/*
** Copyright (C) 2004-2006 by Carnegie Mellon University.
**
** @OPENSOURCE_HEADER_START@
** 
** Use of the SILK system and related source code is subject to the terms 
** of the following licenses:
** 
** GNU Public License (GPL) Rights pursuant to Version 2, June 1991
** Government Purpose License Rights (GPLR) pursuant to DFARS 252.225-7013
** 
** NO WARRANTY
** 
** ANY INFORMATION, MATERIALS, SERVICES, INTELLECTUAL PROPERTY OR OTHER 
** PROPERTY OR RIGHTS GRANTED OR PROVIDED BY CARNEGIE MELLON UNIVERSITY 
** PURSUANT TO THIS LICENSE (HEREINAFTER THE "DELIVERABLES") ARE ON AN 
** "AS-IS" BASIS. CARNEGIE MELLON UNIVERSITY MAKES NO WARRANTIES OF ANY 
** KIND, EITHER EXPRESS OR IMPLIED AS TO ANY MATTER INCLUDING, BUT NOT 
** LIMITED TO, WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE, 
** MERCHANTABILITY, INFORMATIONAL CONTENT, NONINFRINGEMENT, OR ERROR-FREE 
** OPERATION. CARNEGIE MELLON UNIVERSITY SHALL NOT BE LIABLE FOR INDIRECT, 
** SPECIAL OR CONSEQUENTIAL DAMAGES, SUCH AS LOSS OF PROFITS OR INABILITY 
** TO USE SAID INTELLECTUAL PROPERTY, UNDER THIS LICENSE, REGARDLESS OF 
** WHETHER SUCH PARTY WAS AWARE OF THE POSSIBILITY OF SUCH DAMAGES. 
** LICENSEE AGREES THAT IT WILL NOT MAKE ANY WARRANTY ON BEHALF OF 
** CARNEGIE MELLON UNIVERSITY, EXPRESS OR IMPLIED, TO ANY PERSON 
** CONCERNING THE APPLICATION OF OR THE RESULTS TO BE OBTAINED WITH THE 
** DELIVERABLES UNDER THIS LICENSE.
** 
** Licensee hereby agrees to defend, indemnify, and hold harmless Carnegie 
** Mellon University, its trustees, officers, employees, and agents from 
** all claims or demands made against them (and any related losses, 
** expenses, or attorney's fees) arising out of, or relating to Licensee's 
** and/or its sub licensees' negligent use or willful misuse of or 
** negligent conduct or willful misconduct regarding the Software, 
** facilities, or other rights or assistance granted by Carnegie Mellon 
** University under this License, including, but not limited to, any 
** claims of product liability, personal injury, death, damage to 
** property, or violation of any laws or regulations.
** 
** Carnegie Mellon University Software Engineering Institute authored 
** documents are sponsored by the U.S. Department of Defense under 
** Contract F19628-00-C-0003. Carnegie Mellon University retains 
** copyrights in all material produced under this contract. The U.S. 
** Government retains a non-exclusive, royalty-free license to publish or 
** reproduce these documents, or allow others to do so, for U.S. 
** Government purposes only pursuant to the copyright license under the 
** contract clause at 252.227.7013.
** 
** @OPENSOURCE_HEADER_END@
*/

/*
**
**  Exports a method to portably set socket send/receive buffer sizes.
**
*/


#include "silk.h"

RCSIDENT("$SiLK: sku-bigsockbuf.c 3409 2006-04-11 23:06:27Z mthomas $");

#include "utils.h"

/*
 * function: bigsockbuf
 *
 * There is no portable way to determine the max send and receive buffers
 * that can be set for a socket, so guess then decrement that guess by
 * 2K until the call succeeds.  If n > 1MB then the decrement by .5MB
 * instead.
 *
 * returns size or -1 for error
 */
int bigsockbuf(int fd, int dir, int size)
{
    int n, tries;

    /* initial size */
    n = size;
    tries = 0;

    while (n > 4096) {
        if (setsockopt(fd, SOL_SOCKET, dir, (char*)&n, sizeof (n)) < 0) {
            /* anything other than no buffers available is fatal */
            if (errno != ENOBUFS) {
                return -1;
            }
            /* try a smaller value */
            if (n > 1024*1024) { /* most systems not > 256K bytes w/o tweaking */
                n -= 1024*1024;
            }	else {
                n -= 2048;
            }
            ++tries;
        } else {
            return n;
        }
    } /* while */

    /* no increase in buffer size */
    return 0;
}