DnsCodecUtil.java — netty Source File

Source Code

/*
 * Copyright 2019 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.handler.codec.dns;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.handler.codec.CorruptedFrameException;
import io.netty.util.CharsetUtil;

import static io.netty.handler.codec.dns.DefaultDnsRecordDecoder.*;

final class DnsCodecUtil {
    private DnsCodecUtil() {
        // Util class
    }

    static void encodeDomainName(String name, ByteBuf buf) {
        if (ROOT.equals(name)) {
            // Root domain
            buf.writeByte(0);
            return;
        }

        final String[] labels = name.split("\\.");
        for (String label : labels) {
            final int labelLen = label.length();
            if (labelLen == 0) {
                // zero-length label means the end of the name.
                break;
            }

            buf.writeByte(labelLen);
            ByteBufUtil.writeAscii(buf, label);
        }

        buf.writeByte(0); // marks end of name field
    }

    static String decodeDomainName(ByteBuf in) {
        int position = -1;
        int checked = 0;
        final int end = in.writerIndex();
        final int readable = in.readableBytes();

        // Looking at the spec we should always have at least enough readable bytes to read a byte here but it seems
        // some servers do not respect this for empty names. So just workaround this and return an empty name in this
// ... (72 more lines)