Jetty-9 warning: badMessage: 400 Illegal character

Question

I am using jetty-9.2.2 with CometD-3.0.1. I am seeing below warning in my setup. It comes ~4,5 times in a day.:

2014-08-28 08:50:53.712:WARN:oejh.HttpParser:qtp607635164-15194: badMessage:      400 Illegal character for HttpChannelOverHttp@5946f125{r=1,a=IDLE,uri=-}   

There is no details that can be debugged from the warning message. I have already logged a request https://bugs.eclipse.org/bugs/show_bug.cgi?id=443049 to provide detailed warning.

Meanwhile I want to know what is causing this warning? Can I ignore this or some messages are lost because of this?

Answer 1

Change https to http in the url.

I had the same error, then found out it's because my application did not support https, so jetty cannot recognize the https encrypted request.

Answer 2

Update May 2017

For Jetty 9.3+ users, you might see a log message that makes this response code more clear.

See Header parse error after upgrade to Jetty 9.3 for details.

Original Answer

The Bad Message: 400 Illegal Character can occur during parsing of a bad HTTP Request.

That is the HTTP error response that the client sees.

Some (not all) situations in which it can occur.

• The EOL is not "\r\n" (CR + LF) (HTTP spec requirement)
• The HTTP Method token is either not recognized or has invalid whitespace after it
• The HTTP Version is not recognized or has invalid characters
• HTTP Header name does not follow spec
• HTTP Header value does not follow spec

This message is common on public (internet facing) servers.

You have bad HTTP requests coming in. Why?

• A legitimate HTTP client has a bug
• A legitimate HTTP client is not following the HTTP spec
• A non HTTP client attempted to connect to your server (such as attempting to use non-encrypted HTTP on a SSL/TLS/HTTPS port, or even something as odd as an SMTP/IMAP email client attempting to talk to your HTTP port)
• A malicious client is attempting to probe your system for weaknesses