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0.139238ecbPolicy: MOVEONLY: 3 functions to policy.o: (Luke Dashjr)627b9dePolicy: MOVEONLY: Create policy/policy.h with some constants (Jorge Timón)
Wladimir J. van der Laan
9 years ago
16 changed files with 250 additions and 214 deletions
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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// NOTE: This file is intended to be customised by the end user, and includes only local node policy logic
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#include "policy/policy.h" |
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#include "main.h" |
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#include "tinyformat.h" |
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#include "util.h" |
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#include "utilstrencodings.h" |
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#include <boost/foreach.hpp> |
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/**
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* Check transaction inputs to mitigate two |
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* potential denial-of-service attacks: |
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* |
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* 1. scriptSigs with extra data stuffed into them, |
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* not consumed by scriptPubKey (or P2SH script) |
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* 2. P2SH scripts with a crazy number of expensive |
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* CHECKSIG/CHECKMULTISIG operations |
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* |
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* Check transaction inputs, and make sure any |
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* pay-to-script-hash transactions are evaluating IsStandard scripts |
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* |
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* Why bother? To avoid denial-of-service attacks; an attacker |
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* can submit a standard HASH... OP_EQUAL transaction, |
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* which will get accepted into blocks. The redemption |
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* script can be anything; an attacker could use a very |
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* expensive-to-check-upon-redemption script like: |
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* DUP CHECKSIG DROP ... repeated 100 times... OP_1 |
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*/ |
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bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType) |
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{ |
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std::vector<std::vector<unsigned char> > vSolutions; |
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if (!Solver(scriptPubKey, whichType, vSolutions)) |
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return false; |
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if (whichType == TX_MULTISIG) |
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{ |
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unsigned char m = vSolutions.front()[0]; |
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unsigned char n = vSolutions.back()[0]; |
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// Support up to x-of-3 multisig txns as standard
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if (n < 1 || n > 3) |
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return false; |
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if (m < 1 || m > n) |
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return false; |
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} |
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return whichType != TX_NONSTANDARD; |
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} |
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bool IsStandardTx(const CTransaction& tx, std::string& reason) |
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{ |
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if (tx.nVersion > CTransaction::CURRENT_VERSION || tx.nVersion < 1) { |
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reason = "version"; |
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return false; |
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} |
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// Extremely large transactions with lots of inputs can cost the network
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// almost as much to process as they cost the sender in fees, because
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// computing signature hashes is O(ninputs*txsize). Limiting transactions
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// to MAX_STANDARD_TX_SIZE mitigates CPU exhaustion attacks.
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unsigned int sz = tx.GetSerializeSize(SER_NETWORK, CTransaction::CURRENT_VERSION); |
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if (sz >= MAX_STANDARD_TX_SIZE) { |
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reason = "tx-size"; |
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return false; |
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} |
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BOOST_FOREACH(const CTxIn& txin, tx.vin) |
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{ |
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// Biggest 'standard' txin is a 15-of-15 P2SH multisig with compressed
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// keys. (remember the 520 byte limit on redeemScript size) That works
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// out to a (15*(33+1))+3=513 byte redeemScript, 513+1+15*(73+1)+3=1627
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// bytes of scriptSig, which we round off to 1650 bytes for some minor
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// future-proofing. That's also enough to spend a 20-of-20
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// CHECKMULTISIG scriptPubKey, though such a scriptPubKey is not
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// considered standard)
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if (txin.scriptSig.size() > 1650) { |
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reason = "scriptsig-size"; |
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return false; |
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} |
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if (!txin.scriptSig.IsPushOnly()) { |
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reason = "scriptsig-not-pushonly"; |
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return false; |
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} |
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} |
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unsigned int nDataOut = 0; |
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txnouttype whichType; |
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BOOST_FOREACH(const CTxOut& txout, tx.vout) { |
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if (!::IsStandard(txout.scriptPubKey, whichType)) { |
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reason = "scriptpubkey"; |
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return false; |
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} |
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if (whichType == TX_NULL_DATA) |
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nDataOut++; |
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else if ((whichType == TX_MULTISIG) && (!fIsBareMultisigStd)) { |
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reason = "bare-multisig"; |
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return false; |
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} else if (txout.IsDust(::minRelayTxFee)) { |
