=pod =head1 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 =head1 SYNOPSIS #include 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); =head1 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 B bytes are currently required by OpenSSL, but B bytes are available from the underlying BIO (where B > B), then OpenSSL will read all B bytes into its buffer (providing that the buffer is large enough) if reading ahead is on, or B bytes otherwise. Setting the parameter B 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(). =head1 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 B can impact the behaviour of the SSL_pending() function (see L). Since SSL_read() can return B 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 B is not turned off using SSL_CTX_clear_mode(). That will prevent getting B 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. =head1 RETURN VALUES SSL_get_read_ahead() and SSL_CTX_get_read_ahead() return 0 if reading ahead is off, and non zero otherwise. =head1 SEE ALSO L, L =head1 COPYRIGHT Copyright 2015-2016 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 L. =cut