Any asset fee feature

src/Makefile.am

@@ -154,6 +154,7 @@ BITCOIN_CORE_H = \
   deploymentinfo.h \
   deploymentstatus.h \
   dynafed.h \
+  exchangerates.h \
   external_signer.h \
   flatfile.h \
   fs.h \
@@ -355,6 +356,7 @@ libbitcoin_node_a_SOURCES = \
   dynafed.cpp \
   dbwrapper.cpp \
   deploymentstatus.cpp \
+  exchangerates.cpp \
   flatfile.cpp \
   httprpc.cpp \
   httpserver.cpp \
@@ -390,6 +392,7 @@ libbitcoin_node_a_SOURCES = \
   primitives/pak.cpp \
   rest.cpp \
   rpc/blockchain.cpp \
+  rpc/exchangerates.cpp \
   rpc/mining.cpp \
   rpc/misc.cpp \
   rpc/net.cpp \

src/bench/mempool_eviction.cpp

@@ -18,7 +18,7 @@ static void AddTx(const CTransactionRef& tx, const CAmount& nFee, CTxMemPool& po
     LockPoints lp;
     std::set<std::pair<uint256, COutPoint>> setPeginsSpent;
     pool.addUnchecked(CTxMemPoolEntry(
-        tx, nFee, nTime, nHeight,
+        tx, nFee, ::policyAsset, nFee, nTime, nHeight,
         spendsCoinbase, sigOpCost, lp, setPeginsSpent));
 }
 

src/bench/mempool_stress.cpp

@@ -18,7 +18,7 @@ static void AddTx(const CTransactionRef& tx, CTxMemPool& pool) EXCLUSIVE_LOCKS_R
     unsigned int sigOpCost = 4;
     std::set<std::pair<uint256, COutPoint>> setPeginsSpent;
     LockPoints lp;
-    pool.addUnchecked(CTxMemPoolEntry(tx, 1000, nTime, nHeight, spendsCoinbase, sigOpCost, lp, setPeginsSpent));
+    pool.addUnchecked(CTxMemPoolEntry(tx, 1000, ::policyAsset, 1000, nTime, nHeight, spendsCoinbase, sigOpCost, lp, setPeginsSpent));
 }
 
 struct Available {

src/bench/rpc_mempool.cpp

@@ -13,7 +13,7 @@ static void AddTx(const CTransactionRef& tx, const CAmount& fee, CTxMemPool& poo
 {
     LockPoints lp;
     std::set<std::pair<uint256, COutPoint> > setPeginsSpent;
-    pool.addUnchecked(CTxMemPoolEntry(tx, fee, /*time=*/0, /*entry_height=*/1, /*spends_coinbase=*/false, /*sigops_cost=*/4, lp, setPeginsSpent));
+    pool.addUnchecked(CTxMemPoolEntry(tx, fee, ::policyAsset, fee, /*time=*/0, /*entry_height=*/1, /*spends_coinbase=*/false, /*sigops_cost=*/4, lp, setPeginsSpent));
 }
 
 static void RpcMempool(benchmark::Bench& bench)

