Created attachment 25569 [details] Example for null character in URL and missing response headers When sending the ASCII control character null (hexadecimal 00) in a URI, apache does return a HTTP entity (the HTML code), but no HTTP headers. Additionally the URI is truncated (the null and everything after it is missing). If you have a local apache running, try this python script (you need to have a index.html or index.php in your root directory): import urllib2 print 'Valid request:' print urllib2.urlopen('http://localhost/?abc=123&def=456_VALID').read() print '' print 'Invalid request:' print urllib2.urlopen('http://localhost/?abc=123'+chr(0)+'&def=456_INVALID').read() The apache access.log will look like this: ::1 - - [09/Jun/2010:16:44:41 +0200] "GET /?abc=123&def=456_VALID HTTP/1.1" 200 321 "-" "Python-urllib/2.6" ::1 - - [09/Jun/2010:16:44:41 +0200] "GET /?abc=123" 200 94 "-" "-" As you can see in the appended wireshark (libpcap), the headers for the second response are missing! It works on remote (not localhost) apache servers as well. cheers floyd
The null in the invalid URL causes the request line to be terminated before the rest of the URL or the protocol. The response (no headers) is "HTTP 0.9" described here: http://www.w3.org/Protocols/HTTP/AsImplemented.html