pcapplusplus-sys 0.1.0

#define LOG_MODULE PacketLogModuleMplsLayer

#include "MplsLayer.h"
#include "IPv4Layer.h"
#include "IPv6Layer.h"
#include "PayloadLayer.h"
#include "Logger.h"
#include <string.h>
#include <sstream>
#include "EndianPortable.h"

namespace pcpp
{

MplsLayer::MplsLayer(uint32_t mplsLabel, uint8_t ttl, uint8_t experimentalUseValue, bool bottomOfStack)
{
	const size_t headerLen = sizeof(mpls_header);
	m_DataLen = headerLen;
	m_Data = new uint8_t[headerLen];
	memset(m_Data, 0, headerLen);
	m_Protocol = MPLS;

	setMplsLabel(mplsLabel);
	setTTL(ttl);
	setExperimentalUseValue(experimentalUseValue);
	setBottomOfStack(bottomOfStack);
}

bool MplsLayer::isBottomOfStack() const
{
	return (getMplsHeader()->misc & 0x01);
}

void MplsLayer::setBottomOfStack(bool val)
{
	if (!val)
		getMplsHeader()->misc &= 0xFE;
	else
		getMplsHeader()->misc |= 0x1;
}

uint8_t MplsLayer::getExperimentalUseValue() const
{
	return ((getMplsHeader()->misc & 0x0E) >> 1);
}

bool MplsLayer::setExperimentalUseValue(uint8_t val)
{
	// exp value is only 3 bits
	if (val > 7)
	{
		PCPP_LOG_ERROR("Set ExperimentalUse value got an illegal value: " << (int)val << ". Value must be lower than 8");
		return false;
	}

	mpls_header* hdr = getMplsHeader();

	// clear the 3 exp bits
	hdr->misc &= 0xF1;

	// move the 3 bits to their place
	val = val << 1;

	hdr->misc |= val;

	return true;
}

uint32_t MplsLayer::getMplsLabel() const
{
	return (htobe16(getMplsHeader()->hiLabel) << 4) | ((getMplsHeader()->misc & 0xF0) >> 4);
}

bool MplsLayer::setMplsLabel(uint32_t label)
{
	if (label > 0xFFFFF)
	{
		PCPP_LOG_ERROR("MPLS label mustn't exceed 20 bits which is the value 0xffff. Got a parameter with the value 0x" << std::hex << label);
		return false;
	}

	mpls_header* hdr = getMplsHeader();

	// clear the 4 label bits in misc field
	hdr->misc &= 0x0F;

	// take the last nibble of the label value and move this nibble to its place in misc
	uint8_t miscVal = (label & 0x0F) << 4;

	// update misc field
	hdr->misc |= miscVal;

	// get rid of the nibble that went to misc
	label = label >> 4;

	// set the high 2 bytes of the label
	hdr->hiLabel = (uint16_t)htobe16(label);

	return true;
}


void MplsLayer::parseNextLayer()
{
	size_t headerLen = getHeaderLen();
	if (m_DataLen < headerLen + 1)
		return;

	uint8_t* payload = m_Data + sizeof(mpls_header);
	size_t payloadLen = m_DataLen - sizeof(mpls_header);

	if (!isBottomOfStack())
	{
		m_NextLayer = new MplsLayer(payload, payloadLen, this, m_Packet);
		return;
	}

	uint8_t nextNibble = (*((uint8_t*)(m_Data + headerLen)) & 0xF0) >> 4;
	switch (nextNibble)
	{
		case 4:
			m_NextLayer = IPv4Layer::isDataValid(payload, payloadLen)
				? static_cast<Layer*>(new IPv4Layer(payload, payloadLen, this, m_Packet))
				: static_cast<Layer*>(new PayloadLayer(payload, payloadLen, this, m_Packet));
			break;
		case 6:
			m_NextLayer = IPv6Layer::isDataValid(payload, payloadLen)
				? static_cast<Layer*>(new IPv6Layer(payload, payloadLen, this, m_Packet))
				: static_cast<Layer*>(new PayloadLayer(payload, payloadLen, this, m_Packet));
			break;
		default:
			m_NextLayer = new PayloadLayer(payload, payloadLen, this, m_Packet);
	}
}

void MplsLayer::computeCalculateFields()
{
	Layer* nextLayer = getNextLayer();
	if (nextLayer != nullptr)
	{
		setBottomOfStack((nextLayer->getProtocol() != MPLS));
	}
}

std::string MplsLayer::toString() const
{
	std::ostringstream labelStream;
	labelStream << getMplsLabel();
	std::ostringstream expStream;
	expStream << (int)getExperimentalUseValue();
	std::ostringstream ttlStream;
	ttlStream << (int)getTTL();
	std::string bottomOfStack = isBottomOfStack() ? "true" : "false";

	return "MPLS Layer, Label: " + labelStream.str() + ", Exp: " + expStream.str() + ", TTL: " + ttlStream.str() +
			", Bottom of stack: " + bottomOfStack;
}

} // namespace pcpp