src/exchangerates.cpp

@@ -0,0 +1,62 @@
+#include <assetsdir.h>
+#include <exchangerates.h>
+#include <policy/policy.h>
+#include <univalue.h>
+
+#include <fstream>
+
+CAmount ExchangeRateMap::CalculateExchangeValue(const CAmount& amount, const CAsset& asset) {
+    auto it = this->find(asset);
+    if (it == this->end()) {
+        return 0;
+    }
+    auto scaled_value = it->second.m_scaled_value;
+    __uint128_t value = ((__uint128_t)amount * (__uint128_t)scaled_value) / (__uint128_t)exchange_rate_scale;
+    if (value > UINT64_MAX) {
+        return UINT64_MAX;
+    } else {
+        return (uint64_t) value;
+    }
+}
+
+bool ExchangeRateMap::LoadExchangeRatesFromJSONFile(fs::path file_path, std::string& error) {
+    // Read config file
+    std::ifstream ifs(file_path);
+    if (!ifs.is_open()) {
+        error = "Failed to open file";
+        return false;
+    }
+    std::stringstream buffer;
+    buffer << ifs.rdbuf();
+
+    // Parse as JSON
+    std::string rawJson = buffer.str();
+    UniValue json;
+    if (!json.read(rawJson)) {
+        error = "Cannot parse JSON";
+        return false;
+    }
+    std::map<std::string, UniValue> assetMap;
+    json.getObjMap(assetMap);
+
+    // Load exchange rates into map
+    this->clear();
+    for (auto assetEntry : assetMap) {
+        auto assetIdentifier = assetEntry.first;
+        auto assetData = assetEntry.second;
+        CAsset asset = GetAssetFromString(assetIdentifier);
+        if (asset.IsNull()) {
+            error = strprintf("Unknown label and invalid asset hex: %s", assetIdentifier);
+            return false;
+        }
+        CAmount exchangeRateValue;
+        if (assetData.isNum()) {
+            exchangeRateValue = assetData.get_int64();
+        } else {
+            error = strprintf("Invalid value for asset %s: %d", assetIdentifier, assetData.getValStr());
+            return false;
+        }
+        (*this)[asset] = exchangeRateValue;
+    }
+    return true;
+}

src/exchangerates.h

@@ -0,0 +1,53 @@
+
+#ifndef BITCOIN_EXCHANGERATES_H
+#define BITCOIN_EXCHANGERATES_H
+
+#include <fs.h>
+#include <policy/policy.h>
+
+constexpr const CAmount exchange_rate_scale = COIN;
+
+class CAssetExchangeRate
+{
+public:
+    /** Fee rate. */
+    CAmount m_scaled_value;
+
+    CAssetExchangeRate() : m_scaled_value(0) { }
+    CAssetExchangeRate(CAmount amount) : m_scaled_value(amount) { }
+    CAssetExchangeRate(uint64_t amount) : m_scaled_value(amount) { }
+};
+
+class ExchangeRateMap : public std::map<CAsset, CAssetExchangeRate>
+{
+private:
+    ExchangeRateMap() {}
+    ExchangeRateMap(const CAmount& default_asset_rate) {
+        (*this)[::policyAsset] = default_asset_rate;
+    }
+public:
+    static ExchangeRateMap& GetInstance() {
+        static ExchangeRateMap instance(exchange_rate_scale); // Guaranteed to be destroyed and instantiated only once
+        return instance;
+    }
+
+    /**
+     * Calculate the exchange value
+     *
+     * @param[in]   amount       Corresponds to CTxMemPoolEntry.nFeeAmount
+     * @param[in]   asset        Corresponds to CTxMemPoolEntry.nFeeAsset
+     * @return the value at current exchange rate. Corresponds to CTxMemPoolEntry.nFee
+     */
+    CAmount CalculateExchangeValue(const CAmount& amount, const CAsset& asset);
+
+    /**
+     * Populate the exchange rate map using a config file.
+     *
+     * @param[in]   file_path     File path to INI config file where keys are asset labels and values are exchange rates.
+     * @param[in]   error         String reference for storing error message, if there is any.
+     * @return true on success
+     */
+    bool LoadExchangeRatesFromJSONFile(fs::path file_path, std::string& error);
+};
+
+#endif // BITCOIN_EXCHANGERATES_H

src/init.cpp

@@ -17,6 +17,7 @@
 #include <compat/sanity.h>
 #include <consensus/amount.h>
 #include <deploymentstatus.h>
+#include <exchangerates.h>
 #include <fs.h>
 #include <hash.h>
 #include <httprpc.h>
@@ -640,6 +641,9 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-initialreissuancetokens=<n>", "The amount of reissuance tokens created in the genesis block. (default: 0)", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-ct_bits", strprintf("The default number of hiding bits in a rangeproof. Will be exceeded to cover amounts exceeding the maximum hiding value. (default: %d)", 52), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-ct_exponent", strprintf("The hiding exponent. (default: %s)", 0), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-con_any_asset_fees", "Enable transation sees to be paid with any asset (default: false)", ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
+    argsman.AddArg("-exchangeratesjsonfile=<file>", strprintf("Specify path to read-only configuration file with asset valuations. Only used when con_any_asset_fees is enabled. Relative paths will be prefixed by datadir location. (default: %s)", "exchangerates.json"), ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
+
 
