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

1 files changed, 4 insertions, 8 deletions

diff --git a/src/rpc/server.cpp b/src/rpc/server.cpp
index 9eb55880b3..60bf3c28c0 100644
--- a/src/rpc/server.cpp
+++ b/src/rpc/server.cpp
@@ -116,16 +116,12 @@ CAmount AmountFromValue(const UniValue& value)
 
 uint256 ParseHashV(const UniValue& v, std::string strName)
 {
-    std::string strHex;
-    if (v.isStr())
-        strHex = v.get_str();
+    std::string strHex(v.get_str());
+    if (64 != strHex.length())
+        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("%s must be of length %d (not %d, for '%s')", strName, 64, strHex.length(), strHex));
     if (!IsHex(strHex)) // Note: IsHex("") is false
         throw JSONRPCError(RPC_INVALID_PARAMETER, strName+" must be hexadecimal string (not '"+strHex+"')");
-    if (64 != strHex.length())
-        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("%s must be of length %d (not %d)", strName, 64, strHex.length()));
-    uint256 result;
-    result.SetHex(strHex);
-    return result;
+    return uint256S(strHex);
 }
 uint256 ParseHashO(const UniValue& o, std::string strKey)
 {