1.\" $OpenBSD: SSL_CTX_set_read_ahead.3,v 1.4 2018/03/27 17:35:50 schwarze Exp $ 2.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Matt Caswell <matt@openssl.org>. 5.\" Copyright (c) 2015, 2016 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: March 27 2018 $ 52.Dt SSL_CTX_SET_READ_AHEAD 3 53.Os 54.Sh NAME 55.Nm SSL_CTX_set_read_ahead , 56.Nm SSL_CTX_get_read_ahead , 57.Nm SSL_set_read_ahead , 58.Nm SSL_get_read_ahead , 59.Nm SSL_CTX_get_default_read_ahead 60.Nd manage whether to read as many input bytes as possible 61.Sh SYNOPSIS 62.In openssl/ssl.h 63.Ft void 64.Fo SSL_CTX_set_read_ahead 65.Fa "SSL_CTX *ctx" 66.Fa "int yes" 67.Fc 68.Ft long 69.Fo SSL_CTX_get_read_ahead 70.Fa "SSL_CTX *ctx" 71.Fc 72.Ft void 73.Fo SSL_set_read_ahead 74.Fa "SSL *s" 75.Fa "int yes" 76.Fc 77.Ft long 78.Fo SSL_get_read_ahead 79.Fa "const SSL *s" 80.Fc 81.Ft long 82.Fo SSL_CTX_get_default_read_ahead 83.Fa "SSL_CTX *ctx" 84.Fc 85.Sh DESCRIPTION 86.Fn SSL_CTX_set_read_ahead 87and 88.Fn SSL_set_read_ahead 89set whether as many input bytes as possible are read for non-blocking 90reads. 91For example if 92.Ar x 93bytes are currently required by OpenSSL, but 94.Ar y 95bytes are available from the underlying BIO (where 96.Ar y No > Ar x ) , 97then OpenSSL will read all 98.Ar y 99bytes into its buffer (provided that the buffer is large enough) if 100reading ahead is on, or 101.Ar x 102bytes otherwise. 103The parameter 104.Fa yes 105should be 0 to ensure reading ahead is off, or non zero otherwise. 106.Pp 107.Fn SSL_CTX_get_read_ahead 108and 109.Fn SSL_get_read_ahead 110indicate whether reading ahead is set or not. 111.Pp 112.Fn SSL_CTX_get_default_read_ahead 113is identical to 114.Fn SSL_CTX_get_read_ahead . 115.Pp 116These functions are implemented as macros. 117.Pp 118These functions have no effect when used with DTLS. 119.Sh RETURN VALUES 120.Fn SSL_CTX_get_read_ahead 121and 122.Fn SSL_get_read_ahead 123return 0 if reading ahead is off or non-zero otherwise, 124except that the return values are undefined for DTLS. 125.Sh SEE ALSO 126.Xr ssl 3 , 127.Xr SSL_pending 3 128.Sh HISTORY 129.Fn SSL_set_read_ahead 130and 131.Fn SSL_get_read_ahead 132appeared in SSLeay 0.4 or earlier and have been available since 133.Ox 2.4 . 134.Pp 135.Fn SSL_CTX_set_read_ahead , 136.Fn SSL_CTX_get_read_ahead , 137and 138.Fn SSL_CTX_get_default_read_ahead 139first appeared in OpenSSL 0.9.2b and have been available since 140.Ox 2.6 . 141.Sh CAVEATS 142Switching read ahead on can impact the behaviour of the 143.Xr SSL_pending 3 144function. 145