#!/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_1	=> "Recv SCTP CHUNK_DATA (1)",
	sctp_chunk_data_2	=> "Recv SCTP CHUNK_DATA (2)",
	sctp_chunk_data_3	=> "Recv SCTP CHUNK_DATA (3)",
	sctp_chunk_data_4	=> "Recv SCTP CHUNK_DATA (4)",
	sctp_chunk_data_5	=> "Recv SCTP CHUNK_DATA (5)",
	sctp_chunk_data_6	=> "Recv SCTP CHUNK_DATA (6)",
	sctp_chunk_sack_1	=> "Send SCTP CHUNK_SACK (1 and 2)",
	sctp_chunk_sack_2	=> "Send SCTP CHUNK_SACK (1 and 3)",
	sctp_chunk_sack_3	=> "Send SCTP CHUNK_SACK (1, 3 and 4)",
	sctp_chunk_sack_4	=> "Send SCTP CHUNK_SACK (1, 3 to 5)",
);

$IF0 = Link0;

vCapture($IF0);

sctpCheckEnv($IF0);

$SIZE = 1024;
@cwnds = ();

sctpStatusClient($IF0, 6, "-x 6 -c $SIZE");

vListen($IF0);

vAccept($IF0);

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

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

sctpUpdateRecvACK();

for($i = 1; $i < 6; $i++) {
	%ret = vWarpRecv($IF0, 30, 0, 0, "sctp_chunk_data_$i");
	if($ret{status} != 0 || $ret{recvFrame} ne "sctp_chunk_data_$i") {
		vLogHTML('Cannot receive SCTP CHUNK_DATA<BR>');
		vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
		exit $V6evalTool::exitFail;
	}
}

# SACK for first 2 messages shoule increase the cwnd by 1 MTU
vSend($IF0, sctp_chunk_sack_1);
$cwnds[@cwnds] = $cwnds[@cwnds - 1] + 1500;
vLogHTML("<B>Now the cwnd is $cwnds[@cwnds - 1]</B>");
# SACK report the 2nd message is missing
vSend($IF0, sctp_chunk_sack_2);
# SACK report the 2nd message is missing
vSend($IF0, sctp_chunk_sack_3);
# SACK report the 2nd message is missing
vSend($IF0, sctp_chunk_sack_4);

# Do Fast Retransmit on Gap Reports 
%ret = vWarpRecv($IF0, 30, 0, 0, "sctp_chunk_data_2");
if($ret{status} != 0 || $ret{recvFrame} ne "sctp_chunk_data_2") {
	vLogHTML('Cannot receive SCTP CHUNK_DATA<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
	exit $V6evalTool::exitFail;
}

# Upon detection of packet losses from SACK, update cwnd to max(cwnd/2, 4*MTU)
$cwnds[@cwnds] = 6000;
vLogHTML("<B>Now the cwnd is $cwnds[@cwnds - 1]</B>");

%ret = vWarpRecv($IF0, 30, 0, 0, "sctp_chunk_data_2");
if($ret{status} != 0 || $ret{recvFrame} ne "sctp_chunk_data_2") {
	vLogHTML('Cannot receive SCTP CHUNK_DATA<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
	exit $V6evalTool::exitFail;
}

# When the T3-rtx timer expires on an address, update cwnd to 1*MTU
$cwnds[@cwnds] = 1500;
vLogHTML("<B>Now the cwnd is $cwnds[@cwnds - 1]</B>");

sctpUpdateRecvACK(4);
vSend($IF0, sctp_chunk_sack_snd);
sctpUpdateRecvACK(-4);

%ret = vWarpRecv($IF0, 30, 0, 0, "sctp_chunk_data_6");
if($ret{status} != 0 || $ret{recvFrame} ne "sctp_chunk_data_6") {
	vLogHTML('Cannot receive SCTP CHUNK_DATA<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT>'); 
	exit $V6evalTool::exitFail;
}
sctpUpdateRecvACK(5);
vSend($IF0, sctp_chunk_sack_snd);

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

  InitCwndUnderFastRetran2.seq - Verify that cwnd is update correctly when T3-rtx timer expires on an address

=head1 PURPOSE

  To check that cwnd is update correctly after a fast retransmit 
  and T3-rtx timer expires on an address.

=head1 SYNOPSIS

=begin html
<PRE>
  <A HREF="./InitCwndUnderFastRetran2.seq">./InitCwndUnderFastRetran2.seq</A> [-tooloption ...] -pkt <A HREF="./InitCwndUnderFastRetran2.def">./InitCwndUnderFastRetran2.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 messages 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  
                  <----------------       DATA 5

  SACK            ----------------->
  (For DATA 1 and DATA 2)
  SACK            ----------------->
  (For DATA 1 and DATA 3, report DATA 2 is missing)
  SACK            ----------------->
  (For DATA 1, DATA 3 and DATA 4, report DATA 2 is missing)
  SACK            ----------------->
  (For DATA 1, DATA 3 to DATA 5, report DATA 2 is missing)
                  <----------------       DATA 2
  Don't Send SACK  
                  <----------------       DATA 2 (T3-rtx timer expires)

  SACK            ----------------->
  (For all DATAs)
                  <----------------       DATA 6

  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 A,
     when there is association between them.
  3. From endpoint A, send SACK of the first 2 DATA messages to 
     endpoint B.
  4. Check B: Congestion control window is 5880 now.
  5. From endpoint A, send SACK of the 1st, 3rd DATA messages to 
     endpoint B, report the 2nd message is missing.
  6. From endpoint A, send SACK of the 1st, 3rd and 4th DATA messages
     to endpoint B, report the 2nd message is missing.
  7. From endpoint A, send SACK of the 1st, 3rd to 5th DATA messages
     to endpoint B, report the 2nd message is missing.
  8. Check C: The 2nd DATA messages is send again immediately.
  9. Check D: Congestion control window is 6000 now.
  10.Don't send SACK, let T3-rtx timer of DATA2 expires.
  11.The 2nd DATA messages is send again, send SACK of all DATA to
     endpoint B.
  12.Check E: Congestion control window is 1500 now.
  13.Received and SACK the rest DATA messages.

=head1 NOTE

  None

=head1 REFERENCE

  RFC 4960

  7.2.3.  Congestion Control

    Upon detection of packet losses from SACK (see Section 7.2.4), an
    endpoint should do the following:

      ssthresh = max(cwnd/2, 4*MTU)
      cwnd = ssthresh
      partial_bytes_acked = 0

    Basically, a packet loss causes cwnd to be cut in half.

    When the T3-rtx timer expires on an address, SCTP should perform slow
    start by:

=begin html
<PRE>
      <B>ssthresh = max(cwnd/2, 4*MTU)
      cwnd = 1*MTU</B>
</PRE>

=end html

    and ensure that no more than one SCTP packet will be in flight for
    that address until the endpoint receives acknowledgement for
    successful delivery of data to that address.