mdw@git.distorted.org.uk Git - tripe/blob - contrib/knock.in

   1 #! /bin/sh
   2
   3 set -e
   4
   5 ### This script performs the passive side of a dynamic association.  It is
   6 ### intended to be set as the `tripe' user's shell, and invoked via ssh(1).
   7 ### Specifically, for each dynamic peer, add a line to `.ssh/authorized_keys'
   8 ### of the form
   9 ###
  10 ###     command="PEER" ssh-rsa ...
  11 ###
  12 ### There's an additional wrinkle.  Suppose that the passive TrIPE endpoint
  13 ### is behind a NAT, and the SSH gateway is on a different machine.  The
  14 ### gateway should have its own `tripe' user, and this script should again be
  15 ### its shell.  On the gateway, add a `.ssh/authorized_keys' entry
  16 ###
  17 ###     command="tripe@SERVER:PEER" ssh-rsa ...
  18 ###
  19 ### for the dynamic endpoint.  On the passive endpoint itself, you need an
  20 ### entry for the gateway's `tripe' user's key, with no command.
  21
  22 : ${prefix=@prefix@} ${exec_prefix=@exec_prefix@}
  23 : ${bindir=@bindir@}
  24 : ${TRIPEDIR=@configdir@} ${TRIPESOCK=@socketdir@/tripesock}
  25 : ${tripectl=$bindir/tripectl}
  26 export TRIPEDIR TRIPESOCK
  27
  28 ## Make sure we're being called properly, and figure out the peer identity.
  29 case "$#,$1" in
  30   2,-c) ;;
  31   *)
  32     echo >&2 "usage: $0 -c '[SERVER:]PEER [hello|goodbye]'"
  33     exit 1
  34     ;;
  35 esac
  36
  37 ## SSH has smushed all of our arguments together, so let's split them apart
  38 ## again.
  39 set -- $2
  40
  41 ## Examine the peer identifier and work out how to proceed.
  42 case "$#,$1" in
  43   0,*) echo >&2 "$0: missing peer identifier"; exit 1 ;;
  44   *:*) mode=proxy server=${1%:*} user=${1##*:} ;;
  45   *) mode=local user=$1 ;;
  46 esac
  47 shift
  48
  49 ## If there's no action then check to see whether SSH has hidden one
  50 ## somewhere.  Make sure the command looks sensible.
  51 case "$#" in 0) set -- $SSH_ORIGINAL_COMMAND ;; esac
  52 case "$#,$1" in
  53   0, | 1,hello) act=hello ;;
  54   1,goodbye) act=goodbye ;;
  55   *) echo >&2 "$0: unknown action spec \`$*'"; exit 1 ;;
  56 esac
  57
  58 ## Now actually do something.
  59 case "$mode,$act" in
  60   proxy,*)
  61     exec ssh "$server" "$user" "$act"
  62     ;;
  63   local,hello)
  64     exec $tripectl SVCSUBMIT connect passive "$user"
  65     ;;
  66   local,goodbye)
  67     peer=$($tripectl SVCSUBMIT connect userpeer "$user")
  68     exec $tripectl KILL "$peer"
  69     ;;
  70   *)
  71     echo >&2 "$0: unknown mode/action $mode/$act"
  72     exit 1
  73     ;;
  74 esac