fix bugs in serializer and deserializer

This commit is contained in:
Rohan Prinja 2015-06-16 00:55:06 +05:30
parent 2145316f89
commit 0937fcf663
2 changed files with 112 additions and 70 deletions

View File

@ -27,9 +27,14 @@
#:use-module (rnrs enums)
#:export (<dhcp-msg>
make-dhcp-msg
make-dhcp-message ; wrapper for make-dhcp-msg
make-dhcpdiscover
dhcp-msg?
bytevector-slice
dhcp-msg-op set-dhcp-msg-op!
dhcp-msg-htype set-dhcp-msg-htype!
dhcp-msg-hlen set-dhcp-msg-hlen!
@ -49,11 +54,19 @@
set-broadcast-bit
unset-broadcast-bit
option-value
serialize-dhcp-message
deserialize-dhcp-message
message-type
make-dhcpdiscover
map-type-to-code))
serialize-dhcp-msg
deserialize-dhcp-msg
deserialize-options
msg-type
retrieve-secs
retrieve-xid
retrieve-ciaddr
map-type-to-code
map-type-to-op))
;; Magic cookie that starts off the 'options' field
;; in a DHCP message packet.
@ -116,75 +129,77 @@
;; remaining bits are always zero, see Figure 2, RFC 2131.
(define-syntax-rule (set-broadcast-bit msg)
(set-dhcp-msg-flags #x8000))
(define-syntax-rule (unset-broadcast-bit msg)
(set-dhcp-msg-flags 0))
#;(define (serialize-options! opts dst idx)
"Copy the options field OPTS from a <dhcp-message> into a
(define (serialize-options! opts dst idx)
"Copy the options field OPTS from a <dhcp-msg> into a
bytevector. OPTS is a vector, DST is a bytevector.
Copying starts at index IDX in DST. This function mutates DST.
If an option is #f, it means it does not exist, so it is
If an option is #f, it does not exist, so it is
simply ignored whilst serializing."
(let loop ((i 0))
(if (< i 256)
(let loop ((i 0) (to idx))
(if (< i 255)
(let* ((opt (vector-ref opts i)))
(if (eq? #f opt)
(loop (1+ i))
(if (eq? #f opt) ; option not present
(loop (1+ i) to)
(let ((code i)
(len (dhcp-option-len opt))
(val (dhcp-option-val opt)))
(begin
(if (zero? len)
(bytevector-u8-set! dst idx code)
(bytevector-u8-set! dst to code)
(begin
(bytevector-u8-set! dst idx code)
(bytevector-u8-set! dst (1+ idx) len)
(bytevector-copy! val 0 dst (+ idx 2) len)))
(loop (1+ i)))))))))
(bytevector-u8-set! dst to code)
(bytevector-u8-set! dst (1+ to) len)
(bytevector-copy! val 0 dst (+ to 2) len)))
(loop (1+ i) (+ to 2 len))))))
(bytevector-u8-set! dst to 255))))
; Serialize a <dhcp-message> object into a bytevector.
#;(define-method (serialize-dhcp-message (msg <dhcp-message>))
(define (serialize-dhcp-msg msg)
"Serialize a <dhcp-message> record MSG into a bytevector"
(let* ((res (make-bytevector 576 0))
(chaddr (slot-ref msg 'chaddr))
(chaddr (dhcp-msg-chaddr msg))
(chaddr-len (bytevector-length chaddr))
(padded-chaddr (make-bytevector 16 0))
(_ (bytevector-copy! chaddr 0
padded-chaddr (- 16 chaddr-len)
chaddr-len)))
(bytevector-u8-set! res 0 (slot-ref msg 'op))
(bytevector-u8-set! res 1 (slot-ref msg 'htype))
(bytevector-u8-set! res 2 (slot-ref msg 'hlen))
(bytevector-u8-set! res 3 (slot-ref msg 'hops))
(bytevector-u32-set! res 4 (slot-ref msg 'xid) (endianness big))
(bytevector-u16-set! res 8 (slot-ref msg 'secs) (endianness big))
(bytevector-u16-set! res 10 (slot-ref msg 'flags) (endianness big))
(bytevector-copy! (slot-ref msg 'ciaddr) 0 res 12 4)
(bytevector-copy! (slot-ref msg 'yiaddr) 0 res 16 4)
(bytevector-copy! (slot-ref msg 'siaddr) 0 res 20 4)
(bytevector-copy! (slot-ref msg 'giaddr) 0 res 24 4)
(bytevector-u8-set! res 0 (dhcp-msg-op msg))
(bytevector-u8-set! res 1 (dhcp-msg-htype msg))
(bytevector-u8-set! res 2 (dhcp-msg-hlen msg))
(bytevector-u8-set! res 3 (dhcp-msg-hops msg))
(bytevector-u32-set! res 4 (dhcp-msg-xid msg) (endianness big))
(bytevector-u16-set! res 8 (dhcp-msg-secs msg) (endianness big))
(bytevector-u16-set! res 10 (dhcp-msg-flags msg) (endianness big))
(bytevector-copy! (dhcp-msg-ciaddr msg) 0 res 12 4)
(bytevector-copy! (dhcp-msg-yiaddr msg) 0 res 16 4)
(bytevector-copy! (dhcp-msg-siaddr msg) 0 res 20 4)
(bytevector-copy! (dhcp-msg-giaddr msg) 0 res 24 4)
(bytevector-copy! padded-chaddr 0 res 28 16)
(bytevector-copy! (slot-ref msg 'sname) 0 res 44 64)
(bytevector-copy! (slot-ref msg 'file) 0 res 108 128)
(bytevector-copy! (dhcp-msg-sname msg) 0 res 44 64)
(bytevector-copy! (dhcp-msg-file msg) 0 res 108 128)
(bytevector-copy! *magic-cookie* 0 res 236 4)
(serialize-options! (slot-ref msg 'options) res 240)
(serialize-options! (dhcp-msg-options msg) res 240)
res))
; Read options from a bytevector 'src' starting at index
