;;;; 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 route link)

  #:use-module (ice-9 match)

  #:use-module (netlink data)

  #:use-module (netlink route attrs)

  #:use-module (srfi srfi-9)

  #:use-module (rnrs bytevectors)

  #:export (make-link-message

            link-message?

            link-message-family

            link-message-kind

            link-message-index

            link-message-flags

            link-message-attrs

            deserialize-link-message))

(define (align pos to)

  (+ pos -1 (- to (modulo (- pos 1) to))))

(define-data-type link-message

  (lambda (msg)

    (+ 16 (apply + (map (lambda (d) (align (data-size d) 4)) attrs))))

  (lambda (msg pos bv)

    (match msg

      (($ link-message-type family type index flags attrs)

       (bytevector-u16-set! bv pos family (native-endianness))

       (bytevector-u16-set! bv (+ pos 2) type (native-endianness))

       (bytevector-u32-set! bv (+ pos 4) index (native-endianness))

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

       (let loop ((attrs attrs) (pos (+ pos 16)))

         (match attrs

           ((attr attrs ...)

            (serialize attr pos bv)

            (loop attrs (+ pos (align (data-size attr) 4))))

           (() #t))))))

  (family link-message-family link-message-type-family)

  (type link-message-kind link-message-type-type)

  (index link-message-index link-message-type-index)

  (flags link-message-flags link-message-type-flags)

  (attrs link-message-attrs link-message-type-attrs))

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

  (make-link-message

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

    (bytevector-u16-ref bv (+ pos 2) (native-endianness))

    (bytevector-u32-ref bv (+ pos 4) (native-endianness))

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

    (let ((len (bytevector-length bv)))

      (let loop ((pos (+ pos 16)) (attrs '()))

        (if (>= pos len)

            attrs

            (let ((attr (deserialize 'attr decoder bv pos)))

              (loop (+ pos (align (data-size attr) 4))

                    (cons attr attrs))))))))