| 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 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. |
| 16 | ### |
| 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. |
| 21 | ### |
| 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/>. |
| 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, and an IPv6 ADDRESS is enclosed in square |
| 52 | ### brackets (because of the stupid syntax decision to use colons in IPv6 |
| 53 | ### address literals). |
| 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##*/} |
| 63 | : ${TRIPEDIR=@configdir@} |
| 64 | : ${logfile=@logfile@} |
| 65 | : ${TRIPE_IPIF_LOG=${logfile%/*}/tripe-ipif.log} |
| 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=$1 |
| 74 | |
| 75 | ## Arrange for errors to go somewhere. |
| 76 | exec 2>>"$TRIPE_IPIF_LOG" |
| 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. |
| 94 | algs=$(tripectl algs) overhead=nil |
| 95 | while read line; do |
| 96 | for i in $line; do |
| 97 | case $i in bulk-overhead=*) overhead=${i#*=} ;; esac |
| 98 | done |
| 99 | done <<EOF |
| 100 | $algs |
| 101 | EOF |
| 102 | case $overhead in |
| 103 | nil) echo >&2 "$quis[$$]: failed to discover overhead"; exit 1 ;; |
| 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 |
| 113 | INET | INET6) remote_af=$1 remote_ext=$2 ;; |
| 114 | *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;; |
| 115 | esac |
| 116 | ;; |
| 117 | \[*\]:*) |
| 118 | remote_af=INET6 |
| 119 | remote_ext=${remote_ext#\[} |
| 120 | remote_ext=${remote_ext%\]:*} |
| 121 | ;; |
| 122 | *:*) |
| 123 | remote_af=INET |
| 124 | remote_ext=${remote_ext%:*} |
| 125 | ;; |
| 126 | esac |
| 127 | |
| 128 | ## Determine the MTU based on the path. |
| 129 | pmtu=$(pathmtu $remote_ext) |
| 130 | case $remote_af in |
| 131 | INET) iphdrsz=20 ;; |
| 132 | INET6) iphdrsz=40 ;; |
| 133 | esac |
| 134 | mtu=$(( $pmtu - $iphdrsz - 8 - $overhead - 1 )) |
| 135 | |
| 136 | ## Obtain the tunnel and run it. |
| 137 | now=$(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 -------------------------------------------------- |