JsonMappingException causes NullPointerException

Mapping errors that result in a JsonMappingException produce NullPointerException. This is caused by the fact that the client tries to get the error stream from the connection if an IOException is thrown. But JsonMappingException also extends IOException. This means the client will try to get the error stream on JsonMappingException and this causes the NPE because the stream is null:

Caused by: java.lang.NullPointerException: null
    at com.googlecode.jsonrpc4j.NoCloseInputStream.markSupported(NoCloseInputStream.java:85) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.ReadContext.assertReadable(ReadContext.java:29) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcClient.readResponseNode(JsonRpcClient.java:287) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcClient.getValidResponse(JsonRpcClient.java:223) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcClient.readResponse(JsonRpcClient.java:173) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcClient.readResponse(JsonRpcClient.java:500) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcHttpClient.invoke(JsonRpcHttpClient.java:114) ~[jsonrpc4j-1.4.3.jar:1.4.3]
    at com.googlecode.jsonrpc4j.JsonRpcHttpClient.invoke(JsonRpcHttpClient.java:92) ~[jsonrpc4j-1.4.3.jar:1.4.3]

[selene-l]

Yep. Same problem. If the method returns an plain string - it’s OK. But if the method returns an object - the library throws NullPointerException. For example:

{
    "jsonrpc":"2.0",
    "id":"113195884",
    "result":{
        "code":0,
        "message":null,
        "output":{
            "userId":"23f975d1-00af-4ae9-aaca-16863b30e1d0",
            "sessionToken":"cd6405b8-2d4b-4249-8c78-0a647c6cf2a4"
        }
    }
}

The stack trace is identical to the listed above. It seems that somewhere missed checking to null.

[dzolo]

I have got a similar problem. When I send an invalid arguments to a method or do anything else that causes JsonMappingException to be thrown then I will get a NullPointerException on client. The reason is that JsonBasicServer handles all exceptions in invoke method (line 375) to a JSON error but these Jackson exceptions do not have a public constructor. But even if they had one this is invalid behavior.

The fix should be done by rethrowing of IOException that will cause that a proper JsonError.PARSE_ERROR error will be created as response in the handleRequest method.