src: Add import command for low level json

This new operation allows to import low level virtual machine ruleset in
json to make incremental changes using the parse functions of libnftnl.

A basic way to test this new functionality is:

 $ cat file.json | nft import vm json

where the file.json is a ruleset exported in low level json format.

To export json rules in low level virtual machine format
we need to specify "vm" token before json. See below
        $ nft export vm json

and
        $ nft export/import json

will do no operations.
Same goes with  "$nft monitor"

Highly based on work from  Alvaro Neira <alvaroneay@gmail.com>
and Arturo Borrero <arturo@netfilter.org>

Acked-by: Arturo Borrero Gonzalez <arturo@netfilter.org>
Signed-off-by: Shyam Saini <mayhs11saini@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/evaluate.c b/src/evaluate.c
index 7fe738d8..2da589c0 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -3481,6 +3481,8 @@ int cmd_evaluate(struct eval_ctx *ctx, struct cmd *cmd)
 		return 0;
 	case CMD_MONITOR:
 		return cmd_evaluate_monitor(ctx, cmd);
+	case CMD_IMPORT:
+		return 0;
 	default:
 		BUG("invalid command operation %u\n", cmd->op);
 	};