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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 | ### | |
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12 | ### TrIPE is free software: you can redistribute it and/or modify it under |
13 | ### the terms of the GNU General Public License as published by the Free | |
14 | ### Software Foundation; either version 3 of the License, or (at your | |
15 | ### option) any later version. | |
a4f886c3 | 16 | ### |
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17 | ### TrIPE is distributed in the hope that it will be useful, but WITHOUT |
18 | ### ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
19 | ### FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
20 | ### for more details. | |
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21 | ### |
22 | ### You should have received a copy of the GNU General Public License | |
11ad66c2 | 23 | ### along with TrIPE. If not, see <https://www.gnu.org/licenses/>. |
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24 | |
25 | ###-------------------------------------------------------------------------- | |
26 | ### Instructions. | |
27 | ### | |
28 | ### This script is an adaptor for attaching tripe's `slip' tunnel driver to | |
29 | ### `userv-ipif'. The latter is a service for GNU Userv which allows | |
30 | ### otherwise unprivileged users to implement network devices, subject to | |
31 | ### administrative limitations on which addresses can be configured and which | |
32 | ### prefixes routed through them. The software is available as part of the | |
33 | ### `userv-utils' package. | |
34 | ### | |
35 | ### To use this script, you'll need to set up a configuration file | |
36 | ### `$TRIPEDIR/ipif.tab'. This file may contain comments (begining `#') and | |
37 | ### blank lines, both of which are ignored, and entries of the form | |
38 | ### | |
39 | ### PEER REMOTE-EXT LOCAL-INT REMOTE-INT ROUTE,... | |
40 | ### | |
41 | ### The PEER names a peer, as given to tripe's ADD command. REMOTE-EXT is | |
42 | ### the external IP address of the peer, i.e., the one which tripe will send | |
43 | ### its packets to. LOCAL-INT and REMOTE-INT are the local and remote | |
44 | ### addresses to be associated with the point-to-point interface. Finally, | |
45 | ### the ROUTEs are a comma-separated list of PREFIX/LEN pairs declaring | |
46 | ### which prefixes should be routed over this interface. The *-INT and | |
47 | ### ROUTEs fields are passed on to the `userv-ipif' service. The REMOTE-EXT | |
48 | ### field is used (a) by the accompanying `ipif-peers' script to set up the | |
49 | ### peer association, and (b) to determine the correct MTU to set; it | |
50 | ### should have the form ADDRESS[:PORT], where the PORT defaults to 4070 if | |
51 | ### it's not given explicitly. | |
52 | ### | |
53 | ### Having done all of that, and having configured userv-ipif correctly, | |
54 | ### you should set TRIPE_SLIPIF=.../tripe-ipif and everything should just | |
55 | ### work. If you drop the script `ipif-peers' into the $TRIPEDIR/peers | |
56 | ### directory, then the init script will run it and all of the configured | |
57 | ### peers with known remote addresses will be added on startup. | |
58 | ||
59 | set -e | |
60 | quis=${0##*/} | |
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61 | : ${TRIPEDIR=@configdir@} |
62 | : ${logfile=@logfile@} | |
63 | : ${TRIPE_IPIF_LOG=${logfile%/*}/tripe-ipif.log} | |
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64 | |
65 | ## Parse the command line. | |
66 | case $# in 1) ;; *) echo >&2 "Usage: $quis PEER"; exit 1 ;; esac | |
67 | case ${TRIPEDIR+t} in | |
68 | t) ;; | |
69 | *) echo >&2 "$quis: \`TRIPEDIR' unset"; exit 1 ;; | |
70 | esac | |
71 | peer=$1 | |
72 | ||
73 | ## Arrange for errors to go somewhere. | |
01c94fa1 | 74 | exec 2>>"$TRIPE_IPIF_LOG" |
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75 | now=$(date +"%Y-%m-%d %H:%M:%S") |
76 | echo >&2 "$now $quis[$$] running for peer \`$peer'" | |
77 | ||
78 | ## Find the record in the peer table. | |
79 | foundp=nil | |
80 | while read name remote_ext local_int remote_int routes; do | |
81 | case $name in "$peer") foundp=t; break ;; esac | |
82 | done <$TRIPEDIR/ipif.tab | |
83 | case $foundp in | |
84 | nil) echo >&2 "$quis[$$]: unknown peer \`$peer'"; exit 1 ;; | |
85 | esac | |
86 | ||
87 | ## Announce the interface name. We actually have no way to determine this, | |
88 | ## so lie and hope that nobody cares. | |
89 | echo "userv-$peer" | |
90 | ||
91 | ## Now we can interrogate the server without deadlocking it. | |
3849487a | 92 | algs=$(tripectl algs) overhead=nil |
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93 | while read line; do |
94 | for i in $line; do | |
3849487a | 95 | case $i in bulk-overhead=*) overhead=${i#*=} ;; esac |
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96 | done |
97 | done <<EOF | |
98 | $algs | |
99 | EOF | |
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100 | case $overhead in |
101 | nil) echo >&2 "$quis[$$]: failed to discover overhead"; exit 1 ;; | |
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102 | esac |
103 | ||
104 | ## Determine the remote address if none is specified; strip off a port number | |
105 | ## if there is one. | |
106 | case "$remote_ext" in | |
107 | -) | |
108 | addr=$(tripectl addr $peer) | |
109 | set -- $addr | |
110 | case $1 in | |
111 | INET) remote_ext=$2 ;; | |
112 | *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;; | |
113 | esac | |
114 | ;; | |
115 | *:*) | |
116 | remote_ext=${remote_ext%:*} | |
117 | ;; | |
118 | esac | |
119 | ||
120 | ## Determine the MTU based on the path. | |
121 | pmtu=$(pathmtu $remote_ext) | |
3849487a | 122 | mtu=$(( $pmtu - 29 - $overhead )) |
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123 | |
124 | ## Obtain the tunnel and run it. | |
125 | now=$(date +"%Y-%m-%d %H:%M:%S") | |
126 | info="invoking \`userv ipif' for \`$peer'; mtu = $mtu" | |
127 | info="$info; $local_int -> $remote_int${routes+ $routes}" | |
128 | echo >&2 "$now $quis[$$] $info" | |
129 | exec userv root ipif $local_int,$remote_int,$mtu,slip $routes | |
130 | ||
131 | ###----- That's all, folks -------------------------------------------------- |