From 055bf6a8e0c3ed5b39ca215346be40c0b95974f3 Mon Sep 17 00:00:00 2001
From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Tue, 19 Oct 2021 20:01:56 +1100
Subject: [PATCH] allow iface block without actual interface

---
 rrqnet-ifupdown.sh        | 22 ++++++++++++++++------
 rrqnet-ifupdown.sh.8.adoc | 17 ++++++++++-------
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/rrqnet-ifupdown.sh b/rrqnet-ifupdown.sh
index b36131e..4c6ce4d 100755
--- a/rrqnet-ifupdown.sh
+++ b/rrqnet-ifupdown.sh
@@ -18,7 +18,7 @@
 [ -z "$IF_RRQNET_PORT" ] && exit 0
 
 # An rrqnet stanza may have the following settings:
-# rrqnet_port <port>
+# rrqnet_port [ notap ] <port> 
 # rrqnet_nice <nice>
 # rrqnet_remote <remote declaration>
 # rrqnet_options <options>
@@ -29,6 +29,9 @@
 : ${RRQDAEMON:=/usr/sbin/rrqnet}
 : ${NAME:=rrqnet-${IFACE}}
 
+NOTAP="${IF_RRQNET_PORT##notap *}" # empty if 'notap' is used
+IF_RRQNET_PORT="${IF_RRQNET_PORT#notap }"
+
 #function
 configure_tap_bridge() {
     [ -z "$IF_RRQNET_BRIDGE" ] && return 0
@@ -67,18 +70,25 @@ stop_dhclient() {
 
 #function
 start_cable_pre_up() {
-    configure_tap_up || return 1
-    configure_tap_bridge || return 1
+    local TAP
+    TAP="-t $IFACE"
+    if [ -z "$NOTAP" ] ; then
+	echo "Note: $IFACE is an rrqnet without local interface" >&2
+	TAP=""
+    else
+	configure_tap_up || return 1
+	configure_tap_bridge || return 1
+    fi
     [ -z "$IF_RRQNET_NICE" ] || \
         RRQDAEMON="/usr/bin/nice -n $IF_RRQNET_NICE $RRQDAEMON"
     if [ -z "$IF_RRQNET_LOG" ] ; then
 	daemon -U -r -a 10 -n $NAME -- \
 	       $RRQDAEMON $IF_RRQNET_OPTIONS \
-	       -t $IFACE $IF_RRQNET_PORT $IF_RRQNET_REMOTE
+	       $TAP $IF_RRQNET_PORT $IF_RRQNET_REMOTE
     else
 	daemon -U -r -a 10 -n $NAME -E "${IF_RRQNET_LOG#* }" -- \
 	       $RRQDAEMON ${IF_RRQNET_LOG%% *} $IF_RRQNET_OPTIONS \
-	       -t $IFACE $IF_RRQNET_PORT $IF_RRQNET_REMOTE
+	       $TAP $IF_RRQNET_PORT $IF_RRQNET_REMOTE
     fi
 }
 
@@ -109,7 +119,7 @@ stop_cable_pre_down() {
 
 #function
 stop_cable_post_down() {
-    ip link del $IFACE
+    [ -z "$NOTAP" ] || ip link del $IFACE
 }
 
 # main script body
diff --git a/rrqnet-ifupdown.sh.8.adoc b/rrqnet-ifupdown.sh.8.adoc
index 787b294..90a502c 100644
--- a/rrqnet-ifupdown.sh.8.adoc
+++ b/rrqnet-ifupdown.sh.8.adoc
@@ -33,16 +33,19 @@ addresses.
 This script handles the special purpose "option codes" for the IFACE
 blocks that are used for declaring the +rrqnet+ daemon configuration
 to for the +tap+ interface for its virtual cabling. I.e., the IFACE
-stanza is made for the tap interface and it includes one or more of
+block is made for the tap interface and it includes one or more of
 these +rrqnet+ options.
 
 The list of IFACE options for +rrqnet+ are:
 
-*rrqnet_port* _port_::
+*rrqnet_port* [ notap ] _port_::
 
-This IFACE option is required both as way of marking that the stanza
-is for an +rrqnet+ virtual cable +tap+, and to declare which UDP port
-the +rrqnet+ daemon should listen on for incoming cabling.
+This IFACE option is required both as way of marking that the
+configuration block is for an +rrqnet+ virtual cable +tap+, and to
+declare which UDP port the +rrqnet+ daemon should listen on for
+incoming cabling. The port number may be preceded by +notap+ to
+indcate that this +rrqnet+ should not have an actual tap interface on
+the host but rather only serve to interconnect remote connections.
 
 *rrqnet_nice* _nice_::
 
@@ -109,8 +112,8 @@ iface mynet0 inet static
 The above example declares a virtual cable plug for UDP port +3636+
 tunneling through host +111.222.333.444+ port +3636+ where the local
 +tap+ +mynet0+ has ipv4 address +10.0.0.2+. The +rrqnet_port+ option
-marks the stanza as an ++rrqnet+ virtual cabling set up which then is
-duly handled by +rrqnet-ifupdown.sh+.
+marks the IFACE block as an ++rrqnet+ virtual cabling set up which
+then is duly handled by +rrqnet-ifupdown.sh+.
 
 The +rrqnet_options+ in the example tells the +rrqnet+ process to use
 an ipv4-only socket, 10 packet buffers and a single delivery thread,
-- 
2.39.2