/*++ /* 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, (char *) &windowsize, sizeof(windowsize)) < 0) msg_warn("setsockopt SO_SNDBUF %d: %m", windowsize); if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char *) &windowsize, sizeof(windowsize)) < 0) msg_warn("setsockopt SO_RCVBUF %d: %m", windowsize); }