psbt: Allow doubly-present but matching fields when combining exclusi…

…ve fields

src/psbt.c

@@ -2005,12 +2005,17 @@ int wally_psbt_to_base64(const struct wally_psbt *psbt, uint32_t flags, char **o
  return ret;
 }
 
-#define COMBINE_BYTES(typ, member, ALLOW_DUPS) do { \
- if (!dst->member && src->member) { \
- if (!ALLOW_DUPS) return WALLY_EINVAL; \
- ret = wally_psbt_ ## typ ## _set_ ## member(dst, src->member, src->member ## _len); \
- if (ret != WALLY_OK) \
- return ret; \
+#define COMBINE_BYTES(TYP, MEMBER, ALLOW_DUPS) do { \
+ if (src->MEMBER) { \
+ if (dst->MEMBER && !ALLOW_DUPS) { \
+ if (dst->MEMBER ## _len != src->MEMBER ## _len || \
+ memcmp(dst->MEMBER, src->MEMBER, dst->MEMBER ## _len) != 0) \
+ return WALLY_EINVAL; \
+ } else if (!dst->MEMBER) { \
+ ret = wally_psbt_ ## TYP ## _set_ ## MEMBER(dst, src->MEMBER, src->MEMBER ## _len); \
+ if (ret != WALLY_OK) \
+ return ret; \
+ } \
  } } while (0)
 
 static int combine_txs(struct wally_tx **dst, struct wally_tx *src)