RSA_get_ex_new_index(3) - NetBSD Manual Pages

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RSA_get_ex_new_index(3)      OpenSSL      RSA_get_ex_new_index(3)



NAME

       RSA_get_ex_new_index, RSA_set_ex_data, RSA_get_ex_data -
       add application specific data to RSA structures


LIBRARY

       libcrypto, -lcrypto


SYNOPSIS

        #include <openssl/rsa.h>

        int RSA_get_ex_new_index(long argl, void *argp,
                       CRYPTO_EX_new *new_func,
                       CRYPTO_EX_dup *dup_func,
                       CRYPTO_EX_free *free_func);

        int RSA_set_ex_data(RSA *r, int idx, void *arg);

        void *RSA_get_ex_data(RSA *r, int idx);

        typedef int new_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                       int idx, long argl, void *argp);
        typedef void free_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                       int idx, long argl, void *argp);
        typedef int dup_func(CRYPTO_EX_DATA *to, CRYPTO_EX_DATA *from, void *from_d,
                       int idx, long argl, void *argp);



DESCRIPTION

       Several OpenSSL structures can have application specific
       data attached to them.  This has several potential uses,
       it can be used to cache data associated with a structure
       (for example the hash of some part of the structure) or
       some additional data (for example a handle to the data in
       an external library).

       Since the application data can be anything at all it is
       passed and retrieved as a void * type.

       The RSA_get_ex_new_index() function is initially called to
       "register" some new application specific data. It takes
       three optional function pointers which are called when the
       parent structure (in this case an RSA structure) is ini-
       tially created, when it is copied and when it is freed up.
       If any or all of these function pointer arguments are not
       used they should be set to NULL. The precise manner in
       which these function pointers are called is described in
       more detail below. RSA_get_ex_new_index() also takes addi-
       tional long and pointer parameters which will be passed to
       the supplied functions but which otherwise have no special
       meaning. It returns an index which should be stored (typi-
       cally in a static variable) and passed used in the idx
       parameter in the remaining functions. Each successful call
       to RSA_get_ex_new_index() will return an index greater
       than any previously returned, this is important because



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RSA_get_ex_new_index(3)      OpenSSL      RSA_get_ex_new_index(3)


       the optional functions are called in order of increasing
       index value.

       RSA_set_ex_data() is used to set application specific
       data, the data is supplied in the arg parameter and its
       precise meaning is up to the application.

       RSA_get_ex_data() is used to retrieve application specific
       data. The data is returned to the application, this will
       be the same value as supplied to a previous
       RSA_set_ex_data() call.

       new_func() is called when a structure is initially allo-
       cated (for example with RSA_new(). The parent structure
       members will not have any meaningful values at this point.
       This function will typically be used to allocate any
       application specific structure.

       free_func() is called when a structure is being freed up.
       The dynamic parent structure members should not be
       accessed because they will be freed up when this function
       is called.

       new_func() and free_func() take the same parameters. par-
       ent is a pointer to the parent RSA structure. ptr is a the
       application specific data (this wont be of much use in
       new_func(). ad is a pointer to the CRYPTO_EX_DATA struc-
       ture from the parent RSA structure: the functions
       CRYPTO_get_ex_data() and CRYPTO_set_ex_data() can be
       called to manipulate it. The idx parameter is the index:
       this will be the same value returned by
       RSA_get_ex_new_index() when the functions were initially
       registered. Finally the argl and argp parameters are the
       values originally passed to the same corresponding parame-
       ters when RSA_get_ex_new_index() was called.

       dup_func() is called when a structure is being copied.
       Pointers to the destination and source CRYPTO_EX_DATA
       structures are passed in the to and from parameters
       respectively. The from_d parameter is passed a pointer to
       the source application data when the function is called,
       when the function returns the value is copied to the des-
       tination: the application can thus modify the data pointed
       to by from_d and have different values in the source and
       destination.  The idx, argl and argp parameters are the
       same as those in new_func() and free_func().


RETURN VALUES

       RSA_get_ex_new_index() returns a new index or -1 on fail-
       ure (note 0 is a valid index value).

       RSA_set_ex_data() returns 1 on success or 0 on failure.

       RSA_get_ex_data() returns the application data or 0 on



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RSA_get_ex_new_index(3)      OpenSSL      RSA_get_ex_new_index(3)


       failure. 0 may also be valid application data but cur-
       rently it can only fail if given an invalid idx parameter.

       new_func() and dup_func() should return 0 for failure and
       1 for success.

       On failure an error code can be obtained from
       ERR_get_error(3).


BUGS

       dup_func() is currently never called.

       The return value of new_func() is ignored.

       The new_func() function isn't very useful because no mean-
       ingful values are present in the parent RSA structure when
       it is called.


SEE ALSO

       openssl_rsa(3), CRYPTO_set_ex_data(3)


HISTORY

       RSA_get_ex_new_index(), RSA_set_ex_data() and
       RSA_get_ex_data() are available since SSLeay 0.9.0.

































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