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/scanner.l b/src/scanner.l
index 6f19eec9..5402be1c 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -274,6 +274,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 "reset"			{ return RESET; }
 "flush"			{ return FLUSH; }
 "rename"		{ return RENAME; }
+"import"                { return IMPORT; }
 "export"		{ return EXPORT; }
 "monitor"		{ return MONITOR; }
 
@@ -518,6 +519,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 
 "xml"			{ return XML; }
 "json"			{ return JSON; }
+"vm"                    { return VM; }
 
 "exists"		{ return EXISTS; }
 "missing"		{ return MISSING; }