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() and SSL_set_read_ahead() set whether we should read as many input bytes as
       possible (for non-blocking 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().

       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().

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 availale 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 2015-2018 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.

1.1.1                                              2023-05-24                       SSL_CTX_SET_READ_AHEAD(3SSL)