Network Socket Examples

The following give examples of how to use network sockets.

Internet Socket Client Example

The following example demonstrates an Internet socket client. It connects to the HTTP daemon running on the local machine and returns the contents of the root index URL.

(let ((s (socket PF_INET SOCK_STREAM 0)))
  (connect s AF_INET (inet-pton AF_INET "127.0.0.1") 80)
  (display "GET / HTTP/1.0\r\n\r\n" s)

  (do ((line (read-line s) (read-line s)))
      ((eof-object? line))
    (display line)
    (newline)))

Internet Socket Server Example

The following example shows a simple Internet server which listens on port 2904 for incoming connections and sends a greeting back to the client.

(let ((s (socket PF_INET SOCK_STREAM 0)))
  (setsockopt s SOL_SOCKET SO_REUSEADDR 1)
  ;; Specific address?
  ;; (bind s AF_INET (inet-pton AF_INET "127.0.0.1") 2904)
  (bind s AF_INET INADDR_ANY 2904)
  (listen s 5)

  (simple-format #t "Listening for clients in pid: ~S" (getpid))
  (newline)

  (while #t
    (let* ((client-connection (accept s))
           (client-details (cdr client-connection))
           (client (car client-connection)))
      (simple-format #t "Got new client connection: ~S"
                     client-details)
      (newline)
      (simple-format #t "Client address: ~S"
                     (gethostbyaddr
                      (sockaddr:addr client-details)))
      (newline)
      ;; Send back the greeting to the client port
      (display "Hello client\r\n" client)
      (close client))))