src: allow to use variables in flowtable and chain devices

This patch adds support for using variables for devices in the chain and
flowtable definitions, eg.

 define if_main = lo

 table netdev filter1 {
    chain Main_Ingress1 {
        type filter hook ingress device $if_main priority -500; policy accept;
    }
 }

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

1 files changed, 37 insertions, 0 deletions

diff --git a/tests/shell/testcases/chains/0042chain_variable_0 b/tests/shell/testcases/chains/0042chain_variable_0
new file mode 100755
index 00000000..58535f76
--- /dev/null
+++ b/tests/shell/testcases/chains/0042chain_variable_0
@@ -0,0 +1,37 @@
+#!/bin/bash
+
+set -e
+
+ip link add name dummy0 type dummy
+
+EXPECTED="define if_main = \"lo\"
+
+table netdev filter1 {
+	chain Main_Ingress1 {
+		type filter hook ingress device \$if_main priority -500; policy accept;
+	}
+}"
+
+$NFT -f - <<< $EXPECTED
+
+EXPECTED="define if_main = \"lo\"
+
+table netdev filter2 {
+	chain Main_Ingress2 {
+		type filter hook ingress devices = { \$if_main, dummy0 } priority -500; policy accept;
+	}
+}"
+
+$NFT -f - <<< $EXPECTED
+
+EXPECTED="define if_main = { lo, dummy0 }
+
+table netdev filter3 {
+	chain Main_Ingress3 {
+		type filter hook ingress devices = \$if_main priority -500; policy accept;
+	}
+}"
+
+$NFT -f - <<< $EXPECTED
+
+