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)"

4 files changed, 17 insertions, 30 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index f70d506e13..b809fd0f5d 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -252,7 +252,7 @@ static UniValue waitforblock(const JSONRPCRequest& request)
         );
     int timeout = 0;
 
-    uint256 hash = uint256S(request.params[0].get_str());
+    uint256 hash(ParseHashV(request.params[0], "blockhash"));
 
     if (!request.params[1].isNull())
         timeout = request.params[1].get_int();
@@ -706,8 +706,7 @@ static UniValue getblockheader(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "hash"));
 
     bool fVerbose = true;
     if (!request.params[1].isNull())
@@ -800,8 +799,7 @@ static UniValue getblock(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "blockhash"));
 
     int verbosity = 1;
     if (!request.params[1].isNull()) {
@@ -1033,8 +1031,7 @@ UniValue gettxout(const JSONRPCRequest& request)
 
     UniValue ret(UniValue::VOBJ);
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "txid"));
     int n = request.params[1].get_int();
     COutPoint out(hash, n);
     bool fMempool = true;
@@ -1442,8 +1439,7 @@ static UniValue preciousblock(const JSONRPCRequest& request)
             + HelpExampleRpc("preciousblock", "\"blockhash\"")
         );
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "blockhash"));
     CBlockIndex* pblockindex;
 
     {
@@ -1478,8 +1474,7 @@ static UniValue invalidateblock(const JSONRPCRequest& request)
             + HelpExampleRpc("invalidateblock", "\"blockhash\"")
         );
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "blockhash"));
     CValidationState state;
 
     {
@@ -1518,8 +1513,7 @@ static UniValue reconsiderblock(const JSONRPCRequest& request)
             + HelpExampleRpc("reconsiderblock", "\"blockhash\"")
         );
 
-    std::string strHash = request.params[0].get_str();
-    uint256 hash(uint256S(strHash));
+    uint256 hash(ParseHashV(request.params[0], "blockhash"));
 
     {
         LOCK(cs_main);
@@ -1572,7 +1566,7 @@ static UniValue getchaintxstats(const JSONRPCRequest& request)
         LOCK(cs_main);
         pindex = chainActive.Tip();
     } else {
-        uint256 hash = uint256S(request.params[1].get_str());
+        uint256 hash(ParseHashV(request.params[1], "blockhash"));
         LOCK(cs_main);
         pindex = LookupBlockIndex(hash);
         if (!pindex) {
@@ -1711,8 +1705,7 @@ static UniValue getblockstats(const JSONRPCRequest& request)
 
         pindex = chainActive[height];
     } else {
-        const std::string strHash = request.params[0].get_str();
-        const uint256 hash(uint256S(strHash));
+        const uint256 hash(ParseHashV(request.params[0], "hash_or_height"));
         pindex = LookupBlockIndex(hash);
         if (!pindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 85b864e6b9..c95145b204 100644
--- a/src/rpc/mining.cpp
+++ b/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)) {
@@ -456,7 +456,7 @@ 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
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 3b3f43edea..9f94307949 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -229,9 +229,7 @@ static UniValue gettxoutproof(const JSONRPCRequest& request)
     UniValue txids = request.params[0].get_array();
     for (unsigned int idx = 0; idx < txids.size(); idx++) {
         const UniValue& txid = txids[idx];
-        if (txid.get_str().length() != 64 || !IsHex(txid.get_str()))
-            throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid txid ")+txid.get_str());
-        uint256 hash(uint256S(txid.get_str()));
+        uint256 hash(ParseHashV(txid, "txid"));
         if (setTxids.count(hash))
             throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid parameter, duplicated txid: ")+txid.get_str());
        setTxids.insert(hash);
@@ -242,7 +240,7 @@ static UniValue gettxoutproof(const JSONRPCRequest& request)
     uint256 hashBlock;
     if (!request.params[1].isNull()) {
         LOCK(cs_main);
-        hashBlock = uint256S(request.params[1].get_str());
+        hashBlock = ParseHashV(request.params[1], "blockhash");
         pblockindex = LookupBlockIndex(hashBlock);
         if (!pblockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
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)
 {