=pod

=head1 NAME

d2i_ACCESS_DESCRIPTION,
d2i_ADMISSIONS,
d2i_ADMISSION_SYNTAX,
d2i_ASIdOrRange,
d2i_ASIdentifierChoice,
d2i_ASIdentifiers,
d2i_ASN1_BIT_STRING,
d2i_ASN1_BMPSTRING,
d2i_ASN1_ENUMERATED,
d2i_ASN1_GENERALIZEDTIME,
d2i_ASN1_GENERALSTRING,
d2i_ASN1_IA5STRING,
d2i_ASN1_INTEGER,
d2i_ASN1_NULL,
d2i_ASN1_OBJECT,
d2i_ASN1_OCTET_STRING,
d2i_ASN1_PRINTABLE,
d2i_ASN1_PRINTABLESTRING,
d2i_ASN1_SEQUENCE_ANY,
d2i_ASN1_SET_ANY,
d2i_ASN1_T61STRING,
d2i_ASN1_TIME,
d2i_ASN1_TYPE,
d2i_ASN1_UINTEGER,
d2i_ASN1_UNIVERSALSTRING,
d2i_ASN1_UTCTIME,
d2i_ASN1_UTF8STRING,
d2i_ASN1_VISIBLESTRING,
d2i_ASRange,
d2i_AUTHORITY_INFO_ACCESS,
d2i_AUTHORITY_KEYID,
d2i_BASIC_CONSTRAINTS,
d2i_CERTIFICATEPOLICIES,
d2i_CMS_ContentInfo,
d2i_CMS_ReceiptRequest,
d2i_CMS_bio,
d2i_CRL_DIST_POINTS,
d2i_DHxparams,
d2i_DIRECTORYSTRING,
d2i_DISPLAYTEXT,
d2i_DIST_POINT,
d2i_DIST_POINT_NAME,
d2i_DSAPrivateKey,
d2i_DSAPrivateKey_bio,
d2i_DSAPrivateKey_fp,
d2i_DSAPublicKey,
d2i_DSA_PUBKEY,
d2i_DSA_PUBKEY_bio,
d2i_DSA_PUBKEY_fp,
d2i_DSA_SIG,
d2i_DSAparams,
d2i_ECPKParameters,
d2i_ECParameters,
d2i_ECPrivateKey,
d2i_ECPrivateKey_bio,
d2i_ECPrivateKey_fp,
d2i_EC_PUBKEY,
d2i_EC_PUBKEY_bio,
d2i_EC_PUBKEY_fp,
d2i_EDIPARTYNAME,
d2i_ESS_CERT_ID,
d2i_ESS_ISSUER_SERIAL,
d2i_ESS_SIGNING_CERT,
d2i_EXTENDED_KEY_USAGE,
d2i_GENERAL_NAME,
d2i_GENERAL_NAMES,
d2i_IPAddressChoice,
d2i_IPAddressFamily,
d2i_IPAddressOrRange,
d2i_IPAddressRange,
d2i_ISSUING_DIST_POINT,
d2i_NAMING_AUTHORITY,
d2i_NETSCAPE_CERT_SEQUENCE,
d2i_NETSCAPE_SPKAC,
d2i_NETSCAPE_SPKI,
d2i_NOTICEREF,
d2i_OCSP_BASICRESP,
d2i_OCSP_CERTID,
d2i_OCSP_CERTSTATUS,
d2i_OCSP_CRLID,
d2i_OCSP_ONEREQ,
d2i_OCSP_REQINFO,
d2i_OCSP_REQUEST,
d2i_OCSP_RESPBYTES,
d2i_OCSP_RESPDATA,
d2i_OCSP_RESPID,
d2i_OCSP_RESPONSE,
d2i_OCSP_REVOKEDINFO,
d2i_OCSP_SERVICELOC,
d2i_OCSP_SIGNATURE,
d2i_OCSP_SINGLERESP,
d2i_OTHERNAME,
d2i_PBE2PARAM,
d2i_PBEPARAM,
d2i_PBKDF2PARAM,
d2i_PKCS12,
d2i_PKCS12_BAGS,
d2i_PKCS12_MAC_DATA,
d2i_PKCS12_SAFEBAG,
d2i_PKCS12_bio,
d2i_PKCS12_fp,
d2i_PKCS7,
d2i_PKCS7_DIGEST,
d2i_PKCS7_ENCRYPT,
d2i_PKCS7_ENC_CONTENT,
d2i_PKCS7_ENVELOPE,
d2i_PKCS7_ISSUER_AND_SERIAL,
d2i_PKCS7_RECIP_INFO,
d2i_PKCS7_SIGNED,
d2i_PKCS7_SIGNER_INFO,
d2i_PKCS7_SIGN_ENVELOPE,
d2i_PKCS7_bio,
d2i_PKCS7_fp,
d2i_PKCS8_PRIV_KEY_INFO,
d2i_PKCS8_PRIV_KEY_INFO_bio,
d2i_PKCS8_PRIV_KEY_INFO_fp,
