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/*++
/* NAME
/* inet_windowsize 3
/* SUMMARY
/* TCP window scaling control
/* SYNOPSIS
/* #include <iostuff.h>
/*
/* int inet_windowsize;
/*
/* void set_inet_windowsize(sock, windowsize)
/* int sock;
/* int windowsize;
/* DESCRIPTION
/* set_inet_windowsize() overrides the default TCP window size
/* with the specified value. When called before listen() or
/* accept(), this works around broken infrastructure that
/* mis-handles TCP window scaling options.
/*
/* The global inet_windowsize variable is available for other
/* routines to remember that they wish to override the default
/* TCP window size. The variable is not accessed by the
/* set_inet_windowsize() function itself.
/*
/* Arguments:
/* .IP sock
/* TCP communication endpoint, before the connect(2) or listen(2) call.
/* .IP windowsize
/* The preferred TCP window size. This must be > 0.
/* DIAGNOSTICS
/* Panic: interface violation.
/* Warnings: some error return from setsockopt().
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System libraries. */
#include <sys_defs.h>
#include <sys/socket.h>
/* Utility library. */
#include <msg.h>
#include <iostuff.h>
/* Application storage. */
/*
* Tunable to work around broken routers.
*/
int inet_windowsize = 0;
/* set_inet_windowsize - set TCP send/receive window size */
void set_inet_windowsize(int sock, int windowsize)
{
/*
* Sanity check.
*/
if (windowsize <= 0)
msg_panic("inet_windowsize: bad window size %d", windowsize);
/*
* Generic implementation: set the send and receive buffer size before
* listen() or connect().
*/
if (setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (void *) &windowsize,
sizeof(windowsize)) < 0)
msg_warn("setsockopt SO_SNDBUF %d: %m", windowsize);
if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (void *) &windowsize,
sizeof(windowsize)) < 0)
msg_warn("setsockopt SO_RCVBUF %d: %m", windowsize);
}
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