From e83ddb7e8ff97055eeee37672d4fc185c72ed74a Mon Sep 17 00:00:00 2001
From: Patrick Lodder <patricklodder@users.noreply.github.com>
Date: Fri, 8 Oct 2021 21:51:37 +0200
Subject: [PATCH] fees: Allow dust comparison against a given dust limit

Prepares for having more than one dust limit configured, yet
allowing the same function to return whether or not an output is
dust.

Implements the check with nDustLimit (-dustlimit) for relay related
queries, and - for lack of alternatives - uses the same parameter
for CWallet::GetRequiredFee until a wallet-specific dust limit is
introduced
---
 src/dogecoin-fees.cpp        | 8 ++++----
 src/dogecoin-fees.h          | 2 +-
 src/policy/policy.cpp        | 2 +-
 src/primitives/transaction.h | 9 +++++++++
 src/wallet/wallet.cpp        | 2 +-
 5 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/dogecoin-fees.cpp b/src/dogecoin-fees.cpp
index 28e25b5a0..f13bd8d57 100644
--- a/src/dogecoin-fees.cpp
+++ b/src/dogecoin-fees.cpp
@@ -92,7 +92,7 @@ CAmount GetDogecoinMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool
     }
 
     CAmount nMinFee = ::minRelayTxFeeRate.GetFee(nBytes);
-    nMinFee += GetDogecoinDustFee(tx.vout, ::minRelayTxFeeRate);
+    nMinFee += GetDogecoinDustFee(tx.vout, nDustLimit, ::minRelayTxFeeRate);
 
     if (fAllowFree)
     {
@@ -109,12 +109,12 @@ CAmount GetDogecoinMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool
     return nMinFee;
 }
 
-CAmount GetDogecoinDustFee(const std::vector<CTxOut> &vout, CFeeRate &baseFeeRate) {
+CAmount GetDogecoinDustFee(const std::vector<CTxOut> &vout, const CAmount dustLimit, CFeeRate &baseFeeRate) {
     CAmount nFee = 0;
 
-    // To limit dust spam, add base fee for each output less than a COIN
+    // To limit dust spam, add base fee for each output less than the (soft) dustlimit
     BOOST_FOREACH(const CTxOut& txout, vout)
-        if (txout.IsDust(::minRelayTxFeeRate))
+        if (txout.IsDust(dustLimit))
             nFee += baseFeeRate.GetFeePerK();
 
     return nFee;
diff --git a/src/dogecoin-fees.h b/src/dogecoin-fees.h
index b8f98b69b..447761490 100644
--- a/src/dogecoin-fees.h
+++ b/src/dogecoin-fees.h
@@ -28,6 +28,6 @@ CFeeRate GetDogecoinWalletFeeRate();
 CAmount GetDogecoinMinWalletFee(unsigned int nBytes_);
 #endif // ENABLE_WALLET
 CAmount GetDogecoinMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool fAllowFree);
-CAmount GetDogecoinDustFee(const std::vector<CTxOut> &vout, CFeeRate &baseFeeRate);
+CAmount GetDogecoinDustFee(const std::vector<CTxOut> &vout, const CAmount dustLimit, CFeeRate &baseFeeRate);
 
 #endif // BITCOIN_DOGECOIN_FEES_H
diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index 506eb6f17..85d03a52a 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -105,7 +105,7 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnes
         else if ((whichType == TX_MULTISIG) && (!fIsBareMultisigStd)) {
             reason = "bare-multisig";
             return false;
-        } else if (txout.IsDust(dustRelayFee)) {
+        } else if (txout.IsDust(nDustLimit)) {
             reason = "dust";
             return false;
         }
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 63e34697a..26c12a83c 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -206,6 +206,15 @@ public:
         return (nValue < GetDustThreshold(minRelayTxFeeRate));
     }
 
+    // Dogecoin: allow comparison against different dustlimit parameters
+    bool IsDust(const CAmount dustLimit) const
+    {
+      if (scriptPubKey.IsUnspendable())
+          return false;
+
+      return (nValue < dustLimit);
+    }
+
     friend bool operator==(const CTxOut& a, const CTxOut& b)
     {
         return (a.nValue       == b.nValue &&
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 1beeb4362..45639b11c 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2853,7 +2853,7 @@ bool CWallet::AddAccountingEntry(const CAccountingEntry& acentry, CWalletDB *pwa
 CAmount CWallet::GetRequiredFee(const CMutableTransaction& tx, unsigned int nTxBytes)
 {
     // Dogecoin: Add an increased fee for each dust output
-    return std::max(minTxFee.GetFee(nTxBytes) + GetDogecoinDustFee(tx.vout, minTxFee), ::minRelayTxFeeRate.GetFee(nTxBytes));
+    return std::max(minTxFee.GetFee(nTxBytes) + GetDogecoinDustFee(tx.vout, nDustLimit, minTxFee), ::minRelayTxFeeRate.GetFee(nTxBytes));
 }
 
 CAmount CWallet::GetRequiredFee(unsigned int nTxBytes)