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Typed implementation WIP

This commit is contained in:
Tony Garnock-Jones 2013-03-13 17:30:57 -04:00
parent f68f9cb56a
commit af9fa2cea8
5 changed files with 346 additions and 199 deletions
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40
api-untyped.rkt Normal file
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@ -0,0 +1,40 @@
#lang racket/base
;; Untyped struct definitions required to interoperate with typed-matrix's struct-map
;; See also Racket PR 13593.
(require racket-typed-matrix/struct-map)
(provide (struct-out domain))
;; (These utilities need to be defined ahead of the domain struct
;; definition.)
(define (domain=? a b recursive-equal?)
(recursive-equal? (domain-downcased-labels a)
(domain-downcased-labels b)))
(define (domain-hash-1/2 d recursive-hash)
(recursive-hash (domain-downcased-labels d)))
(struct domain (labels downcased-labels)
#:transparent
#:property prop:equal+hash (list domain=? domain-hash-1/2 domain-hash-1/2)
#:property prop:struct-map (lambda (f seed x)
(let-values (((labels seed) (f (domain-labels x) seed)))
(values (make-domain labels) seed))))
;; ListOf<Bytes> -> ListOf<Bytes>
;; Converts the 7-bit ASCII bytes in the argument to lower-case
;; equivalents. Used to normalize case for domain-name comparisons.
(define (downcase-labels labels)
(for/list ([label labels])
(define b (make-bytes (bytes-length label)))
(for ([i (bytes-length label)])
(define v (bytes-ref label i))
(bytes-set! b i (if (<= 65 v 90) (+ 32 v) v)))
b))
;; ListOf<Bytes> -> DomainName
;; Replacement constructor for domain structs. Automatically downcases
;; labels appropriately.
(define (make-domain labels)
(domain labels (downcase-labels labels)))

150
api.rkt
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@ -1,11 +1,16 @@
#lang racket/base
#lang typed/racket/base
;; Definitions for use in the API to the functionality of the library.
(provide (except-out (struct-out domain) domain)
(provide DomainName
(except-out (struct-out domain) domain)
(rename-out [make-domain domain])
domain-root?
domain-parent
IPv4
IPv6
Question
(struct-out question)
question-cyclic?
question-too-glueless?
@ -14,21 +19,30 @@
cname-question
ns-question
AnsweredQuestion
RR
(struct-out answered-question)
(struct-out rr)
CompleteAnswer
(struct-out complete-answer)
empty-complete-answer
merge-answers
extract-addresses
RData
(struct-out hinfo)
(struct-out minfo)
(struct-out mx)
(struct-out soa)
(struct-out wks)
(struct-out srv)
rr-rdata/cast
RRType
QueryType
RRClass
QueryClass
type->value value->type
qtype->value value->qtype
class->value value->class
@ -39,42 +53,39 @@
(require racket/match)
(require racket-typed-matrix/struct-map)
;; (These utilities need to be defined ahead of the domain struct
;; definition.)
(define (domain=? a b recursive-equal?)
(recursive-equal? (domain-downcased-labels a)
(domain-downcased-labels b)))
(define (domain-hash-1/2 d recursive-hash)
(recursive-hash (domain-downcased-labels d)))
;; A DomainName is a (domain ListOf<Bytes>), representing a domain
;; name. The head of the list is the leftmost label; for example,
;; www.google.com is represented as '(#"www" #"google" #"com").
(struct domain (labels downcased-labels)
#:transparent
#:property prop:equal+hash (list domain=? domain-hash-1/2 domain-hash-1/2)
#:property prop:struct-map (lambda (f seed x)
(let-values (((labels seed) (f (domain-labels x) seed)))
(values (make-domain labels) seed))))
(require/typed "api-untyped.rkt"
[#:struct domain ([labels : (Listof Bytes)]
[downcased-labels : (Listof Bytes)])])
(define-type DomainName domain)
;; A ShortString is a String with length 255 or shorter.
;; An IPv4 is a (vector Byte Byte Byte Byte), representing an IPv4
;; address. For example, 127.0.0.1 is represented as (vector 127 0 0
;; 1).
(define-type IPv4 (Vector Byte Byte Byte Byte))
;; An IPv6 is a Vector of length 16 containing Bytes, representing an
;; IPv6 address. For example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334
;; is represented as (vector #x20 #x01 #x0d #xb8 #x85 #xa3 #x00 #x00
;; #x00 #x00 #x8a #x2e #x03 #x70 #x73 #x34).
