ByteBufUtils.java

package net.scapeemulator.util;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;

public final class ByteBufUtils {

	public static ByteBuf rsa(ByteBuf buf, String modulus, String exponent) {
		byte[] bytes = new byte[buf.readableBytes()];
		buf.readBytes(bytes);

		BigInteger cipherText = new BigInteger(bytes);
		BigInteger mod = new BigInteger(modulus);
		BigInteger exp = new BigInteger(exponent);
		BigInteger plainText = cipherText.modPow(exp, mod);

		return Unpooled.wrappedBuffer(plainText.toByteArray());
	}

	public static String readString(ByteBuf buffer) {
		buffer.markReaderIndex();

		int len = 0;
		while (buffer.readUnsignedByte() != 0)
			len++;

		buffer.resetReaderIndex();

		byte[] bytes = new byte[len];
		buffer.readBytes(bytes);
		buffer.readerIndex(buffer.readerIndex() + 1);
		return new String(bytes, StandardCharsets.ISO_8859_1);
	}

	public static void writeString(ByteBuf buffer, String str) {
		byte[] bytes = str.getBytes(StandardCharsets.ISO_8859_1);
		buffer.writeBytes(bytes);
		buffer.writeByte(0);
	}

	public static void writeSmart(ByteBuf buffer, int value) {
		if (value < 128)
			buffer.writeByte(value);
		else
			buffer.writeShort(32768 + value);
	}

	public static void writeWorldListString(ByteBuf buffer, String str) {
		buffer.writeByte(0);
		buffer.writeBytes(str.getBytes(StandardCharsets.ISO_8859_1));
		buffer.writeByte(0);
	}

	private ByteBufUtils() {

	}

}