Forum Discussion
johns
Employee
EmployeeiRule recognize blank space in URI?
Hi, I need to detect blank space in URI and either remove it or rewrite it:
www.mysite.com/some content/showme.html
to
www.mysite.com/some%20content/showme.html
Current solution in place is only recognizing up to the space so it reads:
www.mysite.com/some. and breaks the client request to the server.
I am thinking if I can find out how BIG-IP can detect the space, I will just replace it with characters that I need in its place.
Thanks.
27 Replies
johnsWhat about below?
when CLIENT_ACCEPTED {
TCP::collect 300
}
when CLIENT_DATA {
set matchedURI [regexp -inline "/vMoD.+HTTP" [TCP::payload]]
if { [string length $matchedURI] > 0 } {
set newURI [getfield [getfield $matchedURI " HTTP" 1] "\{" 2]
log local0. "URI was matched. Result: $newURI"
set preencURI [TCP::payload replace 0 [TCP::payload] $newURI]
set encURI [string map { " " %20} $preencURI]
log local0. "encURI is $encURI"
} else {
log local0. "no match"
set uriRewrite 0
}
}
when HTTP_REQUEST {
if {$uriRewrite == 1} {
HTTP::uri $encURI
log local0. "It worked! [HTTP::uri]"
}
}- John, unRuley is saying to not use the HTTP_REQUEST method at all. If you give the HTTP parser any shot at it, it is going to munge the data. You have the URI rewritten in CLIENT_DATA. Just let it go through to the client now.
- johnsAhhh, ok. Thanks, I will give that a try.
- johnsSo, this means I have to find the URI, replace spaces with %20, then find the offset where "GET /" is and replace the number that equals to string length of the URI between GET / and HTTP/1.0?
Does this sound about right? - Yep.
- johnsCouple of questions, I am collecting TCP data up to about 100 under the assumption that 100 will be enough to grab the URI. The request is coming from mobile phones, and I do not want the BIG-IP to hold the connection open (introducing the delay) in case the request is less than 100. Is this something I should be concerned about?
Also, I am thinking of using similar "regexp -inline ".+GET " against TCP::payload to find string up to the URI and calculate the offset, does this look ok?
Thanks. - johnsI ended up with:
when CLIENT_ACCEPTED {
TCP::collect 100
}
when CLIENT_DATA {
Grab characters b/w GET and HTTP version
set matchedURI [regexp -inline "/vMoD.+HTTP" [TCP::payload]]
Find the length of payload up to GET to use as offset
if { [string length $matchedURI] > 0 } {
Parse the URI and convert spaces to %20
set newURI [getfield [getfield $matchedURI " HTTP" 1] "\{" 2]
set encURI [string map { " " %20} $newURI]
Replace the URI with space with the encoded URI
4 is used as offset, counting "GET ", cound not think of better way
TCP::payload replace 4 [string length $newURI] $encURI
log local0. "encURI is $encURI"
set uriRewrite 1
} else {
set uriRewrite 0
log local0. "no match"
}
}
when HTTP_REQUEST {
verify URI is converted as needed with HTTP parser
if {$uriRewrite == 1} {
log local0. "It worked! [HTTP::uri]"
}
}
and it seems to work if I try it with browser (space already encoded since telnet does not seem to let the rule process into HTTP_REQUEST for verification) Would you mind giving me an eyeball on it?
Thanks.