(define-type IPv6 (Vector Byte Byte Byte Byte
Byte Byte Byte Byte
Byte Byte Byte Byte
Byte Byte Byte Byte))
;; A Question is a (question DomainName QueryType QueryClass
;; QuestionContext), representing a DNS question: "What are the RRs
;; for the given name, type and class?" as well as a possible parent
;; question that the answer to this question is to contribute to the
;; answer to.
(struct question (name type class context) #:prefab)
(struct: question
([name : DomainName] [type : QueryType] [class : QueryClass] [context : QuestionContext])
#:prefab)
(define-type Question question)
;; A QuestionContext is one of
;; -- (cname-subq Question), resulting from the expansion of a CNAME
@ -87,32 +98,44 @@
;; excessively-glueless subquestion not represented here, and should
;; *not* in turn be considered for gluelessness-restarting: this is
;; needed to avoid a different kind of infinite loop.
(struct subquestion (parent) #:prefab)
(struct cname-subq subquestion () #:prefab)
(struct ns-subq subquestion () #:prefab)
(struct: subquestion ([parent : Question]) #:prefab)
(struct: cname-subq subquestion () #:prefab)
(struct: ns-subq subquestion () #:prefab)
(define-type QuestionContext (U subquestion cname-subq ns-subq False 'restart))
;; An AnsweredQuestion is an (answered-question Question
;; Maybe<CompleteAnswer>).
(struct answered-question (q a) #:prefab)
(struct: answered-question ([q : Question] [a : (Option CompleteAnswer)]) #:prefab)
(define-type AnsweredQuestion answered-question)
;; A CompleteAnswer is a (complete-answer Set<RR> Set<RR> Set<RR>)
(struct complete-answer (rrs authorities additional) #:prefab)
(struct: complete-answer
([rrs : (Setof RR)] [authorities : (Setof RR)] [additional : (Setof RR)])
#:prefab)
(define-type CompleteAnswer complete-answer)
;; An RR is a (rr DomainName RRType RRClass Uint32 RData),
;; representing a resource record.
(struct rr (name type class ttl rdata) #:prefab)
(struct: rr ([name : DomainName]
[type : RRType]
[class : RRClass]
[ttl : Nonnegative-Integer]
[rdata : RData])
#:prefab)
(define-type RR rr)
;; An RData is one of
;; - a DomainName, for CNAME, MB, MD, MF, MG, MR, NS and PTR records
;; - an IPv4, an "A" record
;; - an IPv6, an "AAAA" record
;; - (hinfo ShortString ShortString), a host information record [O]
;; - (hinfo Bytes Bytes), a host information record [O]
;; - (minfo DomainName DomainName), a mailbox information record [O]
;; - (mx Uint16 DomainName), a mail exchanger record
;; - (soa DomainName DomainName Uint32 Uint32 Uint32 Uint32 Uint32), a
;; start-of-authority record
;; - (wks IPv4 Byte Bytes), a Well-Known Service [O]
;; - (srv Uint16 Uint16 Uint16 DomainName), an "SRV" record
;; - a ListOf<Bytes>, a txt record
;; - a Bytes, either a 'null type RR or any unrecognised RR type.
;;
;; In each case, the RData's variant MUST line up correctly with the
@ -120,17 +143,36 @@
;;
;; Many of these variants are obsolete in today's DNS database (marked
;; [O] above).
(struct hinfo (cpu os) #:prefab)
(struct minfo (rmailbx emailbx) #:prefab)
(struct mx (preference exchange) #:prefab)
(struct soa (mname rname serial refresh retry expire minimum) #:prefab)
(struct wks (address protocol bitmap) #:prefab)
(struct srv (priority weight port target) #:prefab)
(struct: hinfo ([cpu : Bytes] [os : Bytes]) #:prefab)
(struct: minfo ([rmailbx : DomainName] [emailbx : DomainName]) #:prefab)
(struct: mx ([preference : Nonnegative-Integer] [exchange : DomainName]) #:prefab)
(struct: soa ([mname : DomainName]
[rname : DomainName]
[serial : Nonnegative-Integer]
[refresh : Nonnegative-Integer]
[retry : Nonnegative-Integer]
[expire : Nonnegative-Integer]
[minimum : Nonnegative-Integer]) #:prefab)
(struct: wks ([address : IPv4] [protocol : Byte] [bitmap : Bytes]) #:prefab)
(struct: srv ([priority : Nonnegative-Integer]
[weight : Nonnegative-Integer]
[port : Nonnegative-Integer]
[target : DomainName]) #:prefab)
(define-type RData (U DomainName IPv4 IPv6 hinfo minfo mx soa wks srv (Listof Bytes) Bytes))
(define-syntax-rule (rr-rdata/cast Type)
(lambda: ([rr : RR]) (cast (rr-rdata rr) Type)))
;; An RRType is a Symbol or a Number, one of the possibilities given
;; in the following define-mapping. It represents the type of an
;; RR. When used in an RR with an RData, the RRType and the RData
;; variant must correspond.
