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 non-
       zero 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 non-zero 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
       non-zero. 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 unparseable 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 non-zero 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 2015-2016 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>.