;;; pure-pr-ipaddr.el --- convert IP address <-> 32bit integer

;; Copyright (C) 2000 Project Pure.

;; Author: SHIMADA Mitsunobu <simm@pure.fan.gr.jp>
;; Keywords: PURE, process, TCP, network, IP adress

;; $Id: pure-pr-ipaddr.el,v 1.3 2001/07/09 16:12:51 simm Exp $

;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; PURE means "Primitive Universal Relay-chat Environment"
;; PR means "process"

;;; Code:

;; IP address translation (DCC format -> IP address string)
(defun pure-pr-ipaddr-decode (str)
  "Translate IP address, 32bit integer(DCC format) into \"aaa.bbb.ccc.ddd\" string."
  (if (stringp str)
      (let (delimiter num ip0 ip1 ip2 ip3)
	(if (< (length str) 9)
	    (setq num (string-to-number str)
		  ip0 (% num 256) num (/ num 256)
		  ip1 (% num 256) num (/ num 256)
		  ip2 (% num 256) ip3 (/ num 256))
	  (setq delimiter (- (length str) 8)
		num (string-to-number (substring str delimiter))
		ip0 (% num 256)
		num (+ (/ num 256) (* 390625     ; 390625 = 5 ** 8
				      (string-to-number (substring str 0 delimiter))))
		ip1 (% num 256) num (/ num 256)
		ip2 (% num 256) ip3 (/ num 256)))
	(format "%d.%d.%d.%d" ip3 ip2 ip1 ip0))))

;; IP address translation (IP address number -> DCC format)
(defun pure-pr-ipaddr-encode (str)
  "Translate IP address, aaa.bbb.ccc.ddd format into DCC-format 32bit integer."
  (let (res ip3 ip2 ip1 ip0 num)
    (save-match-data
      (when (string-match "^\\([0-9]+\\)\.\\([0-9]+\\)\.\\([0-9]+\\)\.\\([0-9]+\\)$" str)
	(setq ip3 (string-to-number (match-string 1 str))
	      ip2 (string-to-number (match-string 2 str))
	      ip1 (string-to-number (match-string 3 str))
	      ip0 (string-to-number (match-string 4 str))
	      num (+ ip1 (* 256 (+ ip2 (* 256 ip3)))))
	(if (< num 390625)
	    (setq res "")
	  (setq res (number-to-string (/ num 390625))
		num (% num 390625)))
	(format "%s%08d" res (+ ip0 (* 256 num)))))))

;; That's all
(provide 'pure-pr-ipaddr)

;;; pure-pr-ipaddr.el ends here