RSA_set_ex_data
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 applica-
tion 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 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 parame-
ters 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 exam-
ple 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 manipu-
late 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 origi-
nally 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 dif-
ferent 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 suc-
cess.
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.
0.9.7a 2000-09-14 RSA_get_ex_new_index(3)
