netch/Redirector/DNSHandler.cpp

#include "DNSHandler.h"

extern string dnsHost;
extern USHORT dnsPort;

SOCKADDR_IN6 dnsAddr;

void ProcessPacket(ENDPOINT_ID id, SOCKADDR_IN6 target, const char* packet, int length, PNF_UDP_OPTIONS options)
{
	char buffer[1024];

	auto tcpSocket = SocksHelper::Utils::Connect();
	if (tcpSocket != INVALID_SOCKET)
	{
		if (SocksHelper::Utils::Handshake(tcpSocket))
		{
			SocksHelper::UDP udpConn;
			udpConn.tcpSocket = tcpSocket;

			if (udpConn.Associate())
			{
				if (udpConn.CreateUDP())
				{
					if (udpConn.Send(&dnsAddr, packet, length) == length)
					{
						int size = udpConn.Read(NULL, buffer, sizeof(buffer));
						if (size != 0 && size != SOCKET_ERROR)
						{
							nf_udpPostReceive(id, (unsigned char*)&target, buffer, size, options);
						}
					}
				}
			}
		}
	}

	delete[] packet;
	delete[] options;
}

bool DNSHandler::Init()
{
	memset(&dnsAddr, 0, sizeof(SOCKADDR_IN6));
	
	auto ipv4 = (PSOCKADDR_IN)&dnsAddr;
	if (inet_pton(AF_INET, dnsHost.c_str(), &ipv4->sin_addr) == 1)
	{
		ipv4->sin_family = AF_INET;
		ipv4->sin_port = htons(dnsPort);
		return true;
	}

	if (inet_pton(AF_INET6, dnsHost.c_str(), &dnsAddr.sin6_addr) == 1)
	{
		dnsAddr.sin6_family = AF_INET6;
		dnsAddr.sin6_port = htons(dnsPort);
		return true;
	}

	puts("[Redirector][DNSHandler::Init] Call WSAStringToAddress failed");
	return false;
}

bool DNSHandler::IsDNS(PSOCKADDR_IN6 target)
{
	if (target->sin6_family == AF_INET)
	{
		return ((PSOCKADDR_IN)target)->sin_port == htons(53);
	}

	return target->sin6_port == htons(53);
}

void DNSHandler::CreateHandler(ENDPOINT_ID id, PSOCKADDR_IN6 target, const char* packet, int length, PNF_UDP_OPTIONS options)
{
	SOCKADDR_IN6 remote;
	auto buffer = new char[length];
	auto option = (PNF_UDP_OPTIONS)new char[sizeof(NF_UDP_OPTIONS) + options->optionsLength];

	memcpy(&remote, target, sizeof(SOCKADDR_IN6));
	memcpy(buffer, packet, length);
	memcpy(option, options, sizeof(NF_UDP_OPTIONS) + options->optionsLength - 1);

	thread(ProcessPacket, id, remote, buffer, length, option).detach();
}