netfilter: bitwise: add helper for evaluating boolean operations.

Split the code specific to evaluating bitwise boolean operations out
into a separate function.  Similar functions will be added later for
shift operations.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_bitwise.c

@@ -24,16 +24,27 @@ struct nft_bitwise {
 	struct nft_data		xor;
 };
 
+static void nft_bitwise_eval_bool(u32 *dst, const u32 *src,
+				  const struct nft_bitwise *priv)
+{
+	unsigned int i;
+
+	for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
+		dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
+}
+
 void nft_bitwise_eval(const struct nft_expr *expr,
 		      struct nft_regs *regs, const struct nft_pktinfo *pkt)
 {
 	const struct nft_bitwise *priv = nft_expr_priv(expr);
 	const u32 *src = &regs->data[priv->sreg];
 	u32 *dst = &regs->data[priv->dreg];
-	unsigned int i;
 
-	for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
-		dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
+	switch (priv->op) {
+	case NFT_BITWISE_BOOL:
+		nft_bitwise_eval_bool(dst, src, priv);
+		break;
+	}
 }
 
 static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {