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.
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 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.