(define-type RRType (U 'a 'ns 'md 'mf 'cname 'soa 'mb 'mg
'mr 'null 'wks 'ptr 'hinfo 'minfo 'mx 'txt
'aaaa 'srv
Nonnegative-Integer))
(: type->value : RRType -> Nonnegative-Integer)
(: value->type : Nonnegative-Integer -> RRType)
(define-mapping type->value value->type
#:forward-default values
#:backward-default values
@ -156,6 +198,9 @@
;; A QueryType is a Symbol or Number (as given in the following
;; define-mapping) or an RRType. It specifies the kinds of records
;; being sought after in a DNS query.
(define-type QueryType (U RRType 'axfr 'mailb 'maila '*))
(: qtype->value : QueryType -> Nonnegative-Integer)
(: value->qtype : Nonnegative-Integer -> QueryType)
(define-mapping qtype->value value->qtype
#:forward-default type->value
#:backward-default value->type
@ -168,6 +213,9 @@
;; in the following define-mapping. It represents the "class" of DNS
;; records being discussed. All classes except 'in are obsolete in
;; today's DNS databases.
(define-type RRClass (U 'in 'cs 'ch 'hs Nonnegative-Integer))
(: class->value : RRClass -> Nonnegative-Integer)
(: value->class : Nonnegative-Integer -> RRClass)
(define-mapping class->value value->class
#:forward-default values
#:backward-default values
@ -179,6 +227,9 @@
;; A QueryClass is a Symbol or Number (as given in the following
;; define-mapping) or an RRClass. It specifies the "class" of records
;; being sought after in a DNS query.
(define-type QueryClass (U RRClass '*))
(: qclass->value : QueryClass -> Nonnegative-Integer)
(: value->qclass : Nonnegative-Integer -> QueryClass)
(define-mapping qclass->value value->qclass
#:forward-default class->value
#:backward-default value->class
@ -187,6 +238,7 @@
;; ListOf<Bytes> -> ListOf<Bytes>
;; Converts the 7-bit ASCII bytes in the argument to lower-case
;; equivalents. Used to normalize case for domain-name comparisons.
(: downcase-labels : (Listof Bytes) -> (Listof Bytes))
(define (downcase-labels labels)
(for/list ([label labels])
(define b (make-bytes (bytes-length label)))
@ -198,24 +250,25 @@
;; ListOf<Bytes> -> DomainName
;; Replacement constructor for domain structs. Automatically downcases
;; labels appropriately.
(: make-domain : (Listof Bytes) -> DomainName)
(define (make-domain labels)
(domain labels (downcase-labels labels)))
;; DomainName -> Boolean
(: domain-root? : DomainName -> Boolean)
(define (domain-root? d)
(null? (domain-labels d)))
;; DomainName -> Maybe<DomainName>
(: domain-parent : DomainName -> (Option DomainName))
(define (domain-parent d)
(and (pair? (domain-labels d))
(domain (cdr (domain-labels d))
(cdr (domain-downcased-labels d)))))
;; -> CompleteAnswer
(: empty-complete-answer : -> CompleteAnswer)
(define (empty-complete-answer)
(complete-answer (set) (set) (set)))
;; CompleteAnswer CompleteAnswer -> CompleteAnswer
(: merge-answers : CompleteAnswer CompleteAnswer -> CompleteAnswer)
(define (merge-answers a1 a2)
(match-define (complete-answer n1 u1 d1) a1)
(match-define (complete-answer n2 u2 d2) a2)
@ -223,7 +276,7 @@
(set-union u1 u2)
(set-union d1 d2)))
;; DomainName Maybe<CompleteAnswer> -> SetOf<IPv4>
(: extract-addresses : DomainName (Option CompleteAnswer) -> (Setof IPv4))
(define (extract-addresses name ans)
(match ans
[#f ;; name-error/NXDOMAIN, so definitely no addresses.
