expr: add lookup expression for set-based lookups

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

1 files changed, 175 insertions, 0 deletions

diff --git a/src/expr/lookup.c b/src/expr/lookup.c
new file mode 100644
index 0000000..8e533c4
--- /dev/null
+++ b/src/expr/lookup.c
@@ -0,0 +1,175 @@
+/*
+ * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This code has been sponsored by Sophos Astaro <http://www.sophos.com>
+ */
+
+#include "internal.h"
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h> /* for memcpy */
+#include <arpa/inet.h>
+#include <libmnl/libmnl.h>
+#include <linux/netfilter/nf_tables.h>
+#include <libnftables/expr.h>
+#include "data_reg.h"
+#include "expr_ops.h"
+
+#ifndef IFNAMSIZ
+#define IFNAMSIZ	16
+#endif
+
+struct nft_expr_lookup {
+	enum nft_registers	sreg;
+	enum nft_registers	dreg;
+	char			set_name[IFNAMSIZ];
+};
+
+static int
+nft_rule_expr_lookup_set(struct nft_rule_expr *e, uint16_t type,
+			  const void *data, size_t data_len)
+{
+	struct nft_expr_lookup *lookup = (struct nft_expr_lookup *)e->data;
+
+	switch(type) {
+	case NFT_EXPR_LOOKUP_SREG:
+		lookup->sreg = *((uint32_t *)data);
+		break;
+	case NFT_EXPR_LOOKUP_DREG:
+		lookup->dreg = *((uint32_t *)data);
+		break;
+	case NFT_EXPR_LOOKUP_SET:
+		memcpy(lookup->set_name, data, IFNAMSIZ);
+		lookup->set_name[IFNAMSIZ-1] = '\0';
+		break;
+	default:
+		return -1;
+	}
+	return 0;
+}
+
+static const void *
+nft_rule_expr_lookup_get(struct nft_rule_expr *e, uint16_t type, size_t *data_len)
+{
+	struct nft_expr_lookup *lookup = (struct nft_expr_lookup *)e->data;
+
+	switch(type) {
+	case NFT_EXPR_LOOKUP_SREG:
+		if (e->flags & (1 << NFT_EXPR_LOOKUP_SREG)) {
+			*data_len = sizeof(lookup->sreg);
+			return &lookup->sreg;
+		}
+		break;
+	case NFT_EXPR_LOOKUP_DREG:
+		if (e->flags & (1 << NFT_EXPR_LOOKUP_DREG)) {
+			*data_len = sizeof(lookup->dreg);
+			return &lookup->dreg;
+		}
+		break;
+	case NFT_EXPR_LOOKUP_SET:
+		if (e->flags & (1 << NFT_EXPR_LOOKUP_SET))
+			return lookup->set_name;
+		break;
+	default:
+		break;
+	}
+	return NULL;
+}
+
+static int nft_rule_expr_lookup_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type = mnl_attr_get_type(attr);
+
+	if (mnl_attr_type_valid(attr, NFTA_LOOKUP_MAX) < 0)
+		return MNL_CB_OK;
+
+	switch(type) {
+	case NFTA_LOOKUP_SREG:
+	case NFTA_LOOKUP_DREG:
+		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
+			perror("mnl_attr_validate");
+			return MNL_CB_ERROR;
+		}
+		break;
+	case NFTA_LOOKUP_SET:
+		if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0) {
+			perror("mnl_attr_validate");
+			return MNL_CB_ERROR;
+		}
+		break;
+	}
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static void
+nft_rule_expr_lookup_build(struct nlmsghdr *nlh, struct nft_rule_expr *e)
+{
+	struct nft_expr_lookup *lookup = (struct nft_expr_lookup *)e->data;
+
+	if (e->flags & (1 << NFT_EXPR_LOOKUP_SREG))
+		mnl_attr_put_u32(nlh, NFTA_LOOKUP_SREG, htonl(lookup->sreg));
+	if (e->flags & (1 << NFT_EXPR_LOOKUP_DREG))
+		mnl_attr_put_u32(nlh, NFTA_LOOKUP_DREG, htonl(lookup->dreg));
+	if (e->flags & (1 << NFT_EXPR_LOOKUP_SET))
+		mnl_attr_put_strz(nlh, NFTA_LOOKUP_SET, lookup->set_name);
+}
+
+static int
+nft_rule_expr_lookup_parse(struct nft_rule_expr *e, struct nlattr *attr)
+{
+	struct nft_expr_lookup *lookup = (struct nft_expr_lookup *)e->data;
+	struct nlattr *tb[NFTA_LOOKUP_MAX+1] = {};
+	int ret = 0;
+
+	if (mnl_attr_parse_nested(attr, nft_rule_expr_lookup_cb, tb) < 0)
+		return -1;
+
+	if (tb[NFTA_LOOKUP_SREG]) {
+		lookup->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_LOOKUP_SREG]));
+		e->flags |= (1 << NFT_EXPR_LOOKUP_SREG);
+	}
+	if (tb[NFTA_LOOKUP_DREG]) {
+		lookup->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_LOOKUP_DREG]));
+		e->flags |= (1 << NFT_EXPR_LOOKUP_DREG);
+	}
+	if (tb[NFTA_LOOKUP_SET]) {
+		strcpy(lookup->set_name, mnl_attr_get_str(tb[NFTA_LOOKUP_SET]));
+		e->flags |= (1 << NFT_EXPR_LOOKUP_SET);
+	}
+
+	return ret;
+}
+
+static int
+nft_rule_expr_lookup_snprintf(char *buf, size_t size, uint32_t type,
+			       uint32_t flags, struct nft_rule_expr *e)
+{
+	struct nft_expr_lookup *lookup = (struct nft_expr_lookup *)e->data;
+	int len = size, offset = 0, ret;
+
+	ret = snprintf(buf, len, "set=%s sreg=%u dreg=%u\n",
+			lookup->set_name, lookup->sreg, lookup->dreg);
+	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+
+	return offset;
+}
+
+struct expr_ops expr_ops_lookup = {
+	.name		= "lookup",
+	.alloc_len	= sizeof(struct nft_expr_lookup),
+	.max_attr	= NFTA_LOOKUP_MAX,
+	.set		= nft_rule_expr_lookup_set,
+	.get		= nft_rule_expr_lookup_get,
+	.parse		= nft_rule_expr_lookup_parse,
+	.build		= nft_rule_expr_lookup_build,
+	.snprintf	= nft_rule_expr_lookup_snprintf,
+};