Consistently use ParseHashV to validate hash inputs in rpc

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)"

1 files changed, 4 insertions, 8 deletions

diff --git a/src/rpc/server.cpp b/src/rpc/server.cpp
index 10040b1255..85383eb3bc 100644
--- a/src/rpc/server.cpp
+++ b/src/rpc/server.cpp
@@ -117,16 +117,12 @@ 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)
 {