80 lines
3.1 KiB
Racket
80 lines
3.1 KiB
Racket
#lang syndicate
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;; The chat server, using a proxy abstracting over details of the TCP
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;; driver's protocol.
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(require syndicate/protocol/advertise)
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(require (only-in racket/string string-trim))
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(require/activate "../drivers/tcp.rkt")
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(require "../demand-matcher.rkt")
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(struct tcp-remote-open (id) #:prefab)
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(struct tcp-local-open (id) #:prefab)
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(struct tcp-incoming-data (id bytes) #:prefab)
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(struct tcp-outgoing-data (id bytes) #:prefab)
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(struct says (who what) #:prefab)
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(struct present (who) #:prefab)
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(define (tcp-proxy-process them us)
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(define id (seal (list them us)))
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(actor (lambda (e s)
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(match e
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[(message (tcp-channel _ _ bs))
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(transition s (message (tcp-incoming-data id bs)))]
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[(message (tcp-outgoing-data _ bs))
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(transition s (message (tcp-channel us them bs)))]
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[(? patch/removed?)
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(quit)]
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[_ #f]))
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(void)
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(patch-seq (sub (tcp-channel them us ?))
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(sub (advertise (tcp-channel them us ?)))
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(pub (tcp-channel us them ?))
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(sub (tcp-outgoing-data id ?))
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(assert (tcp-remote-open id))
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(sub (tcp-local-open id)))))
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(define (spawn-session id)
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(define user (gensym 'user))
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(define (send-to-remote fmt . vs)
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(message (tcp-outgoing-data id (string->bytes/utf-8 (apply format fmt vs)))))
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(define (say who fmt . vs)
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(unless (equal? who user) (send-to-remote "~a ~a\n" who (apply format fmt vs))))
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(list (send-to-remote "Welcome, ~a.\n" user)
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(actor/stateless
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(lambda (e)
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(match e
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[(message (tcp-incoming-data _ bs))
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(message (says user (string-trim (bytes->string/utf-8 bs))))]
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[(message (says who what))
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(say who "says: ~a" what)]
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[(? patch? p)
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(if (patch/removed? (patch-project p (tcp-remote-open id)))
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(quit)
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(let-values (((arrived departed) (patch-project/set/single p (present (?!)))))
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(list (for/list [(who arrived)] (say who "arrived."))
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(for/list [(who departed)] (say who "departed.")))))]
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[#f #f]))
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(patch-seq
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(sub (says ? ?)) ;; read actual chat messages
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(sub (present ?)) ;; observe peer presence
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(assert (present user)) ;; advertise our presence
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(sub (tcp-incoming-data id ?)) ;; read from remote client
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(sub (tcp-remote-open id)) ;; monitor remote client
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(assert (tcp-local-open id)) ;; indicate our end of the connection is up
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))))
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(spawn-demand-matcher (advertise (tcp-channel (?!) (?! (tcp-listener 5999)) ?))
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(observe (tcp-channel (?!) (?! (tcp-listener 5999)) ?))
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tcp-proxy-process)
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(actor (lambda (e s)
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(if (patch? e)
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(transition s
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(for/list [(id (project-assertions (patch-added e)
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(tcp-remote-open (?!))))]
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(spawn-session id)))
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#f))
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(void)
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(sub (tcp-remote-open ?)))
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