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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * 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:
 *
 *   http://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.buffer.Unpooled;
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
        // case.
        //
        // See:
        // - https://github.com/netty/netty/issues/5014
        // - https://www.ietf.org/rfc/rfc1035.txt , Section 3.1
        if (readable == 0) {
            return ROOT;
        }

        final StringBuilder name = new StringBuilder(readable << 1);
        while (in.isReadable()) {
            final int len = in.readUnsignedByte();
            final boolean pointer = (len & 0xc0) == 0xc0;
            if (pointer) {
                if (position == -1) {
                    position = in.readerIndex() + 1;
                }

                if (!in.isReadable()) {
                    throw new CorruptedFrameException("truncated pointer in a name");
                }

                final int next = (len & 0x3f) << 8 | in.readUnsignedByte();
                if (next >= end) {
                    throw new CorruptedFrameException("name has an out-of-range pointer");
                }
                in.readerIndex(next);

                // check for loops
                checked += 2;
                if (checked >= end) {
                    throw new CorruptedFrameException("name contains a loop.");
                }
            } else if (len != 0) {
                if (!in.isReadable(len)) {
                    throw new CorruptedFrameException("truncated label in a name");
                }
                name.append(in.toString(in.readerIndex(), len, CharsetUtil.UTF_8)).append('.');
                in.skipBytes(len);
            } else { // len == 0
                break;
            }
        }

        if (position != -1) {
            in.readerIndex(position);
        }

        if (name.length() == 0) {
            return ROOT;
        }

        if (name.charAt(name.length() - 1) != '.') {
            name.append('.');
        }

        return name.toString();
    }

    /**
     * Decompress pointer data.
     * @param compression comporession data
     * @return decompressed data
     */
    static ByteBuf decompressDomainName(ByteBuf compression) {
        String domainName = decodeDomainName(compression);
        ByteBuf result = compression.alloc().buffer(domainName.length() << 1);
        encodeDomainName(domainName, result);
        return result;
    }
}