; 'idx' and returns a vector of <dhcp-option> objects.
#;(define (deserialize-options src idx)
(define (deserialize-options src idx)
"Read options from a bytevector SRC starting at index
IDX and returns a vector of <dhcp-option> records. We ignore
the PAD option since its only purpose is to pad the
bytevector; it carries no other useful information."
(define (helper src i res)
(if (= i (bytevector-length src))
res ; nothing more to read from 'src'
(let* ((code (bytevector-u8-ref src i)))
(if (or (= code 0) (code 255))
(begin
(slot-set! res code (make-dhcp-option code 0 #f))
(helper src (+ i 1) res))
(if (= code 255)
res ; we have seen an 'end' option, stop reading
(let* ((len (bytevector-u8-ref src (+ i 1)))
(val (make-bytevector len))
(_ (bytevector-copy! src (+ i 2) val 0 len)))
(begin
(slot-set! res code (make-dhcp-option code len val))
(vector-set! res code (make-dhcp-option code len val))
(helper src (+ i 2 len) res)))))))
(helper src idx (make-vector 256 #f)))
@ -199,20 +214,24 @@ from BV starting at index START"
(bytevector-copy! bv start res 0 len)
res))
#;(define (deserialize-dhcp-message msg)
(make <dhcp-message>
#:op (bytevector-u8-ref msg 0)
#:htype (bytevector-u8-ref msg 1)
#:hops (bytevector-u8-ref msg 2)
#:xid (bytevector-u32-ref msg 4 (endianness big))
#:secs (bytevector-u16-ref msg 8 (endianness big))
#:flags (bytevector-u16-ref msg 10 (endianness big))
#:ciaddr (bytevector-u32-ref msg 12 (endianness big))
#:yiaddr (bytevector-u32-ref msg 16 (endianness big))
#:siaddr (bytevector-u32-ref msg 20 (endianness big))
#:giaddr (bytevector-u32-ref msg 24 (endianness big))
; TODO: chaddr
#:options (deserialize-options msg 240)))
(define (deserialize-dhcp-msg msg)
(make-dhcp-msg
(bytevector-u8-ref msg 0) ; op
(bytevector-u8-ref msg 1) ; htype
(bytevector-u8-ref msg 2) ; hlen
(bytevector-u8-ref msg 3) ; hops
(bytevector-u32-ref msg 4 (endianness big)) ; xid
(bytevector-u16-ref msg 8 (endianness big)) ; secs
(bytevector-u16-ref msg 10 (endianness big)) ; flags
(bytevector-u32-ref msg 12 (endianness big)) ; ciaddr
(bytevector-u32-ref msg 16 (endianness big)) ; yiaddr
(bytevector-u32-ref msg 20 (endianness big)) ; siaddr
(bytevector-u32-ref msg 24 (endianness big)) ; giaddr
(bytevector-slice msg 28 16) ; chaddr
(bytevector-slice msg 44 64) ; sname
(bytevector-slice msg 108 128) ; file
(deserialize-options msg 240) ; options
))
;; Set an <option> in a <dhcp-msg>.
(define-syntax-rule (set-option! msg opt)
@ -224,13 +243,13 @@ from BV starting at index START"
;; Retrieve an option's value from a <dhcp-msg>
;; record MSG given its code CODE.
(define-syntax-rule (option-value msg code)
(let* ((opts (slot-ref msg 'options))
(let* ((opts (dhcp-msg-options msg))
(opt (vector-ref opts code))
(val (dhcp-option-val opt)))
val))
;; Get the DHCP message type. See Section 9.6, RFC 2132.
(define-syntax-rule (message-type msg)
(define-syntax-rule (msg-type msg)
(option-value msg 53))
;; Map a DHCP message type to its single-digit code.
@ -251,17 +270,18 @@ from BV starting at index START"
((eq? 'DHCPNAK type) 2)
(else 1))))
(define (make-dhcp-msg netif type opts)
(define (make-dhcp-message netif type opts)
"Make an instance of <dhcp-msg> for interface NETIF
with message type TYPE and options initialized to OPTS"
(let* ((pair (net-iface-hwaddr netif))
(let* ((dhcp (net-iface-dhcp netif))
(pair (net-iface-hwaddr netif))
(chaddr (car pair))
(htype (cdr pair))
(hlen (bytevector-length chaddr))
(op (map-type-to-op type))
(dhcp (net-iface-dhcp netif))
(msg-type-code (map-name-to-code
'DHCP-MSG-TYPE)))
'DHCP-MESSAGE-TYPE))
(end-code (map-name-to-code 'END)))
(begin
(vector-set! opts
msg-type-code ; 53
@ -319,7 +339,7 @@ ciaddr field in a <dhcp-msg> object."
;; TODO: figure out from 2131 exactly when to
;; return secs since config and when to return 0
(define (retrieve-secs netif type)
#;(define (retrieve-secs netif type)
"Given a <net-interface> NETIF and the message
type TYPE, return the appropriate value for the
secs field in a <dhcp-msg> object."
@ -330,5 +350,8 @@ secs field in a <dhcp-msg> object."
(else (- (current-time) ; might need to change
(dhcp-config-start dhcp))))))
(define-syntax-rule (make-dhcpdiscover netif opts)
(make-dhcp-msg netif 'DHCPDISCOVER opts))
(define (retrieve-secs netif type)
0)
(define (make-dhcpdiscover netif opts)
(make-dhcp-message netif 'DHCPDISCOVER opts))

