Merge #1499: ELIP 202: Implementation of optional sidechain peg-in subsidy and minimum peg-in amount

a18a88b grammar: prefer peg-in to pegin in messages (Byron Hambly)
90b2b3b test: add pegin subsidy functional test (Byron Hambly)
186bb25 validation: check for peg-in subsidy and minimum (Byron Hambly)
51c89c6 subsidy: implementation for claimpegin, createrawpegin, and RPCs (Byron Hambly)
94cde59 subsidy: add chainparams and init (Byron Hambly)
f3b63f4 DecomposePeginWitness: fix deserialization flags for MerkleBlock proof (Byron Hambly)

Pull request description:

  Implementation for [ELIP 202](https://github.com/ElementsProject/ELIPs/blob/main/elip-0202.mediawiki)

ACKs for top commit:
  jsarenik:
    Running ACK a18a88b
  tomt1664:
    Tested ACK a18a88b

Tree-SHA512: 984fe2aa32e6814e14c9535e9fea7e03d3b6cf7a35621ccfb2a081a6ebab01906c5e883c5b505ced53f254401d30b6e975cb05e88efc8d3fbedc79abd0be72a2

Author: psgreco

src/chainparams.cpp

@@ -7,12 +7,13 @@
 
 #include <chainparamsseeds.h>
 #include <consensus/merkle.h>
+#include <crypto/sha256.h>
 #include <deploymentinfo.h>
 #include <hash.h> // for signet block challenge hash
 #include <issuance.h>
 #include <primitives/transaction.h>
+#include <util/moneystr.h>
 #include <util/system.h>
-#include <crypto/sha256.h>
 
 #include <assert.h>
 
@@ -232,6 +233,8 @@ class CMainParams : public CChainParams {
         multi_data_permitted = false;
         accept_discount_ct = false;
         create_discount_ct = false;
+        pegin_subsidy = PeginSubsidy();
+        pegin_minimum = PeginMinimum();
         consensus.has_parent_chain = false;
         g_signed_blocks = false;
         g_con_elementsmode = false;
@@ -379,6 +382,8 @@ class CTestNetParams : public CChainParams {
         multi_data_permitted = false;
         accept_discount_ct = false;
         create_discount_ct = false;
+        pegin_subsidy = PeginSubsidy();
+        pegin_minimum = PeginMinimum();
         consensus.has_parent_chain = false;
         g_signed_blocks = false;
         g_con_elementsmode = false;
@@ -544,6 +549,8 @@ class SigNetParams : public CChainParams {
         multi_data_permitted = false;
         accept_discount_ct = false;
         create_discount_ct = false;
+        pegin_subsidy = PeginSubsidy();
+        pegin_minimum = PeginMinimum();
         consensus.has_parent_chain = false;
         g_signed_blocks = false; // lol
         g_con_elementsmode = false;
@@ -648,6 +655,8 @@ class CRegTestParams : public CChainParams {
         multi_data_permitted = false;
         accept_discount_ct = false;
         create_discount_ct = false;
+        pegin_subsidy = PeginSubsidy();
+        pegin_minimum = PeginMinimum();
         consensus.has_parent_chain = false;
         g_signed_blocks = false;
         g_con_elementsmode = false;
@@ -792,6 +801,39 @@ void CRegTestParams::UpdateActivationParametersFromArgs(const ArgsManager& args)
     }
 }
 
