#!/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 = (
	sctp_chunk_data_loc	=> "Recv SCTP CHUNK_DATA",
);

$IF0 = Link0;

vCapture($IF0);

sctpCheckEnv($IF0);

$SIZE = 1352;
@cwnds = ();

sctpStatusClient($IF0, 5, "-x 5 -c $SIZE");

vListen($IF0);

vAccept($IF0);

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

# Now CWND is 4380
$cwnds[@cwnds] = 4380;
vLogHTML('<B>Now the cwnd is 4380</B>');

for($i = 0; $i < 4; $i++) {
	%ret = vWarpRecv($IF0, 10, 0, 0, sctp_chunk_data_loc);
	if($ret{status} != 0 || $ret{recvFrame} ne sctp_chunk_data_loc) {
		vLogHTML('Cannot receive SCTP CHUNK_DATA<BR>');
		vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
		exit $V6evalTool::exitFail;
	}
}

vLogHTML('<B>flight_size(6760) is greater than cwnd(4380)</B>');

# The SACK for 1 messages should increase the cwnd by 1352
sctpUpdateRecvACK(1);
vSend($IF0, sctp_chunk_sack_snd);
$cwnds[@cwnds] = $cwnds[@cwnds - 1] + $SIZE;
vLogHTML("<B>Now the cwnd is $cwnds[@cwnds - 1]</B>");

# Rest 3 data packet we had recv
sctpUpdateRecvACK(3);
vSend($IF0, sctp_chunk_sack_snd);

# Rest 1 data packet we do not recv
vRecvMsg($IF0, sctp_chunk_data_loc);

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

  InitCwndWhenSACK.seq - The cwnd MUST be increased the size of outstanding DATA chunk(s) acknowledged if it is less than PMTU

=head1 PURPOSE

  To check that if an incoming SACK advances the Cumulative TSN Ack
  Point, and the total size of the previously outstanding DATA chunk(s)
  acknowledged is less than PMTU, cwnd is increased by the total size.

=head1 SYNOPSIS

=begin html
<PRE>
  <A HREF="./InitCwndWhenSACK.seq">./InitCwndWhenSACK.seq</A> [-tooloption ...] -pkt <A HREF="./InitCwndWhenSACK.def">./InitCwndWhenSACK.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
  Don't Send SACK  
                  <----------------       DATA 2
  Don't Send SACK  
                  <----------------       DATA 3
  Don't Send SACK  
                  <----------------       DATA 4
  Don't Send SACK  
  SACK            ----------------->
  (To DATA 1)
  SACK            ----------------->
  (From DATA 2 to DATA 4)
                  <----------------       DATA 5

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

  TEST DESCRIPTION:

  1. Check A: the initial cwnd before DATA transmission is set to 4380.
  2. From endpoint B, send valid DATA message 5 times to endpoint B,
     when there is association between them.
  3. From endpoint A, after received 4 DATA message, send SACK of the
     first DATA to endpoint B.
  4. Check B: Congestion control window is 5732 now.
  5. Received and SACK the rest DATA messages.

=head1 NOTE

  None

=head1 REFERENCE

  RFC 4960

  7.2.1.  Slow-Start

    Beginning data transmission into a network with unknown conditions or
    after a sufficiently long idle period requires SCTP to probe the
    network to determine the available capacity.  The slow-start
    algorithm is used for this purpose at the beginning of a transfer, or
    after repairing loss detected by the retransmission timer.

    o  The initial cwnd before DATA transmission or after a sufficiently
       long idle period MUST be set to min(4*MTU, max (2*MTU, 4380
       bytes)).

    o  The initial cwnd after a retransmission timeout MUST be no more
       than 1*MTU.

    o  The initial value of ssthresh MAY be arbitrarily high (for
       example, implementations MAY use the size of the receiver
       advertised window).

    o  Whenever cwnd is greater than zero, the endpoint is allowed to
       have cwnd bytes of data outstanding on that transport address.

=begin html
<PRE>
    o  When cwnd is less than or equal to ssthresh, an SCTP endpoint MUST
       use the slow-start algorithm to increase cwnd only if the current
       congestion window is being fully utilized, an incoming SACK
       advances the Cumulative TSN Ack Point, and the data sender is not
       in Fast Recovery.  Only when these three conditions are met can
       the cwnd be increased; otherwise, the cwnd MUST not be increased.
       If these conditions are met, then cwnd MUST be increased by, at
       most, the lesser of <B>1) the total size of the previously
       outstanding DATA chunk(s) acknowledged,</B> and 2) the destination's
       path MTU.  This upper bound protects against the ACK-Splitting
       attack outlined in [SAVAGE99].
</PRE>

=end html

    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.