;;;; 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 attrs)

  #:use-module (ice-9 match)

  #:use-module (netlink constant)

  #:use-module (netlink data)

  #:use-module (rnrs bytevectors)

  #:use-module (srfi srfi-9)

  #:export(make-route-attr

           route-attr?

           route-attr-kind

           route-attr-data

           route-attr-size

           make-u8-route-attr

           make-u16-route-attr

           make-u32-route-attr

           make-s32-route-attr

           make-string-route-attr

           make-ethernet-route-attr

           make-ipv4-route-attr

           make-ipv6-route-attr

           make-bv-route-attr

           deserialize-route-attr

           deserialize-route-attr-data-string

           deserialize-route-attr-data-u8

           deserialize-route-attr-data-u32

           deserialize-route-attr-data-s32

           deserialize-route-attr-data-ethernet

           deserialize-route-attr-data-ipv4

           deserialize-route-attr-data-ipv6

           deserialize-route-attr-data-bv

           %default-route-link-attr-decoder

           %default-route-addr-ipv4-attr-decoder

           %default-route-addr-ipv6-attr-decoder))

(define-data-type route-attr

  attr-type-size

  (lambda (attr pos bv)

    (match attr

      (($ route-attr-type type data)

       (bytevector-u16-set! bv pos (attr-type-size attr) (native-endianness))

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

       (serialize data (+ pos 4) bv))))

  (type route-attr-kind route-attr-type-type)

  (data route-attr-data route-attr-type-data))

(define (attr-type-size attr)

  (+ 4 (data-size (route-attr-type-data attr))))

(define (make-u8-route-attr num)

  (make-nl-data

    num

    (const 1)

    (lambda (data pos bv)

      (bytevector-u8-set! bv pos data))))

(define (make-u16-route-attr num)

  (make-nl-data

    num

    (const 2)

    (lambda (data pos bv)

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

(define (make-u32-route-attr num)

  (make-nl-data

    num

    (const 4)

    (lambda (data pos bv)

      (bytevector-u32-set! bv pos data (native-endianness)))))

(define (make-s32-route-attr num)

  (make-nl-data

    num

    (const 4)

    (lambda (data pos bv)

      (bytevector-s32-set! bv pos data (native-endianness)))))

(define (make-string-route-attr str)

  (make-nl-data

    str

    (lambda (str) (bytevector-length (string->utf8 str)))

    (lambda (data pos bv)

      (let ((s (string->utf8 data)))

        (bytevector-copy! s 0 bv pos (bytevector-length s))))))

(define (ethernet->bv addr)

  (u8-list->bytevector (map (lambda (n) (string->number n 16))

                            (string-split addr #\:))))

(define (make-ethernet-route-attr addr)

  (make-nl-data

    addr

    (lambda (addr) (bytevector-length (ethernet->bv addr)))

    (lambda (data pos bv)

      (let ((a (ethernet->bv data)))

        (bytevector-copy! a 0 bv pos (bytevector-length a))))))

(define (ipv4->bv addr)

  (u8-list->bytevector (map (lambda (n) (string->number n))

                            (string-split addr #\.))))

(define (make-ipv4-route-attr addr)

  (make-nl-data

    addr

    (lambda (addr) (bytevector-length (ipv4->bv addr)))

    (lambda (data pos bv)

      (let ((a (ipv4->bv data)))

        (bytevector-copy! a 0 bv pos (bytevector-length a))))))

;16 bytes

(define (ipv6->bv addr)

  (let loop ((num (inet-pton AF_INET6 addr)) (lst '()))

    (match lst

      ((_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _)

       (u8-list->bytevector (reverse lst)))

      (_

       (loop (quotient num 256) (cons (modulo num 256) lst))))))

(define (make-ipv6-route-attr addr)

  (make-nl-data

    addr

    (lambda (addr) (bytevector-length (ipv6->bv addr)))

    (lambda (data pos bv)

