contrib/knock.in: Can now be called from an ordinary shell.

[tripe] / contrib / knock.in

diff --git a/contrib/knock.in b/contrib/knock.in
index 28d8e532d2d80a1557bbfad7ec72a10fbf2b3e1c..b1754d931cc6169c5a4b3e3e46a907337f8ef87f 100755 (executable)
--- a/contrib/knock.in
+++ b/contrib/knock.in
@@ -3,21 +3,29 @@
 set -e
 
 ### This script performs the passive side of a dynamic association.  It is
 set -e
 
 ### This script performs the passive side of a dynamic association.  It is

-### intended to be set as the `tripe' user's shell, and invoked via ssh(1).
-### Specifically, for each dynamic peer, add a line to `.ssh/authorized_keys'
-### of the form
+### intended to be set as the forced command in an `.ssh/authorized_keys'
+### file.  Specifically, for each dynamic peer, add a line to
+### `.ssh/authorized_keys' of the form

 ###
 ###

-###    command="PEER" ssh-rsa ...
+###    environment="TRIPE_USER=PEER" ssh-rsa ...

 ###
 ### There's an additional wrinkle.  Suppose that the passive TrIPE endpoint
 ### is behind a NAT, and the SSH gateway is on a different machine.  The
 ### gateway should have its own `tripe' user, and this script should again be
 ### its shell.  On the gateway, add a `.ssh/authorized_keys' entry
 ###
 ###
 ### There's an additional wrinkle.  Suppose that the passive TrIPE endpoint
 ### is behind a NAT, and the SSH gateway is on a different machine.  The
 ### gateway should have its own `tripe' user, and this script should again be
 ### its shell.  On the gateway, add a `.ssh/authorized_keys' entry
 ###

-###    command="tripe@SERVER:PEER" ssh-rsa ...
+###    environment="TRIPE_USER=tripe@SERVER:PEER" ssh-rsa ...

 ###
 ### for the dynamic endpoint.  On the passive endpoint itself, you need an
 ###
 ### for the dynamic endpoint.  On the passive endpoint itself, you need an

-### entry for the gateway's `tripe' user's key, with no command.
+### entry for the gateway's `tripe' user's key, with `TRIPE_GATEWAY' set to
+### any value, like
+###
+###    environment="TRIPE_GATEWAY=t" ssh-rsa ...
+###
+### For backwards compatibility, it can also be set as the `tripe' user's
+### shell, with the `[tripe@SERVER:]PEER' indicator set as the forced
+### command.  If there are no forced command or `TRIPE_*' environment
+### variables then it is assumed that a gateway is calling.

 
 : ${prefix=@prefix@} ${exec_prefix=@exec_prefix@}
 : ${bindir=@bindir@}
 
 : ${prefix=@prefix@} ${exec_prefix=@exec_prefix@}
 : ${bindir=@bindir@}


@@ -26,28 +34,25 @@ set -e
 export TRIPEDIR TRIPESOCK
 
 ## Make sure we're being called properly, and figure out the peer identity.
 export TRIPEDIR TRIPESOCK
 
 ## Make sure we're being called properly, and figure out the peer identity.

-case "$#,$1" in
-  2,-c) ;;
+case "${TRIPE_USER+t},${TRIPE_GATEWAY+t},$#,$1" in
+  t,,0,) set -- "$TRIPE_USER" ;;
+  ,t,0,) set -- $SSH_ORIGINAL_COMMAND; unset SSH_ORIGINAL_COMMAND ;;
+  ,,2,-c) ;;

   *)
   *)

-    echo >&2 "usage: $0 -c '[SERVER:]PEER [hello|goodbye]'"
+    echo >&2 "usage: $0 -c [SERVER:]PEER [ACTION]"

     exit 1
     ;;
 esac
 
     exit 1
     ;;
 esac
 

-## SSH has smushed all of our arguments together, so let's split them apart
-## again.
-set -- $2
-

 ## Examine the peer identifier and work out how to proceed.
 case "$#,$1" in
 ## Examine the peer identifier and work out how to proceed.
 case "$#,$1" in

-  0,*) echo >&2 "$0: missing peer identifier"; exit 1 ;;
+  0,*) echo >&2 "missing peer identifier"; exit 1 ;;

   *:*) mode=proxy server=${1%:*} user=${1##*:} ;;
   *) mode=local user=$1 ;;
 esac
 shift
 
   *:*) mode=proxy server=${1%:*} user=${1##*:} ;;
   *) mode=local user=$1 ;;
 esac
 shift
 

-## If there's no action then check to see whether SSH has hidden one
-## somewhere.  Make sure the command looks sensible.
+## Fetch the optional command from where SSH stashed it.

 case "$#" in 0) set -- $SSH_ORIGINAL_COMMAND ;; esac
 case "$#,$1" in
   0, | 1,hello) act=hello ;;
 case "$#" in 0) set -- $SSH_ORIGINAL_COMMAND ;; esac
 case "$#,$1" in
   0, | 1,hello) act=hello ;;