schemelib/examples/udp_server.scm

(load "../bindings/libc.scm")
(load "../bindings/utils.scm")

(define (udpsock-create fx)
  (fx 
    (check-err 
      (socket 'AF_INET 'SOCK_DGRAM 'IPPROTO_IP)
      "Unable to init UDP socket")))

(define (udpsock-reuseaddr sock)
  (alloc 
    (ftype-sizeof int)
    (lambda (activation)
      (foreign-set! 'int activation 0 1)
      (check-err
        (setsockopt 
          sock
          'SOL_SOCKET 
          'SO_REUSEADDR
          activation
          (ftype-sizeof int))
        "Unable to set REUSE ADDRESS"))))

(define (udpsock-bind sock host port)
  (alloc 
    (ftype-sizeof sockaddr_in)
    (lambda (raw-addr)
      (let ([addr (make-ftype-pointer sockaddr_in raw-addr)])
        (ftype-set! sockaddr_in (sin_family) addr (domain->int 'AF_INET))
        (ftype-set! sockaddr_in (sin_port) addr (htons port))
        (check-err
          (inet_pton 
            'AF_INET 
            host
            (ftype-pointer-address
              (ftype-&ref sockaddr_in (sin_addr) addr)))
          "Unable to convert your IP address to binary")
        (bind
          sock
          (ftype-pointer-address addr)
          (ftype-sizeof sockaddr_in))))))

(define (udpsock-readblock sock fx)
  (let* 
    ([bufsize 1500] [straddrsize 255]
     [buf (foreign-alloc bufsize)]
     [straddr (make-ftype-pointer 
                char
                (foreign-alloc straddrsize))]
     [addrlen (make-ftype-pointer 
                int 
                (foreign-alloc (ftype-sizeof int)))]
     [addr (make-ftype-pointer 
             sockaddr_in 
             (foreign-alloc (ftype-sizeof sockaddr_in)))]
     [nread (recvfrom sock buf bufsize 'MSG_DEFAULT addr addrlen)])

    ; FIXME add a loop and check fx output to know if we continue
    (fx
      (inet_ntop 
        'AF_INET 
        (ftype-pointer-address
          (ftype-&ref sockaddr_in (sin_addr) addr))
        straddr
        straddrsize)
      (ntohs (ftype-ref sockaddr_in (sin_port) addr))
      buf nread)

    (foreign-free (ftype-pointer-address straddr))
    (foreign-free (ftype-pointer-address addrlen))
    (foreign-free (ftype-pointer-address addr))
    (foreign-free buf)))

(udpsock-create
  (lambda (sock)
    (udpsock-reuseaddr sock)
    (udpsock-bind sock "0.0.0.0" 1337)
    (udpsock-readblock 
      sock 
      (lambda (host port buf size)
        (printf "~a~%" size)
        (printf "~a~%" port)
        (printf "~a~%" host)
        (printf 
          "~a~%" 
          (char*->string
            (make-ftype-pointer char buf)))
))))