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 RA_gt_e_nw_idx) 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. RA_gt_e_nw_idx)
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 RA_gt_e_nw_idx) will return an index greater than any previously returned, this is
important because the optional functions are called in order of increasing index value.
RA_st_e_dt( is used to set application specific data, the data is supplied in the arg parameter
and its precise meaning is up to the application.
RA_gt_e_dt( 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 RA_st_e_dt( call.
nw_fn( is called when a structure is initially allocated (for example with RA_nw). 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.
fe_fn( 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.
nw_fn( and fe_fn( 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 nw_fn(. ad is a pointer to
the CRYPTO_EX_DATA structure from the parent RSA structure: the functions CYT_gt_e_dt( and
CYT_st_e_dt( can be called to manipulate it. The idx parameter is the index: this will be the
same value returned by RA_gt_e_nw_idx) when the functions were initially registered. Finally
the argl and argp parameters are the values originally passed to the same corresponding parameters
when RA_gt_e_nw_idx) was called.
dp_fn( 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 nw_fn( and fe_fn(.
RETURN VALUES
RA_gt_e_nw_idx) returns a new index or -1 on failure (note 0 is a valid index value).
RA_st_e_dt( returns 1 on success or 0 on failure.
RA_gt_e_dt( 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.
nw_fn( and dp_fn( should return 0 for failure and 1 for success.
On failure an error code can be obtained from ERR_get_error(3).
BUGS
dp_fn( is currently never called.
The return value of nw_fn( is ignored.
The nw_fn( 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.
0.9.7l 2000-09-14 RSA_get_ex_new_index(3)
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