d2i_PKCS8_bio,
d2i_PKCS8_fp,
d2i_PKEY_USAGE_PERIOD,
d2i_POLICYINFO,
d2i_POLICYQUALINFO,
d2i_PROFESSION_INFO,
d2i_PROXY_CERT_INFO_EXTENSION,
d2i_PROXY_POLICY,
d2i_RSAPrivateKey,
d2i_RSAPrivateKey_bio,
d2i_RSAPrivateKey_fp,
d2i_RSAPublicKey,
d2i_RSAPublicKey_bio,
d2i_RSAPublicKey_fp,
d2i_RSA_OAEP_PARAMS,
d2i_RSA_PSS_PARAMS,
d2i_RSA_PUBKEY,
d2i_RSA_PUBKEY_bio,
d2i_RSA_PUBKEY_fp,
d2i_SCRYPT_PARAMS,
d2i_SCT_LIST,
d2i_SXNET,
d2i_SXNETID,
d2i_TS_ACCURACY,
d2i_TS_MSG_IMPRINT,
d2i_TS_MSG_IMPRINT_bio,
d2i_TS_MSG_IMPRINT_fp,
d2i_TS_REQ,
d2i_TS_REQ_bio,
d2i_TS_REQ_fp,
d2i_TS_RESP,
d2i_TS_RESP_bio,
d2i_TS_RESP_fp,
d2i_TS_STATUS_INFO,
d2i_TS_TST_INFO,
d2i_TS_TST_INFO_bio,
d2i_TS_TST_INFO_fp,
d2i_USERNOTICE,
d2i_X509,
d2i_X509_ALGOR,
d2i_X509_ALGORS,
d2i_X509_ATTRIBUTE,
d2i_X509_CERT_AUX,
d2i_X509_CINF,
d2i_X509_CRL,
d2i_X509_CRL_INFO,
d2i_X509_CRL_bio,
d2i_X509_CRL_fp,
d2i_X509_EXTENSION,
d2i_X509_EXTENSIONS,
d2i_X509_NAME,
d2i_X509_NAME_ENTRY,
d2i_X509_PUBKEY,
d2i_X509_REQ,
d2i_X509_REQ_INFO,
d2i_X509_REQ_bio,
d2i_X509_REQ_fp,
d2i_X509_REVOKED,
d2i_X509_SIG,
d2i_X509_VAL,
i2d_ACCESS_DESCRIPTION,
i2d_ADMISSIONS,
i2d_ADMISSION_SYNTAX,
i2d_ASIdOrRange,
i2d_ASIdentifierChoice,
i2d_ASIdentifiers,
i2d_ASN1_BIT_STRING,
i2d_ASN1_BMPSTRING,
i2d_ASN1_ENUMERATED,
i2d_ASN1_GENERALIZEDTIME,
i2d_ASN1_GENERALSTRING,
i2d_ASN1_IA5STRING,
i2d_ASN1_INTEGER,
i2d_ASN1_NULL,
i2d_ASN1_OBJECT,
i2d_ASN1_OCTET_STRING,
i2d_ASN1_PRINTABLE,
i2d_ASN1_PRINTABLESTRING,
i2d_ASN1_SEQUENCE_ANY,
i2d_ASN1_SET_ANY,
i2d_ASN1_T61STRING,
i2d_ASN1_TIME,
i2d_ASN1_TYPE,
i2d_ASN1_UNIVERSALSTRING,
i2d_ASN1_UTCTIME,
i2d_ASN1_UTF8STRING,
i2d_ASN1_VISIBLESTRING,
i2d_ASN1_bio_stream,
i2d_ASRange,
i2d_AUTHORITY_INFO_ACCESS,
i2d_AUTHORITY_KEYID,
i2d_BASIC_CONSTRAINTS,
i2d_CERTIFICATEPOLICIES,
i2d_CMS_ContentInfo,
i2d_CMS_ReceiptRequest,
i2d_CMS_bio,
i2d_CRL_DIST_POINTS,
i2d_DHxparams,
i2d_DIRECTORYSTRING,
i2d_DISPLAYTEXT,
i2d_DIST_POINT,
i2d_DIST_POINT_NAME,
i2d_DSAPrivateKey,
i2d_DSAPrivateKey_bio,
i2d_DSAPrivateKey_fp,
i2d_DSAPublicKey,
i2d_DSA_PUBKEY,
i2d_DSA_PUBKEY_bio,
i2d_DSA_PUBKEY_fp,
i2d_DSA_SIG,
i2d_DSAparams,
i2d_ECPKParameters,
i2d_ECParameters,
i2d_ECPrivateKey,
i2d_ECPrivateKey_bio,
i2d_ECPrivateKey_fp,
i2d_EC_PUBKEY,
i2d_EC_PUBKEY_bio,
i2d_EC_PUBKEY_fp,
i2d_EDIPARTYNAME,
i2d_ESS_CERT_ID,
