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Raise a meaningful exception instead of NPE

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Motivation:

When decoding the NAME field in a DNS Resource Record, DnsResponseDecoder
can raise a NullPointerException if the NAME field contains a loop.

Modification:

Instead of raising an NPE, raise CorruptedFrameException so that the
exception itself has meaning.

Result:

Less confusing when a malformed DNS RR is received
This commit is contained in:
Trustin Lee 2014-07-21 16:48:08 -07:00
parent ae9963a40c
commit 923a0e71ac
2 changed files with 4 additions and 5 deletions
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3
codec-dns/src/main/java/io/netty/handler/codec/dns/DnsResponseDecoder.java
View File

@ -19,6 +19,7 @@ import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler; import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.socket.DatagramPacket; import io.netty.channel.socket.DatagramPacket;
import io.netty.handler.codec.CorruptedFrameException;
import io.netty.handler.codec.MessageToMessageDecoder; import io.netty.handler.codec.MessageToMessageDecoder;
import io.netty.util.CharsetUtil; import io.netty.util.CharsetUtil;
@ -99,7 +100,7 @@ public class DnsResponseDecoder extends MessageToMessageDecoder<DatagramPacket>
// check for loops // check for loops
checked += 2; checked += 2;
if (checked >= length) { if (checked >= length) {
return null; throw new CorruptedFrameException("name contains a loop.");
} }
} else { } else {
name.append(buf.toString(buf.readerIndex(), len, CharsetUtil.UTF_8)).append('.'); name.append(buf.toString(buf.readerIndex(), len, CharsetUtil.UTF_8)).append('.');

6
codec-dns/src/test/java/io/netty/handler/codec/dns/DnsResponseTest.java
View File

@ -19,8 +19,7 @@ import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled; import io.netty.buffer.Unpooled;
import io.netty.channel.embedded.EmbeddedChannel; import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.channel.socket.DatagramPacket; import io.netty.channel.socket.DatagramPacket;
import io.netty.handler.codec.DecoderException; import io.netty.handler.codec.CorruptedFrameException;
import org.junit.Assert; import org.junit.Assert;
import org.junit.Rule; import org.junit.Rule;
import org.junit.Test; import org.junit.Test;
@ -100,8 +99,7 @@ public class DnsResponseTest {
public void readMalormedResponseTest() throws Exception { public void readMalormedResponseTest() throws Exception {
EmbeddedChannel embedder = new EmbeddedChannel(new DnsResponseDecoder()); EmbeddedChannel embedder = new EmbeddedChannel(new DnsResponseDecoder());
ByteBuf packet = embedder.alloc().buffer(512).writeBytes(malformedLoopPacket); ByteBuf packet = embedder.alloc().buffer(512).writeBytes(malformedLoopPacket);
exception.expect(DecoderException.class); exception.expect(CorruptedFrameException.class);
exception.expectMessage("java.lang.NullPointerException: name");
embedder.writeInbound(new DatagramPacket(packet, null, new InetSocketAddress(0))); embedder.writeInbound(new DatagramPacket(packet, null, new InetSocketAddress(0)));
} }
} }