1RSA_get_ex_new_index(3) OpenSSL RSA_get_ex_new_index(3)
2
6 RSA_get_ex_new_index, RSA_set_ex_data, RSA_get_ex_data - add
7 application specific data to RSA structures
8
10 #include <openssl/rsa.h>
11 int RSA_get_ex_new_index(long argl, void *argp,
13 CRYPTO_EX_new *new_func,
14 CRYPTO_EX_dup *dup_func,
15 CRYPTO_EX_free *free_func);
16 int RSA_set_ex_data(RSA *r, int idx, void *arg);
18 void *RSA_get_ex_data(RSA *r, int idx);
20 typedef int CRYPTO_EX_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
22 int idx, long argl, void *argp);
23 typedef void CRYPTO_EX_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
24 int idx, long argl, void *argp);
25 typedef int CRYPTO_EX_dup(CRYPTO_EX_DATA *to, CRYPTO_EX_DATA *from, void *from_d,
26 int idx, long argl, void *argp);
27
29 Several OpenSSL structures can have application specific data attached
30 to them. This has several potential uses, it can be used to cache data
31 associated with a structure (for example the hash of some part of the
32 structure) or some additional data (for example a handle to the data in
33 an external library).
34 Since the application data can be anything at all it is passed and
36 retrieved as a void * type.
37 The RSA_get_ex_new_index() function is initially called to "register"
39 some new application specific data. It takes three optional function
40 pointers which are called when the parent structure (in this case an
41 RSA structure) is initially created, when it is copied and when it is
42 freed up. If any or all of these function pointer arguments are not
43 used they should be set to NULL. The precise manner in which these
44 function pointers are called is described in more detail below.
45 RSA_get_ex_new_index() also takes additional long and pointer
46 parameters which will be passed to the supplied functions but which
47 otherwise have no special meaning. It returns an index which should be
48 stored (typically in a static variable) and passed used in the idx
49 parameter in the remaining functions. Each successful call to
50 RSA_get_ex_new_index() will return an index greater than any previously
51 returned, this is important because the optional functions are called
52 in order of increasing index value.
53 RSA_set_ex_data() is used to set application specific data, the data is
55 supplied in the arg parameter and its precise meaning is up to the
56 application.
57 RSA_get_ex_data() is used to retrieve application specific data. The
59 data is returned to the application, this will be the same value as
60 supplied to a previous RSA_set_ex_data() call.
61 new_func() is called when a structure is initially allocated (for
63 example with RSA_new(). The parent structure members will not have any
64 meaningful values at this point. This function will typically be used
65 to allocate any application specific structure.
66 free_func() is called when a structure is being freed up. The dynamic
68 parent structure members should not be accessed because they will be
69 freed up when this function is called.
70 new_func() and free_func() take the same parameters. parent is a
72 pointer to the parent RSA structure. ptr is a the application specific
73 data (this wont be of much use in new_func(). ad is a pointer to the
74 CRYPTO_EX_DATA structure from the parent RSA structure: the functions
75 CRYPTO_get_ex_data() and CRYPTO_set_ex_data() can be called to
76 manipulate it. The idx parameter is the index: this will be the same
77 value returned by RSA_get_ex_new_index() when the functions were
78 initially registered. Finally the argl and argp parameters are the
79 values originally passed to the same corresponding parameters when
80 RSA_get_ex_new_index() was called.
81 dup_func() is called when a structure is being copied. Pointers to the
83 destination and source CRYPTO_EX_DATA structures are passed in the to
84 and from parameters respectively. The from_d parameter is passed a
85 pointer to the source application data when the function is called,
86 when the function returns the value is copied to the destination: the
87 application can thus modify the data pointed to by from_d and have
88 different values in the source and destination. The idx, argl and argp
89 parameters are the same as those in new_func() and free_func().
90
92 RSA_get_ex_new_index() returns a new index or -1 on failure (note 0 is
93 a valid index value).
94 RSA_set_ex_data() returns 1 on success or 0 on failure.
96 RSA_get_ex_data() returns the application data or 0 on failure. 0 may
98 also be valid application data but currently it can only fail if given
99 an invalid idx parameter.
100 new_func() and dup_func() should return 0 for failure and 1 for
102 success.
103 On failure an error code can be obtained from ERR_get_error(3).
105
107 dup_func() is currently never called.
108 The return value of new_func() is ignored.
110 The new_func() function isn't very useful because no meaningful values
112 are present in the parent RSA structure when it is called.
113
115 rsa(3), CRYPTO_set_ex_data(3)
116
118 RSA_get_ex_new_index(), RSA_set_ex_data() and RSA_get_ex_data() are
119 available since SSLeay 0.9.0.
1201.0.2k 2017-01-26 RSA_get_ex_new_index(3)