i2d_ESS_ISSUER_SERIAL,
i2d_ESS_SIGNING_CERT,
i2d_EXTENDED_KEY_USAGE,
i2d_GENERAL_NAME,
i2d_GENERAL_NAMES,
i2d_IPAddressChoice,
i2d_IPAddressFamily,
i2d_IPAddressOrRange,
i2d_IPAddressRange,
i2d_ISSUING_DIST_POINT,
i2d_NAMING_AUTHORITY,
i2d_NETSCAPE_CERT_SEQUENCE,
i2d_NETSCAPE_SPKAC,
i2d_NETSCAPE_SPKI,
i2d_NOTICEREF,
i2d_OCSP_BASICRESP,
i2d_OCSP_CERTID,
i2d_OCSP_CERTSTATUS,
i2d_OCSP_CRLID,
i2d_OCSP_ONEREQ,
i2d_OCSP_REQINFO,
i2d_OCSP_REQUEST,
i2d_OCSP_RESPBYTES,
i2d_OCSP_RESPDATA,
i2d_OCSP_RESPID,
i2d_OCSP_RESPONSE,
i2d_OCSP_REVOKEDINFO,
i2d_OCSP_SERVICELOC,
i2d_OCSP_SIGNATURE,
i2d_OCSP_SINGLERESP,
i2d_OTHERNAME,
i2d_PBE2PARAM,
i2d_PBEPARAM,
i2d_PBKDF2PARAM,
i2d_PKCS12,
i2d_PKCS12_BAGS,
i2d_PKCS12_MAC_DATA,
i2d_PKCS12_SAFEBAG,
i2d_PKCS12_bio,
i2d_PKCS12_fp,
i2d_PKCS7,
i2d_PKCS7_DIGEST,
i2d_PKCS7_ENCRYPT,
i2d_PKCS7_ENC_CONTENT,
i2d_PKCS7_ENVELOPE,
i2d_PKCS7_ISSUER_AND_SERIAL,
i2d_PKCS7_NDEF,
i2d_PKCS7_RECIP_INFO,
i2d_PKCS7_SIGNED,
i2d_PKCS7_SIGNER_INFO,
i2d_PKCS7_SIGN_ENVELOPE,
i2d_PKCS7_bio,
i2d_PKCS7_fp,
i2d_PKCS8PrivateKeyInfo_bio,
i2d_PKCS8PrivateKeyInfo_fp,
i2d_PKCS8_PRIV_KEY_INFO,
i2d_PKCS8_PRIV_KEY_INFO_bio,
i2d_PKCS8_PRIV_KEY_INFO_fp,
i2d_PKCS8_bio,
i2d_PKCS8_fp,
i2d_PKEY_USAGE_PERIOD,
i2d_POLICYINFO,
i2d_POLICYQUALINFO,
i2d_PROFESSION_INFO,
i2d_PROXY_CERT_INFO_EXTENSION,
i2d_PROXY_POLICY,
i2d_PublicKey,
i2d_RSAPrivateKey,
i2d_RSAPrivateKey_bio,
i2d_RSAPrivateKey_fp,
i2d_RSAPublicKey,
i2d_RSAPublicKey_bio,
i2d_RSAPublicKey_fp,
i2d_RSA_OAEP_PARAMS,
i2d_RSA_PSS_PARAMS,
i2d_RSA_PUBKEY,
i2d_RSA_PUBKEY_bio,
i2d_RSA_PUBKEY_fp,
i2d_SCRYPT_PARAMS,
i2d_SCT_LIST,
i2d_SXNET,
i2d_SXNETID,
i2d_TS_ACCURACY,
i2d_TS_MSG_IMPRINT,
i2d_TS_MSG_IMPRINT_bio,
i2d_TS_MSG_IMPRINT_fp,
i2d_TS_REQ,
i2d_TS_REQ_bio,
i2d_TS_REQ_fp,
i2d_TS_RESP,
i2d_TS_RESP_bio,
i2d_TS_RESP_fp,
i2d_TS_STATUS_INFO,
i2d_TS_TST_INFO,
i2d_TS_TST_INFO_bio,
i2d_TS_TST_INFO_fp,
i2d_USERNOTICE,
i2d_X509,
i2d_X509_ALGOR,
i2d_X509_ALGORS,
i2d_X509_ATTRIBUTE,
i2d_X509_CERT_AUX,
i2d_X509_CINF,
i2d_X509_CRL,
i2d_X509_CRL_INFO,
i2d_X509_CRL_bio,
i2d_X509_CRL_fp,
i2d_X509_EXTENSION,
i2d_X509_EXTENSIONS,
i2d_X509_NAME,
i2d_X509_NAME_ENTRY,
i2d_X509_PUBKEY,
i2d_X509_REQ,
i2d_X509_REQ_INFO,
i2d_X509_REQ_bio,
i2d_X509_REQ_fp,
i2d_X509_REVOKED,
i2d_X509_SIG,
i2d_X509_VAL,
- convert objects from/to ASN.1/DER representation

