[libnfnl] expr: add connlimit support

diff --git a/include/buffer.h b/include/buffer.h
index f5568953c4dc..f6626a6f4655 100644
--- a/include/buffer.h
+++ b/include/buffer.h
@@ -50,6 +50,7 @@  int nftnl_buf_expr(struct nftnl_buf *b, int type, uint32_t flags,
 #define COMPAT_FLAGS		"compat_flags"
 #define COMPAT_PROTO		"compat_proto"
 #define CONSUMED		"consumed"
+#define COUNT			"count"
 #define DATA			"data"
 #define DEVICE			"device"
 #define DIR			"dir"
diff --git a/include/libnftnl/expr.h b/include/libnftnl/expr.h
index 45ff5334f6a0..89603c84d869 100644
--- a/include/libnftnl/expr.h
+++ b/include/libnftnl/expr.h
@@ -98,6 +98,11 @@  enum {
 };
 
 enum {
+	NFTNL_EXPR_CONNLIMIT_COUNT = NFTNL_EXPR_BASE,
+	NFTNL_EXPR_CONNLIMIT_FLAGS,
+};
+
+enum {
 	NFTNL_EXPR_BITWISE_SREG	= NFTNL_EXPR_BASE,
 	NFTNL_EXPR_BITWISE_DREG,
 	NFTNL_EXPR_BITWISE_LEN,
diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index 660168ab924a..feed4954bea0 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -1018,6 +1018,24 @@  enum nft_limit_attributes {
 };
 #define NFTA_LIMIT_MAX		(__NFTA_LIMIT_MAX - 1)
 
+enum nft_connlimit_flags {
+	NFT_CONNLIMIT_F_INV	= (1 << 0),
+};
+
+/**
+ * enum nft_connlimit_attributes - nf_tables connlimit expression netlink attributes
+ *
+ * @NFTA_CONNLIMIT_COUNT: number of connections (NLA_U32)
+ * @NFTA_CONNLIMIT_FLAGS: flags (NLA_U32: enum nft_connlimit_flags)
+ */
+enum nft_connlimit_attributes {
+	NFTA_CONNLIMIT_UNSPEC,
+	NFTA_CONNLIMIT_COUNT,
+	NFTA_CONNLIMIT_FLAGS,
+	__NFTA_CONNLIMIT_MAX
+};
+#define NFTA_CONNLIMIT_MAX	(__NFTA_CONNLIMIT_MAX - 1)
+
 /**
  * enum nft_counter_attributes - nf_tables counter expression netlink attributes
  *
@@ -1323,7 +1341,8 @@  enum nft_ct_helper_attributes {
 #define NFT_OBJECT_QUOTA	2
 #define NFT_OBJECT_CT_HELPER	3
 #define NFT_OBJECT_LIMIT	4
-#define __NFT_OBJECT_MAX	5
+#define NFT_OBJECT_CONNLIMIT	5
+#define __NFT_OBJECT_MAX	6
 #define NFT_OBJECT_MAX		(__NFT_OBJECT_MAX - 1)
 
 /**
diff --git a/src/Makefile.am b/src/Makefile.am
index 578b7d36d8a9..1657896d85e8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -27,6 +27,7 @@  libnftnl_la_SOURCES = utils.c		\
 		      expr/byteorder.c	\
 		      expr/cmp.c	\
 		      expr/range.c	\
+		      expr/connlimit.c	\
 		      expr/counter.c	\
 		      expr/ct.c		\
 		      expr/data_reg.c	\
diff --git a/src/expr/connlimit.c b/src/expr/connlimit.c
new file mode 100644
index 000000000000..60965b5d8329
--- /dev/null
+++ b/src/expr/connlimit.c
@@ -0,0 +1,207 @@ 
+/*
+ * (C) 2018 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.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <inttypes.h>
+
+#include <linux/netfilter/nf_tables.h>
+
+#include "internal.h"
+#include <libmnl/libmnl.h>
