Forum Discussion
JosephT
Nimbostratus
NimbostratusHelp write an irule to check and strip transfer-encoding header
We have a need to inspect all http requests and, if an HTTP request contains a Transfer-Encoding header with a value greater than 64 bytes, then we want to remove the Transfer-Encoding header from the HTTP request
I came up with this:
when HTTP_REQUEST {
if { [HTTP::header exists "Transfer-Encoding"] && [HTTP::header "Transfer-Encoding"] > 64 } {
[HTTP::header remove Transfer-Encoding]
}
}
But it doesn't appear to be working correctly. When testing, if the HTTP request contains a Transfer-Encoding header (of any size), the HTTP request just never makes it through.
Any help would be greatly appreciated. TIA!
hoolioCirrostratus
Hi there,
If you add logging you could see in /var/log/ltm that [HTTP::header "Transfer-Encoding"] will return the value of the header. If you want to get the length of the header value you could use string length (Click here). Also, you should be getting a TCL error about an unknown command from this line:
[HTTP::header remove Transfer-Encoding]
The square braces act like backticks in *nix, executing the code within. HTTP::header remove will return 0 or 1 depending on whether it runs successfully. So the braces would be executing 1 which isn't a valid command.
This should work:when HTTP_REQUEST { if { [HTTP::header exists "Transfer-Encoding"] && [string length [HTTP::header "Transfer-Encoding"]] > 64 } { HTTP::header remove Transfer-Encoding } }
Aaron
JosephTAaron. Your irule worked perfectly! Thanks for explaining the use of string length and the braces!!!