chezscheme-socket

A simple TCP library for Chez Scheme

Hint: If you're using Windows you can use the excellent tool Hercules for debugging your socket applications.

Quickstart

Winsock2 Server example

(import (winsock2))

(wsa-startup 2 2)

; Create a server.
(define server (socket AF_INET SOCK_STREAM 0))
(bind s AF_INET INADDR_ANY (htons 8000))

; Start listening for incoming client connections.
(listen server 3) ; Allow up to 3 pending clients waiting for connection

; Check if there are any pending clients
(positive? (wsa-poll server POLLRDNORM 1 0)) ; returns #t means accept will return immediately

; Accept an incoming client connection.
; Note: accept blocks the running thread until a client has been received!
(define client (accept server)) ; returns a socket

; Close a socket when you're done with it.
(close-socket server)

; Send data on a socket with send or send-string.
; Note: send takes a bytevector while send-string takes a string.
(send client (string->utf8 "Hello, client!\n") 0)

; Check if there is incoming information.
(positive? (wsa-poll client POLLRDNORM 1 0)) ; returns #t means recv will return immediately

; Receive data on a socket.
; Note:
;  This procedure blocks the running thread until a message has been received.
;  receive consumes data on a socket up to a number of bytes as specified by the
;  parameter chunk-size. Default is 1024 bytes. If the message is incomplete,
;  invoke receive again to get the rest of the message or parameterize chunk-size
;  with a bigger number.
(utf8->string (recv client 0))

(close-socket client)

; Unload the Windows Socket API with when you're done with it.
(cleanup)

Winsock2 Client example

(import (winsock2))

(wsa-startup 2 2)

; Connect to a server.
(define server (socket AF_INET SOCK_STREAM 0))
(connect s AF_INET (inet_addr "127.0.0.1") (htons 8000))

; Send data on a socket with send or send-string.
; Note: send takes a bytevector while send-string takes a string.
(send server (string->utf8 "Hello, server!\n") 0)

; Check if there is incoming information.
(positive? (wsa-poll server POLLRDNORM 1 0)) ; returns #t means recv will return immediately

; Receive data on a socket.
; Note:
;  This procedure blocks the running thread until a message has been received.
;  receive consumes data on a socket up to a number of bytes as specified by the
;  parameter chunk-size. Default is 1024 bytes. If the message is incomplete,
;  invoke receive again to get the rest of the message or parameterize chunk-size
;  with a bigger number.
(utf8->string (recv server 0))

; Close a socket when you're done with it.
(close-socket server)

; Unload the Windows Socket API with when you're done with it.
(cleanup)

⚠ Thread safety

recv must not be invoked at the same for the same socket time on different threads. The same goes for send.
recv and send can however safely be invoked at the same time for the same socket on different threads without issues.

Notes

Right now this library only wraps some basic functionality in the Windows Socket API (winsock2). I won't go far beyond this except a few things: