{{category scheme}}
{{category プログラミング}}

ソケットを使ってパケットのやりとりを行う
 
 
 (define-module gsup.net.packetutil
   (use srfi-1)
   (use gauche.net)
   (use binary.pack)
   (export-all)
   )
 
 (select-module gsup.net.packetutil)
 
 (define (send-packet-with-socket socket packet)
   (let* ((fd (socket-fd socket))
 	 (out-port (open-output-fd-port fd)))
     (for-each (lambda (x) (write-byte x out-port)) packet)
     (flush out-port)))
 
 (define (send-udp-packet-with-addr src dest port packet)
   (let ((socket (make-socket AF_INET SOCK_DGRAM)))
     (socket-bind socket (make <sockaddr-in> :host src :port port))
     (socket-connect socket (make <sockaddr-in> :host dest :port port))
     (send-packet-with-socket socket packet)))
 ;    (socket-close socket)))
 
 (define (recv-packet-with-socket socket length)
   (let* ((fd (socket-fd socket))
 	 (in-port (open-input-fd-port fd)))
     (unpack "C*" :from-string (read-block length in-port))))
 
 (define (recv-udp-packet-with-addr src dest port length)
   (let ((socket (make-socket AF_INET SOCK_DGRAM)))
     (socket-bind socket (make <sockaddr-in> :host src :port port))
     (socket-connect socket (make <sockaddr-in> :host dest :port port))
     (recv-packet-with-socket socket length)))
 ;    (socket-close socket)))
 
 (define (sendrecv-udp-packet-with-addr src dest port packet length)
   (let ((socket (make-socket AF_INET SOCK_DGRAM)))
     (socket-bind socket (make <sockaddr-in> :host src :port port))
     (socket-connect socket (make <sockaddr-in> :host dest :port port))
     (send-packet-with-socket socket packet)
     (recv-packet-with-socket socket length)))
 ;    (socket-close socket)))
 
 (define (sendrecv-packet-with-socket socket packet length)
   (send-packet-with-socket socket packet)
   (recv-packet-with-socket socket length))
 
 (define (sendrecv-udp-packet-with-addr src dest port packet length)
   (let ((socket (make-socket AF_INET SOCK_DGRAM)))
     (socket-bind socket (make <sockaddr-in> :host src :port port))
     (socket-connect socket (make <sockaddr-in> :host dest :port port))
     (send-packet-with-socket socket packet)
     (recv-packet-with-socket socket length)))
 
 (define (hton32 value)
   (list
    (bit-field value 24 32)
    (bit-field value 16 23)
    (bit-field value  8 15)
    (bit-field value  0  7)))
 
 (define (hton16 value)
   (list
    (bit-field value  8 15)
    (bit-field value  0  7)))
 
 (define (ntoh32 vlist)
   (if (not (= (length vlist) 4))
       #f
       (+ (ash                (car vlist)    24)
 	 (ash           (car (cdr vlist))   16)
 	 (ash      (car (cdr (cdr vlist)))   8)
 	 (ash (car (cdr (cdr (cdr vlist))))  0))))
 
 (define (ntoh16 vlist)
   (if (not (= (length vlist) 2))
       #f
       (+ (ash      (car (cdr (cdr vlist)))   8)
 	 (ash (car (cdr (cdr (cdr vlist))))  0))))
 
 (provide "gsup.net.packetutil")