Forum Discussion

Sake_Blok's avatar
Icon for Nimbostratus rankNimbostratus
May 29, 2012

Catching HTTP errors

Hi All,



To troubleshoot TCL errors in an iRule I use "catch" to catch the error and log some info to /var/log/ltm. This makes it easier to find the packet data in a network trace.



Now I would like to do the same for HTTP errors like these:



011f0007:3: http_process_state_prepend - Invalid action EV_EGRESS_DATA during ST_HTTP_PREPEND_HEADERS (Client side: vip=VS_HTTP profile=http pool=gateway-http)



011f0007:3: http_process_state_prepend - Invalid action EV_INGRESS_DATA during ST_HTTP_PREPEND_HEADERS (Server side: vip=VS_HTTP profile=http pool=gateway-http)



011f0005:3: HTTP header (33304) exceeded maximum allowed size of 32768 (Client side: vip=VS_HTTP profile=http pool=gateway-http)



Is there a way to detect these errors from within the iRule so that extra logging can be done to help in pinpointing the faulty session.



All tips are welcome! :-)







1 Reply

  • Hi Sake,

    These aren't iRule errors so it's not possible to handle them using the iRule catch command. Here's an option for logging large headers. You''ll need to increase the maximum headers limit on the HTTP profile first so the HTTP request will be parsed and the HTTP_REQUEST event will be triggered. Once you identify the large requests using the iRule you can lower the HTTP profile size limit if you want to.

    when HTTP_REQUEST {
            Check the total HTTP headers size
           if {[string length [HTTP::request]] > 10000 }{
                   Check if the URI is very long
                  if {[string length [HTTP::uri]] > 1000}{
                         log local0. "Uri is long. Length [string length [HTTP::uri]], URI: [HTTP::uri]"
                          Exit this event from this iRule
                   Loop through the headers by name
                  foreach header {[HTTP::header names]} { 
                          Check for a long header value
                         if {[string length [HTTP::header value $header]] > 1000 } { 
                               log local0. "Header is long. Header Name: $header,\
                                      Length: [string length [HTTP::header value $header]], Value: [HTTP::header value $header]" 
                                Exit this event from this iRule
                   If we are still here the request was large, but not the URI or any single header.
                   Log the first 1k bytes of the full request
                  log local0. "Request is long: [HTTP::request]"