5 BIO_set_callback_ex, BIO_get_callback_ex, BIO_set_callback, BIO_get_callback,
6 BIO_set_callback_arg, BIO_get_callback_arg, BIO_debug_callback
7 - BIO callback functions
11 #include <openssl/bio.h>
13 typedef long (*BIO_callback_fn_ex)(BIO *b, int oper, const char *argp,
15 long argl, int ret, size_t *processed);
16 typedef long (*BIO_callback_fn)(BIO *b, int oper, const char *argp, int argi,
19 void BIO_set_callback_ex(BIO *b, BIO_callback_fn_ex callback);
20 BIO_callback_fn_ex BIO_get_callback_ex(const BIO *b);
22 void BIO_set_callback(BIO *b, BIO_callack_fn cb);
23 BIO_callack_fn BIO_get_callback(BIO *b);
24 void BIO_set_callback_arg(BIO *b, char *arg);
25 char *BIO_get_callback_arg(const BIO *b);
27 long BIO_debug_callback(BIO *bio, int cmd, const char *argp, int argi,
32 BIO_set_callback_ex() and BIO_get_callback_ex() set and retrieve the BIO
33 callback. The callback is called during most high level BIO operations. It can
34 be used for debugging purposes to trace operations on a BIO or to modify its
37 BIO_set_callback() and BIO_get_callback() set and retrieve the old format BIO
38 callback. New code should not use these functions, but they are retained for
39 backwards compatbility. Any callback set via BIO_set_callback_ex() will get
40 called in preference to any set by BIO_set_callback().
42 BIO_set_callback_arg() and BIO_get_callback_arg() are macros which can be
43 used to set and retrieve an argument for use in the callback.
45 BIO_debug_callback() is a standard debugging callback which prints
46 out information relating to each BIO operation. If the callback
47 argument is set it is interpreted as a BIO to send the information
48 to, otherwise stderr is used.
50 BIO_callback_fn_ex() is the type of the callback function and BIO_callback_fn()
51 is the type of the old format callback function. The meaning of each argument
58 The BIO the callback is attached to is passed in B<b>.
62 B<oper> is set to the operation being performed. For some operations
63 the callback is called twice, once before and once after the actual
64 operation, the latter case has B<oper> or'ed with BIO_CB_RETURN.
68 The length of the data requested to be read or written. This is only useful if
69 B<oper> is BIO_CB_READ, BIO_CB_WRITE or BIO_CB_GETS.
71 =item B<argp> B<argi> B<argl>
73 The meaning of the arguments B<argp>, B<argi> and B<argl> depends on
74 the value of B<oper>, that is the operation being performed.
78 B<processed> is a pointer to a location which will be updated with the amount of
79 data that was actually read or written. Only used for BIO_CB_READ, BIO_CB_WRITE,
80 BIO_CB_GETS and BIO_CB_PUTS.
84 B<ret> is the return value that would be returned to the
85 application if no callback were present. The actual value returned
86 is the return value of the callback itself. In the case of callbacks
87 called before the actual BIO operation 1 is placed in B<ret>, if
88 the return value is not positive it will be immediately returned to
89 the application and the BIO operation will not be performed.
93 The callback should normally simply return B<ret> when it has
94 finished processing, unless it specifically wishes to modify the
95 value returned to the application.
97 =head1 CALLBACK OPERATIONS
99 In the notes below, B<callback> defers to the actual callback
100 function that is called.
106 callback_ex(b, BIO_CB_FREE, NULL, 0, 0, 0L, 1L, NULL)
110 callback(b, BIO_CB_FREE, NULL, 0L, 0L, 1L)
112 is called before the free operation.
114 =item B<BIO_read_ex(b, data, dlen, readbytes)>
116 callback_ex(b, BIO_CB_READ, data, dlen, 0, 0L, 1L, readbytes)
120 callback(b, BIO_CB_READ, data, dlen, 0L, 1L)
122 is called before the read and
124 callback_ex(b, BIO_CB_READ | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, readbytes)
128 callback(b, BIO_CB_READ|BIO_CB_RETURN, data, dlen, 0L, retvalue)
132 =item B<BIO_write(b, data, dlen, written)>
134 callback_ex(b, BIO_CB_WRITE, data, dlen, 0, 0L, 1L, written)
138 callback(b, BIO_CB_WRITE, datat, dlen, 0L, 1L)
140 is called before the write and
142 callback_ex(b, BIO_CB_WRITE | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, written)
146 callback(b, BIO_CB_WRITE|BIO_CB_RETURN, data, dlen, 0L, retvalue)
150 =item B<BIO_gets(b, buf, size)>
152 callback_ex(b, BIO_CB_GETS, buf, size, 0, 0L, 1, NULL, NULL)
156 callback(b, BIO_CB_GETS, buf, size, 0L, 1L)
158 is called before the operation and
160 callback_ex(b, BIO_CB_GETS | BIO_CB_RETURN, buf, size, 0, 0L, retvalue, readbytes)
164 callback(b, BIO_CB_GETS|BIO_CB_RETURN, buf, size, 0L, retvalue)
168 =item B<BIO_puts(b, buf)>
170 callback_ex(b, BIO_CB_PUTS, buf, 0, 0, 0L, 1L, NULL);
174 callback(b, BIO_CB_PUTS, buf, 0, 0L, 1L)
176 is called before the operation and
178 callback_ex(b, BIO_CB_PUTS | BIO_CB_RETURN, buf, 0, 0, 0L, retvalue, written)
182 callback(b, BIO_CB_WRITE|BIO_CB_RETURN, buf, 0, 0L, retvalue)
186 =item B<BIO_ctrl(BIO *b, int cmd, long larg, void *parg)>
188 callback_ex(b, BIO_CB_CTRL, parg, 0, cmd, larg, 1L, NULL)
192 callback(b, BIO_CB_CTRL, parg, cmd, larg, 1L)
194 is called before the call and
196 callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, parg, 0, cmd, larg, ret, NULL)
200 callback(b, BIO_CB_CTRL|BIO_CB_RETURN, parg, cmd, larg, ret)
208 The BIO_debug_callback() function is a good example, its source is
209 in crypto/bio/bio_cb.c
213 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
215 Licensed under the OpenSSL license (the "License"). You may not use
216 this file except in compliance with the License. You can obtain a copy
217 in the file LICENSE in the source distribution or at
218 L<https://www.openssl.org/source/license.html>.