@ -231,27 +284,29 @@
[(complete-answer ns us ds)
(define rrs (set->list (set-union ns us ds)))
(let loop ((names (list name))
(ips (set))
(seen (set)))
(ips ((inst set IPv4)))
(seen ((inst set DomainName))))
(if (null? names)
ips
(let* ((name (car names))
(records (filter (lambda (rr) (equal? name (rr-name rr))) rrs)))
(records (filter (lambda: ([rr : RR]) (equal? name (rr-name rr))) rrs)))
(if (set-member? seen name)
(loop (cdr names) ips seen)
(let ((a-records (filter (lambda (rr) (equal? 'a (rr-type rr))) records))
(cname-records (filter (lambda (rr) (equal? 'cname (rr-type rr))) records)))
(loop (append (map rr-rdata cname-records) (cdr names))
(set-union ips (list->set (map rr-rdata a-records)))
(let ((a-records (filter (lambda: ([rr : RR]) (equal? 'a (rr-type rr))) records))
(cname-records
(filter (lambda: ([rr : RR]) (equal? 'cname (rr-type rr))) records)))
(loop (append (map (rr-rdata/cast DomainName) cname-records) (cdr names))
(set-union ips (list->set (map (rr-rdata/cast IPv4) a-records)))
(set-add seen name)))))))]))
;; Question -> Boolean
;; #t iff this question is being asked in order to supply answers
;; contributing to a parent context that's trying to answer exactly
;; this question.
(: question-cyclic? : Question -> Boolean)
(define (question-cyclic? q)
(match-define (question name type class parent) q)
(let search ((ancestor parent))
(let: search : Boolean ((ancestor : QuestionContext parent))
(match ancestor
[(subquestion (question (== name) (== type) (== class) _)) #t] ;; uh-oh! A cycle!
[(subquestion (question _ _ _ ancestor-parent)) (search ancestor-parent)] ;; recursive case
@ -263,9 +318,10 @@
;; from the outside world, then that's too glueless. See
;; http://cr.yp.to/djbdns/notes.html in the sections "Gluelessness"
;; and "Expiring glue".
(: question-too-glueless? : Question -> Boolean)
(define (question-too-glueless? q)
(define count
(let search ((q q) (acc 0))
(let: search : Integer ((q : Question q) (acc : Integer 0))
(match-define (question _ _ _ parent) q)
(cond
[(ns-subq? parent) (search (subquestion-parent parent) (+ acc 1))]
@ -281,6 +337,7 @@
;; Question -> Boolean
;; #t iff this question is being asked in the context of some
;; excessively glueless subquestion.
(: question-restarted? : Question -> Boolean)
(define (question-restarted? q)
(match-define (question name type class parent) q)
(let search ((ancestor parent))
@ -292,16 +349,19 @@
;; Question -> Question
;; Returns a question equivalent to q, but in a 'restart context, for
;; retracing from the roots in cases of excessive gluelessness.
(: restart-question : Question -> Question)
(define (restart-question q)
(struct-copy question q [context 'restart]))
;; DomainName Question -> Question
;; Produces a new question with CNAME context.
(: cname-question : DomainName Question -> Question)
(define (cname-question name q)
(match-define (question _ type class _) q)
(question name type class (cname-subq q)))
;; DomainName Question -> Question
;; Produces a new question with NS context.
(: ns-question : DomainName Question -> Question)
(define (ns-question name q)
(question name 'a 'in (ns-subq q))) ;; TODO: 'aaaa ?

254
codec.rkt
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@ -1,9 +1,17 @@
#lang racket/base
#lang typed/racket/base
;; DNS wire-protocol codec.
(provide value->query-opcode query-opcode->value
(provide Opcode
ResponseCode
value->query-opcode query-opcode->value
value->query-response-code query-response-code->value
DNSMessage
Direction
Authoritativeness
Truncatedness
RecursionDesired
RecursionAvailable
(struct-out dns-message)
packet->dns-message
@ -17,12 +25,18 @@
(require "api.rkt")
(require "mapping.rkt")
(domain (list #"hello"))
(require racket/match)
(require racket-bitsyntax)
;; An Opcode is a Symbol or a Number, one of the possibilities given
;; in the following define-mapping. It represents a DNS message
;; operation; see the RFC for details.
(define-type Opcode (U 'query 'iquery 'status Nonnegative-Integer))
(: value->query-opcode : Nonnegative-Integer -> Opcode)
(: query-opcode->value : Opcode -> Nonnegative-Integer)
(define-mapping value->query-opcode query-opcode->value
#:forward-default values
#:backward-default values
@ -33,6 +47,11 @@
;; A ResponseCode is a Symbol or a Number, one of the possibilities
;; given in the following define-mapping. It represents the outcome of
;; a DNS query.
(define-type ResponseCode (U 'no-error 'format-error 'server-failure
'name-error 'not-implemented 'refused
Nonnegative-Integer))
(: value->query-response-code : Nonnegative-Integer -> ResponseCode)
(: query-response-code->value : ResponseCode -> Nonnegative-Integer)
(define-mapping value->query-response-code query-response-code->value
(0 no-error)
(1 format-error)
@ -48,57 +67,82 @@
;;
;; Interpreted as either a DNS request or reply, depending on the
;; Direction.
