sunet/scheme/lib/ip.scm

81 lines
2.6 KiB
Scheme

;; converts an ip-string to an 32bit integer internet-address
(define (address32->ip-string ip)
(octet-ip->ip-string (address32->octet-ip ip)))
;; converts an ip-string to an 32bit integer internet-address
(define (ip-string->address32 ip)
(octet-ip->address32 (ip-string->octet-ip ip)))
;; checks if a string is a ip
(define (ip-string? s)
(define (byte-as-string? string)
(let ((number (string->number string)))
(and number
(>= number 0)
(< number 256))))
(cond
((regexp-search ip-string-regexp s)
=> (lambda (match)
(and (byte-as-string? (match:substring match 1))
(byte-as-string? (match:substring match 2))
(byte-as-string? (match:substring match 3))
(byte-as-string? (match:substring match 4)))))
(else #f)))
;; converts an ip-string to octets
(define (ip-string->octet-ip s)
(cond
((regexp-search ip-string-regexp s)
=> (lambda (match)
(list
(ascii->char (string->number (match:substring match 1)))
(ascii->char (string->number (match:substring match 2)))
(ascii->char (string->number (match:substring match 3)))
(ascii->char (string->number (match:substring match 4))))))
(else
(error "invalid ip-string" s))))
;; converts an octeted-ip to a 32bit integer internet-address
(define (octet-ip->address32 ip)
(+ (arithmetic-shift (char->ascii (list-ref ip 0)) 24)
(arithmetic-shift (char->ascii (list-ref ip 1)) 16)
(arithmetic-shift (char->ascii (list-ref ip 2)) 8)
(char->ascii (list-ref ip 3))))
;; converts a 32 bit integer internet-address to an octeted-ip
(define (address32->octet-ip ip)
(list (ascii->char (arithmetic-shift ip -24))
(ascii->char (modulo (arithmetic-shift ip -16) 256))
(ascii->char (modulo (arithmetic-shift ip -8) 256))
(ascii->char (modulo ip 256))))
;; converts an octeted-ip to an human readable ip-string
(define (octet-ip->ip-string s)
(format #f
"~a.~a.~a.~a"
(char->ascii (list-ref s 0))
(char->ascii (list-ref s 1))
(char->ascii (list-ref s 2))
(char->ascii (list-ref s 3))))
;; returns a in-addr.arpa name-string or #f (needed to resolve hostname by ip)
(define (ip-string->in-addr.arpa-string s)
(cond
((regexp-search ip-string-regexp s)
=> (lambda (match)
(string-append
(match:substring match 4) "."
(match:substring match 3) "."
(match:substring match 2) "."
(match:substring match 1) "."
"in-addr.arpa")))
(else #f)))
(define ip-string-regexp (rx (: bos
(submatch (** 1 3 digit)) "."
(submatch (** 1 3 digit)) "."
(submatch (** 1 3 digit)) "."
(submatch (** 1 3 digit))
eos)))