SSL_CTX_SET_READ_AHEAD(3ossl) OpenSSL SSL_CTX_SET_READ_AHEAD(3ossl)
NAME
SSL_CTX_set_read_ahead, SSL_CTX_get_read_ahead, SSL_set_read_ahead,
SSL_get_read_ahead, SSL_CTX_get_default_read_ahead - manage whether to
read as many input bytes as possible
SYNOPSIS
#include <openssl/ssl.h>
void SSL_set_read_ahead(SSL *s, int yes);
int SSL_get_read_ahead(const SSL *s);
SSL_CTX_set_read_ahead(SSL_CTX *ctx, int yes);
long SSL_CTX_get_read_ahead(SSL_CTX *ctx);
long SSL_CTX_get_default_read_ahead(SSL_CTX *ctx);
DESCRIPTION
SSL_CTX_set_read_ahead(3) and SSL_set_read_ahead() set whether we should
read as many input bytes as possible (for nonblocking reads) or not.
For example if x bytes are currently required by OpenSSL, but y bytes
are available from the underlying BIO (where y > x), then OpenSSL will
read all y bytes into its buffer (providing that the buffer is large
enough) if reading ahead is on, or x bytes otherwise. Setting the
parameter yes to 0 turns reading ahead is off, other values turn it on.
SSL_CTX_set_default_read_ahead() is identical to
SSL_CTX_set_read_ahead(3).
SSL_CTX_get_read_ahead() and SSL_get_read_ahead() indicate whether
reading ahead has been set or not. SSL_CTX_get_default_read_ahead() is
identical to SSL_CTX_get_read_ahead().
These functions cannot be used with QUIC SSL objects.
SSL_set_read_ahead() has no effect if called on a QUIC SSL object.
NOTES
These functions have no impact when used with DTLS. The return values
for SSL_CTX_get_read_head() and SSL_get_read_ahead() are undefined for
DTLS. Setting read_ahead can impact the behaviour of the SSL_pending()
function (see SSL_pending(3)).
Since SSL_read() can return SSL_ERROR_WANT_READ for non-application
data records, and SSL_has_pending() can't tell the difference between
processed and unprocessed data, it's recommended that if read ahead is
turned on that SSL_MODE_AUTO_RETRY is not turned off using
SSL_CTX_clear_mode(). That will prevent getting SSL_ERROR_WANT_READ
when there is still a complete record available that hasn't been
processed.
If the application wants to continue to use the underlying transport
(e.g. TCP connection) after the SSL connection is finished using
SSL_shutdown() reading ahead should be turned off. Otherwise the SSL
structure might read data that it shouldn't.
RETURN VALUES
SSL_get_read_ahead() and SSL_CTX_get_read_ahead() return 0 if reading
ahead is off, and non zero otherwise.
SEE ALSO
ssl(7), SSL_pending(3)
COPYRIGHT
Copyright 2015-2023 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.3.2 2024-09-04 SSL_CTX_SET_READ_AHEAD(3ossl)
openssl 3.3.2 - Generated Tue Sep 24 07:17:06 CDT 2024