socket.chezscheme.sls

;; Chez-socket: Extended Socket interface.
;;
;; Interface extensions over basic sockets (SRFI-106).
;;
;; Written by Jerry 2020-2021.
;; SPDX-License-Identifier: Unlicense
;;
;; TODOs
;; - AF_UNIX support
;; ? Numeric IPv4 & IPv6 address builders? eg,
;;   - (ipv4/any) => INADDR_ANY
;;   - (ipv6/any) => IN6ADDR_ANY_INIT
;;   - (ipv6/multicast/link-local fill 1f 10) => "ff:02::1f:10"
;;   - Implicit fill: (ipv6/multicast/site-local ca fe 1) => "ff:05::ca:fe:01"

(library
  (socket)
  (export
    address-info socket-opt-level socket-opt
    socket->port
    ;; Include the srfi-106 versions as this interface extends it, but prefer the original names
    ;; as they're closer to the R6RS port function naming convention.
    (rename
      (open-socket-input-port socket-input-port)
      (open-socket-output-port socket-output-port))
    )
  (import
    (chezscheme)
    (socket impl))
  ;; Re-export the implementation interface.
  ;; TODO hide internals at some point, but this is very handy while developing.
  (export
    (import (except (socket impl) define-bits define-enum)))

  ;; See netdb.h(0P)
  (define-bits address-info
    [addrconfig		*ai-addrconfig*]	; Return only IPv4 or IPv6 addresses depending on config.
    [all		*ai-all*]		; Find both IPv6 and IPv4 addresses.
    [canoname		*ai-canonname*]		; Returned hostname is canonical.
    [numerichost	*ai-numerichost*]	; Lookup hostname for numeric address.
    [v4mapped		*ai-v4mapped*]		; Failed IPv6 addresses are returned as IPv4 mapped IPv6.
    ;; Extensions to SRFI:
    [numericserv	*ai-numericserv*]	; service (port) is a number: prevents name lookup.
    [passive		*ai-passive*]		; Intent to bind(3) socket.
    )

  (define-enum socket-opt-level
    [socket	*sol-socket*]		; getsockopt(2) SOL_SOCKET.
    [ip		*ipproto-ip*]		; ip(7) IPPROTO_IP.
    [tcp	*ipproto-tcp*]		; tcp(7) IPPROTO_TCP.
    [udp	*ipproto-udp*])		; upd(7) IPPROTO_UDP.

  (define-enum socket-opt
    [acceptconn	*so-acceptconn*]	; bool read-only
    [broadcast	*so-broadcast*]		; bool datagram only
    [domain	*so-domain*]		; int read-only: eg, AF_INET6.
    [dontroute	*so-dontroute*]		; bool
    [error	*so-error*]		; read-only: value cleared after read
    [keepalive	*so-keepalive*]		; bool
    [linger	*so-linger*]		; linger struct
    [oobinline	*so-oobinline*]		; bool
    [protocol	*so-protocol*]		; int read-only: eg, IPPROTO_TCP.
    [reuseaddr  *so-reuseaddr*]		; bool
    [type	*so-type*]		; int read-only: eg, SOCK_STREAM.

    ;; ip(7) multicast options.
    [multicast-loop	*ip-multicast-loop*]	; bool: sender also receives own datagrams.
    [multicast-ttl	*ip-multicast-ttl*]	; int: datagram time-to-live.
    ;; The following 3 multicast opts all take ip_mreq(n) structs. As such, C functions are
    ;; provided to hide the struct details and should be used instead. These are here just in case.
    [multicast-if	*ip-multicast-if*]	; Set local interface for multicast socket.
    [add-membership	*ip-add-membership*]	; Join a multicast group.
    [drop-membership	*ip-drop-membership*]	; Leave a multicast group.
    )

  ;; [proc] socket->port: shortcut for creating a transcoded text port from a binary socket
  (define socket->port
    (case-lambda
      [(sock)
       (socket->port sock (native-transcoder))]
      [(sock transcoder)
       (transcoded-port (open-socket-input/output-port sock) transcoder)]))
  )