 #if defined(USE_SYSCALL_SANDBOX)
     argsman.AddArg("-sandbox=<mode>", "Use the experimental syscall sandbox in the specified mode (-sandbox=log-and-abort or -sandbox=abort). Allow only expected syscalls to be used by bitcoind. Note that this is an experimental new feature that may cause bitcoind to exit or crash unexpectedly: use with caution. In the \"log-and-abort\" mode the invocation of an unexpected syscall results in a debug handler being invoked which will log the incident and terminate the program (without executing the unexpected syscall). In the \"abort\" mode the invocation of an unexpected syscall results in the entire process being killed immediately by the kernel without executing the unexpected syscall.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
@@ -1326,8 +1330,22 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
 #endif
 
     // ELEMENTS:
+    g_con_any_asset_fees = gArgs.GetBoolArg("-con_any_asset_fees", false);
+    if (g_con_any_asset_fees) {
+        // If fees can be paid in any asset, node operators need to be able to specify asset exchange 
+        // rates using either the static config file and/or the exchange rates RPCs.
+        RegisterExchangeRatesRPCCommands(tableRPC);
+        std::string file_path_string = gArgs.GetArg("-exchangeratesjsonfile", "");
+        if (!file_path_string.empty()) {
+            fs::path file_path = AbsPathForConfigVal(fs::PathFromString(file_path_string));
+            std::string error;
+            if (!ExchangeRateMap::GetInstance().LoadExchangeRatesFromJSONFile(file_path, error)) {
+                return InitError(strprintf(_("Unable to load exchange rates from JSON file %s: %s"), file_path_string, error));
+            };
+        }
+    }
     policyAsset = CAsset(uint256S(gArgs.GetArg("-feeasset", chainparams.GetConsensus().pegged_asset.GetHex())));
-
+    
     /* Start the RPC server already.  It will be started in "warmup" mode
      * and not really process calls already (but it will signify connections
      * that the server is there and will be ready later).  Warmup mode will

src/node/interfaces.cpp

@@ -612,7 +612,7 @@ class ChainImpl : public Chain
         if (!m_node.mempool) return true;
         LockPoints lp;
         std::set<std::pair<uint256, COutPoint>> setPeginsSpent;
-        CTxMemPoolEntry entry(tx, 0, 0, 0, false, 0, lp, setPeginsSpent);
+        CTxMemPoolEntry entry(tx, 0, ::policyAsset, 0, 0, 0, false, 0, lp, setPeginsSpent);
         CTxMemPool::setEntries ancestors;
         auto limit_ancestor_count = gArgs.GetIntArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
         auto limit_ancestor_size = gArgs.GetIntArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT) * 1000;

src/node/miner.cpp

@@ -114,7 +114,7 @@ void BlockAssembler::resetBlock()
 
     // These counters do not include coinbase tx
     nBlockTx = 0;
-    nFees = 0;
+    feeMap = CAmountMap();
 }
 
