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261
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1 ;;; multicast.el --- lisp frontend for multicast connections in XEmacs
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2
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3 ;; Copyright (C) 1997-1998 Didier Verna.
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4
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5 ;; Author: Didier Verna <verna@inf.enst.fr>
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6 ;; Maintainer: Didier Verna <verna@inf.enst.fr>
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7 ;; Created: Thu Dec 4 16:37:39 1997
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8 ;; Last Revision: Mon Jan 19 19:10:50 1998
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9 ;; Current Version: 0.4
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10 ;; Keywords: dumped comm processes
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11
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12 ;; This file is part of XEmacs.
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13
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14 ;; XEmacs is free software; you can redistribute it and/or modify
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15 ;; it under the terms of the GNU General Public License as published by
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16 ;; the Free Software Foundation; either version 2 of the License, or
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17 ;; (at your option) any later version.
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18
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19 ;; XEmacs is distributed in the hope that it will be useful,
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20 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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21 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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22 ;; GNU General Public License for more details.
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23
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24 ;; You should have received a copy of the GNU General Public License
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25 ;; along with this program; if not, write to the Free Software
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26 ;; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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27
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28
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29 ;;; Commentary:
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30
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31 ;; This file just contains a lisp frontend to the internal function
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32 ;; open-multicast-group-internal written in C and belonging to process.c
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33 ;; Well, nothing much to say about it ... read the doc string.
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34
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35
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36 ;;; Change Log:
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37
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38 ;; Rev. of Mon Jan 19 19:04:44 1998 : packaging cleanup
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39 ;; Rev. of Thu Dec 11 13:54:26 1997 : updated the docstring
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40 ;; Rev. of Mon Dec 8 15:28:47 1997 : Improved the doc string
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41 ;; Rev. of Thu Dec 4 16:38:09 1997 : Initial Version.
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42
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43
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44 ;;; Code:
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45
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46 (defun open-multicast-group (name buffer address)
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47 "Open a multicast connection on the specified address.
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48 Returns a subprocess-object to represent the connection.
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49 Input and output work as for subprocesses; `delete-process' closes it.
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50 Args are NAME BUFFER ADDRESS.
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51 NAME is a name for the process. It is modified if necessary to make it unique.
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52 BUFFER is the buffer (or buffer-name) to associate with the process.
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53 Process output goes at the end of that buffer, unless you specify an output
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54 stream or filter function to handle the output.
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55 BUFFER may be also nil, meaning that this process is not associated with any
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56 buffer
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57 ADDRESS specifies a standard multicast address \"dest/port/ttl\":
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58 dest is an internet address between 224.0.0.0 and 239.255.255.255
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59 port is a communication port like in traditional unicast
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60 ttl is the time-to-live (15 for site, 63 for region and 127 for world).
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61
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62 WARNING: it is *strongly* recommended to avoid using groups beginning with
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63 224 or 239. Such groups are considered 'admin' groups, and may
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64 behave in a surprising way ..."
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65 (let (dest port ttl)
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66 ;; We check only the general form of the multicast address.
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67 ;; The rest will be handled by the internal function.
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68 (string-match "^\\([0-9\\.]+\\)/\\([0-9]+\\)/\\([0-9]+\\)$" address)
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69 (and (not (and (= (match-beginning 0) 0)
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70 (= (match-end 0) (length address))))
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71 (error "malformed multicast address: %s" address))
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72 (and (not (setq dest (match-string 1 address)))
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73 (error "invalid destination specification."))
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74 (and (= 0 (setq port (string-to-int (match-string 2 address))))
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75 (error "invalid port specification."))
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76 (and (= 0 (setq ttl (string-to-int (match-string 3 address))))
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77 (error "invalid ttl specification."))
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78 (open-multicast-group-internal name buffer dest port ttl)
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79 ))
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80
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81 ;;; multicast.el ends here
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