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racket-dns-2012
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Ignore duplicate requests while still processing an earlier repeat

This commit is contained in:
Tony Garnock-Jones 2012-01-25 15:07:33 -05:00
parent 1d110a1845
commit 7217768b9a
1 changed files with 19 additions and 7 deletions
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26
proxy.rkt
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@ -22,6 +22,9 @@
;; searches from. Performs recursive queries. Doesn't yet cache
;; responses, but will do so in future.
;; For discarding retransmitted requests that we're still working on.
(struct active-request (source id) #:transparent)
;; start-proxy : UInt16 ListOf<RR> -> Void
(require racket/pretty)
(define (start-proxy port-number rrs)
@ -30,7 +33,7 @@
(pretty-print zone)
(define boot-server
(os-big-bang 'no-state
(os-big-bang (set) ;; SetOf<ActiveRequest>
;;(spawn dns-spy)
(spawn (timer-relay))
(send-meta-message `(request create-server-socket (udp new ,port-number 512)))
@ -39,8 +42,6 @@
[`(reply create-server-socket ,s)
(transition w
(unsubscribe 'wait-for-server-socket)
(spawn (dns-read-driver s))
(spawn (dns-write-driver s))
(send-meta-message
`(request create-client-socket (udp new 0 512)))
(client-socket-waiter s))]))))
@ -51,17 +52,28 @@
[`(reply create-client-socket ,c)
(transition w
(unsubscribe 'wait-for-client-socket)
(spawn (dns-read-driver s))
(spawn (dns-write-driver s))
(spawn (dns-read-driver c))
(spawn (dns-write-driver c))
(subscribe 'packet-handler (packet-handler s c)))])))
(define (packet-handler s c)
(message-handlers old-state
(message-handlers old-active-requests
[(? bad-dns-packet? p)
(pretty-print p) ;; TODO: perhaps use metalevel events? perhaps don't bother though
old-state]
[(and r (dns-request _ _ (== s))) ;; We only listen for requests on our server socket
(transition old-state (spawn (request-handler zone r c)))]))
old-active-requests]
[(and r (dns-request m source (== s))) ;; We only listen for requests on our server socket
(define req-id (active-request source (dns-message-id m)))
;; TODO: when we have presence/error-handling, remove req-id
;; from active requests once request-handler pseudothread exits.
(if (set-member? old-active-requests req-id)
old-active-requests ;; ignore retransmitted duplicates
(transition (set-add old-active-requests req-id)
(spawn (request-handler zone r c))))]
[(and r (dns-reply m (== s) sink))
(define req-id (active-request sink (dns-message-id m)))
(set-remove old-active-requests req-id)]))
(ground-vm (os-big-bang (void)
;;(spawn udp-spy)