_cmp() returns 0 if the types are identical and nonzero otherwise.
85
86ASN1_TYPE_unpack_sequence() returns a pointer to an ASN.1 structure or
87NULL on failure.
88
89ASN1_TYPE_pack_sequence() return an B<ASN1_TYPE> structure if it succeeds or
90NULL on failure.
91
92=head1 COPYRIGHT
93
94Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
95
96Licensed under the Apache License 2.0 (the "License").  You may not use
97this file except in compliance with the License.  You can obtain a copy
98in the file LICENSE in the source distribution or at
99L<https://www.openssl.org/source/license.html>.
100
101=cut
102