src: add comment support for set declarations

Allow users to add a comment when declaring a named set.

Adds set output handling the comment in both nftables and json
format.

$ nft add table ip x
$ nft add set ip x s {type ipv4_addr\; comment "some_addrs"\; elements = {1.1.1.1, 1.2.3.4}}

$ nft list ruleset
table ip x {
	set s {
		type ipv4_addr;
		comment "some_addrs"
		elements = { 1.1.1.1, 1.2.3.4 }
	}
}

$ nft --json list ruleset
{
    "nftables": [
        {
            "metainfo": {
                "json_schema_version": 1,
                "release_name": "Capital Idea #2",
                "version": "0.9.6"
            }
        },
        {
            "table": {
                "family": "ip",
                "handle": 4857,
                "name": "x"
            }
        },
        {
            "set": {
                "comment": "some_addrs",
                "elem": [
                    "1.1.1.1",
                    "1.2.3.4"
                ],
                "family": "ip",
                "handle": 1,
                "name": "s",
                "table": "x",
                "type": "ipv4_addr"
            }
        }
    ]
}

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

5 files changed, 32 insertions, 1 deletions

diff --git a/src/json.c b/src/json.c
index 888cb371..a9f5000f 100644
--- a/src/json.c
+++ b/src/json.c
@@ -98,6 +98,9 @@ static json_t *set_print_json(struct output_ctx *octx, const struct set *set)
 			"table", set->handle.table.name,
 			"type", set_dtype_json(set->key),
 			"handle", set->handle.handle.id);
+
+	if (set->comment)
+		json_object_set_new(root, "comment", json_string(set->comment));
 	if (datatype_ext)
 		json_object_set_new(root, "map", json_string(datatype_ext));
 
diff --git a/src/mnl.c b/src/mnl.c
index e5e88f3b..388eff8f 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -1042,6 +1042,11 @@ int mnl_nft_set_add(struct netlink_ctx *ctx, struct cmd *cmd,
 				   sizeof(set->desc.field_len[0]));
 	}
 
+	if (set->comment) {
+		if (!nftnl_udata_put_strz(udbuf, NFTNL_UDATA_SET_COMMENT, set->comment))
+			memory_allocation_error();
+	}
+
 	nftnl_set_set_data(nls, NFTNL_SET_USERDATA, nftnl_udata_buf_data(udbuf),
 			   nftnl_udata_buf_len(udbuf));
 	nftnl_udata_buf_free(udbuf);
diff --git a/src/netlink.c b/src/netlink.c
index 2f1dbe17..20b3cdf5 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -661,6 +661,7 @@ void netlink_dump_set(const struct nftnl_set *nls, struct netlink_ctx *ctx)
 
 static int set_parse_udata_cb(const struct nftnl_udata *attr, void *data)
 {
+	unsigned char *value = nftnl_udata_get(attr);
 	const struct nftnl_udata **tb = data;
 	uint8_t type = nftnl_udata_type(attr);
 	uint8_t len = nftnl_udata_len(attr);
@@ -678,6 +679,10 @@ static int set_parse_udata_cb(const struct nftnl_udata *attr, void *data)
 		if (len < 3)
 			return -1;
 		break;
+	case NFTNL_UDATA_SET_COMMENT:
+		if (value[len - 1] != '\0')
+			return -1;
+		break;
 	default:
 		return 0;
 	}
@@ -751,11 +756,11 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 	enum byteorder databyteorder = BYTEORDER_INVALID;
 	const struct datatype *keytype, *datatype = NULL;
 	struct expr *typeof_expr_key, *typeof_expr_data;
+	const char *udata, *comment = NULL;
 	uint32_t flags, key, objtype = 0;
 	const struct datatype *dtype;
 	uint32_t data_interval = 0;
 	bool automerge = false;
-	const char *udata;
 	struct set *set;
 	uint32_t ulen;
 	uint32_t klen;
@@ -783,6 +788,8 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 		typeof_expr_key = set_make_key(ud[NFTNL_UDATA_SET_KEY_TYPEOF]);
 		if (ud[NFTNL_UDATA_SET_DATA_TYPEOF])
 			typeof_expr_data = set_make_key(ud[NFTNL_UDATA_SET_DATA_TYPEOF]);
+		if (ud[NFTNL_UDATA_SET_COMMENT])
+			comment = xstrdup(nftnl_udata_get(ud[NFTNL_UDATA_SET_COMMENT]));
 	}
 
 	key = nftnl_set_get_u32(nls, NFTNL_SET_KEY_TYPE);
@@ -819,6 +826,8 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 	set->handle.table.name = xstrdup(nftnl_set_get_str(nls, NFTNL_SET_TABLE));
 	set->handle.set.name = xstrdup(nftnl_set_get_str(nls, NFTNL_SET_NAME));
 	set->automerge	   = automerge;
+	if (comment)
+		set->comment = comment;
 
 	if (nftnl_set_is_set(nls, NFTNL_SET_EXPR)) {
 		const struct nftnl_expr *nle;
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 167c3158..7e094ff6 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1768,6 +1768,11 @@ set_block		:	/* empty */	{ $$ = $<set>-1; }
 				$$ = $1;
 			}
 			|	set_block	set_mechanism	stmt_separator
+			|	set_block	comment_spec	stmt_separator
+			{
+				$1->comment = $2;
+				$$ = $1;
+			}
 			;
 
 set_block_expr		:	set_expr
diff --git a/src/rule.c b/src/rule.c
index 8dc1792b..2b5685c2 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -367,6 +367,8 @@ void set_free(struct set *set)
 		return;
 	if (set->init != NULL)
 		expr_free(set->init);
+	if (set->comment)
+		xfree(set->comment);
 	handle_free(&set->handle);
 	stmt_free(set->stmt);
 	expr_free(set->key);
@@ -584,6 +586,13 @@ static void set_print_declaration(const struct set *set,
 		time_print(set->gc_int, octx);
 		nft_print(octx, "%s", opts->stmt_separator);
 	}
+
+	if (set->comment) {
+		nft_print(octx, "%s%scomment \"%s\"%s",
+			  opts->tab, opts->tab,
+			  set->comment,
+			  opts->stmt_separator);
+	}
 }
 
 static void do_set_print(const struct set *set, struct print_fmt_options *opts,