src: add command tag in JSON/XML export support

Currently, we can't do incremental updates via JSON/XML.

This patch enriches the existing output to indicate the kind of
update that you want to perform.

So, if we have a ruleset like:

table ip filter {
	chain input {
		type filter hook input priority 0;
	}
}

The new output looks like:

{"nftables":[{"add":[{"table":{"name":"filter",...}}]}]}
              ^^^^^

Where we explicitly indicate that we want to add a table.

We support all the actions that we can do with nft, they are:

 - Add, delete and flush tables and chains.
 - Add, delete, replace and insert rules.
 - Add and delete sets.
 - Add and delete set elements.
 - Flush ruleset.

You only need to add the command tag:

	{"nftables":[{"delete":[{...}, {...},...}]}]}
		       ^^^^^^^^

The possible command tags that you can use are "add", "delete", "insert",
"replace" and "flush".

- Flush table or chain, eg.:

	{"nftables":[{"flush":[{"table":{"name":...}}]}]}

- Delete table, chain, set or rule:

	{"nftables":[{"delete":[{"chain":{"name":...}]}]}

- Replace a rule (you have to  specify the handle):

	{"nftables":[{"replace":[{"rule":{...}}]}]}

- Insert a rule:

	{"nftables":[{"insert":[{"rule":{...}}]}]}

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/buffer.h b/include/buffer.h
index 2b497f2..9d1cb8b 100644
--- a/include/buffer.h
+++ b/include/buffer.h
@@ -26,6 +26,9 @@ union nft_data_reg;
 int nft_buf_open(struct nft_buf *b, int type, const char *tag);
 int nft_buf_close(struct nft_buf *b, int type, const char *tag);
 
+int nft_buf_open_array(struct nft_buf *b, int type, const char *tag);
+int nft_buf_close_array(struct nft_buf *b, int type, const char *tag);
+
 int nft_buf_u32(struct nft_buf *b, int type, uint32_t value, const char *tag);
 int nft_buf_s32(struct nft_buf *b, int type, uint32_t value, const char *tag);
 int nft_buf_u64(struct nft_buf *b, int type, uint64_t value, const char *tag);
@@ -76,5 +79,10 @@ int nft_buf_reg(struct nft_buf *b, int type, union nft_data_reg *reg,
 #define UNIT			"unit"
 #define USE			"use"
 #define XOR			"xor"
+#define ADD			"add"
+#define INSERT			"insert"
+#define DELETE			"delete"
+#define REPLACE			"replace"
+#define FLUSH			"flush"
 
 #endif