=head1 SYNOPSIS

=for comment generic

 TYPE *d2i_TYPE(TYPE **a, unsigned char **pp, long length);
 TYPE *d2i_TYPE_bio(BIO *bp, TYPE **a);
 TYPE *d2i_TYPE_fp(FILE *fp, TYPE **a);

 int i2d_TYPE(TYPE *a, unsigned char **pp);
 int i2d_TYPE_fp(FILE *fp, TYPE *a);
 int i2d_TYPE_bio(BIO *bp, TYPE *a);

=head1 DESCRIPTION

In the description here, I<TYPE> is used a placeholder
for any of the OpenSSL datatypes, such as I<X509_CRL>.

These functions convert OpenSSL objects to and from their ASN.1/DER
encoding.  Unlike the C structures which can have pointers to sub-objects
within, the DER is a serialized encoding, suitable for sending over the
network, writing to a file, and so on.

d2i_TYPE() attempts to decode B<len> bytes at B<*in>. If successful a
pointer to the B<TYPE> structure is returned and B<*in> is incremented to
the byte following the parsed data.  If B<a> is not B<NULL> then a pointer
to the returned structure is also written to B<*a>.  If an error occurred
then B<NULL> is returned.

On a successful return, if B<*a> is not B<NULL> then it is assumed that B<*a>
contains a valid B<TYPE> structure and an attempt is made to reuse it. This
"reuse" capability is present for historical compatibility but its use is
B<strongly discouraged> (see BUGS below, and the discussion in the RETURN
VALUES section).

d2i_TYPE_bio() is similar to d2i_TYPE() except it attempts
to parse data from BIO B<bp>.

d2i_TYPE_fp() is similar to d2i_TYPE() except it attempts
to parse data from FILE pointer B<fp>.

i2d_TYPE() encodes the structure pointed to by B<a> into DER format.
If B<out> is not B<NULL>, it writes the DER encoded data to the buffer
at B<*out>, and increments it to point after the data just written.
If the return value is negative an error occurred, otherwise it
returns the length of the encoded data.

If B<*out> is B<NULL> memory will be allocated for a buffer and the encoded
data written to it. In this case B<*out> is not incremented and it points
to the start of the data just written.

i2d_TYPE_bio() is similar to i2d_TYPE() except it writes
the encoding of the structure B<a> to BIO B<bp> and it
returns 1 for success and 0 for failure.

i2d_TYPE_fp() is similar to i2d_TYPE() except it writes
the encoding of the structure B<a> to BIO B<bp> and it
returns 1 for success and 0 for failure.

These routines do not encrypt private keys and therefore offer no
security; use L<PEM_write_PrivateKey(3)> or similar for writing to files.

=head1 NOTES

The letters B<i> and B<d> in B<i2d_TYPE> stand for
"internal" (that is, an internal C structure) and "DER" respectively.
So B<i2d_TYPE> converts from internal to DER.

The functions can also understand B<BER> forms.

The actual TYPE structure passed to i2d_TYPE() must be a valid
populated B<TYPE> structure -- it B<cannot> simply be fed with an
empty structure such as that returned by TYPE_new().

The encoded data is in binary form and may contain embedded zeroes.
Therefore any FILE pointers or BIOs should be opened in binary mode.
Functions such as strlen() will B<not> return the correct length
of the encoded structure.