View File

@ -19,8 +19,10 @@
(use-modules (srfi srfi-64)
((guix build syscalls) #:select (all-network-interfaces))
(dhcp interfaces)
(dhcp messages)
(dhcp interfaces)
(dhcp dhcp)
(dhcp options base)
(dhcp options names)
(rnrs bytevectors))
@ -31,18 +33,35 @@
(all-network-interfaces)))
'DHCP-INIT))
(define msg
(define msg-type-code (map-name-to-code
'DHCP-MESSAGE-TYPE))
(define original
(make-dhcpdiscover netif (make-vector 256 #f)))
(display (vector-ref (dhcp-msg-options original) 243))
(newline) (newline)
(test-begin "dhcp-messages")
(test-eq "message-type"
(map-type-to-code 'DHCPDISCOVER)
(bytevector-u8-ref (message-type msg) 0))
(bytevector-u8-ref (msg-type original) 0))
(define serialized (serialize-dhcp-message msg))
(define serialized (serialize-dhcp-msg original))
;(define deserialized (deserialize-dhcp-message msg))
;(define opts (deserialize-options serialized 240))
(define deserialized (deserialize-dhcp-msg serialized))
(test-eqv "fields-preserved-xid"
(dhcp-msg-xid deserialized)
(dhcp-msg-xid original))
(test-equal "fields-preserved-options"
(dhcp-msg-options deserialized)
(dhcp-msg-options original))
(test-end)