#!/usr/bin/perl
#
# SCTP Conformance Test Suite Implementation
# (C) Copyright Fujitsu Ltd. 2008, 2009
#
# This file is part of the SCTP Conformance Test Suite implementation.
#
# The SCTP Conformance Test Suite implementation is free software;
# you can redistribute it and/or modify it under the terms of
# the GNU General Public License version 2 as published by
# the Free Software Foundation.
#
# The SCTP Conformance Test Suite implementation is distributed in the
# hope that it will be useful, but WITHOUT ANY WARRANTY; without even
# the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
# PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU CC; see the file COPYING.  If not, write to
# the Free Software Foundation, 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
#
# Please send any bug reports or fixes you make to the
# email address(es):
#    networktest sctp <networktest-sctp@lists.sourceforge.net>
#
# Or submit a bug report through the following website:
#    http://networktest.sourceforge.net/
#
# Written or modified by:
#    Hiroaki Kago <linuxsctp-kg@ml.css.fujitsu.com>
#    Wei Yongjun <yjwei@cn.fujitsu.com>
#
# Any bugs reported given to us we will try to fix... any fixes shared will
# be incorporated into the next SCTP release.
#
##############################################################################
BEGIN {	$V6evalTool::TestVersion = '$Name: REL_1_0_0 $'; }

use lib "../common";
use V6evalTool;
use SCTP;

%pktdesc = ();

$IF0 = Link0;

vCapture($IF0);

sctpCheckEnv($IF0);

sctpStatusClient($IF0, 4);

vListen($IF0);

vAccept($IF0);

vLogHTML('<B>================ Main Test =================</B>');
@cwnds = ();

# Now the cwnd is 4380
$cwnds[@cwnds] = 4380;

vRecvMsg($IF0);
vRecvMsg($IF0);
vRecvMsg($IF0);
vRecvMsg($IF0);

vClose($IF0);

$cwnds[@cwnds] = '-';
@ret = sctpGetRemoteStatus(@cwnds);
for($i = 0; $i < @cwnds; $i++) {
	if((!defined($ret[$i]) && $cwnds[$i] != '-') || $cwnds[$i] != $ret[$i]) {
		vLogHTML(sprintf("The initial cwnd is not update correctly, except %s, but get %s<BR>",
					$cwnds[$i] == '-' ? "NO CHANGE" : $cwnds[$i],
					defined($ret[$i]) ? $ret[$i]: "NO CHANGE"));
		vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
		exit $V6evalTool::exitFail;
	}
}

vLogHTML(OK);
exit $V6evalTool::exitPass;

######################################################################
__END__

=head1 NAME

  InitCwndNotChang.seq - The initial cwnd should not chang as flight_size is less than the cwnd

=head1 PURPOSE

  To check that when the data newly acknowledged by the SACK diminishes
  the amount of data now in flight to less than cwnd, unchanged value of
  cwnd now allows new data to be sent.

=head1 SYNOPSIS

=begin html
<PRE>
  <A HREF="./InitCwndNotChang.seq">./InitCwndNotChang.seq</A> [-tooloption ...] -pkt <A HREF="./InitCwndNotChang.def">./InitCwndNotChang.def</A>
    -tooloption : v6eval tool option
  See Also: <A HREF="../common/STD_PKT_COMMON.def">../common/STD_PKT_COMMON.def</A>
            <A HREF="../common/SCTP_COMMON.def">../common/SCTP_COMMON.def</A>
</PRE>

=end html

=head1 PRE-TEST CONDITION

  Association is established between endpoint A and B. Arrange data 
  in endpoint B such that DATA chunk is sent to endpoint A.

=head1 TEST PROCEDURE

  Endpoint A                            Endpoint B         ULP
  (ESTABLISHED)                         (ESTABLISHED)  
                                                   <-----    Send
                  <----------------       DATA 1

  SACK            ----------------->

                  <----------------       DATA 2

  SACK            ----------------->

                  <----------------       DATA 3

  SACK            ----------------->

                  <----------------       DATA 4

  SACK            ----------------->

  TEST DESCRIPTION:

  1. Check A: the initial cwnd before DATA transmission is set to 4380.
  2. From endpoint B, send valid DATA message 4 times to endpoint B,
     when there is association between them.
  3. From endpoint A, send SACK immediately after received DATA message.
  4. Check B: Congestion control window is not changed.

=head1 NOTE

  None

=head1 REFERENCE

  RFC 4960

  7.2.1.  Slow-Start

    In instances where its peer endpoint is multi-homed, if an endpoint
    receives a SACK that advances its Cumulative TSN Ack Point, then it
    should update its cwnd (or cwnds) apportioned to the destination
    addresses to which it transmitted the acknowledged data.  However, if
    the received SACK does not advance the Cumulative TSN Ack Point, the
    endpoint MUST NOT adjust the cwnd of any of the destination
    addresses.

=begin html
<PRE>
    Because an endpoint's cwnd is not tied to its Cumulative TSN Ack
    Point, as duplicate SACKs come in, even though they may not advance
    the Cumulative TSN Ack Point an endpoint can still use them to clock
    out new data.  <B>That is, the data newly acknowledged by the SACK
    diminishes the amount of data now in flight to less than cwnd, and so
    the current, unchanged value of cwnd now allows new data to be sent.</B>
    On the other hand, the increase of cwnd must be tied to the
    Cumulative TSN Ack Point advancement as specified above.  Otherwise,
    the duplicate SACKs will not only clock out new data, but also will
    adversely clock out more new data than what has just left the
    network, during a time of possible congestion.
</PRE>

=end html

    o  When the endpoint does not transmit data on a given transport
       address, the cwnd of the transport address should be adjusted to
       max(cwnd/2, 4*MTU) per RTO.