(struct dns-message (id
direction
opcode
authoritative
truncated
recursion-desired
recursion-available
response-code
questions
answers
authorities
additional)
#:prefab)
(struct: dns-message ([id : Nonnegative-Integer]
[direction : Direction]
[opcode : Opcode]
[authoritative : Authoritativeness]
[truncated : Truncatedness]
[recursion-desired : RecursionDesired]
[recursion-available : RecursionAvailable]
[response-code : ResponseCode]
[questions : (Listof Question)]
[answers : (Listof RR)]
[authorities : (Listof RR)]
[additional : (Listof RR)])
#:prefab)
(define-type DNSMessage dns-message)
(define-type Direction (U 'request 'response))
(define-type Authoritativeness (U 'non-authoritative 'authoritative))
(define-type Truncatedness (U 'not-truncated 'truncated))
(define-type RecursionDesired (U 'no-recursion-desired 'recursion-desired))
(define-type RecursionAvailable (U 'no-recursion-available 'recursion-available))
;; Bit-syntax type for counted repeats of a value.
;; Example: Length-prefixed list of 32-bit unsigned words:
;; (bit-string-case input ([ len (vals :: (t:ntimes len bits 32)) ] vals))
;; (bit-string (vals :: (t:ntimes bits 32)))
;; (bit-string-case input ([ len (vals :: (t:ntimes Integer len bits 32)) ] vals))
;; (bit-string (vals :: (t:ntimes Integer bits 32)))
(define-syntax t:ntimes
(syntax-rules ()
((_ #t input ks kf times-to-repeat option ...)
(let loop ((count times-to-repeat)
(acc '())
(input input))
(cond
((positive? count) (bit-string-case input
([ (v :: option ...) (rest :: binary) ]
(loop (- count 1) (cons v acc) rest))
(else (kf))))
(else (ks (reverse acc) input)))))
((_ #f vs option ...)
(t:listof #f vs option ...))))
((_ #t input0 ks kf Type times-to-repeat option ...)
(let ()
;; A simple loop without multiple-values or #f is much cleaner
;; here, but I can't find a way of expressing the types
;; required while making that work. This way, we avoid needing
;; to mention the type of the result of calls to ks.
(: loop : Integer (Listof Type) BitString -> (Values (Option (Listof Type)) BitString))
(define (loop count acc input)
(cond
((positive? count) (bit-string-case input
([ (v :: option ...) (rest :: binary) ]
(loop (- count 1) (cons v acc) rest))
(else
(values #f input))))
(else (values (reverse acc) input))))
(let-values (((vs rest) (loop times-to-repeat '() input0)))
(if vs
(ks vs rest)
(kf)))))
((_ #f val Type option ...)
(t:listof #f val Type option ...))))
;; Bit-syntax type for repeats of a value until no more input available.
;; Example: List of 32-bit unsigned words:
;; (bit-string-case input ([ (vals :: (t:listof bits 32)) ] vals))
;; (bit-string (vals :: (t:listof bits 32)))
;; (bit-string-case input ([ (vals :: (t:listof Integer bits 32)) ] vals))
;; (bit-string (vals :: (t:listof Integer bits 32)))
(define-syntax t:listof
(syntax-rules ()
((_ #t input ks kf option ...)
(let loop ((acc '())
(input input))
(bit-string-case input
([ (v :: option ...) (rest :: binary) ]
(loop (cons v acc) rest))
([]
(ks (reverse acc) #""))
(else
(kf)))))
((_ #f vs option ...)
(let loop ((vs vs))
((_ #t input0 ks kf Type option ...)
;; The loop is unrolled once here to let Typed Racket propagate
;; the type of v0 into the type of acc in the loop. When not
;; unrolled, it gives acc type (Listof Any).
;; TODO: come up with some other way of doing this that avoids the duplication.
(bit-string-case input0
([ (v0 :: option ...) (input1 :: binary) ]
(let loop ((acc (list v0))
(input input1))
(bit-string-case input
([ (v :: option ...) (rest :: binary) ]
(loop (cons v acc) rest))
([]
(ks (reverse acc) #""))
(else
(kf)))))
([]
(ks '() #""))
(else
(kf))))
((_ #f vs Type option ...)
(let: loop : BitString ((vs : (Listof Type) vs))
(cond
((pair? vs) (bit-string ((car vs) :: option ...)
