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

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 struc-
       ture) is initially 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 additional 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 (typically 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 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 spe-
       cific 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
       allocated (for example with RSA_new(). The parent struc-
       ture 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 func-
       tion is called.

       new_func() and free_func() take the same parameters.
       parent 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
       structure 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
       parameters 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 destination: 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
       failure (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
       failure. 0 may also be valid application data but cur-
       rently it can only fail if given an invalid idx parame-
       ter.

       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
       meaningful values are present in the parent RSA struc-
       ture when it is called.

SEE ALSO
       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.



0.9.7c                     2000-09-14   RSA_get_ex_new_index(3)
