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d572cb6c DSH |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
b055fceb | 5 | BIO_set_callback_ex, BIO_get_callback_ex, BIO_set_callback, BIO_get_callback, |
121677b4 RS |
6 | BIO_set_callback_arg, BIO_get_callback_arg, BIO_debug_callback, |
7 | BIO_callback_fn_ex, BIO_callback_fn | |
b055fceb | 8 | - BIO callback functions |
d572cb6c DSH |
9 | |
10 | =head1 SYNOPSIS | |
11 | ||
12 | #include <openssl/bio.h> | |
13 | ||
b055fceb MC |
14 | typedef long (*BIO_callback_fn_ex)(BIO *b, int oper, const char *argp, |
15 | size_t len, int argi, | |
16 | long argl, int ret, size_t *processed); | |
91da5e77 RS |
17 | typedef long (*BIO_callback_fn)(BIO *b, int oper, const char *argp, int argi, |
18 | long argl, long ret); | |
d572cb6c | 19 | |
b055fceb MC |
20 | void BIO_set_callback_ex(BIO *b, BIO_callback_fn_ex callback); |
21 | BIO_callback_fn_ex BIO_get_callback_ex(const BIO *b); | |
22 | ||
27b138e9 JS |
23 | void BIO_set_callback(BIO *b, BIO_callback_fn cb); |
24 | BIO_callback_fn BIO_get_callback(BIO *b); | |
91da5e77 RS |
25 | void BIO_set_callback_arg(BIO *b, char *arg); |
26 | char *BIO_get_callback_arg(const BIO *b); | |
27 | ||
28 | long BIO_debug_callback(BIO *bio, int cmd, const char *argp, int argi, | |
29 | long argl, long ret); | |
d572cb6c DSH |
30 | |
31 | =head1 DESCRIPTION | |
32 | ||
b055fceb MC |
33 | BIO_set_callback_ex() and BIO_get_callback_ex() set and retrieve the BIO |
34 | callback. The callback is called during most high level BIO operations. It can | |
35 | be used for debugging purposes to trace operations on a BIO or to modify its | |
36 | operation. | |
37 | ||
38 | BIO_set_callback() and BIO_get_callback() set and retrieve the old format BIO | |
39 | callback. New code should not use these functions, but they are retained for | |
27b138e9 | 40 | backwards compatibility. Any callback set via BIO_set_callback_ex() will get |
b055fceb | 41 | called in preference to any set by BIO_set_callback(). |
d572cb6c DSH |
42 | |
43 | BIO_set_callback_arg() and BIO_get_callback_arg() are macros which can be | |
44 | used to set and retrieve an argument for use in the callback. | |
45 | ||
46 | BIO_debug_callback() is a standard debugging callback which prints | |
47 | out information relating to each BIO operation. If the callback | |
91da5e77 | 48 | argument is set it is interpreted as a BIO to send the information |
d572cb6c DSH |
49 | to, otherwise stderr is used. |
50 | ||
b055fceb MC |
51 | BIO_callback_fn_ex() is the type of the callback function and BIO_callback_fn() |
52 | is the type of the old format callback function. The meaning of each argument | |
53 | is described below: | |
d572cb6c | 54 | |
e1271ac2 | 55 | =over 4 |
2a5f907e CS |
56 | |
57 | =item B<b> | |
58 | ||
d572cb6c DSH |
59 | The BIO the callback is attached to is passed in B<b>. |
60 | ||
2a5f907e CS |
61 | =item B<oper> |
62 | ||
d572cb6c DSH |
63 | B<oper> is set to the operation being performed. For some operations |
64 | the callback is called twice, once before and once after the actual | |
65 | operation, the latter case has B<oper> or'ed with BIO_CB_RETURN. | |
66 | ||
b055fceb MC |
67 | =item B<len> |
68 | ||
