bool GREv0Layer::unsetChecksum()
{
gre_basic_header* header = getGreHeader();
if (header->checksumBit == 0)
{
LOG_ERROR("Couldn't unset checksum as it's already unset");
return false;
}
// if both routing and checksum are unset we need to shorted the layer
bool needToShortenLayer = (header->routingBit == 0);
uint8_t* offsetPtr = getFieldValue(GreChecksumOrRouting, true);
int offset = offsetPtr - m_Data;
if (needToShortenLayer && !shortenLayer(offset, sizeof(uint32_t)))
{
LOG_ERROR("Couldn't extend layer to unset checksum");
return false;
}
if (!needToShortenLayer) // meaning routing bit is set - only zero the checksum field
{
uint16_t* checksumPtr = (uint16_t*)(m_Data + offset);
*checksumPtr = 0;
}
header = getGreHeader();
header->checksumBit = 0;
return true;
}
bool TcpLayer::removeTcpOption(TcpOption optionType)
{
TcpOptionData* opt = getTcpOptionData(optionType);
if (opt == NULL)
{
return false;
}
// calculate total TCP option size
TcpOptionData* curOpt = getFirstTcpOptionData();
size_t totalOptSize = 0;
while (curOpt != NULL)
{
totalOptSize += curOpt->getTotalSize();
curOpt = getNextTcpOptionData(curOpt);
}
totalOptSize -= opt->getTotalSize();
int offset = (uint8_t*)opt - m_Data;
if (!shortenLayer(offset, opt->getTotalSize()))
{
return false;
}
adjustTcpOptionTrailer(totalOptSize);
m_TcpOptionsCount--;
return true;
}
bool TcpLayer::removeTcpOption(TcpOptionType optionType)
{
TcpOption opt = getTcpOption(optionType);
if (opt.isNull())
{
return false;
}
// calculate total TCP option size
TcpOption curOpt = getFirstTcpOption();
size_t totalOptSize = 0;
while (!curOpt.isNull())
{
totalOptSize += curOpt.getTotalSize();
curOpt = getNextTcpOption(curOpt);
}
totalOptSize -= opt.getTotalSize();
int offset = opt.getRecordBasePtr() - m_Data;
if (!shortenLayer(offset, opt.getTotalSize()))
{
return false;
}
adjustTcpOptionTrailer(totalOptSize);
m_OptionReader.changeTLVRecordCount(-1);
return true;
}
bool TcpLayer::removeAllTcpOptions()
{
int offset = sizeof(tcphdr);
if (!shortenLayer(offset, getHeaderLen()-offset))
return false;
getTcpHeader()->dataOffset = sizeof(tcphdr)/4;
m_NumOfTrailingBytes = 0;
m_TcpOptionsCount = 0;
return true;
}
bool TcpLayer::removeAllTcpOptions()
{
int offset = sizeof(tcphdr);
if (!shortenLayer(offset, getHeaderLen()-offset))
return false;
getTcpHeader()->dataOffset = sizeof(tcphdr)/4;
m_NumOfTrailingBytes = 0;
m_OptionReader.changeTLVRecordCount(0-getTcpOptionCount());
return true;
}
bool PPPoEDiscoveryLayer::removeTag(PPPoEDiscoveryLayer::PPPoETagTypes tagType)
{
PPPoEDiscoveryLayer::PPPoETag* tag = getTag(tagType);
if (tag == NULL)
{
LOG_ERROR("Couldn't find tag");
return false;
}
int offset = (uint8_t*)tag - m_Data;
return shortenLayer(offset, tag->getTagTotalSize());
}
void TcpLayer::adjustTcpOptionTrailer(size_t totalOptSize)
{
int newNumberOfTrailingBytes = 0;
while ((totalOptSize + newNumberOfTrailingBytes) % 4 != 0)
newNumberOfTrailingBytes++;
if (newNumberOfTrailingBytes < m_NumOfTrailingBytes)
shortenLayer(sizeof(tcphdr)+totalOptSize, m_NumOfTrailingBytes - newNumberOfTrailingBytes);
else if (newNumberOfTrailingBytes > m_NumOfTrailingBytes)
extendLayer(sizeof(tcphdr)+totalOptSize, newNumberOfTrailingBytes - m_NumOfTrailingBytes);
m_NumOfTrailingBytes = newNumberOfTrailingBytes;