+// ELEMENTS
+PeginSubsidy ParsePeginSubsidy(const ArgsManager& args) {
+    PeginSubsidy pegin_subsidy;
+
+    pegin_subsidy.height = args.GetIntArg("-peginsubsidyheight", std::numeric_limits<int>::max());
+    if (pegin_subsidy.height < 0) {
+        throw std::runtime_error(strprintf("Invalid block height (%d) for -peginsubsidyheight. Must be positive.", pegin_subsidy.height));
+    }
+    if (std::optional<CAmount> amount = ParseMoney(args.GetArg("-peginsubsidythreshold", "0"))) {
+        pegin_subsidy.threshold = amount.value();
+    } else {
+        throw std::runtime_error("Invalid -peginsubsidythreshold");
+    }
+
+    return pegin_subsidy;
+};
+
+PeginMinimum ParsePeginMinimum(const ArgsManager& args) {
+    PeginMinimum pegin_minimum;
+
+    pegin_minimum.height = args.GetIntArg("-peginminheight", std::numeric_limits<int>::max());
+    if (pegin_minimum.height < 0) {
+        throw std::runtime_error(strprintf("Invalid block height (%d) for -peginminheight. Must be positive.", pegin_minimum.height));
+    }
+    if (std::optional<CAmount> amount = ParseMoney(args.GetArg("-peginminamount", "0"))) {
+        pegin_minimum.amount = amount.value();
+    } else {
+        throw std::runtime_error("Invalid -peginminamount");
+    }
+
+    return pegin_minimum;
+};
+
 /**
  * Custom params for testing.
  */
@@ -932,6 +974,11 @@ class CCustomParams : public CRegTestParams {
         consensus.start_p2wsh_script = args.GetIntArg("-con_start_p2wsh_script", consensus.start_p2wsh_script);
         create_discount_ct = args.GetBoolArg("-creatediscountct", create_discount_ct);
         accept_discount_ct = args.GetBoolArg("-acceptdiscountct", accept_discount_ct) || create_discount_ct;
+        pegin_subsidy = ParsePeginSubsidy(args);
+        pegin_minimum = ParsePeginMinimum(args);
+        if (pegin_subsidy.threshold < pegin_minimum.amount) {
+            throw std::runtime_error(strprintf("Peg-in subsidy threshold (%s) must be greater than or equal to peg-in minimum amount (%s)", FormatMoney(pegin_subsidy.threshold), FormatMoney(pegin_minimum.amount)));
+        }
 
         // Calculate pegged Bitcoin asset
         std::vector<unsigned char> commit = CommitToArguments(consensus, strNetworkID);
@@ -1178,6 +1225,11 @@ class CLiquidV1Params : public CChainParams {
         multi_data_permitted = true;
         create_discount_ct = args.GetBoolArg("-creatediscountct", false);
         accept_discount_ct = args.GetBoolArg("-acceptdiscountct", true) || create_discount_ct;
+        pegin_subsidy = ParsePeginSubsidy(args);
+        pegin_minimum = ParsePeginMinimum(args);
+        if (pegin_subsidy.threshold < pegin_minimum.amount) {
+            throw std::runtime_error(strprintf("Peg-in subsidy threshold (%s) must be greater than or equal to peg-in minimum amount (%s)", FormatMoney(pegin_subsidy.threshold), FormatMoney(pegin_minimum.amount)));
+        }
 
         parentGenesisBlockHash = uint256S("000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f");
         const bool parent_genesis_is_null = parentGenesisBlockHash == uint256();
@@ -1538,6 +1590,11 @@ class CLiquidV1TestParams : public CLiquidV1Params {
         multi_data_permitted = args.GetBoolArg("-multi_data_permitted", multi_data_permitted);
         create_discount_ct = args.GetBoolArg("-creatediscountct", create_discount_ct);
         accept_discount_ct = args.GetBoolArg("-acceptdiscountct", accept_discount_ct) || create_discount_ct;
+        pegin_subsidy = ParsePeginSubsidy(args);
+        pegin_minimum = ParsePeginMinimum(args);
+        if (pegin_subsidy.threshold < pegin_minimum.amount) {
+            throw std::runtime_error(strprintf("Peg-in subsidy threshold (%s) must be greater than or equal to peg-in minimum amount (%s)", FormatMoney(pegin_subsidy.threshold), FormatMoney(pegin_minimum.amount)));
+        }
 
         if (args.IsArgSet("-parentgenesisblockhash")) {
             parentGenesisBlockHash = uint256S(args.GetArg("-parentgenesisblockhash", ""));

src/chainparams.h

@@ -28,6 +28,27 @@ struct CCheckpointData {
     }
 };
 