((loop (cdr vs)) :: binary)))
@ -142,7 +186,7 @@
;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
;; </rfc1035>
;; Bytes -> DNSMessage
(: packet->dns-message : BitString -> DNSMessage)
;; Parse an encoded DNS message packet into the corresponding Racket
;; structure. Raises an exception on failure.
(define (packet->dns-message packet)
@ -163,16 +207,16 @@
(ancount :: bits 16)
(nscount :: bits 16)
(arcount :: bits 16)
(q-section :: (t:ntimes qdcount (t:question packet)))
(a-section :: (t:ntimes ancount (t:rr packet)))
(auth-section :: (t:ntimes nscount (t:rr packet)))
(additional-section :: (t:ntimes arcount (t:rr packet))) ]
(q-section :: (t:ntimes Question qdcount (t:question packet)))
(a-section :: (t:ntimes RR ancount (t:rr packet)))
(auth-section :: (t:ntimes RR nscount (t:rr packet)))
(additional-section :: (t:ntimes RR arcount (t:rr packet))) ]
(dns-message id qr (value->query-opcode opcode)
aa tc rd ra
(value->query-response-code rcode)
q-section a-section auth-section additional-section))))
;; DNSMessage -> Bytes
(: dns-message->packet : DNSMessage -> Bytes)
;; Render a Racket structured DNS message using the DNS binary encoding.
(define (dns-message->packet m)
(bit-string->bytes
@ -191,10 +235,10 @@
((length (dns-message-answers m)) :: bits 16)
((length (dns-message-authorities m)) :: bits 16)
((length (dns-message-additional m)) :: bits 16)
((dns-message-questions m) :: (t:ntimes (t:question)))
((dns-message-answers m) :: (t:ntimes (t:rr)))
((dns-message-authorities m) :: (t:ntimes (t:rr)))
((dns-message-additional m) :: (t:ntimes (t:rr))))))
((dns-message-questions m) :: (t:ntimes Question (t:question)))
((dns-message-answers m) :: (t:ntimes RR (t:rr)))
((dns-message-authorities m) :: (t:ntimes RR (t:rr)))
((dns-message-additional m) :: (t:ntimes RR (t:rr))))))
;; Bit-syntax type for a single bit, represented in Racket as one of
;; two possible symbolic values.
@ -228,13 +272,14 @@
((_ #f val)
(encode-domain-name val))))
;; DomainName -> Bitstring
(: encode-domain-name : DomainName -> BitString)
(define (encode-domain-name name)
(define labels (domain-labels name))
(bit-string (labels :: (t:listof (t:pascal-string "Label" 64)))
(bit-string (labels :: (t:listof Bytes (t:pascal-string "Label" 64)))
(0 :: integer bytes 1))) ;; end of list of labels!
;; Bytes Bytes ListOf<Natural> -> ListOf<Bytes>
(: parse-domain-name :
BitString BitString (Listof Natural) -> (Values (Listof Bytes) BitString))
;; PRECONDITION: input never empty
;; INVARIANT: pointers-followed contains every "jump target" we have
;; jumped to so far during decoding of this domain-name, in order to
@ -273,13 +318,14 @@
([ len (body :: binary bytes len) (rest :: binary) ]
(ks (bit-string->bytes body) rest))
(else (kf))))
((_ #f s)
(t:pascal-string #f s "Character-string" 256))
((_ #f s string-kind length-limit)
(let ((len (bytes-length s)))
(when (>= len length-limit)
(error 't:pascal-string "~s too long: ~v" string-kind s))
(bit-string len (s :: binary))))))
((_ #f val)
(t:pascal-string #f val "Character-string" 256))
((_ #f val string-kind length-limit)
(let: ([s : Bytes val])
(let ((len (bytes-length s)))
(when (>= len length-limit)
(error 't:pascal-string "~s too long: ~v" string-kind s))
(bit-string len (s :: binary)))))))
;; <rfc1035>
;; The question section is used to carry the "question" in most queries,
@ -314,10 +360,11 @@
(value->qclass qclass)
#f)
tail))))
((_ #f q)
(bit-string ((question-name q) :: (t:domain-name))
((qtype->value (question-type q)) :: bits 16)
((qclass->value (question-class q)) :: bits 16)))))
((_ #f val)
(let: ([q : Question val])
(bit-string ((question-name q) :: (t:domain-name))
((qtype->value (question-type q)) :: bits 16)
((qclass->value (question-class q)) :: bits 16))))))
;; <rfc1035>
;; All RRs have the same top level format shown below:
@ -348,43 +395,35 @@
;; packet because the RR may contain nested domain-names.
