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stevehuffy's avatar
stevehuffy
Icon for Nimbostratus rankNimbostratus
Apr 21, 2015

Problem with output of E-Tag in iRule

Trying to output an E-Tag, the output does not match the input and I can't figure out how to do it. Looks like it should be easy, but have spent too much time on it, so asking here.

My simple iRule to test with:

when HTTP_REQUEST {
   log local0. "test header- [HTTP::header values X-Test]"
}

Test1:

curl http:// -H 'X-Test: "test"'
-
: test header- {"test"}

Test2:

curl http:// -H 'X-Test: W/"test"'
-
: test header- W/\"test\"

I want output to look like this, respectively:

: test header- "test"
: test header- W/"test"

There must be an easy way to do it, I am just not good enough with iRules. TCL lets me do it:

$ tclsh
% puts {"test"}
"test"
% puts W/\"test\"
W/"test"

Please help.

application delivery
devops
iRules

2 Replies

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  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Apr 21, 2015

    just wondering if we can use simple tcl string.

     config

root@(ve11c)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm rule qux
ltm rule qux {
    when HTTP_REQUEST {
  log local0. "test header- [string map {\\ ""} [HTTP::header values X-Test]]"
}
}

 /var/log/ltm
Apr 21 12:41:41 ve11c info tmm1[5649]: Rule /Common/qux : test header- W/"test"
  • stevehuffy's avatar
    stevehuffy
    Icon for Nimbostratus rankNimbostratus
    Apr 21, 2015

    Yeh, thanks. Was hoping for something more generic that would support other headers, but I guess similar will do for my use case, as E-Tags seem to only have a specific format. I am not sure why HTTP::header adds more characters to the actual HTTP header, but would have thought something like this would have reformatted: [puts [HTTP::header values X-Test]], but can't find anything easily.

    So I am now doing this (hopefully it will provide the original E-Tag ok - it will be going in a 304 response):

    log local0. "from irule HTTP::headers- [HTTP::header values X-Test]"
log local0. "to get it to original- [string map {\\\" "\""} [string trim [HTTP::header values X-Test] \{\}]]"

    Test1

    $ curl http:// -H 'X-Test: "test"'
-
 : from irule HTTP::headers- {"test"}
 : to get it to original- "test"

    Test2

    $ curl http:// -H 'X-Test: W/"test"'
-
 : from irule HTTP::headers- W/\"test\"
 : to get it to original- W/"test"

    Test3 (the iRule doesn't handle this, but hopefully an E-tag is never formatted like this)

    $ curl http:// -H 'X-Test: W/"ba8ba5c\"37e1fce1:0"'
-
 : from irule HTTP::headers- {W/"ba8ba5c\"37e1fce1:0"}
 : to get it to original- W/"ba8ba5c"37e1fce1:0"