+// ELEMENTS
+struct PeginSubsidy {
+    int height{std::numeric_limits<int>::max()};
+    CAmount threshold{0};
+
+    PeginSubsidy() {};
+    bool IsDefined() {
+        return threshold > 0 || height < std::numeric_limits<int>::max();
+    };
+};
+
+struct PeginMinimum {
+    int height{std::numeric_limits<int>::max()};
+    CAmount amount{0};
+
+    PeginMinimum() {};
+    bool IsDefined() {
+        return amount > 0 || height < std::numeric_limits<int>::max();
+    };
+};
+
 struct AssumeutxoHash : public BaseHash<uint256> {
     explicit AssumeutxoHash(const uint256& hash) : BaseHash(hash) {}
 };
@@ -138,6 +159,8 @@ class CChainParams
     bool GetMultiDataPermitted() const { return multi_data_permitted; }
     bool GetAcceptDiscountCT() const { return accept_discount_ct; }
     bool GetCreateDiscountCT() const { return create_discount_ct; }
+    PeginSubsidy GetPeginSubsidy() const { return pegin_subsidy; }
+    PeginMinimum GetPeginMinimum() const { return pegin_minimum; }
 
 protected:
     CChainParams() {}
@@ -173,6 +196,8 @@ class CChainParams
     bool multi_data_permitted;
     bool accept_discount_ct;
     bool create_discount_ct;
+    PeginSubsidy pegin_subsidy;
+    PeginMinimum pegin_minimum;
 };
 
 /**

src/dynafed.cpp

@@ -123,3 +123,34 @@ DynaFedParamEntry ComputeNextBlockCurrentParameters(const CBlockIndex* pindexPre
     }
 }
 
+bool ParseFedPegQuorum(const CScript& fedpegscript, int& t, int& n) {
+    CScript::const_iterator it = fedpegscript.begin();
+    std::vector<unsigned char> vch;
+    opcodetype opcode;
+
+    // parse the required threshold number
+    if (!fedpegscript.GetOp(it, opcode, vch)) return false;
+    t = CScript::DecodeOP_N(opcode);
+    if (t < 1 || t > MAX_PUBKEYS_PER_MULTISIG) return false;
+
+    // support a fedpegscript like OP_TRUE if we're at the end of the script
+    if (it == fedpegscript.end()) return true;
+
+    // count the pubkeys
+    int pubkeys = 0;
+    while (fedpegscript.GetOp(it, opcode, vch)) {
+        if (opcode != 0x21) break;
+        if (vch.size() != 33) return false;
+        pubkeys++;
+    }
+
+    // parse the total number of pubkeys
+    n = CScript::DecodeOP_N(opcode);
+    if (n < 1 || n > MAX_PUBKEYS_PER_MULTISIG || n < t) return false;
+    if (pubkeys != n) return false;
+
+    // the next opcode must be OP_CHECKMULTISIG
+    if (!fedpegscript.GetOp(it, opcode, vch)) return false;
+
+    return opcode == OP_CHECKMULTISIG;
+}

src/dynafed.h

@@ -15,5 +15,10 @@ DynaFedParamEntry ComputeNextBlockFullCurrentParameters(const CBlockIndex* pinde
  * publish signblockscript-related fields */
 DynaFedParamEntry ComputeNextBlockCurrentParameters(const CBlockIndex* pindexPrev, const Consensus::Params& consensus);
 
+/* Get the threshold (t) and maybe the total pubkeys (n) of the first OP_CHECKMULTISIG in the fedpegscript.
+ * Assumes the fedpegscript starts with the threshold, otherwise returns false.
+ * Uses CScript::DecodeOP_N, so only supports up to a threshold of 16, otherwise asserts.
+ * Supports a fedpegscript like OP_TRUE by returning early. */
+bool ParseFedPegQuorum(const CScript& fedpegscript, int& t, int& n);
 
