ASN1_TYPE_GET

Section: OpenSSL (3)
Updated: 2020-07-28
Page Index

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 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 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

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>.