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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 | |
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51 | ### it's not given explicitly, and an IPv6 ADDRESS is enclosed in square |
52 | ### brackets (because of the stupid syntax decision to use colons in IPv6 | |
53 | ### address literals). | |
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54 | ### |
55 | ### Having done all of that, and having configured userv-ipif correctly, | |
56 | ### you should set TRIPE_SLIPIF=.../tripe-ipif and everything should just | |
57 | ### work. If you drop the script `ipif-peers' into the $TRIPEDIR/peers | |
58 | ### directory, then the init script will run it and all of the configured | |
59 | ### peers with known remote addresses will be added on startup. | |
60 | ||
61 | set -e | |
62 | quis=${0##*/} | |
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63 | : ${TRIPEDIR=@configdir@} |
64 | : ${logfile=@logfile@} | |
65 | : ${TRIPE_IPIF_LOG=${logfile%/*}/tripe-ipif.log} | |
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66 | |
67 | ## Parse the command line. | |
68 | case $# in 1) ;; *) echo >&2 "Usage: $quis PEER"; exit 1 ;; esac | |
69 | case ${TRIPEDIR+t} in | |
70 | t) ;; | |
71 | *) echo >&2 "$quis: \`TRIPEDIR' unset"; exit 1 ;; | |
72 | esac | |
73 | peer=$1 | |
74 | ||
75 | ## Arrange for errors to go somewhere. | |
01c94fa1 | 76 | exec 2>>"$TRIPE_IPIF_LOG" |
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77 | now=$(date +"%Y-%m-%d %H:%M:%S") |
78 | echo >&2 "$now $quis[$$] running for peer \`$peer'" | |
79 | ||
80 | ## Find the record in the peer table. | |
81 | foundp=nil | |
82 | while read name remote_ext local_int remote_int routes; do | |
83 | case $name in "$peer") foundp=t; break ;; esac | |
84 | done <$TRIPEDIR/ipif.tab | |
85 | case $foundp in | |
86 | nil) echo >&2 "$quis[$$]: unknown peer \`$peer'"; exit 1 ;; | |
87 | esac | |
88 | ||
89 | ## Announce the interface name. We actually have no way to determine this, | |
90 | ## so lie and hope that nobody cares. | |
91 | echo "userv-$peer" | |
92 | ||
93 | ## Now we can interrogate the server without deadlocking it. | |
3849487a | 94 | algs=$(tripectl algs) overhead=nil |
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95 | while read line; do |
96 | for i in $line; do | |
3849487a | 97 | case $i in bulk-overhead=*) overhead=${i#*=} ;; esac |
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98 | done |
99 | done <<EOF | |
100 | $algs | |
101 | EOF | |
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102 | case $overhead in |
103 | nil) echo >&2 "$quis[$$]: failed to discover overhead"; exit 1 ;; | |
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104 | esac |
105 | ||
106 | ## Determine the remote address if none is specified; strip off a port number | |
107 | ## if there is one. | |
108 | case "$remote_ext" in | |
109 | -) | |
110 | addr=$(tripectl addr $peer) | |
111 | set -- $addr | |
112 | case $1 in | |
811b576b | 113 | INET | INET6) remote_af=$1 remote_ext=$2 ;; |
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114 | *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;; |
115 | esac | |
116 | ;; | |
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117 | \[*\]:*) |
118 | remote_af=INET6 | |
119 | remote_ext=${remote_ext#\[} | |
120 | remote_ext=${remote_ext%\]:*} | |
121 | ;; | |
a4f886c3 | 122 | *:*) |
811b576b | 123 | remote_af=INET |
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124 | remote_ext=${remote_ext%:*} |
125 | ;; | |
126 | esac | |
127 | ||
128 | ## Determine the MTU based on the path. | |
129 | pmtu=$(pathmtu $remote_ext) | |
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130 | case $remote_af in |
131 | INET) iphdrsz=20 ;; | |
132 | INET6) iphdrsz=40 ;; | |
133 | esac | |
134 | mtu=$(( $pmtu - $iphdrsz - 8 - $overhead - 1 )) | |
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135 | |
136 | ## Obtain the tunnel and run it. | |
137 | now=$(date +"%Y-%m-%d %H:%M:%S") | |
138 | info="invoking \`userv ipif' for \`$peer'; mtu = $mtu" | |
139 | info="$info; $local_int -> $remote_int${routes+ $routes}" | |
140 | echo >&2 "$now $quis[$$] $info" | |
141 | exec userv root ipif $local_int,$remote_int,$mtu,slip $routes | |
142 | ||
143 | ###----- That's all, folks -------------------------------------------------- |