66 lines
2.2 KiB
Racket
66 lines
2.2 KiB
Racket
#lang racket/base
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;; DNS drivers using racket-typed-matrix.
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(require racket/set)
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(require racket/match)
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(require "codec.rkt")
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(require racket-typed-matrix/sugar-untyped)
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(require racket-typed-matrix/drivers/udp-untyped)
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(provide (struct-out bad-dns-packet)
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(struct-out dns-request)
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(struct-out dns-reply)
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dns-read-driver
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dns-write-driver
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dns-spy)
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(struct bad-dns-packet (detail source sink reason) #:prefab)
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(struct dns-request (message source sink) #:prefab)
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(struct dns-reply (message source sink) #:prefab)
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(define (dns-read-driver s)
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(transition 'no-state
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(at-meta-level
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(endpoint #:subscriber (udp-packet-pattern (wild) s (wild))
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[(udp-packet source (== s) #"")
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(begin (log-info "Debug dump packet received")
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(send-message `(debug-dump)))]
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[(udp-packet source (== s) body)
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(send-message
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(with-handlers ((exn:fail? (lambda (e)
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(bad-dns-packet body source s 'unparseable))))
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(define message (packet->dns-message body))
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(case (dns-message-direction message)
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((request) (dns-request message source s))
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((response) (dns-reply message source s)))))]))))
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(define (dns-write-driver s)
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(define (translate message sink)
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(with-handlers ((exn:fail? (lambda (e)
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(send-message (bad-dns-packet message s sink 'unencodable)))))
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(at-meta-level
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(send-message (udp-packet s sink (dns-message->packet message))))))
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(transition 'no-state
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(endpoint #:subscriber (dns-request (wild) s (wild))
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[(dns-request message (== s) sink) (translate message sink)])
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(endpoint #:subscriber (dns-reply (wild) s (wild))
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[(dns-reply message (== s) sink) (translate message sink)])))
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(define (dns-spy)
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(spawn #:child
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(transition 'none
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(endpoint #:subscriber (wild) #:observer
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[(dns-request message source sink)
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(begin (log-info (format "DNS: ~v asks ~v ~v~n : ~v"
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source sink (dns-message-id message)
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(dns-message-questions message)))
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(void))]
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[(dns-reply message source sink)
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(begin (log-info (format "DNS: ~v answers ~v~n : ~v"
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source sink
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message))
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(void))]
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[x
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(begin (log-info (format "DNS: ~v" x))
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(void))]))))
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