+ Complete parsing for /etc/resolv.conf
+ use search or domain field from resolv.conf to determine FQDNs
This commit is contained in:
mainzelm
parent
29fc6b1b9d
commit
7e6da5347e
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@ -1011,28 +1011,157 @@
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nss-with-no-reply
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(lset-difference equal? other-nameservers tried)))))))))))
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;; parses the resolv.conf file and returns a list of found nameserver
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(define (dns-find-nameserver-list)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Parsing of /etc/resolv.conf
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(define (parse-nameserver rest-of-line)
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(let ((match (regexp-search
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(rx (: (submatch (** 1 3 digit) "."
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(** 1 3 digit) "."
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(** 1 3 digit) "."
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(** 1 3 digit))
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(* white))); don't complain about tailing white space
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rest-of-line)))
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(if match
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(cons 'nameserver (match:substring match 1))
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(signal 'resolv.conf-parse-error))))
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; could be more restrictive...
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(define domain-name-regexp (rx (+ (| alphanum #\. #\-))))
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(define (parse-domain rest-of-line)
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(let ((match (regexp-search
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(rx (: (submatch ,domain-name-regexp)
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(* white))); don't complain about tailing white space
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rest-of-line)))
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(if match
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(cons 'domain (match:substring match 1))
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(signal 'resolv.conf-parse-error))))
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(define (parse-search rest-of-line)
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(let ((domains (regexp-fold-right domain-name-regexp
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(lambda (match junk accu)
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(cons (match:substring match 0) accu))
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'()
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rest-of-line)))
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(if (null? domains)
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(signal 'resolv.conf-parse-error)
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(cons 'search domains))))
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(define (parse-sortlist rest-of-line)
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(let ((netmask-pairs (regexp-fold-right (rx (+ (| digit #\. #\/)))
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(lambda (match junk accu)
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(cons (match:substring match 0) accu))
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'()
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rest-of-line)))
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(if (null? netmask-pairs)
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(signal 'resolv.conf-parse-error)
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(cons 'sortlist netmask-pairs))))
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(define (parse-options rest-of-line)
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(regexp-fold-right
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(rx (| "debug" "no_tld_query" (: "ndots:" (submatch digit))))
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(lambda (match junk accu)
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(let ((str (match:substring match 0)))
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(cond ((string=? str "debug")
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(cons 'debug accu))
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((string=? str "no_tld_query")
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(cons 'no_tld_query accu))
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(else (cons (cons 'ndots
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(string->number (match:substring match 1))) accu)))))
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'()
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rest-of-line))
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;; TODO: cache result
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(define (parse-resolv.conf)
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(define (adjust-result rev-result have-search-or-domain? nameservers)
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(cond ((null? rev-result)
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(if (null? nameservers)
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'()
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(list (cons 'nameserver nameservers))))
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((eq? (caar rev-result) 'domain)
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(if have-search-or-domain?
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(adjust-result (cdr rev-result) have-search-or-domain? nameservers)
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(cons (car rev-result)
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(adjust-result (cdr rev-result)
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#t
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nameservers))))
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((eq? (caar rev-result) 'search)
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(if have-search-or-domain?
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(adjust-result (cdr rev-result) have-search-or-domain? nameservers)
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(cons (car rev-result)
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(adjust-result (cdr rev-result)
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#t
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nameservers))))
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((eq? (caar rev-result) 'nameserver)
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(adjust-result (cdr rev-result)
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have-search-or-domain?
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(cons (cdar rev-result)
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nameservers)))
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(else (cons (car rev-result)
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(adjust-result (cdr rev-result)
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have-search-or-domain?
