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 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 additional
long and pointer parameters which will be passed to the sup-
plied 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.
MirOS BSD #10-current 2005-02-05 1
RSA_GET_EX_NEW_INDEX(3) OpenSSL RSA_GET_EX_NEW_INDEX(3)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 struc-
tures 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 func-
tion 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 VALUESRSA_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.
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RSA_GET_EX_NEW_INDEX(3) OpenSSL RSA_GET_EX_NEW_INDEX(3)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).
BUGSdup_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 ALSOrsa(3), CRYPTO_set_ex_data(3)HISTORYRSA_get_ex_new_index(), RSA_set_ex_data() and
RSA_get_ex_data() are available since SSLeay 0.9.0.
MirOS BSD #10-current 2005-02-05 3
