have verifytxoutproof check the number of txns in proof structure

Github-Pull: #13452
Rebased-From: ed82f1700006830b6fe34572b66245c1487ccd29

src/merkleblock.h

@@ -115,6 +115,12 @@ public:
      * returns the merkle root, or 0 in case of failure
      */
     uint256 ExtractMatches(std::vector<uint256> &vMatch, std::vector<unsigned int> &vnIndex);
+
+    /** Get number of transactions the merkle proof is indicating for cross-reference with
+     * local blockchain knowledge.
+     */
+    unsigned int GetNumTransactions() const { return nTransactions; };
+
 };
 
 

src/rpc/rawtransaction.cpp

@@ -290,7 +290,7 @@ UniValue verifytxoutproof(const JSONRPCRequest& request)
             "\nArguments:\n"
             "1. \"proof\"    (string, required) The hex-encoded proof generated by gettxoutproof\n"
             "\nResult:\n"
-            "[\"txid\"]      (array, strings) The txid(s) which the proof commits to, or empty array if the proof is invalid\n"
+            "[\"txid\"]      (array, strings) The txid(s) which the proof commits to, or empty array if the proof can not be validated.\n"
         );
 
     CDataStream ssMB(ParseHexV(request.params[0], "proof"), SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS);
@@ -306,11 +306,16 @@ UniValue verifytxoutproof(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    if (!mapBlockIndex.count(merkleBlock.header.GetHash()) || !chainActive.Contains(mapBlockIndex[merkleBlock.header.GetHash()]))
+    if (!mapBlockIndex.count(merkleBlock.header.GetHash()) || !chainActive.Contains(mapBlockIndex[merkleBlock.header.GetHash()]) || mapBlockIndex[merkleBlock.header.GetHash()]->nTx == 0)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
 
-    for (const uint256& hash : vMatch)
-        res.push_back(hash.GetHex());
+    // Check if proof is valid, only add results if so
+    if (mapBlockIndex[merkleBlock.header.GetHash()]->nTx == merkleBlock.txn.GetNumTransactions()) {
+        for (const uint256& hash : vMatch) {
+            res.push_back(hash.GetHex());
+        }
+    }
+
     return res;
 }