Merge #13424: Consistently validate txid / blockhash length and encoding in rpc calls

5eb20f81d9 Consistently use ParseHashV to validate hash inputs in rpc (Ben Woosley)

Pull request description:

  ParseHashV validates the length and encoding of the string and throws
  an informative RPC error on failure, which is as good or better than
  these alternative calls.

  Note I switched ParseHashV to check string length first, because
  IsHex tests that the length is even, and an error like:
  "must be of length 64 (not 63, for X)" is much more informative than
  "must be hexadecimal string (not X)" in that case.

  Split from #13420

Tree-SHA512: f0786b41c0d7793ff76e4b2bb35547873070bbf7561d510029e8edb93f59176277efcd4d183b3185532ea69fc0bbbf3dbe9e19362e8017007ae9d51266cd78ae

src/rpc/mining.cpp

@@ -247,7 +247,7 @@ static UniValue prioritisetransaction(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    uint256 hash = ParseHashStr(request.params[0].get_str(), "txid");
+    uint256 hash(ParseHashV(request.params[0], "txid"));
     CAmount nAmount = request.params[2].get_int64();
 
     if (!(request.params[1].isNull() || request.params[1].get_real() == 0)) {
@@ -455,7 +455,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
             // Format: <hashBestChain><nTransactionsUpdatedLast>
             std::string lpstr = lpval.get_str();
 
-            hashWatchedChain.SetHex(lpstr.substr(0, 64));
+            hashWatchedChain = ParseHashV(lpstr.substr(0, 64), "longpollid");
             nTransactionsUpdatedLastLP = atoi64(lpstr.substr(64));
         }
         else