;;;; Copyright (C) 2020 Julien Lepiller <julien@lepiller.eu>

;;;; 

;;;; This library is free software; you can redistribute it and/or

;;;; modify it under the terms of the GNU Lesser General Public

;;;; License as published by the Free Software Foundation; either

;;;; version 3 of the License, or (at your option) any later version.

;;;; 

;;;; This library is distributed in the hope that it will be useful,

;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of

;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

;;;; Lesser General Public License for more details.

;;;; 

;;;; You should have received a copy of the GNU Lesser General Public

;;;; License along with this library; if not, write to the Free Software

;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

;;;; 

(define-module (netlink message)

  #:use-module (ice-9 match)

  #:use-module (netlink data)

  #:use-module (netlink standard)

  #:use-module (rnrs bytevectors)

  #:use-module (srfi srfi-9)

  #:export (make-message

            message?

            message-kind

            message-flags

            message-seq

            message-pid

            message-data

            deserialize-message

            deserialize-message-header))

(define-data-type message

  message-type-len

  (lambda (msg pos bv)

    (match msg

      (($ message-type type flags seq pid data)

       (bytevector-u32-set! bv pos (message-type-len msg) (native-endianness))

       (bytevector-u16-set! bv (+ pos 4) type (native-endianness))

       (bytevector-u16-set! bv (+ pos 6) flags (native-endianness))

       (bytevector-u32-set! bv (+ pos 8) seq (native-endianness))

       (bytevector-u32-set! bv (+ pos 12) pid (native-endianness))

       (serialize data (+ 16 pos) bv))))

  (type  message-kind  message-type-type)

  (flags message-flags message-type-flags)

  (seq   message-seq   message-type-seq)

  (pid   message-pid   message-type-pid)

  (data  message-data  message-type-data))

(define (message-type-len msg)

  (+ 16 (data-size (message-type-data msg))))

(define (deserialize-message decoder bv pos)

  (let* ((len (bytevector-u32-ref bv pos (native-endianness)))

         (type (bytevector-u16-ref bv (+ pos 4) (native-endianness)))

         (data (make-bytevector len))

         (deserialize (get-next-deserialize decoder 'message type)))

    (bytevector-copy! bv pos data 0 len)

    (let ((data (deserialize decoder data 16)))

      (make-message

        type

        (bytevector-u16-ref bv (+ pos 6) (native-endianness))

        (bytevector-u32-ref bv (+ pos 8) (native-endianness))

        (bytevector-u32-ref bv (+ pos 12) (native-endianness))

        (if (< (data-size data) (- len 16))

            (make-nl-data #f (const (- len 16)) (const (make-bytevector 0)))

            data)))))

(define (deserialize-message-header decoder bv pos)

  (make-message

    (bytevector-u16-ref bv (+ pos 4) (native-endianness))

    (bytevector-u16-ref bv (+ pos 6) (native-endianness))

    (bytevector-u32-ref bv (+ pos 8) (native-endianness))

    (bytevector-u32-ref bv (+ pos 12) (native-endianness))

    no-data))