src: add last statement

This new statement allows you to know how long ago there was a matching
packet.

 # nft list ruleset
 table ip x {
        chain y {
		[...]
                ip protocol icmp last used 49m54s884ms counter packets 1 bytes 64
	}
 }

if this statement never sees a packet, then the listing says:

 ip protocol icmp last used never counter packets 0 bytes 0

Add tests/py in this patch too.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 21 insertions, 0 deletions

diff --git a/tests/py/any/last.t b/tests/py/any/last.t
new file mode 100644
index 00000000..5c530461
--- /dev/null
+++ b/tests/py/any/last.t
@@ -0,0 +1,13 @@
+:input;type filter hook input priority 0
+:ingress;type filter hook ingress device lo priority 0
+
+*ip;test-ip4;input
+*ip6;test-ip6;input
+*inet;test-inet;input
+*arp;test-arp;input
+*bridge;test-bridge;input
+*netdev;test-netdev;ingress
+
+last;ok
+last used 300s;ok;last
+last used foo;fail
diff --git a/tests/py/any/last.t.payload b/tests/py/any/last.t.payload
new file mode 100644
index 00000000..ed47d0f3
--- /dev/null
+++ b/tests/py/any/last.t.payload
@@ -0,0 +1,8 @@
+# last
+ip
+  [ last never ]
+
+# last used 300s
+ip
+  [ last 300000 ]
+