contrib/tripe-ipif.in: Fixing for IPv6.

Accept `INET6' addresses from the server; detect IPv6 literals from the
configuration file; and adjust the MTU accordingly to compensate for the
different IP header lengths.

diff --git a/contrib/tripe-ipif.in b/contrib/tripe-ipif.in
index d0118a4..3d2aa82 100755 (executable)
--- a/contrib/tripe-ipif.in
+++ b/contrib/tripe-ipif.in
@@ -48,7 +48,9 @@
 ### field is used (a) by the accompanying `ipif-peers' script to set up the
 ### peer association, and (b) to determine the correct MTU to set; it
 ### should have the form ADDRESS[:PORT], where the PORT defaults to 4070 if
-### it's not given explicitly.
+### it's not given explicitly, and an IPv6 ADDRESS is enclosed in square
+### brackets (because of the stupid syntax decision to use colons in IPv6
+### address literals).
 ###
 ### Having done all of that, and having configured userv-ipif correctly,
 ### you should set TRIPE_SLIPIF=.../tripe-ipif and everything should just
@@ -108,18 +110,28 @@ case "$remote_ext" in
     addr=$(tripectl addr $peer)
     set -- $addr
     case $1 in
-      INET) remote_ext=$2 ;;
+      INET | INET6) remote_af=$1 remote_ext=$2 ;;
       *) echo >&2 "$quis: unexpected address family \`$1'"; exit 1 ;;
     esac
     ;;
+  \[*\]:*)
+    remote_af=INET6
+    remote_ext=${remote_ext#\[}
+    remote_ext=${remote_ext%\]:*}
+    ;;
   *:*)
+    remote_af=INET
     remote_ext=${remote_ext%:*}
     ;;
 esac
 
 ## Determine the MTU based on the path.
 pmtu=$(pathmtu $remote_ext)
-mtu=$(( $pmtu - 29 - $overhead ))
+case $remote_af in
+  INET) iphdrsz=20 ;;
+  INET6) iphdrsz=40 ;;
+esac
+mtu=$(( $pmtu - $iphdrsz - 8 - $overhead - 1 ))
 
 ## Obtain the tunnel and run it.
 now=$(date +"%Y-%m-%d %H:%M:%S")