1SSL_CTX_SET_READ_AHEAD(3)           OpenSSL          SSL_CTX_SET_READ_AHEAD(3)
2
3
4

NAME

6       SSL_CTX_set_read_ahead, SSL_CTX_get_read_ahead, SSL_set_read_ahead,
7       SSL_get_read_ahead, SSL_CTX_get_default_read_ahead - manage whether to
8       read as many input bytes as possible
9

SYNOPSIS

11        #include <openssl/ssl.h>
12
13        void SSL_set_read_ahead(SSL *s, int yes);
14        int SSL_get_read_ahead(const SSL *s);
15
16        SSL_CTX_set_read_ahead(SSL_CTX *ctx, int yes);
17        long SSL_CTX_get_read_ahead(SSL_CTX *ctx);
18        long SSL_CTX_get_default_read_ahead(SSL_CTX *ctx);
19

DESCRIPTION

21       SSL_CTX_set_read_ahead() and SSL_set_read_ahead() set whether we should
22       read as many input bytes as possible (for nonblocking reads) or not.
23       For example if x bytes are currently required by OpenSSL, but y bytes
24       are available from the underlying BIO (where y > x), then OpenSSL will
25       read all y bytes into its buffer (providing that the buffer is large
26       enough) if reading ahead is on, or x bytes otherwise.  Setting the
27       parameter yes to 0 turns reading ahead is off, other values turn it on.
28       SSL_CTX_set_default_read_ahead() is identical to
29       SSL_CTX_set_read_ahead().
30
31       SSL_CTX_get_read_ahead() and SSL_get_read_ahead() indicate whether
32       reading ahead has been set or not.  SSL_CTX_get_default_read_ahead() is
33       identical to SSL_CTX_get_read_ahead().
34

NOTES

36       These functions have no impact when used with DTLS. The return values
37       for SSL_CTX_get_read_head() and SSL_get_read_ahead() are undefined for
38       DTLS. Setting read_ahead can impact the behaviour of the SSL_pending()
39       function (see SSL_pending(3)).
40
41       Since SSL_read() can return SSL_ERROR_WANT_READ for non-application
42       data records, and SSL_has_pending() can't tell the difference between
43       processed and unprocessed data, it's recommended that if read ahead is
44       turned on that SSL_MODE_AUTO_RETRY is not turned off using
45       SSL_CTX_clear_mode().  That will prevent getting SSL_ERROR_WANT_READ
46       when there is still a complete record available that hasn't been
47       processed.
48
49       If the application wants to continue to use the underlying transport
50       (e.g. TCP connection) after the SSL connection is finished using
51       SSL_shutdown() reading ahead should be turned off.  Otherwise the SSL
52       structure might read data that it shouldn't.
53

RETURN VALUES

55       SSL_get_read_ahead() and SSL_CTX_get_read_ahead() return 0 if reading
56       ahead is off, and non zero otherwise.
57

SEE ALSO

59       ssl(7), SSL_pending(3)
60

62       Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
63
64       Licensed under the OpenSSL license (the "License").  You may not use
65       this file except in compliance with the License.  You can obtain a copy
66       in the file LICENSE in the source distribution or at
67       <https://www.openssl.org/source/license.html>.
68
69
70
711.1.1q                            2022-07-21         SSL_CTX_SET_READ_AHEAD(3)
Impressum