Tricky X-Forwarded-For header

From: Jean-Baptiste Quenot <jbq#caraldi.com>
Date: Fri, 22 Feb 2008 12:48:11 +0100

Hi there,

All my HTTP requests go through haproxy 1.3.14.2, and I have a reqirep statement in the config to rename the inbound X-Forwarded-For header to X-Orig-Forwarded-For, so that I only have one IP in the X-Forwarded-For header.

This works fine, and *most of the time* I receive the X-Forwarded-For header correctly. But on some occasions, this header is missing from the HTTP request. Is it possible that somewhere in the haproxy code this header is discarded under certain conditions?

Please find below a tcpdump-captured excerpt of the HTTP conversation for one of the requests that is missing the valuable header:

GET /html/ads.html HTTP/1.1
Host: myhostname.com
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.1.12)... Accept: text/xml,application/xml,application/xhtml+xml,text/html...

Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive: 300
Connection: keep-alive
Referer: http://myhostname.com/otherpage Cookie: u_np=jbq; u_lc=en-UK; __utmz=25405474.119546... Authorization: Basic amJxOnRhcmVkT2ww

HTTP/1.1 200 OK
Date: Thu, 21 Feb 2008 17:17:11 GMT
Server: Apache/2.2.3 (Debian) DAV/2
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 20
Keep-Alive: timeout=15, max=99
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8

Oh and BTW, I heard that haproxy is not configured to support keep-alive by default, so I wonder why I see the keep-alive header in the logs. I didn't add any keep-alive-related option in the configuration.

Thanks in advance,

-- 
Jean-Baptiste Quenot
http://caraldi.com/jbq/blog/

Received on 2008/02/22 12:48