 #endif // BITCOIN_DYNAFED_H

src/init.cpp

@@ -629,7 +629,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-mainchainrpcpassword=<pwd>", "The rpc password which the daemon will use to connect to the trusted mainchain daemon to validate peg-ins, if enabled. (default: cookie auth)", ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE, OptionsCategory::ELEMENTS);
     argsman.AddArg("-mainchainrpccookiefile=<file>", "The bitcoind cookie auth path which the daemon will use to connect to the trusted mainchain daemon to validate peg-ins. (default: `<datadir>/regtest/.cookie`)", ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
     argsman.AddArg("-mainchainrpctimeout=<n>", strprintf("Timeout in seconds during mainchain RPC requests, or 0 for no timeout. (default: %d)", DEFAULT_HTTP_CLIENT_TIMEOUT), ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
-    argsman.AddArg("-peginconfirmationdepth=<n>", strprintf("Pegin claims must be this deep to be considered valid. (default: %d)", DEFAULT_PEGIN_CONFIRMATION_DEPTH), ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
+    argsman.AddArg("-peginconfirmationdepth=<n>", strprintf("Peg-in claims must be this deep to be considered valid. (default: %d)", DEFAULT_PEGIN_CONFIRMATION_DEPTH), ArgsManager::ALLOW_ANY, OptionsCategory::ELEMENTS);
     argsman.AddArg("-parentpubkeyprefix", strprintf("The byte prefix, in decimal, of the parent chain's base58 pubkey address. (default: %d)", 111), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-parentscriptprefix", strprintf("The byte prefix, in decimal, of the parent chain's base58 script address. (default: %d)", 196), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-parent_bech32_hrp", strprintf("The human-readable part of the parent chain's bech32 encoding. (default: %s)", "bc"), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
@@ -642,6 +642,10 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-ct_exponent", strprintf("The hiding exponent. (default: %s)", 0), ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-acceptdiscountct", "Accept discounted fees for Confidential Transactions (default: 1 in liquidtestnet and liquidv1, 0 otherwise)", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-creatediscountct", "Create Confidential Transactions with discounted fees (default: 0). Setting this to 1 will also set 'acceptdiscountct' to 1.", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-peginsubsidyheight", "The block height at which peg-in transactions must have a burn subsidy (default: not active). The subsidy is an OP_RETURN output, with its value equal to the feerate of the parent transaction multiplied by the vsize of spending the P2WSH output created by the peg-in (feerate * 396 sats for liquidv1). ", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-peginsubsidythreshold", "The output value below which peg-in transactions must have a burn subsidy (default: 0). Peg-ins above this value do not require the subsidy.", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-peginminheight", "The block height at which a minimum peg-in value is enforced (default: not active).", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-peginminamount", "The minimum value for a peg-in transaction after peginminheight (default: unset).", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
 
