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Forum Discussion

JosephT's avatar
JosephT
Icon for Nimbostratus rankNimbostratus
Oct 24, 2008

Help 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...
application delivery
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devops
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hoolio's avatar
hoolio
Icon for Cirrostratus rankCirrostratus
Oct 24, 2008
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