CS3700-project2/router

#!/usr/bin/env racket
#lang racket
; vim:syntax=racket

(require json
         "iputil.rkt"
         "unix-socket.rkt")

;; info : Peer
;; sock-in : Input-Port
;; sock-out : Output-Port
(struct peer-conn
  [info sock-in sock-out]
  #:transparent)

;; Str [Listof Peer-Conn] -> [-> Void]
;; --
;; runs router logic given peer connections. returns thunk that, when called, aborts the
;; router.
(define (run-router/conns ans peer-conns)
  (define mail
    (make-channel))

  (define peer-threads
    (for/list ([pc (in-list peer-conns)])
      (match-define (peer-conn peer sock-in sock-out) pc)
      (thread (λ ()
                (define buf (make-bytes 65536))
                (let loop ()
                  (define len (read-bytes-avail! buf sock-in))
                  (printf "got ~a bytes from ~a...\n" len peer)
                  (define jsexpr (bytes->jsexpr (subbytes buf 0 len)))
                  (channel-put mail (list peer jsexpr))
                  (loop))))))

  (define (loop)
    (match-define (list peer data) (channel-get mail))
    (printf "from ~a:\n~s\n" peer data)
    (loop))

  (printf "waiting for messages...\n")
  (loop))

;; Str [Listof Peer] ->
;; Router main
(define (run-router asn peers)
  (displayln asn)
  (map displayln peers)
  (displayln "------------")
  (with-handlers ([exn:break:terminate? (λ (e)
                                          (printf "time to die.\n"))])
    (run-router/conns
     asn
     (for/list ([peer (in-list peers)])
       (define-values [sock-in sock-out]
         (unix-socket-connect (ip->string (peer-ip peer))
                              'SOCK-SEQPACKET))
       (peer-conn peer
                  sock-in
                  sock-out)))))

(module+ main
  (command-line
   #:program "router"
   #:args
   (asn . peers)
   (with-output-to-file "log.txt"
     #:exists 'replace
     (λ ()
       ;; Run the router
       (run-router asn (map string->peer peers))))))

(module+ test

  (define-values [in1 out1] (make-pipe))
  (define-values [in2 out2] (make-pipe))
  (define p1 (peer-conn (string->peer "1.2.3.4-cust") in1 out1))
  (define p2 (peer-conn (string->peer "1.2.3.5-peer") in2 out2))

;  (define abort-router
    (run-router/conns "123"
                      (list p1 p2))

  (void
   (write-string "{\"a\": 1, \"b\": [1,2,3]}" out1)))