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sign: fix PayloadCksum for odd boundary between protocols

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This commit is contained in:
Srivats P 2016-11-01 16:30:13 +05:30
parent 50fec9fa5a
commit 46449a02a3
1 changed files with 19 additions and 4 deletions
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23
common/abstractprotocol.cpp
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@ -22,6 +22,8 @@ along with this program. If not, see <http://www.gnu.org/licenses/>
#include "protocollistiterator.h"
#include "streambase.h"
#include "byteswap.h"
#include <qendian.h>
/*!
@ -972,18 +974,29 @@ out:
quint32 AbstractProtocol::protocolFramePayloadCksum(int streamIndex,
CksumType cksumType, CksumScope cksumScope) const
{
quint32 sum = 0;
quint32 sum;
quint16 cksum;
AbstractProtocol *p = next;
Q_ASSERT(cksumType == CksumIp);
if (!p)
return 0xFFFF;
cksum = p->protocolFrameCksum(streamIndex, cksumType);
sum = (quint16) ~cksum;
if (cksumScope == CksumScopeAdjacentProtocol)
goto out;
p = p->next;
while (p)
{
// when combining cksums, a non-first protocol starting at odd offset
// needs a byte swap (see RFC 1071 section(s) 2A, 2B)
cksum = p->protocolFrameCksum(streamIndex, cksumType);
if (p->protocolFrameOffset(streamIndex) & 0x1)
cksum = swap16(cksum);
sum += (quint16) ~cksum;
if (cksumScope == CksumScopeAdjacentProtocol)
goto out;
p = p->next;
}
@ -998,7 +1011,9 @@ out:
while(sum>>16)
sum = (sum & 0xFFFF) + (sum >> 16);
return (quint16) ~sum;
cksum = (quint16) ~sum;
qDebug("%s: cksum = %u", __FUNCTION__, cksum);
return cksum;
}
// Stein's binary GCD algo - from wikipedia