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-rw-r--r--src/util/inet_windowsize.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/src/util/inet_windowsize.c b/src/util/inet_windowsize.c
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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);
+}