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author | cvs2svn <admin@example.com> | 2002-05-15 02:29:24 +0000 |
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committer | cvs2svn <admin@example.com> | 2002-05-15 02:29:24 +0000 |
commit | 027351f729b9e837200dae6e1520cda6577ab930 (patch) | |
tree | e25a717057aa4529e433fc3b1fac8d4df8db3a5c /src/lib/libcrypto/doc/RSA_get_ex_new_index.pod | |
parent | aeeae06a79815dc190061534d47236cec09f9e32 (diff) | |
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This commit was manufactured by cvs2git to create branch 'unlabeled-1.1.1'.
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1 | =pod | ||
2 | |||
3 | =head1 NAME | ||
4 | |||
5 | RSA_get_ex_new_index, RSA_set_ex_data, RSA_get_ex_data - add application specific data to RSA structures | ||
6 | |||
7 | =head1 SYNOPSIS | ||
8 | |||
9 | #include <openssl/rsa.h> | ||
10 | |||
11 | int RSA_get_ex_new_index(long argl, void *argp, | ||
12 | CRYPTO_EX_new *new_func, | ||
13 | CRYPTO_EX_dup *dup_func, | ||
14 | CRYPTO_EX_free *free_func); | ||
15 | |||
16 | int RSA_set_ex_data(RSA *r, int idx, void *arg); | ||
17 | |||
18 | void *RSA_get_ex_data(RSA *r, int idx); | ||
19 | |||
20 | int new_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad, | ||
21 | int idx, long argl, void *argp); | ||
22 | |||
23 | void free_func(void *parent, void *ptr, CRYPTO_EX_DATA *ad, | ||
24 | int idx, long argl, void *argp); | ||
25 | |||
26 | int dup_func(CRYPTO_EX_DATA *to, CRYPTO_EX_DATA *from, void *from_d, | ||
27 | int idx, long argl, void *argp); | ||
28 | |||
29 | =head1 DESCRIPTION | ||
30 | |||
31 | Several OpenSSL structures can have application specific data attached to them. | ||
32 | This has several potential uses, it can be used to cache data associated with | ||
33 | a structure (for example the hash of some part of the structure) or some | ||
34 | additional data (for example a handle to the data in an external library). | ||
35 | |||
36 | Since the application data can be anything at all it is passed and retrieved | ||
37 | as a B<void *> type. | ||
38 | |||
39 | The B<RSA_get_ex_new_index()> function is initially called to "register" some | ||
40 | new application specific data. It takes three optional function pointers which | ||
41 | are called when the parent structure (in this case an RSA structure) is | ||
42 | initially created, when it is copied and when it is freed up. If any or all of | ||
43 | these function pointer arguments are not used they should be set to NULL. The | ||
44 | precise manner in which these function pointers are called is described in more | ||
45 | detail below. B<RSA_get_ex_new_index()> also takes additional long and pointer | ||
46 | parameters which will be passed to the supplied functions but which otherwise | ||
47 | have no special meaning. It returns an B<index> which should be stored | ||
48 | (typically in a static variable) and passed used in the B<idx> parameter in | ||
49 | the remaining functions. Each successful call to B<RSA_get_ex_new_index()> | ||
50 | will return an index greater than any previously returned, this is important | ||
51 | because the optional functions are called in order of increasing index value. | ||
52 | |||
53 | B<RSA_set_ex_data()> is used to set application specific data, the data is | ||
54 | supplied in the B<arg> parameter and its precise meaning is up to the | ||
55 | application. | ||
56 | |||
57 | B<RSA_get_ex_data()> is used to retrieve application specific data. The data | ||
58 | is returned to the application, this will be the same value as supplied to | ||
59 | a previous B<RSA_set_ex_data()> call. | ||
60 | |||
61 | B<new_func()> is called when a structure is initially allocated (for example | ||
62 | with B<RSA_new()>. The parent structure members will not have any meaningful | ||
63 | values at this point. This function will typically be used to allocate any | ||
64 | application specific structure. | ||
65 | |||
66 | B<free_func()> is called when a structure is being freed up. The dynamic parent | ||
67 | structure members should not be accessed because they will be freed up when | ||
68 | this function is called. | ||
69 | |||
70 | B<new_func()> and B<free_func()> take the same parameters. B<parent> is a | ||
71 | pointer to the parent RSA structure. B<ptr> is a the application specific data | ||
72 | (this wont be of much use in B<new_func()>. B<ad> is a pointer to the | ||
73 | B<CRYPTO_EX_DATA> structure from the parent RSA structure: the functions | ||
74 | B<CRYPTO_get_ex_data()> and B<CRYPTO_set_ex_data()> can be called to manipulate | ||
75 | it. The B<idx> parameter is the index: this will be the same value returned by | ||
76 | B<RSA_get_ex_new_index()> when the functions were initially registered. Finally | ||
77 | the B<argl> and B<argp> parameters are the values originally passed to the same | ||
78 | corresponding parameters when B<RSA_get_ex_new_index()> was called. | ||
79 | |||
80 | B<dup_func()> is called when a structure is being copied. Pointers to the | ||
81 | destination and source B<CRYPTO_EX_DATA> structures are passed in the B<to> and | ||
82 | B<from> parameters respectively. The B<from_d> parameter is passed a pointer to | ||
83 | the source application data when the function is called, when the function returns | ||
84 | the value is copied to the destination: the application can thus modify the data | ||
85 | pointed to by B<from_d> and have different values in the source and destination. | ||
86 | The B<idx>, B<argl> and B<argp> parameters are the same as those in B<new_func()> | ||
87 | and B<free_func()>. | ||
88 | |||
89 | =head1 RETURN VALUES | ||
90 | |||
91 | B<RSA_get_ex_new_index()> returns a new index or -1 on failure (note 0 is a valid | ||
92 | index value). | ||
93 | |||
94 | B<RSA_set_ex_data()> returns 1 on success or 0 on failure. | ||
95 | |||
96 | B<RSA_get_ex_data()> returns the application data or 0 on failure. 0 may also | ||
97 | be valid application data but currently it can only fail if given an invalid B<idx> | ||
98 | parameter. | ||
99 | |||
100 | B<new_func()> and B<dup_func()> should return 0 for failure and 1 for success. | ||
101 | |||
102 | On failure an error code can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>. | ||
103 | |||
104 | =head1 BUGS | ||
105 | |||
106 | B<dup_func()> is currently never called. | ||
107 | |||
108 | The return value of B<new_func()> is ignored. | ||
109 | |||
110 | The B<new_func()> function isn't very useful because no meaningful values are | ||
111 | present in the parent RSA structure when it is called. | ||
112 | |||
113 | =head1 SEE ALSO | ||
114 | |||
115 | L<rsa(3)|rsa(3)>, L<CRYPTO_set_ex_data(3)|CRYPTO_set_ex_data(3)> | ||
116 | |||
117 | =head1 HISTORY | ||
118 | |||
119 | RSA_get_ex_new_index(), RSA_set_ex_data() and RSA_get_ex_data() are | ||
120 | available since SSLeay 0.9.0. | ||
121 | |||
122 | =cut | ||