src: enable json echo output when reading native syntax

This patch fixes a bug in which nft did not print any output when
specifying --echo and --json and reading nft native syntax.

This patch respects behavior when input is json, in which the output
would be the identical input plus the handles.

Adds a json_echo member inside struct nft_ctx to build and store the json object
containing the json command objects, the object is built using a mock
monitor to reuse monitor json code. This json object is only used when
we are sure we have not read json from input.

[ added json_alloc_echo() to compile without json support --pablo ]

Fixes: https://bugzilla.netfilter.org/show_bug.cgi?id=1446
Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
Tested-by: Eric Garver <eric@garver.life>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 15 insertions, 2 deletions

diff --git a/src/json.c b/src/json.c
index ac3b1c83..0b398bf0 100644
--- a/src/json.c
+++ b/src/json.c
@@ -1895,9 +1895,15 @@ int do_command_list_json(struct netlink_ctx *ctx, struct cmd *cmd)
 static void monitor_print_json(struct netlink_mon_handler *monh,
 			       const char *cmd, json_t *obj)
 {
+	struct nft_ctx *nft = monh->ctx->nft;
+
 	obj = json_pack("{s:o}", cmd, obj);
-	json_dumpf(obj, monh->ctx->nft->output.output_fp, 0);
-	json_decref(obj);
+	if (nft_output_echo(&nft->output) && !nft->json_root) {
+		json_array_append_new(nft->json_echo, obj);
+	} else {
+		json_dumpf(obj, nft->output.output_fp, 0);
+		json_decref(obj);
+	}
 }
 
 void monitor_print_table_json(struct netlink_mon_handler *monh,
@@ -1941,3 +1947,10 @@ void monitor_print_rule_json(struct netlink_mon_handler *monh,
 
 	monitor_print_json(monh, cmd, rule_print_json(octx, r));
 }
+
+void json_alloc_echo(struct nft_ctx *nft)
+{
+	nft->json_echo = json_array();
+	if (!nft->json_echo)
+		memory_allocation_error();
+}