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, 15 insertions, 6 deletions

diff --git a/src/table.c b/src/table.c
index e947394..ab0a8ea 100644
--- a/src/table.c
+++ b/src/table.c
@@ -419,12 +419,12 @@ static int nft_table_snprintf_default(char *buf, size_t size, struct nft_table *
 			t->table_flags, t->use);
 }
 
-int nft_table_snprintf(char *buf, size_t size, struct nft_table *t,
-		       uint32_t type, uint32_t flags)
+static int nft_table_cmd_snprintf(char *buf, size_t size, struct nft_table *t,
+				  uint32_t cmd, uint32_t type, uint32_t flags)
 {
 	int ret, len = size, offset = 0;
 
-	ret = nft_event_header_snprintf(buf+offset, len, type, flags);
+	ret = nft_cmd_header_snprintf(buf + offset, len, cmd, type, flags);
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
 	switch (type) {
@@ -440,15 +440,23 @@ int nft_table_snprintf(char *buf, size_t size, struct nft_table *t,
 	}
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
-	ret = nft_event_footer_snprintf(buf+offset, len, type, flags);
+	ret = nft_cmd_footer_snprintf(buf + offset, len, cmd, type, flags);
 	SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
 
 	return offset;
 }
+
+int nft_table_snprintf(char *buf, size_t size, struct nft_table *t,
+		       uint32_t type, uint32_t flags)
+{
+	return nft_table_cmd_snprintf(buf, size, t, nft_flag2cmd(flags), type,
+				      flags);
+}
 EXPORT_SYMBOL(nft_table_snprintf);
 
 static inline int nft_table_do_snprintf(char *buf, size_t size, void *t,
-					uint32_t type, uint32_t flags)
+					uint32_t cmd, uint32_t type,
+					uint32_t flags)
 {
 	return nft_table_snprintf(buf, size, t, type, flags);
 }
@@ -456,7 +464,8 @@ static inline int nft_table_do_snprintf(char *buf, size_t size, void *t,
 int nft_table_fprintf(FILE *fp, struct nft_table *t, uint32_t type,
 		      uint32_t flags)
 {
-	return nft_fprintf(fp, t, type, flags, nft_table_do_snprintf);
+	return nft_fprintf(fp, t, NFT_CMD_UNSPEC, type, flags,
+			   nft_table_do_snprintf);
 }
 EXPORT_SYMBOL(nft_table_fprintf);