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Make the handling of the tcp window explicit for the SYN_SENT case

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in tcp_outout().  This is currently not strictly necessary but paves
the way to simplify the entire SYN options handling quite a bit.
Clarify comment.  No change in effective behavour with this commit.

RFC1323 requires the window field in a SYN (i.e., a <SYN> or
<SYN,ACK>) segment itself never be scaled.
This commit is contained in:
Andre Oppermann 2007-06-09 21:19:12 +00:00
parent 5396d0f8d8
commit 104ebb2a45
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=170470
1 changed files with 10 additions and 4 deletions
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14
sys/netinet/tcp_output.c
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@ -906,9 +906,6 @@ tcp_output(struct tcpcb *tp)
/*
* Calculate receive window. Don't shrink window,
* but avoid silly window syndrome.
*
* XXX: RFC1323: The Window field in a SYN (i.e., a <SYN> or
* <SYN,ACK>) segment itself is never scaled.
*/
if (recwin < (long)(so->so_rcv.sb_hiwat / 4) &&
recwin < (long)tp->t_maxseg)
@ -917,8 +914,17 @@ tcp_output(struct tcpcb *tp)
recwin = (long)(tp->rcv_adv - tp->rcv_nxt);
if (recwin > (long)TCP_MAXWIN << tp->rcv_scale)
recwin = (long)TCP_MAXWIN << tp->rcv_scale;
th->th_win = htons((u_short) (recwin >> tp->rcv_scale));
/*
* According to RFC1323 the window field in a SYN (i.e., a <SYN>
* or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK>
* case is handled in syncache.
*/
if (flags & TH_SYN)
th->th_win = htons((u_short)
(min(sbspace(&so->so_rcv), TCP_MAXWIN)));
else
th->th_win = htons((u_short)(recwin >> tp->rcv_scale));
/*
* Adjust the RXWIN0SENT flag - indicate that we have advertised