mwan3: support latest iputils ping

iputils upstream changed build params with version s20200821
Latest OpenWRT iputils ping now appears to report the openwrt
version tag, rather than iputils date tag

This commit sends a test ping to localhost to evaluate the
capabilities of iputils ping.

Signed-off-by: Aaron Goodman <redacted>

diff --git a/net/mwan3/files/usr/sbin/mwan3track b/net/mwan3/files/usr/sbin/mwan3track
index d4a5f44abbc02bf60864d35d2e4580cc7a9489aa..bd8954c073be5ba32c405ad3e48c9f5a1def2cce 100755 (executable)
--- a/net/mwan3/files/usr/sbin/mwan3track
+++ b/net/mwan3/files/usr/sbin/mwan3track
@@ -40,19 +40,35 @@ if_up() {
        stop_subprocs
 }
 
+ping_test_host() {
+       if [ "$FAMILY" = "ipv6" ]; then
+               echo "::1"
+       else
+               echo "127.0.0.1"
+       fi
+}
+
+get_ping_command() {
+       if [ -x "/usr/bin/ping" ] && /usr/bin/ping -${FAMILY#ipv} -c1 -q $(ping_test_host) &>/dev/null; then
+               # -4 option added in iputils c3e68ac6 so need to check if we can use it
+               # or if we must use ping and ping6
+               echo "/usr/bin/ping -${FAMILY#ipv}"
+       elif [ "$FAMILY" = "ipv6" ] && [ -x "/usr/bin/ping6" ]; then
+               echo "/usr/bin/ping6"
+       elif [ "$FAMILY" = "ipv4" ] && [ -x "/usr/bin/ping" ]; then
+               echo "/usr/bin/ping"
+       elif [ -x "/bin/ping" ]; then
+               echo "/bin/ping -${FAMILY#ipv}"
+       else
+               return 1
+       fi
+}
+
 validate_track_method() {
        case "$1" in
                ping)
-                       if [ -x "/usr/bin/ping" ] && [ "$(/usr/bin/ping -V | grep -o '[0-9]*$')" -gt 20150519 ]; then
-                               # -4 option added in iputils c3e68ac6
-                               PING="/usr/bin/ping -${FAMILY#ipv}"
-                       elif [ "$FAMILY" = "ipv6" ] && [ -x "/usr/bin/ping6" ]; then
-                               PING="/usr/bin/ping6"
-                       elif [ "$FAMILY" = "ipv4" ] && [ -x "/usr/bin/ping" ]; then
-                               PING="/usr/bin/ping"
-                       elif [ -x "/bin/ping" ]; then
-                               PING="/bin/ping -${FAMILY#ipv}"
-                       else
+                       PING=$(get_ping_command)
+                       if [ $? -ne 0 ]; then
                                LOG warn "Missing ping. Please enable BUSYBOX_DEFAULT_PING and recompile busybox or install iputils-ping package."
                                return 1
                        fi