main.cpp

/*	<3 Pinkie Pie

	Thanks to P5yl0 (original C# implementation) & Meishu (pure JS port).

	Original C# source:
	https://github.com/P5yl0/TeraEmulator_2117a/tree/master/Tera_Emulator_Source_2117/GameServer/Crypt
*/

#ifdef __GNUC__
	#define __forceinline __attribute__((always_inline))
#endif

#include <node.h>
#include <node_buffer.h>
#include <node_object_wrap.h>

namespace {
	using namespace v8;
	using namespace node;

	class TeraCrypto : public ObjectWrap {
		unsigned int d1[55], d2[57], d3[58];

		int i1 = 0, i2 = 0, i3 = 0,
			b1 = 0, b2 = 0, b3 = 0,
			pos = 0;

		unsigned int sum1 = 0, sum2 = 0, sum3 = 0,
			sum = 0;

		TeraCrypto(const unsigned int* data) {
			for(int i = 0; i < 55; i++) d1[i] = data[i];
			for(int i = 0; i < 57; i++) d2[i] = data[i + 55];
			for(int i = 0; i < 58; i++) d3[i] = data[i + 112];
		}

		void apply(char* data, int length) {
			if(pos) { // Previously non-aligned data
				int off = 4 - pos;
				length -= off;

				if(length < 0) off += length;

				// Slow: individual bytes
				switch(off) {
					case 1:
						(data++)[0] ^= ((char*)&sum)[pos];
						pos = (pos + 1) & 3;
						break;
					case 2:
						(data++)[0] ^= ((char*)&sum)[pos];
						(data++)[0] ^= ((char*)&sum)[pos + 1];
						pos = (pos + 2) & 3;
						break;
					case 3:
						(data++)[0] ^= ((char*)&sum)[pos];
						(data++)[0] ^= ((char*)&sum)[pos + 1];
						(data++)[0] ^= ((char*)&sum)[pos + 2];
						pos = 0;
						break;
				}

				if(length <= 0) return;
			}

			int len4 = length / 4;

			// Fast: 4 bytes per round
			for(int i = 0; i < len4; i++) {
				next();
				((unsigned int*)data)[0] ^= sum;
				data += 4;
			}

			if(length %= 4) { // Additional non-aligned data
				next();

				// Slow: individual bytes
				switch(length) {
					case 1:
						data[0] ^= ((char*)&sum)[pos++];
						break;
					case 2:
						(data++)[0] ^= ((char*)&sum)[pos++];
						data[0] ^= ((char*)&sum)[pos++];
						break;
					case 3:
						(data++)[0] ^= ((char*)&sum)[pos++];
						(data++)[0] ^= ((char*)&sum)[pos++];
						data[0] ^= ((char*)&sum)[pos++];
						break;
				}
			}
		}

		__forceinline void next() {
			int result = b1 & b2 | b3 & (b1 | b2);

			if(result == b1) {
				unsigned long long tmp = (unsigned long long)d1[i1] + (unsigned long long)d1[(i1 + 31) % 55];
				i1 = (i1 + 1) % 55;
				b1 = tmp >> 32;
				sum1 = (unsigned int)tmp;
			}
			if(result == b2) {
				unsigned long long tmp = (unsigned long long)d2[i2] + (unsigned long long)d2[(i2 + 50) % 57];
				i2 = (i2 + 1) % 57;
				b2 = tmp >> 32;
				sum2 = (unsigned int)tmp;
			}
			if(result == b3) {
				unsigned long long tmp = (unsigned long long)d3[i3] + (unsigned long long)d3[(i3 + 39) % 58];
				i3 = (i3 + 1) % 58;
				b3 = tmp >> 32;
				sum3 = (unsigned int)tmp;
			}

			sum = sum1 ^ sum2 ^ sum3;
		}

		static void Apply(const FunctionCallbackInfo<Value>& args) {
			if(args.Length() < 1) return;

			Local<Object> buf = args[0]->ToObject();

			if(!Buffer::HasInstance(buf)) return;

			TeraCrypto* obj = ObjectWrap::Unwrap<TeraCrypto>(args.Holder());
			obj->apply(Buffer::Data(buf), Buffer::Length(buf));
		}

		static void New(const FunctionCallbackInfo<Value>& args) {
			if(!args.IsConstructCall()) {
				Isolate* isolate = args.GetIsolate();
				isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "Constructor cannot be be invoked without \"new\"")));
				return;
			}
			if(args.Length() < 1) {
				Isolate* isolate = args.GetIsolate();
				isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "key is required")));
				return;
			}

			Local<Object> buf = args[0]->ToObject();

			if(!Buffer::HasInstance(buf)) {
				Isolate* isolate = args.GetIsolate();
				isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "key must be a buffer")));
				return;
			}
			if(Buffer::Length(buf) != 680) {
				Isolate* isolate = args.GetIsolate();
				isolate->ThrowException(Exception::TypeError(String::NewFromUtf8(isolate, "key must be 680 bytes long")));
				return;
			}

			TeraCrypto* obj = new TeraCrypto((unsigned int*)Buffer::Data(buf));
			obj->Wrap(args.This());
			args.GetReturnValue().Set(args.This());
		}

	public:
		static void Init(Local<Object> module) {
			Isolate* isolate = module->GetIsolate();

			Local<FunctionTemplate> tpl = FunctionTemplate::New(isolate, New);
			tpl->SetClassName(String::NewFromUtf8(isolate, "TeraCrypto"));
			tpl->InstanceTemplate()->SetInternalFieldCount(1);

			NODE_SET_PROTOTYPE_METHOD(tpl, "apply", Apply);

			module->Set(String::NewFromUtf8(isolate, "exports"), tpl->GetFunction());
		}
	};

	void Init(Local<Object> exports, Local<Object> module) {
		TeraCrypto::Init(module);
	}

	NODE_MODULE(NODE_GYP_MODULE_NAME, Init)
}