No response returned when URL contains query parameters and ends with %

[dolaru]

Elasticsearch version: 5.0.1

Plugins installed: []

JVM version: OpenJDK 1.8.0_111

OS version: Ubuntu 16.04.1 LTS

Description of the problem including expected versus actual behavior:
If query parameters are passed and the request URL ends with %, no response is returned and Netty throws an exception (noticed in ES log)

Steps to reproduce:

1. Do GET /?%
2. Notice that no response is returned.
3. Notice that Netty threw an exception by looking in ES's log.

Provide logs (if relevant):

[2016-12-05T14:30:07,049][WARN ][o.e.h.n.Netty4HttpServerTransport] [results-qa3] caught exception while handling client http traffic, closing connection [id: 0xd9952abd, L:/192.168.62.163:9201 - R:/10.4.20.252:52107]
java.lang.IllegalArgumentException: unterminated escape sequence at end of string: %
        at org.elasticsearch.rest.RestUtils.decode(RestUtils.java:171) ~[elasticsearch-5.0.1.jar:5.0.1]
        at org.elasticsearch.rest.RestUtils.decodeComponent(RestUtils.java:139) ~[elasticsearch-5.0.1.jar:5.0.1]
        at org.elasticsearch.rest.RestUtils.decodeComponent(RestUtils.java:103) ~[elasticsearch-5.0.1.jar:5.0.1]
        at org.elasticsearch.rest.RestUtils.decodeQueryString(RestUtils.java:77) ~[elasticsearch-5.0.1.jar:5.0.1]
        at org.elasticsearch.rest.RestRequest.<init>(RestRequest.java:54) ~[elasticsearch-5.0.1.jar:5.0.1]
        at org.elasticsearch.http.netty4.Netty4HttpRequest.<init>(Netty4HttpRequest.java:44) ~[transport-netty4-5.0.1.jar:5.0.1]
        at org.elasticsearch.http.netty4.Netty4HttpRequestHandler.channelRead0(Netty4HttpRequestHandler.java:67) ~[transport-netty4-5.0.1.jar:5.0.1]
        at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105) ~[netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at org.elasticsearch.http.netty4.pipelining.HttpPipeliningHandler.channelRead(HttpPipeliningHandler.java:66) [transport-netty4-5.0.1.jar:5.0.1]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at org.elasticsearch.http.netty4.cors.Netty4CorsHandler.channelRead(Netty4CorsHandler.java:76) [transport-netty4-5.0.1.jar:5.0.1]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:293) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:267) [netty-codec-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:86) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:350) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1334) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:372) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:358) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:926) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:129) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:610) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:513) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:467) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:437) [netty-transport-4.1.5.Final.jar:4.1.5.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:873) [netty-common-4.1.5.Final.jar:4.1.5.Final]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_111]

[nik9000]

Yeah, you certainly don't expect a good response, but you expect some kind of response....

[dolaru]

@nik9000 i would expect the same response i'm getting from GET /%:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "unterminated escape sequence at end of string: %"
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "unterminated escape sequence at end of string: %"
  },
  "status": 400
}

[nik9000]

expect the same response i'm getting from GET /%

Pretty much, yes.

[jasontedor]

The difference is that % in /% is part of the path, and % in /?% is part of a parameter.

[jasontedor]

This bug turned out to be really serious in that there were leaked byte buffers in hand here. A lesson for future triaging.