B-A-C: Also organized dedicated mount namespace for each host

So that smcrouted could be run separately on each.

namespace_demo/topo-B-A-C.sh

@@ -9,25 +9,41 @@
 #
 #
 # should be run under unshare -mrun .
-# use nsenter --net={A,B,C} to enter into network namespace of A/B/C.
+# use xnsenter {A,B,C} to enter into namespaces of A/B/C.
 #
 # Based on https://github.com/troglobit/smcroute/tree/master/test
 
-rm -f A B C
-touch A B C
+rm -rf A B C
+mkdir A B C
 PID=$$
 
+# `xunshare <dir> ...`  -- unshare net/mount/... namespaces to be referenced by dir
+xunshare() {
+    ref=$1
+    shift
+    touch $ref/mnt $ref/net
+    unshare --mount=$ref/mnt --net=$ref/net "$@"
+}
+
+# `xnsenter <dir> ...`  -- nsenter net/mount/... namespaces to be referenced by dir
+xnsenter() {
+    ref=$1
+    shift
+    nsenter --mount=$ref/mnt --net=$ref/net --wd=. "$@"
+}
+
+
 # B-br0-A
-unshare --net=B -- ip link set lo up
-nsenter --net=B -- ip link add b1 type veth peer B1
-nsenter --net=B -- ip link set B1 netns $PID
-nsenter --net=B -- ip link set b1 up
+xunshare B -- ip link set lo up
+xnsenter B -- ip link add b1 type veth peer B1
+xnsenter B -- ip link set B1 netns $PID
+xnsenter B -- ip link set b1 up
 ip link set B1 up
 
-unshare --net=A -- ip link set lo up
-nsenter --net=A -- ip link add a1 type veth peer A1
-nsenter --net=A -- ip link set A1 netns $PID
-nsenter --net=A -- ip link set a1 up
+xunshare A -- ip link set lo up
+xnsenter A -- ip link add a1 type veth peer A1
+xnsenter A -- ip link set A1 netns $PID
+xnsenter A -- ip link set a1 up
 ip link set A1 up
 
 ip link add br0 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -36,15 +52,15 @@ ip link set A1 master br0
 ip link set br0 up
 
 # A-br1-C
-nsenter --net=A -- ip link add a2 type veth peer A2
-nsenter --net=A -- ip link set A2 netns $PID
-nsenter --net=A -- ip link set a2 up
+xnsenter A -- ip link add a2 type veth peer A2
+xnsenter A -- ip link set A2 netns $PID
+xnsenter A -- ip link set a2 up
 ip link set A2 up
 
-unshare --net=C -- ip link set lo up
-nsenter --net=C -- ip link add c1 type veth peer C1
-nsenter --net=C -- ip link set C1 netns $PID
-nsenter --net=C -- ip link set c1 up
+xunshare C -- ip link set lo up
+xnsenter C -- ip link add c1 type veth peer C1
+xnsenter C -- ip link set C1 netns $PID
+xnsenter C -- ip link set c1 up
 ip link set C1 up
 
 ip link add br1 type bridge # vlan_filtering 1 mcast_snooping 0
@@ -54,27 +70,32 @@ ip link set br1 up
 
 
 # addresses
-nsenter --net=B -- ip addr add 10.0.0.1/24 dev b1
-nsenter --net=A -- ip addr add 10.0.0.2/24 dev a1
-nsenter --net=C -- ip addr add 20.0.0.1/24 dev c1
-nsenter --net=A -- ip addr add 20.0.0.2/24 dev a2
+xnsenter B -- ip addr add 10.0.0.1/24 dev b1
+xnsenter A -- ip addr add 10.0.0.2/24 dev a1
+xnsenter C -- ip addr add 20.0.0.1/24 dev c1
+xnsenter A -- ip addr add 20.0.0.2/24 dev a2
 
 # multicast routing
-nsenter --net=B -- ip route add 224.0.0.0/4 dev b1
-nsenter --net=C -- ip route add 224.0.0.0/4 dev c1
+xnsenter B -- ip route add 224.0.0.0/4 dev b1
+xnsenter C -- ip route add 224.0.0.0/4 dev c1
 
-nsenter --net=A -- ip route add    224.0.0.0/4 dev a1   # NOTE on A 224.0.0.0/4 is routed
-nsenter --net=A -- ip route append 224.0.0.0/4 dev a2   # to _both_ a1 and a2
+xnsenter A -- ip route add    224.0.0.0/4 dev a1   # NOTE on A 224.0.0.0/4 is routed
+xnsenter A -- ip route append 224.0.0.0/4 dev a2   # to _both_ a1 and a2
 
 
 # mount private /var/run so that smcrouted can be started
-# we start will start it only in A, so keeping /var/run shared to everywhere,
-# even if dirty, is ok.
-mount -t tmpfs none /var/run
+xnsenter A -- mount -t tmpfs none /var/run
+xnsenter B -- mount -t tmpfs none /var/run
+xnsenter C -- mount -t tmpfs none /var/run
+
+echo
+echo
+echo
+xnsenter B -- pwd
 
 
 # open terminals in A B C for play
-nsenter --net=B -- xfce4-terminal --title=B &
-nsenter --net=C -- xfce4-terminal --title=C &
-nsenter --net=A -- xfce4-terminal --title=A &
-nsenter --net=A -- xfce4-terminal --title=A2 &
+xnsenter B -- xfce4-terminal --title=B &
+xnsenter C -- xfce4-terminal --title=C &
+xnsenter A -- xfce4-terminal --title=A &
+xnsenter A -- xfce4-terminal --title=A2 &