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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 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 RRSSAA__ggeett__eexx__nneeww__iinnddeexx(()) 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.
RRSSAA__ggeett__eexx__nneeww__iinnddeexx(()) 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
RRSSAA__ggeett__eexx__nneeww__iinnddeexx(()) will return an index greater than any previously
returned, this is important because the optional functions are called
in order of increasing index value.
RRSSAA__sseett__eexx__ddaattaa(()) is used to set application specific data, the data is
supplied in the arg parameter and its precise meaning is up to the
application.
RRSSAA__ggeett__eexx__ddaattaa(()) 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 RRSSAA__sseett__eexx__ddaattaa(()) call.
nneeww__ffuunncc(()) is called when a structure is initially allocated (for
example with RRSSAA__nneeww(()). 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.
ffrreeee__ffuunncc(()) 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.
nneeww__ffuunncc(()) and ffrreeee__ffuunncc(()) 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 nneeww__ffuunncc(()). ad is a pointer to the
CRYPTO_EX_DATA structure from the parent RSA structure: the functions
CCRRYYPPTTOO__ggeett__eexx__ddaattaa(()) and CCRRYYPPTTOO__sseett__eexx__ddaattaa(()) can be called to
manipulate it. The idx parameter is the index: this will be the same
value returned by RRSSAA__ggeett__eexx__nneeww__iinnddeexx(()) when the functions were
initially registered. Finally the argl and argp parameters are the
values originally passed to the same corresponding parameters when
RRSSAA__ggeett__eexx__nn