+#include <libnftnl/expr.h>
+#include <libnftnl/rule.h>
+
+struct nftnl_expr_connlimit {
+	uint32_t	count;
+	uint32_t	flags;
+};
+
+static int
+nftnl_expr_connlimit_set(struct nftnl_expr *e, uint16_t type,
+			  const void *data, uint32_t data_len)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+
+	switch(type) {
+	case NFTNL_EXPR_CONNLIMIT_COUNT:
+		connlimit->count = *((uint32_t *)data);
+		break;
+	case NFTNL_EXPR_CONNLIMIT_FLAGS:
+		connlimit->flags = *((uint32_t *)data);
+		break;
+	default:
+		return -1;
+	}
+	return 0;
+}
+
+static const void *
+nftnl_expr_connlimit_get(const struct nftnl_expr *e, uint16_t type,
+			  uint32_t *data_len)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+
+	switch(type) {
+	case NFTNL_EXPR_CONNLIMIT_COUNT:
+		*data_len = sizeof(connlimit->count);
+		return &connlimit->count;
+	case NFTNL_EXPR_CONNLIMIT_FLAGS:
+		*data_len = sizeof(connlimit->flags);
+		return &connlimit->flags;
+	}
+	return NULL;
+}
+
+static int nftnl_expr_connlimit_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_CONNLIMIT_MAX) < 0)
+		return MNL_CB_OK;
+
+	switch(type) {
+	case NFTA_CONNLIMIT_COUNT:
+	case NFTA_CONNLIMIT_FLAGS:
+		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
+			abi_breakage();
+		break;
+	}
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static void
+nftnl_expr_connlimit_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+
+	if (e->flags & (1 << NFTNL_EXPR_CONNLIMIT_COUNT))
+		mnl_attr_put_u32(nlh, NFTA_CONNLIMIT_COUNT,
+				 htonl(connlimit->count));
+	if (e->flags & (1 << NFTNL_EXPR_CONNLIMIT_FLAGS))
+		mnl_attr_put_u32(nlh, NFTA_CONNLIMIT_FLAGS,
+				 htonl(connlimit->flags));
+}
+
+static int
+nftnl_expr_connlimit_parse(struct nftnl_expr *e, struct nlattr *attr)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+	struct nlattr *tb[NFTA_CONNLIMIT_MAX+1] = {};
+
+	if (mnl_attr_parse_nested(attr, nftnl_expr_connlimit_cb, tb) < 0)
+		return -1;
+
+	if (tb[NFTA_CONNLIMIT_COUNT]) {
+		connlimit->count =
+			ntohl(mnl_attr_get_u32(tb[NFTA_CONNLIMIT_COUNT]));
+		e->flags |= (1 << NFTNL_EXPR_CONNLIMIT_COUNT);
+	}
+	if (tb[NFTA_CONNLIMIT_FLAGS]) {
+		connlimit->flags =
+			ntohl(mnl_attr_get_u32(tb[NFTA_CONNLIMIT_FLAGS]));
+		e->flags |= (1 << NFTNL_EXPR_CONNLIMIT_FLAGS);
+	}
+
+	return 0;
+}
+
+static int
+nftnl_expr_connlimit_json_parse(struct nftnl_expr *e, json_t *root,
+				 struct nftnl_parse_err *err)
+{
+#ifdef JSON_PARSING
+	uint32_t uval32;
+
+	if (nftnl_jansson_parse_val(root, "count", NFTNL_TYPE_U32, &uval32,
+				    err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_CONNLIMIT_COUNT, uval32);
+
+	if (nftnl_jansson_parse_val(root, "flags", NFTNL_TYPE_U32, &uval32,
+				    err) == 0)
+		nftnl_expr_set_u32(e, NFTNL_EXPR_CONNLIMIT_FLAGS, uval32);
