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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

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 CRYPTO_EX_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                                  int idx, long argl, void *argp);
        typedef void CRYPTO_EX_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                                    int idx, long argl, void *argp);
        typedef int CRYPTO_EX_dup(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 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 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 allocated (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. 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 currently 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 meaningful values are present in the parent RSA
       structure 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.



50                                               2013-03-05                          RSA_get_ex_new_index(3)