evaluate: clone variable expression if there is more than one reference

Clone the expression that defines the variable value if there are
multiple references to it in the ruleset. This saves heap memory
consumption in case the variable defines a set with a huge number of
elements.

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

2 files changed, 30 insertions, 0 deletions

diff --git a/tests/shell/testcases/nft-f/0030variable_reuse_0 b/tests/shell/testcases/nft-f/0030variable_reuse_0
new file mode 100755
index 00000000..8afc54aa
--- /dev/null
+++ b/tests/shell/testcases/nft-f/0030variable_reuse_0
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -e
+
+RULESET="define test = { 1.1.1.1 }
+
+table ip x {
+        set y {
+                type ipv4_addr
+                elements = { 2.2.2.2, \$test }
+        }
+
+        set z {
+                type ipv4_addr
+                elements = { 3.3.3.3, \$test }
+        }
+}"
+
+$NFT -f - <<< "$RULESET"
diff --git a/tests/shell/testcases/nft-f/dumps/0030variable_reuse_0.nft b/tests/shell/testcases/nft-f/dumps/0030variable_reuse_0.nft
new file mode 100644
index 00000000..635901f4
--- /dev/null
+++ b/tests/shell/testcases/nft-f/dumps/0030variable_reuse_0.nft
@@ -0,0 +1,11 @@
+table ip x {
+	set y {
+		type ipv4_addr
+		elements = { 1.1.1.1, 2.2.2.2 }
+	}
+
+	set z {
+		type ipv4_addr
+		elements = { 1.1.1.1, 3.3.3.3 }
+	}
+}