testenv: wait for interface addresses to settle during setup

When configuring IPv6 addresses on an interface, they can be marked as
"tentative" until duplicate address detection (DAD) settles, which means
ping won't work. We try to turn off DAD, but that doesn't always work
either, depending on the global settings on the host; so add an explicit
wait after interface config.

Fixes #159.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: tohojo

testenv/testenv.sh

@@ -188,6 +188,21 @@ set_sysctls()
     done
 }
 
+wait_for_dev()
+{
+    local iface="$1"
+    local in_ns="${2:-}"
+    local retries=5 # max retries
+    local nscmd=
+
+    [ -n "$in_ns" ] && nscmd="ip netns exec $in_ns"
+    while [ "$retries" -gt "0" ]; do
+        if ! $nscmd ip addr show dev $iface | grep -q tentative; then return 0; fi
+        sleep 0.5
+        retries=$((retries -1))
+    done
+}
+
 get_vlan_prefix()
 {
     # Split the IPv6 prefix, and add the VLAN ID to the upper byte of the fourth
@@ -285,7 +300,10 @@ setup()
 
     echo -n "Setup environment '$NS' with peer ip ${INSIDE_IP6}"
     [ "$ENABLE_IPV4" -eq "1" ] && echo " and ${INSIDE_IP4}." || echo "."
+    echo "Waiting for interface configuration to settle..."
     echo ""
+    wait_for_dev "$NS" && wait_for_dev veth0 "$NS"
+
     LEGACY_IP=0 USE_VLAN=0 run_ping -c 1
 
     echo "$NS" > "$STATEDIR/current"