iRule to allow access to a uri only from a specific source subnet

This wiki page talks about checking ip addresses.

Basically, the irule you're looking for would be similar to this. You should be able to change it up as necessary.

when HTTP_REQUEST {
     The switch statement is good for conditionals and easy to manage. 
     The '-glob' parameter marks the switch to allow wildcards (the "*")
    switch -glob -- [string tolower [HTTP::uri]] {
        "/something/test/testing" {
            if { [IP::addr [IP::client_addr] equals 10.1.1.0/24] } {
                 Process the traffic
                pool POOL_NAME
            } else {
                 Drop the connection (you can also use reject instead of drop)
                drop
            }
        }
    }
}