expr: byteorder: Do not print unset values in json

It changes the parse and the snprint functions to omit unset values.

Now, This part of a json file is gotten without unset elements.

Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/expr/byteorder.c b/src/expr/byteorder.c
index 9372d303d92fcd60211ddca3feb570a37e275928..3659918764f6b25e4e94e015132911a84405b2c1 100644 (file)
--- a/src/expr/byteorder.c
+++ b/src/expr/byteorder.c
@@ -202,35 +202,26 @@ nft_rule_expr_byteorder_json_parse(struct nft_rule_expr *e, json_t *root,
        uint32_t sreg, dreg, len, size;
        int ntoh;
 
-       if (nft_jansson_parse_reg(root, "sreg", NFT_TYPE_U32, &sreg, err) < 0)
-               return -1;
-
-       nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_SREG, sreg);
-
-       if (nft_jansson_parse_reg(root, "dreg", NFT_TYPE_U32, &dreg, err) < 0)
-               return -1;
+       if (nft_jansson_parse_reg(root, "sreg", NFT_TYPE_U32, &sreg, err) == 0)
+               nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_SREG, sreg);
 
-       nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_DREG, dreg);
+       if (nft_jansson_parse_reg(root, "dreg", NFT_TYPE_U32, &dreg, err) == 0)
+               nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_DREG, dreg);
 
        op = nft_jansson_parse_str(root, "op", err);
-       if (op == NULL)
-               return -1;
-
-       ntoh = nft_str2ntoh(op);
-       if (ntoh < 0)
-               return -1;
-
-       nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_OP, ntoh);
-
-       if (nft_jansson_parse_val(root, "len", NFT_TYPE_U32, &len, err) < 0)
-               return -1;
+       if (op != NULL) {
+               ntoh = nft_str2ntoh(op);
+               if (ntoh < 0)
+                       return -1;
 
-       nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_LEN, len);
+               nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_OP, ntoh);
+       }
 
-       if (nft_jansson_parse_val(root, "size", NFT_TYPE_U32, &size, err) < 0)
-               return -1;
+       if (nft_jansson_parse_val(root, "len", NFT_TYPE_U32, &len, err) == 0)
+               nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_LEN, len);
 
-       nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_SIZE, size);
+       if (nft_jansson_parse_val(root, "size", NFT_TYPE_U32, &size, err) == 0)
+               nft_rule_expr_set_u32(e, NFT_EXPR_BYTEORDER_SIZE, size);
 
        return 0;
 #else
@@ -287,15 +278,34 @@ static int nft_rule_expr_byteorder_snprintf_json(char *buf, size_t size,
        struct nft_expr_byteorder *byteorder = nft_expr_data(e);
        int len = size, offset = 0, ret;
 
-       ret = snprintf(buf, len, "\"sreg\":%u,"
-                                "\"dreg\":%u,"
-                                "\"op\":\"%s\","
-                                "\"len\":%u,"
-                                "\"size\":%u",
-                      byteorder->sreg, byteorder->dreg,
-                      expr_byteorder_str[byteorder->op],
-                      byteorder->len, byteorder->size);
-       SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       if (e->flags & (1 << NFT_EXPR_BYTEORDER_SREG)) {
+               ret = snprintf(buf + offset, len, "\"sreg\":%u,",
+                              byteorder->sreg);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       }
+       if (e->flags & (1 << NFT_EXPR_BYTEORDER_DREG)) {
+               ret = snprintf(buf + offset, len, "\"dreg\":%u,",
+                              byteorder->dreg);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       }
+       if (e->flags & (1 << NFT_EXPR_BYTEORDER_OP)) {
+               ret = snprintf(buf + offset, len, "\"op\":\"%s\",",
+                              expr_byteorder_str[byteorder->op]);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       }
+       if (e->flags & (1 << NFT_EXPR_BYTEORDER_LEN)) {
+               ret = snprintf(buf + offset, len, "\"len\":%u,",
+                              byteorder->len);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       }
+       if (e->flags & (1 << NFT_EXPR_BYTEORDER_SIZE)) {
+               ret = snprintf(buf + offset, len, "\"size\":%u,",
+                              byteorder->size);
+               SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
+       }
+
+       if (offset > 0)
+               offset--;
 
        return offset;
 }