testDecodeMessageCompression() — netty Function Reference

Source Code

codec-dns/src/test/java/io/netty/handler/codec/dns/DefaultDnsRecordDecoderTest.java lines 214–280

    @Test
    public void testDecodeMessageCompression() throws Exception {
        // See https://www.ietf.org/rfc/rfc1035 [4.1.4. Message compression]
        DefaultDnsRecordDecoder decoder = new DefaultDnsRecordDecoder();
        byte[] rfcExample = { 1, 'F', 3, 'I', 'S', 'I', 4, 'A', 'R', 'P', 'A',
                0, 3, 'F', 'O', 'O',
                (byte) 0xC0, 0, // this is 20 in the example
                (byte) 0xC0, 6, // this is 26 in the example
        };
        DefaultDnsRawRecord rawPlainRecord = null;
        DefaultDnsRawRecord rawUncompressedRecord = null;
        DefaultDnsRawRecord rawUncompressedIndexedRecord = null;
        ByteBuf buffer = Unpooled.wrappedBuffer(rfcExample);
        try {
            // First lets test that our utility function can correctly handle index references and decompression.
            String plainName = DefaultDnsRecordDecoder.decodeName(buffer.duplicate());
            assertEquals("F.ISI.ARPA.", plainName);
            String uncompressedPlainName = DefaultDnsRecordDecoder.decodeName(buffer.duplicate().setIndex(16, 20));
            assertEquals(plainName, uncompressedPlainName);
            String uncompressedIndexedName = DefaultDnsRecordDecoder.decodeName(buffer.duplicate().setIndex(12, 20));
            assertEquals("FOO." + plainName, uncompressedIndexedName);

            // Now lets make sure out object parsing produces the same results for non PTR type (just use CNAME).
            rawPlainRecord = (DefaultDnsRawRecord) decoder.decodeRecord(
                    plainName, DnsRecordType.CNAME, DnsRecord.CLASS_IN, 60, buffer, 0, 11);
            assertEquals(plainName, rawPlainRecord.name());
            assertEquals(plainName, DefaultDnsRecordDecoder.decodeName(rawPlainRecord.content()));

            rawUncompressedRecord = (DefaultDnsRawRecord) decoder.decodeRecord(
                    uncompressedPlainName, DnsRecordType.CNAME, DnsRecord.CLASS_IN, 60, buffer, 16, 4);
            assertEquals(uncompressedPlainName, rawUncompressedRecord.name());
            assertEquals(uncompressedPlainName, DefaultDnsRecordDecoder.decodeName(rawUncompressedRecord.content()));

            rawUncompressedIndexedRecord = (DefaultDnsRawRecord) decoder.decodeRecord(
                    uncompressedIndexedName, DnsRecordType.CNAME, DnsRecord.CLASS_IN, 60, buffer, 12, 8);
            assertEquals(uncompressedIndexedName, rawUncompressedIndexedRecord.name());
            assertEquals(uncompressedIndexedName,
                         DefaultDnsRecordDecoder.decodeName(rawUncompressedIndexedRecord.content()));

            // Now lets make sure out object parsing produces the same results for PTR type.
            DnsPtrRecord ptrRecord = (DnsPtrRecord) decoder.decodeRecord(
                    plainName, DnsRecordType.PTR, DnsRecord.CLASS_IN, 60, buffer, 0, 11);
            assertEquals(plainName, ptrRecord.name());
            assertEquals(plainName, ptrRecord.hostname());

            ptrRecord = (DnsPtrRecord) decoder.decodeRecord(
                    uncompressedPlainName, DnsRecordType.PTR, DnsRecord.CLASS_IN, 60, buffer, 16, 4);
            assertEquals(uncompressedPlainName, ptrRecord.name());
            assertEquals(uncompressedPlainName, ptrRecord.hostname());

            ptrRecord = (DnsPtrRecord) decoder.decodeRecord(
                    uncompressedIndexedName, DnsRecordType.PTR, DnsRecord.CLASS_IN, 60, buffer, 12, 8);
            assertEquals(uncompressedIndexedName, ptrRecord.name());
            assertEquals(uncompressedIndexedName, ptrRecord.hostname());
        } finally {
            if (rawPlainRecord != null) {
                rawPlainRecord.release();
            }
            if (rawUncompressedRecord != null) {
                rawUncompressedRecord.release();
            }
            if (rawUncompressedIndexedRecord != null) {
                rawUncompressedIndexedRecord.release();
            }
            buffer.release();
        }
    }