Forum Discussion

Mohanad_313515's avatar
Mohanad_313515
Icon for Nimbostratus rankNimbostratus
Apr 04, 2019

irule to insert action parameter inside Content-Type header for xml request

Hello   we have a lot of xml services using soap version 1.2, im facing issue regarding validate soap action header using xml profile.   To summarize, while SOAP 1.1 would have these HTTP headers...
ASM Advanced WAF
security
Kai_Wilke's avatar
Kai_Wilke
Icon for MVP rankMVP
Apr 05, 2019

Hi Mohanad,

the iRule below uses a 

HTTP::collect
approach, to intercept and buffer the POST request destined to your web service. If the entire POST-Body (or a maximum of X bytes amount) has been buffered, the iRule will use a combination of the 
[getfield]
, 
[substr]
and 
[URI::basename]
commands to extract the last portion of the URL defined in the 
Action
XML element. If a action value could be extracted, the iRule will replace the Content-Type HTTP-Header with a new value including the extracted action value. Once the HTTP-Header has been changed, the request is released from the buffer and send to your web service...

when RULE_INIT {
     Defining the maximum HTTP::collect size 
    set static::maximum_http_collect_size 1048576 ; Its 1 Mbyte per POST request. This should be lowered if possible
}
when HTTP_REQUEST {
    if { ( [HTTP::method] eq "POST" )
     and ( [HTTP::path] ends_with "/Service.svc" ) } then {
        if { not [string is integer [HTTP::header value "Content-Length"]] } then {
             Skipping the malformated Content-Length header...         
        } elseif { [HTTP::header value "Content-Length"] >= $static::maximum_post_collect_size } then {
             Collecting the HTTP payload until maximum size has been reached
            HTTP::collect $static::maximum_http_collect_size
        } elseif { [HTTP::header value "Content-Length"] > 0 } then {
             Collecting the full HTTP payload.
            HTTP::collect [HTTP::header value "Content-Length"]
        }
    }
}
when HTTP_REQUEST_DATA {
    set action_value [URI::basename [substr [getfield [HTTP::payload] "" 2] 0 "<"]]
    log local0.debug "Found the action = $action_value"
    if { $action_value ne "" } then {
        HTTP::header remove "Content-Type"
        HTTP::header insert "Content-Type" "application/soap xml; charset=utf-8; action=http://tempuri.org/IACHService/$action_value"
        log local0.debug "New Header Value: [HTTP::header value "Content-Type"]"
    }
}

Note: I'm sorry if I've wasted some of your valuable time with my previous 

STREAM_MATCH
approach. Well, the 
STREAM_MATCH
approach is still superior in my opinion, since it does not need to buffer the entire payload into LTMs memory. But unfortunately it changes the ongoing request slightly, which may have certain side effects within your application which we don't know yet. The 
HTTP::collect
approach is not bad at all. If you tweak the maximum collect size to a minimum (e.g. just a few kbyte), the impact to buffer portions of the request could be minimized to an acceptable degree.

Cheers, Kai