128 lines
4.0 KiB
Racket
128 lines
4.0 KiB
Racket
#lang racket/base
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;; Definitions for use in the API to the functionality of the library.
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(provide (struct-out question)
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(struct-out rr)
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(struct-out hinfo)
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(struct-out minfo)
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(struct-out mx)
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(struct-out soa)
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(struct-out wks)
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(struct-out srv)
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type->value value->type
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qtype->value value->qtype
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class->value value->class
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qclass->value value->qclass)
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(require "mapping.rkt")
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;; A QueryResponder is a (Question -> Either<ListOf<RR>, Failure>), a
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;; function from DNS query to DNS response or failure.
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;; A DomainName is a ListOf<Bytes>, representing a domain name. The
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;; head of the list is the leftmost label; for example, www.google.com
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;; is represented as '(#"www" #"google" #"com").
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;; A ShortString is a String with length 255 or shorter.
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;; An IPv4 is a (vector Byte Byte Byte Byte), representing an IPv4
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;; address. For example, 127.0.0.1 is represented as (vector 127 0 0
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;; 1).
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;; An IPv6 is a Vector of length 16 containing Bytes, representing an
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;; IPv6 address. For example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334
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;; is represented as (vector #x20 #x01 #x0d #xb8 #x85 #xa3 #x00 #x00
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;; #x00 #x00 #x8a #x2e #x03 #x70 #x73 #x34).
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;; A Question is a (question DomainName QueryType QueryClass),
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;; representing a DNS question: "What are the RRs for the given name,
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;; type and class?"
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(struct question (name type class) #:transparent)
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;; An RR is a (rr DomainName RRType RRClass Uint32 RData),
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;; representing a resource record.
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(struct rr (name type class ttl rdata) #:transparent)
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;; An RData is one of
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;; - an IPv4, an "A" record
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;; - an IPv6, an "AAAA" record
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;; - (hinfo ShortString ShortString), a host information record [O]
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;; - (minfo DomainName DomainName), a mailbox information record [O]
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;; - (mx Uint16 DomainName), a mail exchanger record
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;; - (soa DomainName DomainName Uint32 Uint32 Uint32 Uint32 Uint32), a
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;; start-of-authority record
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;; - (wks IPv4 Byte Bytes), a Well-Known Service [O]
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;; - (srv Uint16 Uint16 Uint16 DomainName), an "SRV" record
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;; - a Bytes, either a 'null type RR or any unrecognised RR type.
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;;
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;; In each case, the RData's variant MUST line up correctly with the
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;; type field of any RR containing it.
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;;
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;; Many of these variants are obsolete in today's DNS database (marked
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;; [O] above).
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(struct hinfo (cpu os) #:transparent)
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(struct minfo (rmailbx emailbx) #:transparent)
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(struct mx (preference exchange) #:transparent)
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(struct soa (mname rname serial refresh retry expire minimum) #:transparent)
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(struct wks (address protocol bitmap) #:transparent)
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(struct srv (priority weight port target) #:transparent)
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;; An RRType is a Symbol or a Number, one of the possibilities given
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;; in the following define-mapping. It represents the type of an
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;; RR. When used in an RR with an RData, the RRType and the RData
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;; variant must correspond.
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(define-mapping type->value value->type
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#:forward-default values
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#:backward-default values
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(a 1)
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(ns 2)
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(md 3)
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(mf 4)
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(cname 5)
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(soa 6)
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(mb 7)
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(mg 8)
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(mr 9)
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(null 10)
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(wks 11)
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(ptr 12)
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(hinfo 13)
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(minfo 14)
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(mx 15)
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(txt 16)
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(aaaa 28)
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(srv 33))
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;; A QueryType is a Symbol or Number (as given in the following
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;; define-mapping) or an RRType. It specifies the kinds of records
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;; being sought after in a DNS query.
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(define-mapping qtype->value value->qtype
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#:forward-default type->value
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#:backward-default value->type
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(axfr 252)
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(mailb 253)
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(maila 254)
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(* 255))
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;; An RRClass is a Symbol or a Number, one of the possibilities given
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;; in the following define-mapping. It represents the "class" of DNS
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;; records being discussed. All classes except 'in are obsolete in
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;; today's DNS databases.
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(define-mapping class->value value->class
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#:forward-default values
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#:backward-default values
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(in 1)
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(cs 2)
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(ch 3)
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(hs 4))
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;; A QueryClass is a Symbol or Number (as given in the following
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;; define-mapping) or an RRClass. It specifies the "class" of records
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;; being sought after in a DNS query.
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(define-mapping qclass->value value->qclass
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#:forward-default class->value
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#:backward-default value->class
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(* 255))
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