The ways that B<*in> and B<*out> are incremented after the operation
can trap the unwary. See the B<WARNINGS> section for some common
errors.
The reason for this-auto increment behaviour is to reflect a typical
usage of ASN1 functions: after one structure is encoded or decoded
another will be processed after it.

The following points about the data types might be useful:

=over 4

=item B<ASN1_OBJECT>

Represents an ASN1 OBJECT IDENTIFIER.

=item B<DHparams>

Represents a PKCS#3 DH parameters structure.

=item B<DHparamx>

Represents a ANSI X9.42 DH parameters structure.

=item B<DSA_PUBKEY>

Represents a DSA public key using a B<SubjectPublicKeyInfo> structure.

=item B<DSAPublicKey, DSAPrivateKey>

Use a non-standard OpenSSL format and should be avoided; use B<DSA_PUBKEY>,
B<PEM_write_PrivateKey(3)>, or similar instead.

=item B<RSAPublicKey>

Represents a PKCS#1 RSA public key structure.

=item B<X509_ALGOR>

Represents an B<AlgorithmIdentifier> structure as used in IETF RFC 6960 and
elsewhere.

=item B<X509_Name>

Represents a B<Name> type as used for subject and issuer names in
IETF RFC 6960 and elsewhere.

=item B<X509_REQ>

Represents a PKCS#10 certificate request.

=item B<X509_SIG>

Represents the B<DigestInfo> structure defined in PKCS#1 and PKCS#7.

=back

=head1 EXAMPLES

Allocate and encode the DER encoding of an X509 structure:

 int len;
 unsigned char *buf;

 buf = NULL;
 len = i2d_X509(x, &buf);
 if (len < 0)
     /* error */

Attempt to decode a buffer:

 X509 *x;
 unsigned char *buf, *p;
 int len;

 /* Set up buf and len to point to the input buffer. */
 p = buf;
 x = d2i_X509(NULL, &p, len);
 if (x == NULL)
     /* error */

Alternative technique:

 X509 *x;
 unsigned char *buf, *p;
 int len;

 /* Set up buf and len to point to the input buffer. */
 p = buf;
 x = NULL;

 if (d2i_X509(&x, &p, len) == NULL)
     /* error */

=head1 WARNINGS

Using a temporary variable is mandatory. A common
mistake is to attempt to use a buffer directly as follows:

 int len;
 unsigned char *buf;

 len = i2d_X509(x, NULL);
 buf = OPENSSL_malloc(len);
 ...
 i2d_X509(x, &buf);
 ...
 OPENSSL_free(buf);

This code will result in B<buf> apparently containing garbage because
it was incremented after the call to point after the data just written.
Also B<buf> will no longer contain the pointer allocated by OPENSSL_malloc()
and the subsequent call to OPENSSL_free() is likely to crash.

Another trap to avoid is misuse of the B<a> argument to d2i_TYPE():

 X509 *x;

 if (d2i_X509(&x, &p, len) == NULL)
     /* error */

This will probably crash somewhere in d2i_X509(). The reason for this
is that the variable B<x> is uninitialized and an attempt will be made to
interpret its (invalid) value as an B<X509> structure, typically causing
a segmentation violation. If B<x> is set to NULL first then this will not
happen.

=head1 BUGS

In some versions of OpenSSL the "reuse" behaviour of d2i_TYPE() when
B<*px> is valid is broken and some parts of the reused structure may
persist if they are not present in the new one. As a result the use
of this "reuse" behaviour is strongly discouraged.

i2d_TYPE() will not return an error in many versions of OpenSSL,
if mandatory fields are not initialized due to a programming error
then the encoded structure may contain invalid data or omit the
fields entirely and will not be parsed by d2i_TYPE(). This may be
fixed in future so code should not assume that i2d_TYPE() will
always succeed.

Any function which encodes a structure (i2d_TYPE(),
i2d_TYPE() or i2d_TYPE()) may return a stale encoding if the
structure has been modified after deserialization or previous
serialization. This is because some objects cache the encoding for
efficiency reasons.

=head1 RETURN VALUES

d2i_TYPE(), d2i_TYPE_bio() and d2i_TYPE_fp() return a valid B<TYPE> structure
or B<NULL> if an error occurs.  If the "reuse" capability has been used with
a valid structure being passed in via B<a>, then the object is not freed in
the event of error but may be in a potentially invalid or inconsistent state.

i2d_TYPE() returns the number of bytes successfully encoded or a negative
value if an error occurs.

i2d_TYPE_bio() and i2d_TYPE_fp() return 1 for success and 0 if an error
occurs.

=head1 COPYRIGHT

Copyright 1998-2018 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
L<https://www.openssl.org/source/license.html>.

=cut