69 | The length of the data requested to be read or written. This is only useful if | |
70 | B<oper> is BIO_CB_READ, BIO_CB_WRITE or BIO_CB_GETS. | |
71 | ||
2a5f907e CS |
72 | =item B<argp> B<argi> B<argl> |
73 | ||
d572cb6c DSH |
74 | The meaning of the arguments B<argp>, B<argi> and B<argl> depends on |
75 | the value of B<oper>, that is the operation being performed. | |
76 | ||
b055fceb MC |
77 | =item B<processed> |
78 | ||
79 | B<processed> is a pointer to a location which will be updated with the amount of | |
4e3973b4 | 80 | data that was actually read or written. Only used for BIO_CB_READ, BIO_CB_WRITE, |
b055fceb MC |
81 | BIO_CB_GETS and BIO_CB_PUTS. |
82 | ||
2a5f907e CS |
83 | =item B<ret> |
84 | ||
91da5e77 | 85 | B<ret> is the return value that would be returned to the |
d572cb6c DSH |
86 | application if no callback were present. The actual value returned |
87 | is the return value of the callback itself. In the case of callbacks | |
91da5e77 | 88 | called before the actual BIO operation 1 is placed in B<ret>, if |
d572cb6c DSH |
89 | the return value is not positive it will be immediately returned to |
90 | the application and the BIO operation will not be performed. | |
91 | ||
91da5e77 RS |
92 | =back |
93 | ||
94 | The callback should normally simply return B<ret> when it has | |
95 | finished processing, unless it specifically wishes to modify the | |
d572cb6c DSH |
96 | value returned to the application. |
97 | ||
98 | =head1 CALLBACK OPERATIONS | |
99 | ||
91da5e77 RS |
100 | In the notes below, B<callback> defers to the actual callback |
101 | function that is called. | |
102 | ||
d572cb6c DSH |
103 | =over 4 |
104 | ||
105 | =item B<BIO_free(b)> | |
106 | ||
b055fceb MC |
107 | callback_ex(b, BIO_CB_FREE, NULL, 0, 0, 0L, 1L, NULL) |
108 | ||
109 | or | |
110 | ||
111 | callback(b, BIO_CB_FREE, NULL, 0L, 0L, 1L) | |
112 | ||
113 | is called before the free operation. | |
114 | ||
4e3973b4 | 115 | =item B<BIO_read_ex(b, data, dlen, readbytes)> |
d572cb6c | 116 | |
c911e5da | 117 | callback_ex(b, BIO_CB_READ, data, dlen, 0, 0L, 1L, NULL) |
b055fceb MC |
118 | |
119 | or | |
120 | ||
4e3973b4 BK |
121 | callback(b, BIO_CB_READ, data, dlen, 0L, 1L) |
122 | ||
b055fceb MC |
123 | is called before the read and |
124 | ||
2947af32 | 125 | callback_ex(b, BIO_CB_READ | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, |
c911e5da | 126 | &readbytes) |
b055fceb MC |
127 | |
128 | or | |
129 | ||
4e3973b4 | 130 | callback(b, BIO_CB_READ|BIO_CB_RETURN, data, dlen, 0L, retvalue) |
d572cb6c | 131 | |
d572cb6c DSH |
132 | after. |
133 | ||
4e3973b4 | 134 | =item B<BIO_write(b, data, dlen, written)> |
b055fceb | 135 | |
c911e5da | 136 | callback_ex(b, BIO_CB_WRITE, data, dlen, 0, 0L, 1L, NULL) |
b055fceb MC |
137 | |
138 | or | |
139 | ||
4e3973b4 | 140 | callback(b, BIO_CB_WRITE, datat, dlen, 0L, 1L) |
b055fceb MC |
141 | |
142 | is called before the write and | |
143 | ||
2947af32 | 144 | callback_ex(b, BIO_CB_WRITE | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, |
c911e5da | 145 | &written) |
b055fceb MC |
146 | |
147 | or | |
148 | ||
4e3973b4 | 149 | callback(b, BIO_CB_WRITE|BIO_CB_RETURN, data, dlen, 0L, retvalue) |
d572cb6c | 150 | |
d572cb6c DSH |
151 | after. |
