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1d39620b34
This library is meant to be small and quick. It's based on WPACKET,
which was extended to support DER writing. The way it's used is a
bit unusual, as it's used to write the structures backward into a
given buffer. A typical quick call looks like this:
/*
* Fill in this structure:
*
* something ::= SEQUENCE {
* id OBJECT IDENTIFIER,
* x [0] INTEGER OPTIONAL,
* y [1] BOOLEAN OPTIONAL,
* n INTEGER
* }
*/
unsigned char buf[nnnn], *p = NULL;
size_t encoded_len = 0;
WPACKET pkt;
int ok;
ok = WPACKET_init_der(&pkt, buf, sizeof(buf)
&& DER_w_start_sequence(&pkt, -1)
&& DER_w_bn(&pkt, -1, bn)
&& DER_w_boolean(&pkt, 1, bool)
&& DER_w_precompiled(&pkt, -1, OID, sizeof(OID))
&& DER_w_end_sequence(&pkt, -1)
&& WPACKET_finish(&pkt)
&& WPACKET_get_total_written(&pkt, &encoded_len)
&& (p = WPACKET_get_curr(&pkt)) != NULL;
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11450)
49 lines
1.4 KiB
Plaintext
49 lines
1.4 KiB
Plaintext
=pod
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=head1 NAME
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DER_w_precompiled
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- internal DER writers for precompiled DER blobs
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=head1 SYNOPSIS
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#include "internal/der.h"
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int DER_w_precompiled(WPACKET *pkt, int tag,
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const unsigned char *precompiled,
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size_t precompiled_n);
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=head1 DESCRIPTION
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There may be already existing DER blobs that can simply be copied to
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the buffer held by I<pkt>. For example, precompiled values, such as
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OIDs (for example, C<id-sha256>) or complete AlgorithmIdentifiers
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(for example, C<sha256Identifier>). To add those as an element in a
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structure being DER encoded, use DER_w_precompiled().
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DER_w_precompiled() will simply take the DER encoded blob given as
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I<precompiled> with length I<precompiled_n> and add it to the buffer
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held by I<pkt>.
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=head1 RETURN VALUES
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DER_w_precompiled() returns 1 on success and 0 on failure. Failure
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may mean that the buffer held by the I<pkt> is too small, but may also
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mean that the values given to the functions are invalid, such as the provided
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I<tag> value being too large for the implementation.
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=head1 SEE ALSO
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L<DERlib(7)>
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=head1 COPYRIGHT
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Copyright 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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