Split resolver algorithm from network-query implementation
This commit is contained in:
Tony Garnock-Jones
parent
171aea110c
commit
ba92bbb1ff
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@ -0,0 +1,3 @@
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#lang racket/signature
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network-query/addresses ;; Question CompiledZone NS-RR ListOf<IPv4> -> Maybe<CompiledZone>
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@ -0,0 +1,137 @@
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#lang racket/unit
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(require racket/pretty)
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(require racket/match)
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(require "api.rkt")
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(require "codec.rkt")
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(require "zonedb.rkt")
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(require "udp-operations-sig.rkt")
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(require "network-query-sig.rkt")
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(import udp-operations^)
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(export network-query^)
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(define first-timeout 3) ;; seconds
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;; seconds -> Maybe<seconds>
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(define (next-timeout timeout)
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(case timeout
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((3) 11)
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((11) 45)
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((45) #f)))
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;; IPv4 -> String
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(define (ip->host-name ip-address)
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(match-define (vector a b c d) ip-address)
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(format "~a.~a.~a.~a" a b c d))
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(define (make-network-query-packet q)
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(dns-message->packet
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(dns-message (random 65536)
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'request
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'query
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'non-authoritative
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'not-truncated
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'no-recursion-desired
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'no-recursion-available
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'no-error
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(list q)
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'()
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'()
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'())))
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;; incorporate-dns-reply :
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;; DNSMessage CompiledZone RR<NS> ( -> Maybe<CompiledZone> )
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;; -> Maybe<CompiledZone>
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;;
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;; Incorporates RRs from the answer, authorities, and additional
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;; sections of the passed-in `message` to the passed-in `zone`,
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;; returning the augmented zone. RRs are only incorporated if their
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;; `rr-name` falls in the bailiwick of the given `ns-rr`. All of this
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;; only happens if the passed-in message's `dns-message-response-code`
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;; is `'no-error`: if it's `'name-error`, then `#f` is returned, and
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;; if it's any other code,the `keep-trying` thunk is invoked. (If the
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;; caller is `network-query/addresses`, then `keep-trying` will try
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;; other servers from the list of IPs available.)
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(define (incorporate-dns-reply message zone ns-rr keep-trying)
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(case (dns-message-response-code message)
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[(no-error)
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(foldl (lambda (claim-rr zone)
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(if (in-bailiwick? (rr-name claim-rr) ns-rr)
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(incorporate-rr claim-rr zone)
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zone))
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zone
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(append (dns-message-answers message)
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(dns-message-authorities message)
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(dns-message-additional message)))]
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[(name-error) #f]
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[else (keep-trying)]))
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;; network-query/addresses :
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;; Question CompiledZone RR<NS> ListOf<IPv4> -> Maybe<CompiledZone>
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;;
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;; Repeatedly uses `network-query/addresses/timeout` to try asking the
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;; whole of `server-ips` the question `q`, starting with a timeout of
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;; `first-timeout` seconds and increasing each time
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;; `network-query/addresses/timeout` returns `'no-answer` up to a
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;; give-up timeout limit.
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(define (network-query/addresses q zone ns-rr server-ips)
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(let ((s (udp-open-socket #f #f)))
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(let try-with-timeout ((timeout first-timeout))
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(match (network-query/addresses/timeout s q zone ns-rr server-ips timeout)
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['no-answer
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(define new-timeout (next-timeout timeout))
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(if new-timeout
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(try-with-timeout new-timeout)
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zone)]
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[result result]))))
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;; network-query/addresses/timeout :
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;; UdpSocket Question CompiledZone RR<NS> ListOf<IPv4> Seconds
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;; -> (or Maybe<CompiledZone> 'no-answer)
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;;
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;; Sends the question to each of the servers whose addresses are given
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;; in `server-ips` using `network-query/address/timeout`, one at a
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;; time, in order, trying the next in the list only if `'no-answer`
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;; results from the most recent communication attempt. If and when the
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;; list is exhausted, `'no-answer` is returned.
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(define (network-query/addresses/timeout s q zone ns-rr server-ips timeout)
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;; TODO: randomize ordering of servers in list.
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(let search ((remaining-ips server-ips))
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(if (null? remaining-ips)
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'no-answer
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(match (network-query/address/timeout s q zone ns-rr (car remaining-ips) timeout)
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['no-answer (search (cdr remaining-ips))]
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[result result]))))
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;; network-query/address/timeout :
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;; UdpSocket Question CompiledZone RR<NS> IPv4 Seconds
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;; -> (or Maybe<CompiledZone> 'no-answer)
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;;
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;; Sends the question to the server address `server-ip` given. Waits
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;; `timeout` seconds for an answer: if one arrives, it is incorporated
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;; into the passed-in `zone` (using `incorporate-dns-reply`), and the
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;; result is returned to the caller. If the timeout expires before a
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;; reply is received, or some error result is received from the
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;; server, `'no-answer` is returned to the caller.
