[PATCH libnftnl 2/3] chain: add userdata and comment support

["Jose M. Guisado Gomez" <guigom@xxxxxxxxxx>]

Adds NFTNL_CHAIN_USERDATA, in order to support userdata for chains.

Adds NFTNL_UDATA_CHAIN_COMMENT chain userdata type to support storing a
comment.

Relies on NFTA_CHAIN_USERDATA.

Signed-off-by: Jose M. Guisado Gomez <guigom@xxxxxxxxxx>
---
 include/libnftnl/chain.h            |  1 +
 include/libnftnl/udata.h            |  6 ++++++
 include/linux/netfilter/nf_tables.h |  2 ++
 src/chain.c                         | 31 +++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+)

diff --git a/include/libnftnl/chain.h b/include/libnftnl/chain.h
index 0e57a5a..f56e581 100644
--- a/include/libnftnl/chain.h
+++ b/include/libnftnl/chain.h
@@ -34,6 +34,7 @@ enum nftnl_chain_attr {
 	NFTNL_CHAIN_DEVICES,
 	NFTNL_CHAIN_FLAGS,
 	NFTNL_CHAIN_ID,
+	NFTNL_CHAIN_USERDATA,
 	__NFTNL_CHAIN_MAX
 };
 #define NFTNL_CHAIN_MAX (__NFTNL_CHAIN_MAX - 1)
diff --git a/include/libnftnl/udata.h b/include/libnftnl/udata.h
index 2e38fcc..dbf3a60 100644
--- a/include/libnftnl/udata.h
+++ b/include/libnftnl/udata.h
@@ -15,6 +15,12 @@ enum nftnl_udata_table_types {
 };
 #define NFTNL_UDATA_TABLE_MAX (__NFTNL_UDATA_TABLE_MAX - 1)
 
+enum nftnl_udata_chain_types {
+	NFTNL_UDATA_CHAIN_COMMENT,
+	__NFTNL_UDATA_CHAIN_MAX
+};
+#define NFTNL_UDATA_CHAIN_MAX (__NFTNL_UDATA_CHAIN_MAX - 1)
+
 enum nftnl_udata_rule_types {
 	NFTNL_UDATA_RULE_COMMENT,
 	NFTNL_UDATA_RULE_EBTABLES_POLICY,
diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index 8099777..77d178a 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -197,6 +197,7 @@ enum nft_table_attributes {
  * @NFTA_CHAIN_TYPE: type name of the string (NLA_NUL_STRING)
  * @NFTA_CHAIN_COUNTERS: counter specification of the chain (NLA_NESTED: nft_counter_attributes)
  * @NFTA_CHAIN_FLAGS: chain flags
+ * @NFTA_CHAIN_USERDATA: user data (NLA_BINARY)
  */
 enum nft_chain_attributes {
 	NFTA_CHAIN_UNSPEC,
@@ -211,6 +212,7 @@ enum nft_chain_attributes {
 	NFTA_CHAIN_PAD,
 	NFTA_CHAIN_FLAGS,
 	NFTA_CHAIN_ID,
+	NFTA_CHAIN_USERDATA,
 	__NFTA_CHAIN_MAX
 };
 #define NFTA_CHAIN_MAX		(__NFTA_CHAIN_MAX - 1)
diff --git a/src/chain.c b/src/chain.c
index 94efa90..aac9da6 100644
--- a/src/chain.c
+++ b/src/chain.c
@@ -51,6 +51,11 @@ struct nftnl_chain {
 	uint32_t	flags;
 	uint32_t	chain_id;
 
+	struct {
+		void		*data;
+		uint32_t	len;
+	} user;
+
 	struct list_head rule_list;
 };
 
@@ -125,6 +130,8 @@ void nftnl_chain_free(const struct nftnl_chain *c)
 		xfree(c->type);
 	if (c->flags & (1 << NFTNL_CHAIN_DEV))
 		xfree(c->dev);
+	if (c->flags & (1 << NFTNL_CHAIN_USERDATA))
+		xfree(c->user.data);
 	if (c->flags & (1 << NFTNL_CHAIN_DEVICES)) {
 		for (i = 0; i < c->dev_array_len; i++)
 			xfree(c->dev_array[i]);
@@ -290,6 +297,16 @@ int nftnl_chain_set_data(struct nftnl_chain *c, uint16_t attr,
 	case NFTNL_CHAIN_ID:
 		memcpy(&c->chain_id, data, sizeof(c->chain_id));
 		break;
+	case NFTNL_CHAIN_USERDATA:
+		if (c->flags & (1 << NFTNL_CHAIN_USERDATA))
+			xfree(c->user.data);
+
+		c->user.data = malloc(data_len);
+		if (!c->user.data)
+			return -1;
+		memcpy(c->user.data, data, data_len);
+		c->user.len = data_len;
+		break;
 	}
 	c->flags |= (1 << attr);
 	return 0;
@@ -391,6 +408,9 @@ const void *nftnl_chain_get_data(const struct nftnl_chain *c, uint16_t attr,
 	case NFTNL_CHAIN_ID:
 		*data_len = sizeof(uint32_t);
 		return &c->chain_id;
+	case NFTNL_CHAIN_USERDATA:
+		*data_len = c->user.len;
+		return c->user.data;
 	}
 	return NULL;
 }
@@ -513,6 +533,8 @@ void nftnl_chain_nlmsg_build_payload(struct nlmsghdr *nlh, const struct nftnl_ch
 		mnl_attr_put_u32(nlh, NFTA_CHAIN_FLAGS, htonl(c->chain_flags));
 	if (c->flags & (1 << NFTNL_CHAIN_ID))
 		mnl_attr_put_u32(nlh, NFTA_CHAIN_ID, htonl(c->chain_id));
+	if (c->flags & (1 << NFTNL_CHAIN_USERDATA))
+		mnl_attr_put(nlh, NFTA_CHAIN_USERDATA, c->user.len, c->user.data);
 }
 
 EXPORT_SYMBOL(nftnl_chain_rule_add);
@@ -576,6 +598,10 @@ static int nftnl_chain_parse_attr_cb(const struct nlattr *attr, void *data)
 		if (mnl_attr_validate(attr, MNL_TYPE_U64) < 0)
 			abi_breakage();
 		break;
+	case NFTA_CHAIN_USERDATA:
+		if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
+			abi_breakage();
+		break;
 	}
 
 	tb[type] = attr;
@@ -777,6 +803,11 @@ int nftnl_chain_nlmsg_parse(const struct nlmsghdr *nlh, struct nftnl_chain *c)
 		c->chain_id = ntohl(mnl_attr_get_u32(tb[NFTA_CHAIN_ID]));
 		c->flags |= (1 << NFTNL_CHAIN_ID);
 	}
+	if (tb[NFTA_CHAIN_USERDATA]) {
+		nftnl_chain_set_data(c, NFTNL_CHAIN_USERDATA,
+				     mnl_attr_get_payload(tb[NFTA_CHAIN_USERDATA]),
+				     mnl_attr_get_payload_len(tb[NFTA_CHAIN_USERDATA]));
+	}
 
 	c->family = nfg->nfgen_family;
 	c->flags |= (1 << NFTNL_CHAIN_FAMILY);
-- 
2.27.0