 #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);
@@ -1964,7 +1968,7 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     if (gArgs.GetBoolArg("-validatepegin", Params().GetConsensus().has_parent_chain)) {
         uiInterface.InitMessage(_("Awaiting mainchain RPC warmup").translated);
         if (!MainchainRPCCheck()) {
-            const std::string err_msg = "ERROR: elements is set to verify pegins but cannot get a valid response from the mainchain daemon. Please check debug.log for more information.\n\nIf you haven't setup a bitcoind please get the latest stable version from https://bitcoincore.org/en/download/ or if you do not need to validate pegins set in your elements configuration validatepegin=0";
+            const std::string err_msg = "ERROR: elements is set to verify peg-ins but cannot get a valid response from the mainchain daemon. Please check debug.log for more information.\n\nIf you haven't setup a bitcoind please get the latest stable version from https://bitcoincore.org/en/download/ or if you do not need to validate peg-ins set in your elements configuration validatepegin=0";
             // We fail immediately if this node has RPC server enabled
             if (gArgs.GetBoolArg("-server", false)) {
                 InitError(Untranslated(err_msg));
@@ -1975,6 +1979,23 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
                 gArgs.SoftSetArg("-validatepegin", "0");
             }
         }
+        // if we are validating peg-in subsidy or minimum then we require bitcoind >= v25
+        if (Params().GetPeginSubsidy().IsDefined() || Params().GetPeginMinimum().IsDefined()) {
+            UniValue params(UniValue::VARR);
+            UniValue reply = CallMainChainRPC("getnetworkinfo", params);
+            if (reply["error"].isStr()) {
+                InitError(Untranslated(reply["error"].get_str()));
+                return false;
+            } else {
+                const int version = reply["result"]["version"].get_int();
+                const std::string& subversion = reply["result"]["subversion"].get_str();
+                if (version < 250000 && subversion.find("Satoshi") != std::string::npos) {
+                    const std::string err = strprintf("ERROR: parent bitcoind must be version 25 or newer for peg-in subsidy/minimum validation. Found version: %s", version);
+                    InitError(Untranslated(err));
+                    return false;
+                }
+            }
+        }
     }
 
     // Call ActivateBestChain every 30 seconds. This is almost always a

src/pegins.cpp

@@ -577,7 +577,7 @@ bool DecomposePeginWitness(const CScriptWitness& witness, CAmount& value, CAsset
         tx = elem_tx;
     }
 
-    CDataStream ss_proof(stack[5], SER_NETWORK, PROTOCOL_VERSION);
+    CDataStream ss_proof(stack[5], SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS);
     if (Params().GetConsensus().ParentChainHasPow()) {
         Sidechain::Bitcoin::CMerkleBlock tx_proof;
         ss_proof >> tx_proof;

src/rpc/blockchain.cpp

@@ -40,6 +40,7 @@
 #include <txdb.h>
 #include <txmempool.h>
 #include <undo.h>
+#include <util/moneystr.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <util/translation.h>
@@ -3134,6 +3135,25 @@ static RPCHelpMan getsidechaininfo()
         obj.pushKV("parent_chain_signblockscript_hex", HexStr(consensus.parent_chain_signblockscript));
         obj.pushKV("parent_pegged_asset", consensus.parent_pegged_asset.GetHex());
     }
+
+    PeginMinimum pegin_minimum = Params().GetPeginMinimum();
+    if (pegin_minimum.amount > 0) {
+        obj.pushKV("pegin_min_amount", FormatMoney(pegin_minimum.amount));
+    }
+    if (pegin_minimum.height < std::numeric_limits<int>::max()) {
+        obj.pushKV("pegin_min_height", pegin_minimum.height);
+        obj.pushKV("pegin_min_active", chainman.ActiveTip()->nHeight >= pegin_minimum.height);
+    }
+
+    PeginSubsidy pegin_subsidy = Params().GetPeginSubsidy();
+    if (pegin_subsidy.threshold > 0) {
+        obj.pushKV("pegin_subsidy_threshold", FormatMoney(pegin_subsidy.threshold));
+    }
+    if (pegin_subsidy.height < std::numeric_limits<int>::max()) {
+        obj.pushKV("pegin_subsidy_height", pegin_subsidy.height);
+        obj.pushKV("pegin_subsidy_active", chainman.ActiveTip()->nHeight >= pegin_subsidy.height);
+    }
+
     return obj;
 },
     };

src/rpc/client.cpp

@@ -239,6 +239,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "calculateasset", 3, "blind_reissuance" },
     { "updatepsbtpegin", 1, "input" },
     { "updatepsbtpegin", 2, "value" },
+    { "claimpegin", 3, "fee_rate" },
+    { "createrawpegin", 3, "fee_rate" },
 
 };
 // clang-format on