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RSA_GET_EX_NEW_INDEX(3) | Library Functions Manual | RSA_GET_EX_NEW_INDEX(3) |
NAME
RSA_get_ex_new_index
,
RSA_set_ex_data
,
RSA_get_ex_data
,
CRYPTO_EX_new
,
CRYPTO_EX_dup
,
CRYPTO_EX_free
—
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);
#include
<openssl/crypto.h>
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. TheRSA_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 as 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, which 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(3). 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 the application specific data (this
won't 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 that 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 NULL
on failure.
NULL
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).
SEE ALSO
BIO_set_ex_data(3), CRYPTO_set_ex_data(3), DH_set_ex_data(3), DSA_set_ex_data(3), RSA_new(3), SSL_CTX_set_ex_data(3), SSL_SESSION_set_ex_data(3), SSL_set_ex_data(3), X509_STORE_CTX_set_ex_data(3), X509_STORE_set_ex_data(3)HISTORY
These functions first appeared in SSLeay 0.9.0 and have been available since OpenBSD 2.4.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.March 31, 2022 | Debian |