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ASN1_TYPE_GET(3)                    OpenSSL                   ASN1_TYPE_GET(3)
NAME
       ASN1_TYPE_get, ASN1_TYPE_set, ASN1_TYPE_set1, ASN1_TYPE_cmp,
       ASN1_TYPE_unpack_sequence, ASN1_TYPE_pack_sequence - ASN1_TYPE utility
       functions
SYNOPSIS
        #include <openssl/asn1.h>
        int ASN1_TYPE_get(const ASN1_TYPE *a);
        void ASN1_TYPE_set(ASN1_TYPE *a, int type, void *value);
        int ASN1_TYPE_set1(ASN1_TYPE *a, int type, const void *value);
        int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b);
        void *ASN1_TYPE_unpack_sequence(const ASN1_ITEM *it, const ASN1_TYPE *t);
        ASN1_TYPE *ASN1_TYPE_pack_sequence(const ASN1_ITEM *it, void *s,
                                           ASN1_TYPE **t);
DESCRIPTION
       These functions allow an ASN1_TYPE structure to be manipulated. The
       ASN1_TYPE structure can contain any ASN.1 type or constructed type such
       as a SEQUENCE: it is effectively equivalent to the ASN.1 ANY type.
       ASN1_TYPE_get() returns the type of a.
       ASN1_TYPE_set() sets the value of a to type and value. This function
       uses the pointer value internally so it must not be freed up after the
       call.
       ASN1_TYPE_set1() sets the value of a to type a copy of value.
       ASN1_TYPE_cmp() compares ASN.1 types a and b and returns 0 if they are
       identical and nonzero otherwise.
       ASN1_TYPE_unpack_sequence() attempts to parse the SEQUENCE present in t
       using the ASN.1 structure it. If successful it returns a pointer to the
       ASN.1 structure corresponding to it which must be freed by the caller.
       If it fails it return NULL.
       ASN1_TYPE_pack_sequence() attempts to encode the ASN.1 structure s
       corresponding to it into an ASN1_TYPE. If successful the encoded
       ASN1_TYPE is returned. If t and *t are not NULL the encoded type is
       written to t overwriting any existing data. If t is not NULL but *t is
       NULL the returned ASN1_TYPE is written to *t.
NOTES
       The type and meaning of the value parameter for ASN1_TYPE_set() and
       ASN1_TYPE_set1() is determined by the type parameter.  If type is
       V_ASN1_NULL value is ignored. If type is V_ASN1_BOOLEAN then the
       boolean is set to TRUE if value is not NULL. If type is V_ASN1_OBJECT
       then value is an ASN1_OBJECT structure. Otherwise type is and
       ASN1_STRING structure. If type corresponds to a primitive type (or a
       string type) then the contents of the ASN1_STRING contain the content
       octets of the type. If type corresponds to a constructed type or a
       tagged type (V_ASN1_SEQUENCE, V_ASN1_SET or V_ASN1_OTHER) then the
       ASN1_STRING contains the entire ASN.1 encoding verbatim (including tag
       and length octets).
       ASN1_TYPE_cmp() may not return zero if two types are equivalent but
       have different encodings. For example the single content octet of the
       boolean TRUE value under BER can have any nonzero encoding but
       ASN1_TYPE_cmp() will only return zero if the values are the same.
       If either or both of the parameters passed to ASN1_TYPE_cmp() is NULL
       the return value is nonzero. Technically if both parameters are NULL
       the two types could be absent OPTIONAL fields and so should match,
       however, passing NULL values could also indicate a programming error
       (for example an unparsable type which returns NULL) for types which do
       not match. So applications should handle the case of two absent values
       separately.
RETURN VALUES
       ASN1_TYPE_get() returns the type of the ASN1_TYPE argument.
       ASN1_TYPE_set() does not return a value.
       ASN1_TYPE_set1() returns 1 for success and 0 for failure.
       ASN1_TYPE_cmp() returns 0 if the types are identical and nonzero
       otherwise.
       ASN1_TYPE_unpack_sequence() returns a pointer to an ASN.1 structure or
       NULL on failure.
       ASN1_TYPE_pack_sequence() return an ASN1_TYPE structure if it succeeds
       or NULL on failure.
COPYRIGHT
       Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>;.
1.1.1k                            2021-03-25                  ASN1_TYPE_GET(3)