(define-syntax t:rr
(syntax-rules ()
((_ #t input ks kf whole-packet)
(decode-rr whole-packet input ks kf))
((_ #f rr)
(encode-rr rr))))
((_ #t input ks kf whole-packet0)
(let ((whole-packet whole-packet0))
(bit-string-case input
([ (name :: (t:domain-name whole-packet))
(type-number :: bits 16)
(class :: bits 16)
(ttl :: bits 32)
(rdlength :: bits 16)
(rdata :: binary bytes rdlength)
(tail :: binary) ]
(let ((type (value->type type-number)))
(ks (rr name
type
(value->class class)
ttl
(decode-rdata whole-packet type rdata))
tail)))
(else (kf)))))
((_ #f val)
(let: ([rr : RR val])
(let ((encoded-rdata (encode-rdata (rr-type rr) (rr-rdata rr))))
(bit-string ((rr-name rr) :: (t:domain-name))
((type->value (rr-type rr)) :: bits 16)
((class->value (rr-class rr)) :: bits 16)
((rr-ttl rr) :: bits 32)
((quotient (bit-string-length encoded-rdata) 8) :: bits 16)
(encoded-rdata :: binary)))))))
;; Bytes Bytes (RR Bytes -> A) ( -> A) -> A
;; Helper for t:rr.
(define (decode-rr whole-packet input ks kf)
(bit-string-case input
([ (name :: (t:domain-name whole-packet))
(type-number :: bits 16)
(class :: bits 16)
(ttl :: bits 32)
(rdlength :: bits 16)
(rdata :: binary bytes rdlength)
(tail :: binary) ]
(let ((type (value->type type-number)))
(ks (rr name
type
(value->class class)
ttl
(decode-rdata whole-packet type rdata))
tail)))
(else (kf))))
;; RR -> Bitstring
;; Helper for t:rr.
(define (encode-rr rr)
(let ((encoded-rdata (encode-rdata (rr-type rr) (rr-rdata rr))))
(bit-string ((rr-name rr) :: (t:domain-name))
((type->value (rr-type rr)) :: bits 16)
((class->value (rr-class rr)) :: bits 16)
((rr-ttl rr) :: bits 32)
((/ (bit-string-length encoded-rdata) 8) :: bits 16)
(encoded-rdata :: binary))))
;; Bytes RRType Bytes -> RData
(: decode-rdata : BitString RRType BitString -> RData)
;; Decode RData according to the RRType. Takes the whole packet for
;; the same reason as t:rr does.
(define (decode-rdata whole-packet type rdata)
@ -413,7 +452,7 @@
(minimum :: bits 32) ]
(soa mname rname serial refresh retry expire minimum))))
((txt) (bit-string-case rdata
([ (strs :: (t:listof (t:pascal-string))) ]
([ (strs :: (t:listof Bytes (t:pascal-string))) ]
strs)))
((a) (bit-string-case rdata
([ a b c d ]
@ -423,7 +462,7 @@
(list->vector (bytes->list (bit-string->bytes ipv6-addr))))))
((wks) (bit-string-case rdata
([ a b c d protocol (bitmap :: binary) ]
(wks (vector a b c d) protocol bitmap))))
(wks (vector a b c d) protocol (bit-string->bytes bitmap)))))
((srv) (bit-string-case rdata
([ (priority :: bits 16)
(weight :: bits 16)
@ -432,7 +471,7 @@
(srv priority weight port target))))
(else (bit-string->bytes rdata))))
;; RRType RData -> Bitstring
(: encode-rdata : RRType RData -> BitString)
;; Encode RData according to the RRType.
(define (encode-rdata type rdata)
(case type
@ -451,7 +490,7 @@
((soa-retry rdata) :: bits 32)
((soa-expire rdata) :: bits 32)
((soa-minimum rdata) :: bits 32)))
((txt) (bit-string (rdata :: (t:listof (t:pascal-string)))))
((txt) (bit-string (rdata :: (t:listof Bytes (t:pascal-string)))))
((a) (match rdata ((vector a b c d) (bit-string a b c d))))
((aaaa) (bit-string ((list->bytes (vector->list rdata)) :: binary bits 128)))
((wks) (match (wks-address rdata)
@ -464,4 +503,5 @@
(else rdata)))
;; UInt32
(: max-ttl : Nonnegative-Integer)
(define max-ttl #xffffffff)

14
mapping.rkt
View File

@ -1,4 +1,4 @@
#lang racket/base
#lang typed/racket/base
;; Macros for defining weak and extensible mappings between sets of values
(provide define-mapping)
@ -13,13 +13,13 @@
((_ fn bn fd bd (lhs rhs) ...)
(begin
(define (fn l)
(case l
((lhs) 'rhs) ...