+
+	return 0;
+#else
+	errno = EOPNOTSUPP;
+	return -1;
+#endif
+}
+
+static int nftnl_expr_connlimit_export(char *buf, size_t size,
+				     const struct nftnl_expr *e, int type)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+	NFTNL_BUF_INIT(b, buf, size);
+
+	if (e->flags & (1 << NFTNL_EXPR_CONNLIMIT_COUNT))
+		nftnl_buf_u32(&b, type, connlimit->count, COUNT);
+	if (e->flags & (1 << NFTNL_EXPR_CONNLIMIT_FLAGS))
+		nftnl_buf_u32(&b, type, connlimit->flags, FLAGS);
+
+	return nftnl_buf_done(&b);
+}
+
+static int nftnl_expr_connlimit_snprintf_default(char *buf, size_t len,
+					       const struct nftnl_expr *e)
+{
+	struct nftnl_expr_connlimit *connlimit = nftnl_expr_data(e);
+
+	return snprintf(buf, len, "count %u flags %x ",
+			connlimit->count, connlimit->flags);
+}
+
+static int nftnl_expr_connlimit_snprintf(char *buf, size_t len, uint32_t type,
+				       uint32_t flags,
+				       const struct nftnl_expr *e)
+{
+	switch (type) {
+	case NFTNL_OUTPUT_DEFAULT:
+		return nftnl_expr_connlimit_snprintf_default(buf, len, e);
+	case NFTNL_OUTPUT_XML:
+	case NFTNL_OUTPUT_JSON:
+		return nftnl_expr_connlimit_export(buf, len, e, type);
+	default:
+		break;
+	}
+	return -1;
+}
+
+static bool nftnl_expr_connlimit_cmp(const struct nftnl_expr *e1,
+				   const struct nftnl_expr *e2)
+{
+	struct nftnl_expr_connlimit *c1 = nftnl_expr_data(e1);
+	struct nftnl_expr_connlimit *c2 = nftnl_expr_data(e2);
+	bool eq = true;
+
+	if (e1->flags & (1 << NFTNL_EXPR_CONNLIMIT_COUNT))
+		eq &= (c1->count == c2->count);
+	if (e1->flags & (1 << NFTNL_EXPR_CONNLIMIT_FLAGS))
+		eq &= (c1->flags == c2->flags);
+
+	return eq;
+}
+
+struct expr_ops expr_ops_connlimit = {
+	.name		= "connlimit",
+	.alloc_len	= sizeof(struct nftnl_expr_connlimit),
+	.max_attr	= NFTA_CONNLIMIT_MAX,
+	.cmp		= nftnl_expr_connlimit_cmp,
+	.set		= nftnl_expr_connlimit_set,
+	.get		= nftnl_expr_connlimit_get,
+	.parse		= nftnl_expr_connlimit_parse,
+	.build		= nftnl_expr_connlimit_build,
+	.snprintf	= nftnl_expr_connlimit_snprintf,
+	.json_parse	= nftnl_expr_connlimit_json_parse,
+};
diff --git a/src/expr_ops.c b/src/expr_ops.c
index 041bd357d370..6b63847e961f 100644
--- a/src/expr_ops.c
+++ b/src/expr_ops.c
@@ -7,6 +7,7 @@ 
 extern struct expr_ops expr_ops_bitwise;
 extern struct expr_ops expr_ops_byteorder;
 extern struct expr_ops expr_ops_cmp;
+extern struct expr_ops expr_ops_connlimit;
 extern struct expr_ops expr_ops_counter;
 extern struct expr_ops expr_ops_ct;
 extern struct expr_ops expr_ops_dup;
@@ -43,6 +44,7 @@  static struct expr_ops *expr_ops[] = {
 	&expr_ops_bitwise,
 	&expr_ops_byteorder,
 	&expr_ops_cmp,
+	&expr_ops_connlimit,
 	&expr_ops_counter,
 	&expr_ops_ct,
 	&expr_ops_dup,