mirror of https://github.com/openssl/openssl
102 lines
4.0 KiB
Plaintext
102 lines
4.0 KiB
Plaintext
=pod
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=head1 NAME
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ASN1_TYPE_get, ASN1_TYPE_set, ASN1_TYPE_set1, ASN1_TYPE_cmp, ASN1_TYPE_unpack_sequence, ASN1_TYPE_pack_sequence - ASN1_TYPE utility
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functions
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=head1 SYNOPSIS
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#include <openssl/asn1.h>
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int ASN1_TYPE_get(const ASN1_TYPE *a);
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void ASN1_TYPE_set(ASN1_TYPE *a, int type, void *value);
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int ASN1_TYPE_set1(ASN1_TYPE *a, int type, const void *value);
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int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b);
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void *ASN1_TYPE_unpack_sequence(const ASN1_ITEM *it, const ASN1_TYPE *t);
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ASN1_TYPE *ASN1_TYPE_pack_sequence(const ASN1_ITEM *it, void *s,
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ASN1_TYPE **t);
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=head1 DESCRIPTION
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These functions allow an B<ASN1_TYPE> structure to be manipulated. The
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B<ASN1_TYPE> structure can contain any ASN.1 type or constructed type
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such as a SEQUENCE: it is effectively equivalent to the ASN.1 ANY type.
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ASN1_TYPE_get() returns the type of I<a> or 0 if it fails.
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ASN1_TYPE_set() sets the value of I<a> to I<type> and I<value>. This
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function uses the pointer I<value> internally so it must B<not> be freed
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up after the call.
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ASN1_TYPE_set1() sets the value of I<a> to I<type> a copy of I<value>.
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ASN1_TYPE_cmp() compares ASN.1 types I<a> and I<b> and returns 0 if
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they are identical and nonzero otherwise.
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ASN1_TYPE_unpack_sequence() attempts to parse the SEQUENCE present in
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I<t> using the ASN.1 structure I<it>. If successful it returns a pointer
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to the ASN.1 structure corresponding to I<it> which must be freed by the
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caller. If it fails it return NULL.
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ASN1_TYPE_pack_sequence() attempts to encode the ASN.1 structure I<s>
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corresponding to I<it> into an B<ASN1_TYPE>. If successful the encoded
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B<ASN1_TYPE> is returned. If I<t> and I<*t> are not NULL the encoded type
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is written to I<t> overwriting any existing data. If I<t> is not NULL
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but I<*t> is NULL the returned B<ASN1_TYPE> is written to I<*t>.
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=head1 NOTES
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The type and meaning of the I<value> parameter for ASN1_TYPE_set() and
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ASN1_TYPE_set1() is determined by the I<type> parameter.
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If I<type> is B<V_ASN1_NULL> I<value> is ignored. If I<type> is
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B<V_ASN1_BOOLEAN>
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then the boolean is set to TRUE if I<value> is not NULL. If I<type> is
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B<V_ASN1_OBJECT> then value is an B<ASN1_OBJECT> structure. Otherwise I<type>
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is and B<ASN1_STRING> structure. If I<type> corresponds to a primitive type
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(or a string type) then the contents of the B<ASN1_STRING> contain the content
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octets of the type. If I<type> corresponds to a constructed type or
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a tagged type (B<V_ASN1_SEQUENCE>, B<V_ASN1_SET> or B<V_ASN1_OTHER>) then the
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B<ASN1_STRING> contains the entire ASN.1 encoding verbatim (including tag and
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length octets).
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ASN1_TYPE_cmp() may not return zero if two types are equivalent but have
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different encodings. For example the single content octet of the boolean TRUE
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value under BER can have any nonzero encoding but ASN1_TYPE_cmp() will
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only return zero if the values are the same.
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If either or both of the parameters passed to ASN1_TYPE_cmp() is NULL the
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return value is nonzero. Technically if both parameters are NULL the two
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types could be absent OPTIONAL fields and so should match, however, passing
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NULL values could also indicate a programming error (for example an
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unparsable type which returns NULL) for types which do B<not> match. So
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applications should handle the case of two absent values separately.
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=head1 RETURN VALUES
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ASN1_TYPE_get() returns the type of the B<ASN1_TYPE> argument.
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ASN1_TYPE_set() does not return a value.
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ASN1_TYPE_set1() returns 1 for success and 0 for failure.
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ASN1_TYPE_cmp() returns 0 if the types are identical and nonzero otherwise.
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ASN1_TYPE_unpack_sequence() returns a pointer to an ASN.1 structure or
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NULL on failure.
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ASN1_TYPE_pack_sequence() return an B<ASN1_TYPE> structure if it succeeds or
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NULL on failure.
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=head1 COPYRIGHT
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Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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