(else (fd l))))
(cond
((eqv? l 'lhs) 'rhs) ...
(else (fd l))))
(define (bn r)
(case r
((rhs) 'lhs) ...
(else (bd r))))))))
(cond
((eqv? r 'rhs) 'lhs) ...
(else (bd r))))))))
;; Symbol -> raised exn:fail:contract
;; Used by default to complain when no specific mapping is found.

87
tk-dns.rkt
View File

@ -1,11 +1,11 @@
#lang racket/base
#lang typed/racket/base
;; DNS drivers using racket-typed-matrix.
(require racket/set)
(require racket/match)
(require "codec.rkt")
(require racket-typed-matrix/sugar-untyped)
(require racket-typed-matrix/drivers/udp-untyped)
(require racket-typed-matrix/sugar-typed)
(require racket-typed-matrix/drivers/udp)
(provide (struct-out bad-dns-packet)
(struct-out dns-request)
@ -14,25 +14,27 @@
dns-write-driver
dns-spy)
(struct bad-dns-packet (detail source sink reason) #:prefab)
(struct dns-request (message source sink) #:prefab)
(struct dns-reply (message source sink) #:prefab)
(struct: bad-dns-packet
([detail : Any] [source : UdpAddress] [sink : UdpAddress] [reason : Symbol]) #:prefab)
(struct: dns-request ([message : DNSMessage] [source : UdpAddress] [sink : UdpAddress]) #:prefab)
(struct: dns-reply ([message : DNSMessage] [source : UdpAddress] [sink : UdpAddress]) #:prefab)
(define (dns-read-driver s)
(transition 'no-state
(transition: (void) : Void
(at-meta-level
(endpoint #:subscriber (udp-packet-pattern (wild) s (wild))
[(udp-packet source (== s) #"")
(begin (log-info "Debug dump packet received")
(send-message `(debug-dump)))]
[(udp-packet source (== s) body)
(send-message
(with-handlers ((exn:fail? (lambda (e)
(bad-dns-packet body source s 'unparseable))))
(define message (packet->dns-message body))
(case (dns-message-direction message)
((request) (dns-request message source s))
((response) (dns-reply message source s)))))]))))
(endpoint: : Void
#:subscriber (udp-packet-pattern (wild) s (wild))
[(udp-packet source (== s) #"")
(begin (log-info "Debug dump packet received")
(send-message `(debug-dump)))]
[(udp-packet source (== s) body)
(send-message
(with-handlers ((exn:fail? (lambda (e)
(bad-dns-packet body source s 'unparseable))))
(define message (packet->dns-message body))
(case (dns-message-direction message)
((request) (dns-request message source s))
((response) (dns-reply message source s)))))]))))
(define (dns-write-driver s)
(define (translate message sink)
@ -40,26 +42,31 @@
(send-message (bad-dns-packet message s sink 'unencodable)))))
(at-meta-level
(send-message (udp-packet s sink (dns-message->packet message))))))
(transition 'no-state
(endpoint #:subscriber (dns-request (wild) s (wild))
[(dns-request message (== s) sink) (translate message sink)])
(endpoint #:subscriber (dns-reply (wild) s (wild))
[(dns-reply message (== s) sink) (translate message sink)])))
(transition: (void) : Void
(endpoint: : Void
#:subscriber (dns-request (wild) s (wild))
[(dns-request message (== s) sink) (translate message sink)])
(endpoint: : Void
#:subscriber (dns-reply (wild) s (wild))
[(dns-reply message (== s) sink) (translate message sink)])))
(: dns-spy : (All (ParentState) -> (Action ParentState)))
(define (dns-spy)
(spawn #:child
(transition 'none
(endpoint #:subscriber (wild) #:observer
[(dns-request message source sink)
(begin (log-info (format "DNS: ~v asks ~v ~v~n : ~v"
source sink (dns-message-id message)
(dns-message-questions message)))
(void))]
[(dns-reply message source sink)
(begin (log-info (format "DNS: ~v answers ~v~n : ~v"
source sink
message))
(void))]
[x
(begin (log-info (format "DNS: ~v" x))
(void))]))))
(spawn: #:parent : ParentState
#:child : Void
(transition: (void) : Void
(endpoint: : Void
#:subscriber (wild) #:observer
[(dns-request message source sink)
(begin (log-info (format "DNS: ~v asks ~v ~v~n : ~v"
source sink (dns-message-id message)
(dns-message-questions message)))
(void))]
[(dns-reply message source sink)
(begin (log-info (format "DNS: ~v answers ~v~n : ~v"
source sink
message))
(void))]
[x
(begin (log-info (format "DNS: ~v" x))
(void))]))))