152 | ||
4e3973b4 | 153 | =item B<BIO_gets(b, buf, size)> |
d572cb6c | 154 | |
4e3973b4 | 155 | callback_ex(b, BIO_CB_GETS, buf, size, 0, 0L, 1, NULL, NULL) |
b055fceb MC |
156 | |
157 | or | |
158 | ||
4e3973b4 | 159 | callback(b, BIO_CB_GETS, buf, size, 0L, 1L) |
b055fceb MC |
160 | |
161 | is called before the operation and | |
162 | ||
2947af32 | 163 | callback_ex(b, BIO_CB_GETS | BIO_CB_RETURN, buf, size, 0, 0L, retvalue, |
c911e5da | 164 | &readbytes) |
b055fceb MC |
165 | |
166 | or | |
167 | ||
4e3973b4 | 168 | callback(b, BIO_CB_GETS|BIO_CB_RETURN, buf, size, 0L, retvalue) |
b055fceb | 169 | |
d572cb6c DSH |
170 | after. |
171 | ||
4e3973b4 | 172 | =item B<BIO_puts(b, buf)> |
d572cb6c | 173 | |
4e3973b4 | 174 | callback_ex(b, BIO_CB_PUTS, buf, 0, 0, 0L, 1L, NULL); |
b055fceb MC |
175 | |
176 | or | |
177 | ||
4e3973b4 | 178 | callback(b, BIO_CB_PUTS, buf, 0, 0L, 1L) |
b055fceb MC |
179 | |
180 | is called before the operation and | |
181 | ||
c911e5da | 182 | callback_ex(b, BIO_CB_PUTS | BIO_CB_RETURN, buf, 0, 0, 0L, retvalue, &written) |
b055fceb MC |
183 | |
184 | or | |
185 | ||
c911e5da | 186 | callback(b, BIO_CB_PUTS|BIO_CB_RETURN, buf, 0, 0L, retvalue) |
b055fceb | 187 | |
d572cb6c DSH |
188 | after. |
189 | ||
190 | =item B<BIO_ctrl(BIO *b, int cmd, long larg, void *parg)> | |
191 | ||
b055fceb MC |
192 | callback_ex(b, BIO_CB_CTRL, parg, 0, cmd, larg, 1L, NULL) |
193 | ||
194 | or | |
195 | ||
196 | callback(b, BIO_CB_CTRL, parg, cmd, larg, 1L) | |
197 | ||
198 | is called before the call and | |
199 | ||
200 | callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, parg, 0, cmd, larg, ret, NULL) | |
201 | ||
202 | or | |
203 | ||
204 | callback(b, BIO_CB_CTRL|BIO_CB_RETURN, parg, cmd, larg, ret) | |
4e3973b4 | 205 | |
b055fceb | 206 | after. |
d572cb6c | 207 | |
c911e5da BE |
208 | Note: B<cmd> == B<BIO_CTRL_SET_CALLBACK> is special, because B<parg> is not the |
209 | argument of type B<BIO_info_cb> itself. In this case B<parg> is a pointer to | |
210 | the actual call parameter, see B<BIO_callback_ctrl>. | |
211 | ||
d572cb6c DSH |
212 | =back |
213 | ||
214 | =head1 EXAMPLE | |
215 | ||
216 | The BIO_debug_callback() function is a good example, its source is | |
217 | in crypto/bio/bio_cb.c | |
218 | ||
1f13ad31 PY |
219 | =head1 RETURN VALUES |
220 | ||
221 | BIO_get_callback_ex() and BIO_get_callback() return the callback function | |
222 | previously set by a call to BIO_set_callback_ex() and BIO_set_callback() | |
223 | respectively. | |
224 | ||
225 | BIO_get_callback_arg() returns a B<char> pointer to the value previously set | |
226 | via a call to BIO_set_callback_arg(). | |
227 | ||
228 | BIO_debug_callback() returns 1 or B<ret> if it's called after specific BIO | |
229 | operations. | |
230 | ||
e2f92610 RS |
231 | =head1 COPYRIGHT |
232 | ||
61f805c1 | 233 | Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 | 234 | |
4746f25a | 235 | Licensed under the Apache License 2.0 (the "License"). You may not use |
e2f92610 RS |
236 | this file except in compliance with the License. You can obtain a copy |
237 | in the file LICENSE in the source distribution or at | |
238 | L<https://www.openssl.org/source/license.html>. | |
239 | ||
240 | =cut |