json: collapse set element commands from parser

Update json parser to collapse {add,create} element commands to reduce
memory consumption in the case of large sets defined by one element per
command:

{"nftables": [{"add": {"element": {"family": "ip", "table": "x", "name":
"y", "elem": [{"set": ["1.1.0.0"]}]}}},...]}

Add CTX_F_COLLAPSED flag to report that command has been collapsed.

This patch reduces memory consumption by ~32% this case.

Fixes: 20f1c60ac8c8 ("src: collapse set element commands from parser")
Reported-by: Eric Garver <eric@garver.life>
Tested-by: Eric Garver <eric@garver.life>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/parser_json.c b/src/parser_json.c
index 37ec34cb7796402d048847e3a7e616abbfbe5523..68c0600df0857e8e521ec79687876175dff27b17 100644 (file)
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -18,6 +18,7 @@
 #include <netlink.h>
 #include <parser.h>
 #include <rule.h>
+#include <cmd.h>
 #include <sctp_chunk.h>
 #include <socket.h>
 
@@ -49,6 +50,7 @@
 #define CTX_F_SES      (1 << 6)        /* set_elem_expr_stmt */
 #define CTX_F_MAP      (1 << 7)        /* LHS of map_expr */
 #define CTX_F_CONCAT   (1 << 8)        /* inside concat_expr */
+#define CTX_F_COLLAPSED        (1 << 9)
 
 struct json_ctx {
        struct nft_ctx *nft;
@@ -3490,6 +3492,15 @@ static struct cmd *json_parse_cmd_add_element(struct json_ctx *ctx,
                handle_free(&h);
                return NULL;
        }
+
+       if ((op == CMD_CREATE || op == CMD_ADD) &&
+           nft_cmd_collapse_elems(op, ctx->cmds, &h, expr)) {
+               handle_free(&h);
+               expr_free(expr);
+               ctx->flags |= CTX_F_COLLAPSED;
+               return NULL;
+       }
+
        return cmd_alloc(op, cmd_obj, &h, int_loc, expr);
 }
 
@@ -4319,6 +4330,11 @@ static int __json_parse(struct json_ctx *ctx)
                cmd = json_parse_cmd(ctx, value);
 
                if (!cmd) {
+                       if (ctx->flags & CTX_F_COLLAPSED) {
+                               ctx->flags &= ~CTX_F_COLLAPSED;
+                               continue;
+                       }
+
                        json_error(ctx, "Parsing command array at index %zd failed.", index);
                        return -1;
                }