Code for reproducing <div class="snippet-clipboard-content notranslate position-re

nanocbor_get_key_tstr returns NANOCBOR_OK even when key is not present about nanocbor HOT 3 OPEN

bergzand commented on June 19, 2024

nanocbor_get_key_tstr returns NANOCBOR_OK even when key is not present

from nanocbor.

Comments (3)

bergzand commented on June 19, 2024

Thanks for the report, this is indeed a bug.

It is caused by the nanocbor_skip call that overwrites the res value returned by the nanocbor_get_key_tstr call. This means that if the final element of the map is skipped with nanocbor_skip and the key is not found, the res value is taken from the nanocbor_skip call and returned.

I'll have a fix out asap

from nanocbor.

bergzand commented on June 19, 2024

I have to check if I don't cause a regression here, but I think this patch should fix your issue:

diff --git a/src/decoder.c b/src/decoder.c
index 80e69f2..2fc2282 100644
--- a/src/decoder.c
+++ b/src/decoder.c
@@ -433,8 +433,9 @@ int nanocbor_get_key_tstr(nanocbor_value_t *start, const char *key,
         const uint8_t *s = NULL;
         size_t s_len = 0;
 
-        if ((res = nanocbor_get_tstr(value, &s, &s_len)) < 0) {
-            break;
+        int call_res = NANOCBOR_OK;
+        if ((call_res = nanocbor_get_tstr(value, &s, &s_len)) < 0) {
+            return call_res;
         }
 
         if (s_len == len && !strncmp(key, (const char *)s, len)) {
@@ -442,8 +443,8 @@ int nanocbor_get_key_tstr(nanocbor_value_t *start, const char *key,
             break;
         }
 
-        if ((res = nanocbor_skip(value)) < 0) {
-            break;
+        if ((call_res = nanocbor_skip(value)) < 0) {
+            return call_res;
         }
     }