Desire to view contents of If-Modified-Since & If-None-Match http headers

I just tried the following on 11.5.3:

when HTTP_REQUEST {
    log local0. "headers = [HTTP::header names]"

    if { [HTTP::header exists If-None-Match] } {
        log local0. "If-None-Match"
    }
}

and with the following request:

GET / HTTP/1.1
Host:
If-None-Match: foo

the following is logged:

 Rule /Common/test : headers = Host If-None-Match
 Rule /Common/test : If-None-Match

just as I'd expect.

Can you switch the HSL to local logging (just for debugging; in general, HSL logging is a better production choice)? Can you also verify you see no errors in the log otherwise?

For logging/modifying specific headers, I find that using a loop is usually the best way to parse through them:

when HTTP_REQUEST {
    set rqst_headers [HTTP::header names]
    set hsl [HSL::open -proto UDP -pool HIGH_SPEED_LOGGING]
    HSL::send $hsl "REQUEST HEADERS = $rqst_headers"
    foreach request_header [HTTP::header names] {
        if { $request_header eq "If-None-Match" } {
            HSL::send $hsl " $request_header = [HTTP::header values $request_header] "
        }
    }
}

The result should be that the If-None-Match header is logged along with the value using this format:

HEADER NAME = HEADER VALUE

Hope this helps!

Hi OTS02,

in the past I've seen some really strage behavior, when using unquoted conditions containing "-" signs. Well, it should work, but somehow its doesn't work well everytime...?

when CLIENT_ACCEPTED {
    set hsl [HSL::open -proto UDP -pool HIGH_SPEED_LOGGING]
}
when HTTP_REQUEST {
    HSL::send $hsl "REQUEST HEADERS = [HTTP::header names]"
    if { [set since_modded [HTTP::header value "If-Modified-Since"]] ne "" } {
        HSL::send $hsl "If-Modified-Since exists: CACHE DISCOVERY $since_modded "
    }
    if { [set none_match [HTTP::header value "If-None-Match"]] ne "" } {
        HSL::send $hsl "If-None-Match exists: CACHE DISCOVERY $none_match "
    }
}

Note: I've tweaked your iRule a little bit to increase its performance. Its now using the CLIENT_ACCEPTED event to define the HSL connection and using a [set since_modded [HTTP::header value "If-Modified-Since"]] ne "" syntax to check for existence ( header ne "" is faster then header exists) and store the results in a single step. Well, the code could be further optimized by skipping the $variable creation at all, but I assume you need to process the results further...

Cheers, Kai