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1 | #! /bin/sh |
2 | ### | |
3 | ### TRIPE_SLIPIF dynamic allocation script for use with `userv-ipif' | |
4 | ### | |
5 | ### (c) 2012 Mark Wooding | |
6 | ### | |
7 | ||
8 | ###----- Licensing notice --------------------------------------------------- | |
9 | ### | |
10 | ### This file is part of Trivial IP Encryption (TrIPE). | |
11 | ### | |
12 | ### TrIPE is free software; you can redistribute it and/or modify | |
13 | ### it under the terms of the GNU General Public License as published by | |
14 | ### the Free Software Foundation; either version 2 of the License, or | |
15 | ### (at your option) any later version. | |
16 | ### | |
17 | ### TrIPE is distributed in the hope that it will be useful, | |
18 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ### GNU General Public License for more details. | |
21 | ### | |
22 | ### You should have received a copy of the GNU General Public License | |
23 | ### along with TrIPE; if not, write to the Free Software Foundation, | |
24 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
26 | ###-------------------------------------------------------------------------- | |
27 | ### Instructions. | |
28 | ### | |
29 | ### This script is an adaptor for attaching tripe's `slip' tunnel driver to | |
30 | ### `userv-ipif'. The latter is a service for GNU Userv which allows | |
31 | ### otherwise unprivileged users to implement network devices, subject to | |
32 | ### administrative limitations on which addresses can be configured and which | |
33 | ### prefixes routed through them. The software is available as part of the | |
34 | ### `userv-utils' package. | |
35 | ### | |
36 | ### To use this script, you'll need to set up a configuration file | |
37 | ### `$TRIPEDIR/ipif.tab'. This file may contain comments (begining `#') and | |
38 | ### blank lines, both of which are ignored, and entries of the form | |
39 | ### | |
40 | ### PEER REMOTE-EXT LOCAL-INT REMOTE-INT ROUTE,... | |
41 | ### | |
42 | ### The PEER names a peer, as given to tripe's ADD command. REMOTE-EXT is | |
43 | ### the external IP address of the peer, i.e., the one which tripe will send | |
44 | ### its packets to. LOCAL-INT and REMOTE-INT are the local and remote | |
45 | ### addresses to be associated with the point-to-point interface. Finally, | |
46 | ### the ROUTEs are a comma-separated list of PREFIX/LEN pairs declaring | |
47 | ### which prefixes should be routed over this interface. The *-INT and | |
48 | ### ROUTEs fields are passed on to the `userv-ipif' service. The REMOTE-EXT | |
49 | ### field is used (a) by the accompanying `ipif-peers' script to set up the | |
50 | ### peer association, and (b) to determine the correct MTU to set; it | |
51 | ### should have the form ADDRESS[:PORT], where the PORT defaults to 4070 if | |
52 | ### it's not given explicitly. | |
53 | ### | |
54 | ### Having done all of that, and having configured userv-ipif correctly, | |
55 | ### you should set TRIPE_SLIPIF=.../tripe-ipif and everything should just | |
56 | ### work. If you drop the script `ipif-peers' into the $TRIPEDIR/peers | |
57 | ### directory, then the init script will run it and all of the configured | |
58 | ### peers with known remote addresses will be added on startup. | |
59 | ||
60 | set -e | |
61 | quis=${0##*/} | |
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62 | : ${TRIPEDIR=@configdir@} |
63 | : ${logfile=@logfile@} | |
64 | : ${TRIPE_IPIF_LOG=${logfile%/*}/tripe-ipif.log} | |
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65 | |
66 | ## Parse the command line. | |
67 | case $# in 1) ;; *) echo >&2 "Usage: $quis PEER"; exit 1 ;; esac | |
68 | case ${TRIPEDIR+t} in | |
69 | t) ;; | |
70 | *) echo >&2 "$quis: \`TRIPEDIR' unset"; exit 1 ;; | |
71 | esac | |
72 | peer=$1 | |
73 | ||
74 | ## Arrange for errors to go somewhere. | |
01c94fa1 | 75 | exec 2>>"$TRIPE_IPIF_LOG" |
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76 | now=$(date +"%Y-%m-%d %H:%M:%S") |
77 | echo >&2 "$now $quis[$$] running for peer \`$peer'" | |
78 | ||
79 | ## Find the record in the peer table. | |
80 | foundp=nil | |
81 | while read name remote_ext local_int remote_int routes; do | |
82 | case $name in "$peer") foundp=t; break ;; esac | |
83 | done <$TRIPEDIR/ipif.tab | |
84 | case $foundp in | |
85 | nil) echo >&2 "$quis[$$]: unknown peer \`$peer'"; exit 1 ;; | |
86 | esac | |
87 | ||
88 | ## Announce the interface name. We actually have no way to determine this, | |
89 | ## so lie and hope that nobody cares. | |
90 | echo "userv-$peer" | |
91 | ||
92 | ## Now we can interrogate the server without deadlocking it. | |
93 | algs=$(tripectl algs) tagsz=nil blksz=nil | |
94 | while read line; do | |
95 | for i in $line; do | |
96 | case $i in | |
97 | cipher-blksz=*) blksz=${i#*=} ;; | |
98 | mac-tagsz=*) tagsz=${i#*=} ;; | |
99 | esac | |
100 | done | |
101 | done <<EOF | |
102 | $algs | |
103 | EOF | |
104 | case ,$tagsz,$blksz, in | |
105 | *,nil,*) echo >&2 "$quis[$$]: failed to discover cipher suite"; exit 1 ;; | |
106 | esac | |
107 | ||
108 | ## Determine the remote address if none is specified; strip off a port number | |
109 | ## if there is one. | |
110 | case "$remote_ext" in | |
111 | -) | |
112 | addr=$(tripectl addr $peer) | |
113 | set -- $addr | |
114 | case $1 in | |
115 | INET) remote_ext=$2 ;; | |
116 | *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;; | |
117 | esac | |
118 | ;; | |
119 | *:*) | |
120 | remote_ext=${remote_ext%:*} | |
121 | ;; | |
122 | esac | |
123 | ||
124 | ## Determine the MTU based on the path. | |
125 | pmtu=$(pathmtu $remote_ext) | |
126 | mtu=$(( $pmtu - 33 - $tagsz - $blksz )) | |
127 | ||
128 | ## Obtain the tunnel and run it. | |
129 | now=$(date +"%Y-%m-%d %H:%M:%S") | |
130 | info="invoking \`userv ipif' for \`$peer'; mtu = $mtu" | |
131 | info="$info; $local_int -> $remote_int${routes+ $routes}" | |
132 | echo >&2 "$now $quis[$$] $info" | |
133 | exec userv root ipif $local_int,$remote_int,$mtu,slip $routes | |
134 | ||
135 | ###----- That's all, folks -------------------------------------------------- |