GRETunnel.cpp

#include <iostream>
#include <winsock2.h>
#include <wintun.h>
#include <ws2ipdef.h>
#include <iphlpapi.h>
#include <mstcpip.h>
#include <WS2tcpip.h>
#include <thread>
#include <filesystem>
#include "include/wintun.h"

#include "wintun_helper.h"
#include "GRE.h"
#include "easylogging++.h"
#include "wintun.h"

#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "Iphlpapi.lib")

bool reset_adapter = false;
GRE* gre;
WINTUN_ADAPTER_HANDLE Adapter;
WINTUN_SESSION_HANDLE Session;

void configure_logging() {
	el::Configurations conf;
	conf.setToDefault();

	conf.set(el::Level::Global, el::ConfigurationType::ToFile, "true");
	conf.set(el::Level::Global, el::ConfigurationType::Filename, "./gre.log");
	conf.setGlobally(el::ConfigurationType::Format, "%datetime{%d/%M/%Y %H:%m:%s} [%level] %msg");

	el::Loggers::reconfigureLogger("default", conf);

}

INITIALIZE_EASYLOGGINGPP
int main(int argc, char* argv[])
{
	std::cout << "GRE Tunnel for Windows" << std::endl << std::endl;
	if (argc < 5 || argc > 7) {
		std::cerr << "At least 2 arguments must be given" << std::endl <<
			"Arguments: gre_tunnel.exe GRE_BIND_IP GRE_SERVER INTERFACE_IP GATEWAY_IP [CIDR (30)] [ADAPTER_NAME]" << std::endl;
		return 0;
	}
	configure_logging();


	LOG(DEBUG) << "Starting GRE Application";

	const char* gre_bind_ip = argv[1];
	const char* server_ip = argv[2];

	const char* bind_ip = argv[3];
	const char* gateway_ip = argv[4];
	const wchar_t* adapter_name;
	const char* _adapter_name;
	int cidr;

	// Default CIDR is 30
	if (argc >= 6) {
		cidr = atoi(argv[5]);
		if (cidr == 0) LOG(FATAL) << "CIDR " << cidr << " is invalid.";
	}
	else
		cidr = 30;

	if (argc == 7)
	{
		adapter_name = GetWC(argv[6]);
		_adapter_name = argv[6];
	}
	else
	{
		adapter_name = L"GRE_Tunnel";
		_adapter_name = "GRE_Tunnel";
	}

	std::cout << "My IP on the GRE network: " << bind_ip << "/" << cidr << std::endl <<
		"GRE server IP           : " << server_ip << std::endl <<
		"GRE server IP (Gateway) : " << gateway_ip << std::endl <<
		"GRE binding IP          : " << gre_bind_ip << std::endl;
	std::wcout << L"Adapter name            : " << adapter_name << std::endl << std::endl;

	if (!validateIpAddress(bind_ip) || !validateIpAddress(gre_bind_ip) || !validateIpAddress(server_ip)
		|| !validateIpAddress(gateway_ip)) {
		LOG(FATAL) << "Failed to parse IPv4";
	}

	HMODULE MWintun = wt_LoadModule();
	if (!InitializeWintun(MWintun)) {
		LOG(FATAL) << "Failed to initialize WinTun: " << GetLastError() << std::endl << "Please make sure that wintun.dll exists";
		return 0;
	}

	Adapter = WintunCreateAdapter(L"GRE_Tunnel", adapter_name, NULL);
	if (!Adapter) {
		LOG(FATAL) << "Failed to create Wintun adapter: " << GetLastError();
		return 0;
	}

	SetConsoleCtrlHandler(exit_handler, TRUE);

	MIB_UNICASTIPADDRESS_ROW AddressRow;
	InitializeUnicastIpAddressEntry(&AddressRow);
	WintunGetAdapterLUID(Adapter, &AddressRow.InterfaceLuid);
	AddressRow.Address.Ipv4.sin_family = AF_INET;
	inet_pton(AF_INET, bind_ip, &AddressRow.Address.Ipv4.sin_addr.S_un.S_addr);

	AddressRow.OnLinkPrefixLength = cidr;
	AddressRow.DadState = IpDadStatePreferred;
	auto LastError = CreateUnicastIpAddressEntry(&AddressRow);

	if (LastError != ERROR_SUCCESS && LastError != ERROR_OBJECT_ALREADY_EXISTS)
	{
		LOG(FATAL) << "Failed to assign IP: " << LastError;
		WintunCloseAdapter(Adapter);
		return 0;
	}

	Session = WintunStartSession(Adapter, WINTUN_MAX_RING_CAPACITY);
	if (!Session)
	{
		LOG(FATAL) << "Failed to create adapter";
		WintunCloseAdapter(Adapter);
		return 0;
	}

	char comm[256];
	sprintf_s(comm, 256, "netsh interface ip set address name=\"%s\" static %s 255.255.255.252 %s 300", _adapter_name, bind_ip, gateway_ip);
	LOG(INFO) << comm;
	system(comm);
	memset(comm, '0', 256);
	sprintf_s(comm, 256, "netsh interface ip set subinterface \"%s\" mtu=1476 store=persistent", _adapter_name);
	LOG(INFO) << comm;
	system(comm);



	gre = new GRE(server_ip, gre_bind_ip);

	std::thread t1(wintun_receive_loop);

	gre->receiver(MWintun);
}