Fix some fee logic: (RIPD-614)

* fee_default sets cost in drops of reference transaction
* Offline signing uses fee_default
* Signing multiplier maximum works correctly
* Fix bugs in load fee track
* Remove dead code, add comments

doc/rippled-example.cfg

@@ -602,6 +602,13 @@
 #
 #
 #
+# [fee_default]
+#
+#   Sets the base cost of a transaction in drops. Used when the server has
+#   no other source of fee information, such as signing transactions offline.
+#
+#
+#
 #-------------------------------------------------------------------------------
 #
 # 6. HTTPS Client

src/ripple/app/ledger/Ledger.cpp

@@ -2018,7 +2018,7 @@ void Ledger::updateFees ()
     if (mBaseFee)
         return;
     std::uint64_t baseFee = getConfig ().FEE_DEFAULT;
-    std::uint32_t referenceFeeUnits = 10;
+    std::uint32_t referenceFeeUnits = getConfig ().TRANSACTION_FEE_BASE;
     std::uint32_t reserveBase = getConfig ().FEE_ACCOUNT_RESERVE;
     std::int64_t reserveIncrement = getConfig ().FEE_OWNER_RESERVE;
 
@@ -2054,6 +2054,7 @@ void Ledger::updateFees ()
 
 std::uint64_t Ledger::scaleFeeBase (std::uint64_t fee)
 {
+    // Converts a fee in fee units to a fee in drops
     updateFees ();
     return getApp().getFeeTrack ().scaleFeeBase (
         fee, mBaseFee, mReferenceFeeUnits);

src/ripple/app/ledger/Ledger.h

@@ -451,22 +451,24 @@ public:
 
     std::uint32_t getReferenceFeeUnits ()
     {
+        // Returns the cost of the reference transaction in fee units
         updateFees ();
         return mReferenceFeeUnits;
     }
 
     std::uint64_t getBaseFee ()
     {
+        // Returns the cost of the reference transaction in drops
         updateFees ();
         return mBaseFee;
     }
 
     std::uint64_t getReserve (int increments)
     {
+        // Returns the required reserve in drops
         updateFees ();
-        return scaleFeeBase (
-            static_cast<std::uint64_t> (increments) * mReserveIncrement
-            + mReserveBase);
+        return static_cast<std::uint64_t> (increments) * mReserveIncrement
+            + mReserveBase;
     }
 
     std::uint64_t getReserveInc ()

src/ripple/app/transactors/Transactor.cpp

@@ -99,7 +99,8 @@ void Transactor::calculateFee ()
 
 std::uint64_t Transactor::calculateBaseFee ()
 {
-    return getConfig ().FEE_DEFAULT;
+    // Returns the fee in fee units
+    return getConfig ().TRANSACTION_FEE_BASE;
 }
 
 TER Transactor::payFee ()

src/ripple/core/impl/Config.cpp

@@ -49,6 +49,9 @@ namespace ripple {
 #define DEFAULT_FEE_OFFER               DEFAULT_FEE_DEFAULT
 #define DEFAULT_FEE_OPERATION           1
 
+// Fee in fee units
+#define DEFAULT_TRANSACTION_FEE_BASE    10
+
 #define SECTION_DEFAULT_NAME    ""
 
 IniFileSections
@@ -323,7 +326,7 @@ Config::Config ()
     PEER_PRIVATE            = false;
     PEERS_MAX               = 0;    // indicates "use default"
 
-    TRANSACTION_FEE_BASE    = DEFAULT_FEE_DEFAULT;
+    TRANSACTION_FEE_BASE    = DEFAULT_TRANSACTION_FEE_BASE;
 
     NETWORK_QUORUM          = 0;    // Don't need to see other nodes
     VALIDATION_QUORUM       = 1;    // Only need one node to vouch

src/ripple/core/impl/LoadFeeTrackImp.h

@@ -46,9 +46,9 @@ public:
         bool big = (fee > midrange);
 
         if (big)                // big fee, divide first to avoid overflow
-            fee /= baseFee;
+            fee /= referenceFeeUnits;
         else                    // normal fee, multiply first for accuracy
-            fee *= referenceFeeUnits;
+            fee *= baseFee;
 
         std::uint32_t feeFactor = std::max (mLocalTxnLoadFee, mRemoteTxnLoadFee);
 
@@ -63,9 +63,9 @@ public:
         }
 
         if (big)                // Fee was big to start, must now multiply
-            fee *= referenceFeeUnits;
+            fee *= baseFee;
         else                    // Fee was small to start, mst now divide
-            fee /= baseFee;
+            fee /= referenceFeeUnits;
 
         return fee;
     }
@@ -73,7 +73,7 @@ public:
     // Scale from fee units to millionths of a ripple
     std::uint64_t scaleFeeBase (std::uint64_t fee, std::uint64_t baseFee, std::uint32_t referenceFeeUnits)
     {
-        return mulDiv (fee, referenceFeeUnits, baseFee);
+        return mulDiv (fee, baseFee, referenceFeeUnits);
     }
 
     std::uint32_t getRemoteFee ()

src/ripple/rpc/impl/TransactionSign.cpp

@@ -73,11 +73,12 @@ static void autofill_fee (
         }
     }
 
-    std::uint64_t const feeDefault = getConfig().FEE_DEFAULT;
+    // Default fee in fee units
+    std::uint64_t const feeDefault = getConfig().TRANSACTION_FEE_BASE;
 
     // Administrative endpoints are exempt from local fees
     std::uint64_t const fee = ledger->scaleFeeLoad (feeDefault, admin);
-    std::uint64_t const limit = mult * feeDefault;
+    std::uint64_t const limit = mult * ledger->scaleFeeBase (feeDefault);
 
     if (fee > limit)
     {
@@ -280,17 +281,6 @@ Json::Value transactionSign (
             return e;
     }
 
-    if (!tx_json.isMember ("Fee")) {
-        auto const& transactionType = tx_json["TransactionType"].asString ();
-        if ("AccountSet" == transactionType
-            || "OfferCreate" == transactionType
-            || "OfferCancel" == transactionType
-            || "TrustSet" == transactionType)
-        {
-            tx_json["Fee"] = (int) getConfig ().FEE_DEFAULT;
-        }
-    }
-
     if (!tx_json.isMember ("Sequence"))
         tx_json["Sequence"] = asSrc->getSeq ();