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(define (network-query/address/timeout s q zone ns-rr server-ip timeout)
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(define server-host-name (ip->host-name server-ip))
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(define server-port 53)
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(write `(querying ,server-host-name ,server-port with timeout ,timeout)) (newline)
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(udp-send-to s server-host-name server-port (make-network-query-packet q))
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(define buffer (make-bytes 512)) ;; maximum DNS reply length
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(define result (udp-receive/timeout s buffer timeout))
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;; TODO: correlate query-ID
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;; TODO: maybe receive only specifically from the queried IP address?
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(if result
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(let* ((reply-length (car result))
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(packet (subbytes buffer 0 reply-length))
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(reply-message (packet->dns-message packet)))
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(pretty-print `(response ,result ,reply-message))
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(incorporate-dns-reply reply-message
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zone
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ns-rr
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(lambda () 'no-answer)))
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'no-answer))
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@ -1,4 +1,3 @@
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#lang racket/signature
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network-query ;; Question CompiledZone NS-RR -> CompiledZone
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resolve-from-zone ;; Question CompiledZone SOA-RR Boolean Set<NS-RR> -> QuestionResult
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@ -10,9 +10,11 @@
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(require "codec.rkt")
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(require "zonedb.rkt")
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(require "ground-udp-operations-unit.rkt")
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(require "network-query-unit.rkt")
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(require "resolver-unit.rkt")
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(define-values/invoke-unit/infer (link resolver@ ground-udp-operations@))
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(define-values/invoke-unit/infer
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(link resolver@ network-query@ ground-udp-operations@))
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;; (require racket/trace)
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;; (trace ;;resolve-from-zone
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@ -7,10 +7,10 @@
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(require "api.rkt")
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(require "codec.rkt")
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(require "zonedb.rkt")
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(require "udp-operations-sig.rkt")
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(require "network-query-sig.rkt")
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(require "resolver-sig.rkt")
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(import udp-operations^)
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(import network-query^)
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(export resolver^)
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(define (answer-available? q zone)
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@ -111,132 +111,6 @@
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(define (random-element a-nonempty-list)
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(car a-nonempty-list))
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(define first-timeout 3) ;; seconds
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;; seconds -> Maybe<seconds>
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(define (next-timeout timeout)
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(case timeout
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((3) 11)
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((11) 45)
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((45) #f)))
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;; IPv4 -> String
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(define (ip->host-name ip-address)
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(match-define (vector a b c d) ip-address)
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(format "~a.~a.~a.~a" a b c d))
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(define (negative-network-query-result zone)
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zone)
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(define (make-network-query-packet q)
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(dns-message->packet
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(dns-message (random 65536)
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'request
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'query
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'non-authoritative
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'not-truncated
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'no-recursion-desired
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'no-recursion-available
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'no-error
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(list q)
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'()
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'()
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'())))
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;; incorporate-dns-reply :
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;; DNSMessage CompiledZone RR<NS> ( -> Maybe<CompiledZone> )
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;; -> Maybe<CompiledZone>
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;;
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;; Incorporates RRs from the answer, authorities, and additional
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;; sections of the passed-in `message` to the passed-in `zone`,
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;; returning the augmented zone. RRs are only incorporated if their
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;; `rr-name` falls in the bailiwick of the given `ns-rr`. All of this
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;; only happens if the passed-in message's `dns-message-response-code`
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;; is `'no-error`: if it's `'name-error`, then `#f` is returned, and
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;; if it's any other code,the `keep-trying` thunk is invoked. (If the
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;; caller is `network-query/addresses`, then `keep-trying` will try
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;; other servers from the list of IPs available.)
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(define (incorporate-dns-reply message zone ns-rr keep-trying)
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(case (dns-message-response-code message)
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[(no-error)
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(foldl (lambda (claim-rr zone)
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(if (in-bailiwick? (rr-name claim-rr) ns-rr)
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(incorporate-rr claim-rr zone)
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zone))
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zone
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(append (dns-message-answers message)
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(dns-message-authorities message)
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(dns-message-additional message)))]
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[(name-error) #f]
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[else (keep-trying)]))
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;; network-query/addresses :
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;; Question CompiledZone RR<NS> ListOf<IPv4> -> Maybe<CompiledZone>
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;;
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;; Repeatedly uses `network-query/addresses/timeout` to try asking the
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;; whole of `server-ips` the question `q`, starting with a timeout of
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;; `first-timeout` seconds and increasing each time
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;; `network-query/addresses/timeout` returns `'no-answer` up to a
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;; give-up timeout limit.
