plucky (3) ASN1_ex_new_func.3ssl.gz

Provided by: libssl-doc_3.4.1-1ubuntu1_all bug

NAME
       ASN1_EXTERN_FUNCS, ASN1_ex_d2i, ASN1_ex_d2i_ex, ASN1_ex_i2d, ASN1_ex_new_func, ASN1_ex_new_ex_func,
       ASN1_ex_free_func, ASN1_ex_print_func, IMPLEMENT_EXTERN_ASN1 - ASN.1 external function support


SYNOPSIS
        #include <openssl/asn1t.h>

        typedef int ASN1_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
                                const ASN1_ITEM *it, int tag, int aclass, char opt,
                                ASN1_TLC *ctx);
        typedef int ASN1_ex_d2i_ex(ASN1_VALUE **pval, const unsigned char **in, long len,
                                   const ASN1_ITEM *it, int tag, int aclass, char opt,
                                   ASN1_TLC *ctx, OSSL_LIB_CTX *libctx,
                                   const char *propq);
        typedef int ASN1_ex_i2d(const ASN1_VALUE **pval, unsigned char **out,
                                const ASN1_ITEM *it, int tag, int aclass);
        typedef int ASN1_ex_new_func(ASN1_VALUE **pval, const ASN1_ITEM *it);
        typedef int ASN1_ex_new_ex_func(ASN1_VALUE **pval, const ASN1_ITEM *it,
                                        OSSL_LIB_CTX *libctx, const char *propq);
        typedef void ASN1_ex_free_func(ASN1_VALUE **pval, const ASN1_ITEM *it);
        typedef int ASN1_ex_print_func(BIO *out, const ASN1_VALUE **pval,
                                       int indent, const char *fname,
                                       const ASN1_PCTX *pctx);

        struct ASN1_EXTERN_FUNCS_st {
           void *app_data;
           ASN1_ex_new_func *asn1_ex_new;
           ASN1_ex_free_func *asn1_ex_free;
           ASN1_ex_free_func *asn1_ex_clear;
           ASN1_ex_d2i *asn1_ex_d2i;
           ASN1_ex_i2d *asn1_ex_i2d;
           ASN1_ex_print_func *asn1_ex_print;
           ASN1_ex_new_ex_func *asn1_ex_new_ex;
           ASN1_ex_d2i_ex *asn1_ex_d2i_ex;
        };
        typedef struct ASN1_EXTERN_FUNCS_st ASN1_EXTERN_FUNCS;

        #define IMPLEMENT_EXTERN_ASN1(sname, tag, fptrs)


DESCRIPTION
       ASN.1 data structures templates are typically defined in OpenSSL using a series of macros such as
       ASN1_SEQUENCE(), ASN1_SEQUENCE_END() and so on. Instead templates can also be defined based entirely on
       external functions. These external functions are called to perform operations such as creating a new
       ASN1_VALUE or converting an ASN1_VALUE to or from DER encoding.

       The macro IMPLEMENT_EXTERN_ASN1() can be used to create such an externally defined structure. The name of
       the structure should be supplied in the sname parameter. The tag for the structure (e.g. typically
       V_ASN1_SEQUENCE) should be supplied in the tag parameter. Finally a pointer to an ASN1_EXTERN_FUNCS
       structure should be supplied in the fptrs parameter.

       The ASN1_EXTERN_FUNCS structure has the following entries.

       app_data
           A pointer to arbitrary application specific data.

       asn1_ex_new
           A "new" function responsible for constructing a new ASN1_VALUE object. The newly constructed value
           should be stored in *pval. The it parameter is a pointer to the ASN1_ITEM template object created via
           the IMPLEMENT_EXTERN_ASN1() macro.

           Returns a positive value on success or 0 on error.

       asn1_ex_free
           A "free" function responsible for freeing the ASN1_VALUE passed in *pval that was previously
           allocated via a "new" function. The it parameter is a pointer to the ASN1_ITEM template object
           created via the IMPLEMENT_EXTERN_ASN1() macro.

       asn1_ex_clear
           A "clear" function responsible for clearing any data in the ASN1_VALUE passed in *pval and making it
           suitable for reuse. The it parameter is a pointer to the ASN1_ITEM template object created via the
           IMPLEMENT_EXTERN_ASN1() macro.

       asn1_ex_d2i
           A "d2i" function responsible for converting DER data with the tag tag and class class into an
           ASN1_VALUE. If *pval is non-NULL then the ASN_VALUE it points to should be reused. Otherwise a new
           ASN1_VALUE should be allocated and stored in *pval. *in points to the DER data to be decoded and len
           is the length of that data. After decoding *in should be updated to point at the next byte after the
           decoded data. If the ASN1_VALUE is considered optional in this context then opt will be nonzero.
           Otherwise it will be zero. The it parameter is a pointer to the ASN1_ITEM template object created via
           the IMPLEMENT_EXTERN_ASN1() macro. A pointer to the current ASN1_TLC context (which may be required
           for other ASN1 function calls) is passed in the ctx parameter.

           The asn1_ex_d2i entry may be NULL if asn1_ex_d2i_ex has been specified instead.

           Returns <= 0 on error or a positive value on success.

       asn1_ex_i2d
           An "i2d" function responsible for converting an ASN1_VALUE into DER encoding.  On entry *pval will
           contain the ASN1_VALUE to be encoded. If default tagging is to be used then tag will be -1 on entry.
           Otherwise if implicit tagging should be used then tag and aclass will be the tag and associated
           class.

           If out is not NULL then this function should write the DER encoded data to the buffer in *out, and
           then increment *out to point to immediately after the data just written.

           If out is NULL then no data should be written but the length calculated and returned as if it were.

           The asn1_ex_i2d entry may be NULL if asn1_ex_i2d_ex has been specified instead.

           The return value should be negative if a fatal error occurred, or 0 if a non-fatal error occurred.
           Otherwise it should return the length of the encoded data.

       asn1_ex_print
           A "print" function. out is the BIO to print the output to. *pval is the ASN1_VALUE to be printed.
           indent is the number of spaces of indenting to be printed before any data is printed. fname is
           currently unused and is always "". pctx is a pointer to the ASN1_PCTX for the print operation.

           Returns 0 on error or a positive value on success. If the return value is 2 then an additional
           newline will be printed after the data printed by this function.

       asn1_ex_new_ex
           This is the same as asn1_ex_new except that it is additionally passed the OSSL_LIB_CTX to be used in
           libctx and any property query string to be used for algorithm fetching in the propq parameter. See
           "ALGORITHM FETCHING" in crypto(7) for further details. If asn1_ex_new_ex is non NULL, then it will
           always be called in preference to asn1_ex_new.

       asn1_ex_d2i_ex
           This is the same as asn1_ex_d2i except that it is additionally passed the OSSL_LIB_CTX to be used in
           libctx and any property query string to be used for algorithm fetching in the propq parameter. See
           "ALGORITHM FETCHING" in crypto(7) for further details. If asn1_ex_d2i_ex is non NULL, then it will
           always be called in preference to asn1_ex_d2i.


RETURN VALUES
       Return values for the various callbacks are as described above.


SEE ALSO
       ASN1_item_new_ex(3)


HISTORY
       The asn1_ex_new_ex and asn1_ex_d2i_ex callbacks were added in OpenSSL 3.0.


       Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.