 std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn, std::chrono::seconds min_tx_age, DynaFedParamEntry* proposed_entry, const std::vector<CScript>* commit_scripts)
@@ -193,21 +193,38 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     CMutableTransaction coinbaseTx;
     coinbaseTx.vin.resize(1);
     coinbaseTx.vin[0].prevout.SetNull();
-    coinbaseTx.vout.resize(1);
-    coinbaseTx.vout[0].scriptPubKey = scriptPubKeyIn;
-    coinbaseTx.vout[0].nAsset = policyAsset;
-    coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
-    if (g_con_elementsmode) {
-        if(chainparams.GetConsensus().subsidy_asset != policyAsset) {
-            // Only claim the subsidy if it's the same as the policy asset.
-            coinbaseTx.vout[0].nValue = nFees;
+    coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
+    if (feeMap.size() == 0) {
+        feeMap[::policyAsset] = 0;
+    }
+    int index = 0;
+    for (auto& fee : feeMap) {
+        auto& feeAsset = fee.first;
+        auto& feeAmount = fee.second;
+        if (!g_con_any_asset_fees && feeAsset != ::policyAsset) {
+            continue;
+        }
+        CTxOut newTxOut;
+        newTxOut.scriptPubKey = scriptPubKeyIn;
+        newTxOut.nAsset = feeAsset;
+        newTxOut.nValue = feeAmount;
+        if (feeAsset == chainparams.GetConsensus().subsidy_asset) {
+            newTxOut.nValue = feeAmount + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
         }
-        // 0-value outputs must be unspendable
-        if (coinbaseTx.vout[0].nValue.GetAmount() == 0) {
-            coinbaseTx.vout[0].scriptPubKey = CScript() << OP_RETURN;
+        if (g_con_elementsmode) {
+            if (chainparams.GetConsensus().subsidy_asset != policyAsset) {
+                // Only claim the subsidy if it's the same as the policy asset.
+                newTxOut.nValue = feeAmount;
+            }
+            // 0-value outputs must be unspendable
+            if (newTxOut.nValue.GetAmount() == 0) {
+                newTxOut.scriptPubKey = CScript() << OP_RETURN;
+            }
         }
+        coinbaseTx.vout.push_back(newTxOut);
+        pblocktemplate->vTxFees[index] = -feeAmount;
+        index++;
     }
-    coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
     // Non-consensus commitment output before finishing coinbase transaction
     if (commit_scripts && !commit_scripts->empty()) {
         for (auto commit_script: *commit_scripts) {
@@ -216,9 +233,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     }
     pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx));
     pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev, chainparams.GetConsensus());
-    pblocktemplate->vTxFees[0] = -nFees;
-
-    LogPrintf("CreateNewBlock(): block weight: %u txs: %u fees: %ld sigops %d\n", GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost);
+    LogPrintf("CreateNewBlock(): block weight: %u txs: %u fees: %s sigops %d\n", GetBlockWeight(*pblock), nBlockTx, feeMap, nBlockSigOpsCost);
 
     // Fill in header
     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
@@ -290,7 +305,7 @@ void BlockAssembler::AddToBlock(CTxMemPool::txiter iter)
     nBlockWeight += iter->GetTxWeight();
     ++nBlockTx;
     nBlockSigOpsCost += iter->GetSigOpCost();
-    nFees += iter->GetFee();
+    feeMap[iter->GetFeeAsset()] += iter->GetFeeAmount();
     inBlock.insert(iter);
 
     bool fPrintPriority = gArgs.GetBoolArg("-printpriority", DEFAULT_PRINTPRIORITY);

src/node/miner.h

@@ -140,7 +140,7 @@ class BlockAssembler
     uint64_t nBlockWeight;
     uint64_t nBlockTx;
     uint64_t nBlockSigOpsCost;
-    CAmount nFees;
+    CAmountMap feeMap;
     CTxMemPool::setEntries inBlock;
 
     // Chain context for the block

src/primitives/transaction.cpp

@@ -13,6 +13,7 @@
 #include <assert.h>
 
 bool g_con_elementsmode = false;
+bool g_con_any_asset_fees = false;
 
 const int32_t CTransaction::CURRENT_VERSION = 2;
 

src/primitives/transaction.h

@@ -27,6 +27,7 @@ static const int SERIALIZE_TRANSACTION_NO_WITNESS = 0x40000000;
 // ELEMENTS:
 // Globals to avoid circular dependencies.
 extern bool g_con_elementsmode;
+extern bool g_con_any_asset_fees;
 
 /** An outpoint - a combination of a transaction hash and an index n into its vout */
 class COutPoint

src/rpc/client.cpp

@@ -241,6 +241,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "calculateasset", 3, "blind_reissuance" },
     { "updatepsbtpegin", 1, "input" },
     { "updatepsbtpegin", 2, "value" },
+    { "setfeeexchangerates", 0, "rates"},
 
 };
 // clang-format on