From c40e9ad51b1fc0129f116466a31663112a0a5f4c Mon Sep 17 00:00:00 2001
From: Jon Griffiths <jon_p_griffiths@yahoo.com>
Date: Mon, 24 Aug 2020 10:28:20 +1200
Subject: [PATCH] psbt: Allow doubly-present but matching fields when combining
 exclusive fields

---
 src/psbt.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/psbt.c b/src/psbt.c
index 3e015c981..9b0421994 100644
--- a/src/psbt.c
+++ b/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)