      (let ((a (ipv6->bv data)))

        (bytevector-copy! a 0 bv pos (bytevector-length a))))))

(define (make-bv-route-attr bv)

  (make-nl-data

    bv

    (lambda (bv) (bytevector-length bv))

    (lambda (data pos bv)

      (bytevector-copy! data 0 bv pos (bytevector-length data)))))

(define (deserialize-route-attr message-type)

  (lambda (decoder bv pos)

    (let* ((len (bytevector-u16-ref bv pos (native-endianness)))

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

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

           (data-bv (make-bytevector (- len 4))))

      (bytevector-copy! bv (+ pos 4) data-bv 0 (- len 4))

      (make-route-attr

        type

        (deserialize decoder data-bv 0)))))

(define (deserialize-route-attr-data-string decoder bv pos)

  (make-string-route-attr

    (or (false-if-exception (utf8->string bv))

        (make-string (bytevector-length bv) #\a))))

(define (deserialize-route-attr-data-u32 decoder bv pos)

  (make-u32-route-attr (bytevector-u32-ref bv pos (native-endianness))))

(define (deserialize-route-attr-data-s32 decoder bv pos)

  (make-s32-route-attr (bytevector-s32-ref bv pos (native-endianness))))

(define (deserialize-route-attr-data-u8 decoder bv pos)

  (make-u8-route-attr (bytevector-u8-ref bv pos)))

(define (deserialize-route-attr-data-bv decoder bv pos)

  (make-bv-route-attr bv))

(define (deserialize-route-attr-data-ethernet decoder bv pos)

  (make-ethernet-route-attr

    (string-join (map (lambda (n) (number->string n 16))

                      (bytevector->u8-list bv))

                 ":")))

(define (deserialize-route-attr-data-ipv4 decoder bv pos)

  (make-ipv4-route-attr

    (string-join (map (lambda (n) (number->string n))

                      (bytevector->u8-list bv))

                 ".")))

(define (deserialize-route-attr-data-ipv6 decoder bv pos)

  (define (ipv6->number addr)

    (let loop ((addr (bytevector->u8-list addr)) (num 0))

      (match addr

        (() num)

        ((byte addr ...)

         (loop addr (+ (* 256 num) byte))))))

  (make-ipv6-route-attr

    (inet-ntop AF_INET6 (ipv6->number bv))))

(define %default-route-link-attr-decoder

  `((,IFLA_ADDRESS . ,deserialize-route-attr-data-ethernet)

    (,IFLA_BROADCAST . ,deserialize-route-attr-data-ethernet)

    (,IFLA_IFNAME . ,deserialize-route-attr-data-string)

    (,IFLA_MTU . ,deserialize-route-attr-data-u32)

    (,IFLA_LINK . ,deserialize-route-attr-data-u32)

    (,IFLA_QDISC . ,deserialize-route-attr-data-string)

    ;; TODO: struct rtnl_link_stats

    ;(,IFLA_STATS . ,deserialize-route-attr-data-stats)

    (default . ,deserialize-route-attr-data-bv)))

(define (default-route-addr-attr-decoder address-decoder)

  `((,IFA_ADDRESS . ,address-decoder)

    (,IFA_LOCAL . ,address-decoder)

    (,IFA_LABEL . ,deserialize-route-attr-data-string)

    (,IFA_BROADCAST . ,address-decoder)

    (,IFA_ANYCAST . ,address-decoder)

    ;; TODO: struct ifa_cacheinfo

    ;(,IFA_CACHEINFO . ,deserialize-route-attr-data-cache-info)

    (default . ,deserialize-route-attr-data-bv)))

(define %default-route-addr-ipv4-attr-decoder

  (default-route-addr-attr-decoder deserialize-route-attr-data-ipv4))

(define %default-route-addr-ipv6-attr-decoder

  (default-route-addr-attr-decoder deserialize-route-attr-data-ipv6))