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nameservers)))))
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(with-input-from-file "/etc/resolv.conf"
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(lambda ()
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(let loop ((ns '()))
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(let loop ((rev-result '()))
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(let ((l (read-line)))
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(cond
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((eof-object? l)
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(if (null? ns)
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(dns-error 'no-nameservers)
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ns))
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(adjust-result rev-result #f '()))
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((regexp-search
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(rx (: "nameserver" (+ (| " " "\t")
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(submatch (** 1 3 digit)
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(= 3 (: "." (** 1 3 digit)))))))
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(rx (: "nameserver" (+ (| " " "\t")
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(submatch (* any))
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eos)))
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l)
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=> (lambda (match)
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(loop (append ns (list (ip-string->address32 (match:substring match 1)))))))
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(else
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(loop ns))))))))
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(loop (cons (parse-nameserver (match:substring match 1))
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rev-result))))
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((regexp-search
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(rx (: "domain" (+ (| " " "\t")
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(submatch (* any))
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eos)))
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l)
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=> (lambda (match)
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(loop (cons (parse-domain (match:substring match 1))
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rev-result))))
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((regexp-search
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(rx (: "search" (+ (| " " "\t")
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(submatch (* any))
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eos)))
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l)
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=> (lambda (match)
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(loop (cons (parse-search (match:substring match 1))
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rev-result))))
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((regexp-search
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(rx (: "sortlist" (+ (| " " "\t")
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(submatch (* any))
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eos)))
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l)
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=> (lambda (match)
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(parse-sortlist (match:substring match 1))))
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((regexp-search
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(rx (: "options" (+ (| " " "\t")
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(submatch (* any))
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eos)))
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l)
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=> (lambda (match)
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(parse-options (match:substring match 1))))
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(else (signal 'resolv.conf-parse-error))))))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Figure out the default name servers
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(define (dns-find-nameserver-list)
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(cond ((assoc 'nameserver (parse-resolv.conf))
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=> (lambda (nameserver.list)
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(cdr nameserver.list)))
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(else '())))
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;; returns the first found nameserver
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(define (dns-find-nameserver)
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(let ((ns (dns-find-nameserver-list)))
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@ -1046,12 +1175,12 @@
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;; (dns-lookup-name nameserver) is called.
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(define (check-args args)
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(if (null? args)
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(dns-find-nameserver-list)
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(map ip-string->address32 (dns-find-nameserver-list))
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(map (lambda (nameserver)
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(cond
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((address32? nameserver) nameserver)
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((ip-string? nameserver) (ip-string->address32 nameserver))
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(else (dns-lookup-name nameserver (dns-find-nameserver-list)))))
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(else (map (dns-lookup-name nameserver (dns-find-nameserver-list))))))
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(car args))))
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;; dns-lookup with more options than dns-lookup-*
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@ -1311,19 +1440,44 @@
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fqdn))))
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(dns-lookup-ip ip32)))
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;;; TODO THIS USES gethostbyname
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(define (is-fqdn? name)
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(regexp-search? (rx #\.) name))
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(define (maybe-dns-lookup-name name)
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(call-with-current-continuation
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(lambda (k)
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(with-handler (lambda (cond more)
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(if (dns-error? cond)
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(k #f)
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(more)))
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(lambda ()
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(dns-lookup-name name))))))
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(define (domains-for-search)
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(let ((resolv.conf (parse-resolv.conf)))
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(cond ((assoc 'domain resolv.conf)
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=> (lambda (pair)
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(list (cdr pair))))
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((assoc 'search resolv.conf)
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=> (lambda (pair)
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(cdr pair)))
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(else '()))))
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(define (host-fqdn name-or-socket-address)
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(if (socket-address? name-or-socket-address)
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(socket-address->fqdn name-or-socket-address #f)
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;; TODO: try looking up with domain from "search" appended
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(internet-address->fqdn
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(car
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(host-info:addresses
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(host-info name-or-socket-address)))
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#f)))
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(let ((name name-or-socket-address))
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(if (is-fqdn? name)
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name
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(let lp ((domains (domains-for-search)))
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(if (null? domains)
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#f
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(cond ((maybe-dns-lookup-name (string-append name "." (car domains)))
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=> (lambda (ip)
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(dns-lookup-ip ip)))
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(else (lp (cdr domains))))))))))
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;;; TODO THIS USES gethostbyname
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(define (system-fqdn)
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;; TODO: isn't this simply (host-fqdn (system-name))?
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(internet-address->fqdn (car (host-info:addresses (host-info (system-name))))
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#t))
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(host-fqdn (system-name)))
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