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_fn_ex, BIO_callback_fn
8 - BIO callback functions
12 #include <openssl/bio.h>
14 typedef long (*BIO_callback_fn_ex)(BIO *b, int oper, const char *argp,
16 long argl, int ret, size_t *processed);
17 typedef long (*BIO_callback_fn)(BIO *b, int oper, const char *argp, int argi,
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);
23 void BIO_set_callback(BIO *b, BIO_callack_fn cb);
24 BIO_callack_fn BIO_get_callback(BIO *b);
25 void BIO_set_callback_arg(BIO *b, char *arg);
26 char *BIO_get_callback_arg(const BIO *b);
28 long BIO_debug_callback(BIO *bio, int cmd, const char *argp, int argi,
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
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
40 backwards compatbility. Any callback set via BIO_set_callback_ex() will get
41 called in preference to any set by BIO_set_callback().
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.
46 BIO_debug_callback() is a standard debugging callback which prints
47 out information relating to each BIO operation. If the callback
48 argument is set it is interpreted as a BIO to send the information
49 to, otherwise stderr is used.
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
59 The BIO the callback is attached to is passed in B<b>.
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.
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.
72 =item B<argp> B<argi> B<argl>
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.
79 B<processed> is a pointer to a location which will be updated with the amount of
80 data that was actually read or written. Only used for BIO_CB_READ, BIO_CB_WRITE,
81 BIO_CB_GETS and BIO_CB_PUTS.
85 B<ret> is the return value that would be returned to the
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
88 called before the actual BIO operation 1 is placed in B<ret>, if
89 the return value is not positive it will be immediately returned to
90 the application and the BIO operation will not be performed.
94 The callback should normally simply return B<ret> when it has
95 finished processing, unless it specifically wishes to modify the
96 value returned to the application.
98 =head1 CALLBACK OPERATIONS
100 In the notes below, B<callback> defers to the actual callback
101 function that is called.
107 callback_ex(b, BIO_CB_FREE, NULL, 0, 0, 0L, 1L, NULL)
111 callback(b, BIO_CB_FREE, NULL, 0L, 0L, 1L)
113 is called before the free operation.
115 =item B<BIO_read_ex(b, data, dlen, readbytes)>
117 callback_ex(b, BIO_CB_READ, data, dlen, 0, 0L, 1L, readbytes)
121 callback(b, BIO_CB_READ, data, dlen, 0L, 1L)
123 is called before the read and
125 callback_ex(b, BIO_CB_READ | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, readbytes)
129 callback(b, BIO_CB_READ|BIO_CB_RETURN, data, dlen, 0L, retvalue)
133 =item B<BIO_write(b, data, dlen, written)>
135 callback_ex(b, BIO_CB_WRITE, data, dlen, 0, 0L, 1L, written)
139 callback(b, BIO_CB_WRITE, datat, dlen, 0L, 1L)
141 is called before the write and
143 callback_ex(b, BIO_CB_WRITE | BIO_CB_RETURN, data, dlen, 0, 0L, retvalue, written)
147 callback(b, BIO_CB_WRITE|BIO_CB_RETURN, data, dlen, 0L, retvalue)
151 =item B<BIO_gets(b, buf, size)>
153 callback_ex(b, BIO_CB_GETS, buf, size, 0, 0L, 1, NULL, NULL)
157 callback(b, BIO_CB_GETS, buf, size, 0L, 1L)
159 is called before the operation and
161 callback_ex(b, BIO_CB_GETS | BIO_CB_RETURN, buf, size, 0, 0L, retvalue, readbytes)
165 callback(b, BIO_CB_GETS|BIO_CB_RETURN, buf, size, 0L, retvalue)
169 =item B<BIO_puts(b, buf)>
171 callback_ex(b, BIO_CB_PUTS, buf, 0, 0, 0L, 1L, NULL);
175 callback(b, BIO_CB_PUTS, buf, 0, 0L, 1L)
177 is called before the operation and
179 callback_ex(b, BIO_CB_PUTS | BIO_CB_RETURN, buf, 0, 0, 0L, retvalue, written)
183 callback(b, BIO_CB_WRITE|BIO_CB_RETURN, buf, 0, 0L, retvalue)
187 =item B<BIO_ctrl(BIO *b, int cmd, long larg, void *parg)>
189 callback_ex(b, BIO_CB_CTRL, parg, 0, cmd, larg, 1L, NULL)
193 callback(b, BIO_CB_CTRL, parg, cmd, larg, 1L)
195 is called before the call and
197 callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, parg, 0, cmd, larg, ret, NULL)
201 callback(b, BIO_CB_CTRL|BIO_CB_RETURN, parg, cmd, larg, ret)
209 The BIO_debug_callback() function is a good example, its source is
210 in crypto/bio/bio_cb.c
214 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
216 Licensed under the OpenSSL license (the "License"). You may not use
217 this file except in compliance with the License. You can obtain a copy
218 in the file LICENSE in the source distribution or at
219 L<https://www.openssl.org/source/license.html>.