<html><head/><body><html><head></head><body>Hi all, My immediate need for a response to the message below has passed, but I'd still like to know for next time, at least if my idea of a solution was accurate. Anybody? Thanks, jmj -- Sent from my Android phone with K-9 Mail. <div class="gmail_quote">Jordan Johnson <jmj@fellowhuman.com> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Hi all, I have my students handing in an assignment via the handin server, in which I've asked them to use bitmap/url to load a particular image from my Web server. This obviously runs afoul of the sandbox rules, so I looked into the sandbox configuration docs and believe that what I need to do is something like > (sandbox-network-guard > (lambda (caller host port cli/srv) > (unless (and (equal? host "<a href="http://my-server.com">my-server.com</a>") > (= port 80) > (eq? cli/srv 'client)) > (error caller > "network permissions denied; failed to contact ~a:~a" > host port)))) (I would restrict it further to allow only fetching the one particular file, but don't see how.) The question I have is, how should I install this lambda in the sandbox-network-guard parameter so that it works properly? The problems I see are: 1. If I simply include the above code before the (check: ...) expression, it seems to work correctly for the first assignment handed in, and none thereafter. 2. Writing (parameterize ([sandbox-network-guard (lambda ...)]) (check: ...)) doesn't work, because (check: ...) must be at top-level to provide the checker function. Thanks, jmj <pre style="white-space: pre-wrap; word-wrap:break-word; font-family: monospace; margin-top: 0px">____________________ Racket Users list: <a href="http://lists.racket-lang.org/users">http://lists.racket-lang.org/users</a> </pre></blockquote></div></body></html></body></html>