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(define (network-query/addresses q zone ns-rr server-ips)
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(let ((s (udp-open-socket #f #f)))
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(let try-with-timeout ((timeout first-timeout))
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(match (network-query/addresses/timeout s q zone ns-rr server-ips timeout)
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['no-answer
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(define new-timeout (next-timeout timeout))
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(if new-timeout
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(try-with-timeout new-timeout)
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(negative-network-query-result zone))]
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[result result]))))
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;; network-query/addresses/timeout :
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;; UdpSocket Question CompiledZone RR<NS> ListOf<IPv4> Seconds
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;; -> (or Maybe<CompiledZone> 'no-answer)
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;;
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;; Sends the question to each of the servers whose addresses are given
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;; in `server-ips` using `network-query/address/timeout`, one at a
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;; time, in order, trying the next in the list only if `'no-answer`
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;; results from the most recent communication attempt. If and when the
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;; list is exhausted, `'no-answer` is returned.
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(define (network-query/addresses/timeout s q zone ns-rr server-ips timeout)
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;; TODO: randomize ordering of servers in list.
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(let search ((remaining-ips server-ips))
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(if (null? remaining-ips)
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'no-answer
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(match (network-query/address/timeout s q zone ns-rr (car remaining-ips) timeout)
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['no-answer (search (cdr remaining-ips))]
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[result result]))))
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;; network-query/address/timeout :
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;; UdpSocket Question CompiledZone RR<NS> IPv4 Seconds
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;; -> (or Maybe<CompiledZone> 'no-answer)
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;;
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;; Sends the question to the server address `server-ip` given. Waits
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;; `timeout` seconds for an answer: if one arrives, it is incorporated
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;; into the passed-in `zone` (using `incorporate-dns-reply`), and the
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;; result is returned to the caller. If the timeout expires before a
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;; reply is received, or some error result is received from the
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;; server, `'no-answer` is returned to the caller.
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(define (network-query/address/timeout s q zone ns-rr server-ip timeout)
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(define server-host-name (ip->host-name server-ip))
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(define server-port 53)
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(write `(querying ,server-host-name ,server-port with timeout ,timeout)) (newline)
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(udp-send-to s server-host-name server-port (make-network-query-packet q))
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(define buffer (make-bytes 512)) ;; maximum DNS reply length
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(define result (udp-receive/timeout s buffer timeout))
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;; TODO: correlate query-ID
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;; TODO: maybe receive only specifically from the queried IP address?
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(if result
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(let* ((reply-length (car result))
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(packet (subbytes buffer 0 reply-length))
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(reply-message (packet->dns-message packet)))
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(pretty-print `(response ,result ,reply-message))
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(incorporate-dns-reply reply-message
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zone
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ns-rr
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(lambda () 'no-answer)))
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'no-answer))
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(define (network-query q zone ns-rr)
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(define ns-name (rr-rdata ns-rr))
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;; ^ the rr-name is the subzone origin; the rr-rdata is the
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@ -246,11 +120,11 @@
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#f
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#t
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(set))
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[#f (negative-network-query-result zone)] ;; Can't find the address of the nameserver!
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[#f zone] ;; Can't find the address of the nameserver!
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[(question-result _ enhanced-zone answers _ _)
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(define address-rrs (filter-by-type answers 'a))
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(if (set-empty? address-rrs)
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(negative-network-query-result zone) ;; Again, no addresses for the nameserver!
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zone ;; Again, no addresses for the nameserver!
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(network-query/addresses q
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enhanced-zone
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ns-rr
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@ -11,11 +11,13 @@
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(require "codec.rkt")
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(require "zonedb.rkt")
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(require "ground-udp-operations-unit.rkt")
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(require "network-query-unit.rkt")
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(require "resolver-unit.rkt")
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(require "dump-bytes.rkt")
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(require "simple-udp-service.rkt")
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(define-values/invoke-unit/infer (link resolver@ ground-udp-operations@))
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(define-values/invoke-unit/infer
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(link resolver@ network-query@ ground-udp-operations@))
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;; Instantiated with a SOA record for the zone it is serving as well
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;; as a zone's worth of DNS data which is used to answer queries
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