expr: add expr_ops_by_type()

Fetch expression operation from the expression type.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

2 files changed, 13 insertions, 0 deletions

diff --git a/include/expression.h b/include/expression.h
index 717b6755..d502fc2a 100644
--- a/include/expression.h
+++ b/include/expression.h
@@ -169,6 +169,7 @@ struct expr_ops {
 };
 
 const struct expr_ops *expr_ops(const struct expr *e);
+const struct expr_ops *expr_ops_by_type(enum expr_types etype);
 
 /**
  * enum expr_flags
diff --git a/src/expression.c b/src/expression.c
index 6fa2f1dd..a7bbde7e 100644
--- a/src/expression.c
+++ b/src/expression.c
@@ -1222,3 +1222,15 @@ const struct expr_ops *expr_ops(const struct expr *e)
 
 	BUG("Unknown expression type %d\n", e->etype);
 }
+
+const struct expr_ops *expr_ops_by_type(enum expr_types etype)
+{
+	switch (etype) {
+	case EXPR_PAYLOAD:
+		return &payload_expr_ops;
+	default:
+		break;
+	}
+
+	BUG("Unknown expression type %d\n", etype);
+}