for (int i = 0; i < m_NumOfTrailingBytes; i++)
m_Data[sizeof(tcphdr) + totalOptSize + i] = TCPOPT_DUMMY;
getTcpHeader()->dataOffset = (sizeof(tcphdr) + totalOptSize + m_NumOfTrailingBytes)/4;
}
bool GREv1Layer::unsetAcknowledgmentNum()
{
gre1_header* header = getGreHeader();
if (header->ackSequenceNumBit == 0)
{
LOG_ERROR("Couldn't unset ack number as it's already unset");
return false;
}
uint8_t* offsetPtr = getFieldValue(GreAck, true);
int offset = offsetPtr - m_Data;
if (!shortenLayer(offset, sizeof(uint32_t)))
{
LOG_ERROR("Couldn't shorted layer to unset ack number");
return false;
}
header = getGreHeader();
header->ackSequenceNumBit = 0;
return true;
}
bool GREv0Layer::unsetKey()
{
gre_basic_header* header = getGreHeader();
if (header->keyBit == 0)
{
LOG_ERROR("Couldn't unset key as it's already unset");
return false;
}
uint8_t* offsetPtr = getFieldValue(GreKey, true);
int offset = offsetPtr - m_Data;
if (!shortenLayer(offset, sizeof(uint32_t)))
{
LOG_ERROR("Couldn't shorted layer to unset key");
return false;
}
header = (gre_basic_header*)m_Data;
header->keyBit = 0;
return true;
}
bool GreLayer::unsetSequenceNumber()
{
gre_basic_header* header = (gre_basic_header*)m_Data;
if (header->sequenceNumBit == 0)
{
LOG_ERROR("Couldn't unset sequence number as it's already unset");
return false;
}
uint8_t* offsetPtr = getFieldValue(GreSeq, true);
int offset = offsetPtr - m_Data;
if (!shortenLayer(offset, sizeof(uint32_t)))
{
LOG_ERROR("Couldn't shorted layer to unset sequence number");
return false;
}
header = (gre_basic_header*)m_Data;
header->sequenceNumBit = 0;
return true;
}
bool PPPoEDiscoveryLayer::removeAllTags()
{
int offset = sizeof(pppoe_header);
return shortenLayer(offset, m_DataLen-offset);
}
bool DnsLayer::removeResource(IDnsResource* resourceToRemove)
{
if (resourceToRemove == NULL)
{
LOG_DEBUG("resourceToRemove cannot be NULL");
return false;
}
// find the resource preceding resourceToRemove
IDnsResource* prevResource = m_ResourceList;
if (m_ResourceList != resourceToRemove)
{
while (prevResource != NULL)
{
IDnsResource* temp = prevResource->getNextResource();
if (temp == resourceToRemove)
break;
prevResource = temp;
}
}
if (prevResource == NULL)
{
LOG_DEBUG("Resource not found");
return false;
}
// shorten the layer and fix offset in layer for all next DNS resources in the packet
if (!shortenLayer(resourceToRemove->m_OffsetInLayer, resourceToRemove->getSize(), resourceToRemove))
{
LOG_ERROR("Couldn't shorten the DNS layer, resource cannot be removed");
return false;
}
// remove resourceToRemove from the resources linked list
if (m_ResourceList != resourceToRemove)
{
prevResource->setNexResource(resourceToRemove->getNextResource());
}
else
{
m_ResourceList = resourceToRemove->getNextResource();
}
// check whether resourceToRemove was the first of its type
if (getFirstResource(resourceToRemove->getType()) == resourceToRemove)
{
IDnsResource* nextResource = resourceToRemove->getNextResource();
if (nextResource != NULL && nextResource->getType() == resourceToRemove->getType())
setFirstResource(resourceToRemove->getType(), nextResource);
else
setFirstResource(resourceToRemove->getType(), NULL);
}
// free resourceToRemove memory
delete resourceToRemove;
return true;
}
