3 ### TRIPE_SLIPIF dynamic allocation script for use with `userv-ipif'
5 ### (c) 2012 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
10 ### This file is part of Trivial IP Encryption (TrIPE).
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.
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
22 ### You should have received a copy of the GNU General Public License
23 ### along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
25 ###--------------------------------------------------------------------------
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.
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
39 ### PEER REMOTE-EXT LOCAL-INT REMOTE-INT ROUTE,...
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, and an IPv6 ADDRESS is enclosed in square
52 ### brackets (because of the stupid syntax decision to use colons in IPv6
53 ### address literals).
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.
63 : ${TRIPEDIR=@configdir@}
64 : ${logfile=@logfile@}
65 : ${TRIPE_IPIF_LOG=${logfile%/*}/tripe-ipif.log}
67 ## Parse the command line.
68 case $# in 1) ;; *) echo >&2 "Usage: $quis PEER"; exit 1 ;; esac
71 *) echo >&2 "$quis: \`TRIPEDIR' unset"; exit 1 ;;
75 ## Arrange for errors to go somewhere.
76 exec 2>>"$TRIPE_IPIF_LOG"
77 now=$(date +"%Y-%m-%d %H:%M:%S")
78 echo >&2 "$now $quis[$$] running for peer \`$peer'"
80 ## Find the record in the peer table.
82 while read name remote_ext local_int remote_int routes; do
83 case $name in "$peer") foundp=t; break ;; esac
84 done <$TRIPEDIR/ipif.tab
86 nil) echo >&2 "$quis[$$]: unknown peer \`$peer'"; exit 1 ;;
89 ## Announce the interface name. We actually have no way to determine this,
90 ## so lie and hope that nobody cares.
93 ## Now we can interrogate the server without deadlocking it.
94 algs=$(tripectl algs) overhead=nil
97 case $i in bulk-overhead=*) overhead=${i#*=} ;; esac
103 nil) echo >&2 "$quis[$$]: failed to discover overhead"; exit 1 ;;
106 ## Determine the remote address if none is specified; strip off a port number
108 case "$remote_ext" in
110 addr=$(tripectl addr $peer)
113 INET | INET6) remote_af=$1 remote_ext=$2 ;;
114 *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;;
119 remote_ext=${remote_ext#\[}
120 remote_ext=${remote_ext%\]:*}
124 remote_ext=${remote_ext%:*}
128 ## Determine the MTU based on the path.
129 pmtu=$(pathmtu $remote_ext)
134 mtu=$(( $pmtu - $iphdrsz - 8 - $overhead - 1 ))
136 ## Obtain the tunnel and run it.
137 now=$(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
143 ###----- That's all, folks --------------------------------------------------