[nft PATCH] parser_json: Fix and simplify verdict expression parsing

[Phil Sutter]

Parsing of the "target" property was flawed in two ways:

* The value was extracted twice. Drop the first unconditional one.
* Expression allocation required since commit f1e8a129ee428 was broken,
  The expression was allocated only if the property was not present.

Fixes: f1e8a129ee428 ("src: Introduce chain_expr in jump and goto statements")
Signed-off-by: Phil Sutter <p...@nwl.cc>
---
 src/parser_json.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/parser_json.c b/src/parser_json.c
index 19cdefd392014..4c7ee9911c42f 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -1053,13 +1053,22 @@ static struct expr *json_parse_range_expr(struct 
json_ctx *ctx,
        return range_expr_alloc(int_loc, expr_low, expr_high);
 }
 
+static struct expr *json_alloc_chain_expr(const char *chain)
+{
+       if (!chain)
+               return NULL;
+
+       return constant_expr_alloc(int_loc, &string_type, BYTEORDER_HOST_ENDIAN,
+                                  NFT_CHAIN_MAXNAMELEN * BITS_PER_BYTE, chain);
+}
+
 static struct expr *json_parse_verdict_expr(struct json_ctx *ctx,
                                            const char *type, json_t *root)
 {
        const struct {
                int verdict;
                const char *name;
-               bool chain;
+               bool need_chain;
        } verdict_tbl[] = {
                { NFT_CONTINUE, "continue", false },
                { NFT_JUMP, "jump", true },
@@ -1068,27 +1077,19 @@ static struct expr *json_parse_verdict_expr(struct 
json_ctx *ctx,
                { NF_ACCEPT, "accept", false },
                { NF_DROP, "drop", false },
        };
-       struct expr *chain_expr = NULL;
        const char *chain = NULL;
        unsigned int i;
 
-       json_unpack(root, "{s:s}", "target", &chain);
-       if (!chain)
-               chain_expr = constant_expr_alloc(int_loc, &string_type,
-                                                BYTEORDER_HOST_ENDIAN,
-                                                NFT_CHAIN_MAXNAMELEN *
-                                                BITS_PER_BYTE, chain);
-
        for (i = 0; i < array_size(verdict_tbl); i++) {
                if (strcmp(type, verdict_tbl[i].name))
                        continue;
 
-               if (verdict_tbl[i].chain &&
+               if (verdict_tbl[i].need_chain &&
                    json_unpack_err(ctx, root, "{s:s}", "target", &chain))
                        return NULL;
 
-               return verdict_expr_alloc(int_loc,
-                                         verdict_tbl[i].verdict, chain_expr);
+               return verdict_expr_alloc(int_loc, verdict_tbl[i].verdict,
+                                         json_alloc_chain_expr(chain));
        }
        json_error(ctx, "Unknown verdict '%s'.", type);
        return NULL;
-- 
2.21.0