[newlib-cygwin] TCP: send full initial window when timestamps are in use

[Sebastian Huber <sh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=7b30b9f648a25f3b615730864ddc86a433a93333

commit 7b30b9f648a25f3b615730864ddc86a433a93333
Author: Richard Scheffenegger <rscheff@FreeBSD.org>
Date:   Fri Sep 25 10:38:19 2020 +0000

    TCP: send full initial window when timestamps are in use
    
    The fastpath in tcp_output tries to send out
    full segments, and avoid sending partial segments by
    comparing against the static t_maxseg variable.
    That value does not consider tcp options like timestamps,
    while the initial window calculation is using
    the correct dynamic tcp_maxseg() function.
    
    Due to this interaction, the last, full size segment
    is considered too short and not sent out immediately.
    
    Reviewed by:    tuexen
    MFC after:      2 weeks
    Sponsored by:   NetApp, Inc.
    Differential Revision:  https://reviews.freebsd.org/D26478

Diff:
---
 newlib/libc/sys/rtems/include/netinet/tcp.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/newlib/libc/sys/rtems/include/netinet/tcp.h b/newlib/libc/sys/rtems/include/netinet/tcp.h
index 0a5226836..faf142959 100644
--- a/newlib/libc/sys/rtems/include/netinet/tcp.h
+++ b/newlib/libc/sys/rtems/include/netinet/tcp.h
@@ -80,6 +80,8 @@ struct tcphdr {
 	u_short	th_urp;			/* urgent pointer */
 };
 
+#define	PADTCPOLEN(len)		((((len) / 4) + !!((len) % 4)) * 4)
+
 #define	TCPOPT_EOL		0
 #define	   TCPOLEN_EOL			1
 #define	TCPOPT_PAD		0		/* padding after EOL */