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reason = "dust"; |
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return false; |
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} |
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} |
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// only one OP_RETURN txout is permitted
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if (nDataOut > 1) { |
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reason = "multi-op-return"; |
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return false; |
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} |
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return true; |
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} |
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bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs) |
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{ |
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if (tx.IsCoinBase()) |
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return true; // Coinbases don't use vin normally
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for (unsigned int i = 0; i < tx.vin.size(); i++) |
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{ |
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const CTxOut& prev = mapInputs.GetOutputFor(tx.vin[i]); |
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std::vector<std::vector<unsigned char> > vSolutions; |
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txnouttype whichType; |
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// get the scriptPubKey corresponding to this input:
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const CScript& prevScript = prev.scriptPubKey; |
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if (!Solver(prevScript, whichType, vSolutions)) |
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return false; |
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int nArgsExpected = ScriptSigArgsExpected(whichType, vSolutions); |
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if (nArgsExpected < 0) |
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return false; |
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// Transactions with extra stuff in their scriptSigs are
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// non-standard. Note that this EvalScript() call will
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// be quick, because if there are any operations
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// beside "push data" in the scriptSig
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// IsStandardTx() will have already returned false
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// and this method isn't called.
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std::vector<std::vector<unsigned char> > stack; |
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if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker())) |
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return false; |
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if (whichType == TX_SCRIPTHASH) |
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{ |
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if (stack.empty()) |
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return false; |
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CScript subscript(stack.back().begin(), stack.back().end()); |
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std::vector<std::vector<unsigned char> > vSolutions2; |
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txnouttype whichType2; |
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if (Solver(subscript, whichType2, vSolutions2)) |
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{ |
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int tmpExpected = ScriptSigArgsExpected(whichType2, vSolutions2); |
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if (tmpExpected < 0) |
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return false; |
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nArgsExpected += tmpExpected; |
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} |
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else |
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{ |
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// Any other Script with less than 15 sigops OK:
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unsigned int sigops = subscript.GetSigOpCount(true); |
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// ... extra data left on the stack after execution is OK, too:
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return (sigops <= MAX_P2SH_SIGOPS); |
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} |
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} |
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if (stack.size() != (unsigned int)nArgsExpected) |
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return false; |
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} |
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return true; |
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} |
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@ -0,0 +1,58 @@
@@ -0,0 +1,58 @@
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_POLICY_H |
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#define BITCOIN_POLICY_H |
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#include "consensus/consensus.h" |
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#include "script/interpreter.h" |
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#include "script/standard.h" |
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#include <string> |
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class CCoinsViewCache; |
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/** Default for -blockmaxsize and -blockminsize, which control the range of sizes the mining code will create **/ |
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static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000; |
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static const unsigned int DEFAULT_BLOCK_MIN_SIZE = 0; |
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/** Default for -blockprioritysize, maximum space for zero/low-fee transactions **/ |
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static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 50000; |
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/** The maximum size for transactions we're willing to relay/mine */ |
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static const unsigned int MAX_STANDARD_TX_SIZE = 100000; |
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/** Maximum number of signature check operations in an IsStandard() P2SH script */ |
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static const unsigned int MAX_P2SH_SIGOPS = 15; |
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/** The maximum number of sigops we're willing to relay/mine in a single tx */ |
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static const unsigned int MAX_STANDARD_TX_SIGOPS = MAX_BLOCK_SIGOPS/5; |
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/**
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* Standard script verification flags that standard transactions will comply |
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* with. However scripts violating these flags may still be present in valid |
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* blocks and we must accept those blocks. |
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*/ |
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static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS | |
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SCRIPT_VERIFY_DERSIG | |
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SCRIPT_VERIFY_STRICTENC | |
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SCRIPT_VERIFY_MINIMALDATA | |
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SCRIPT_VERIFY_NULLDUMMY | |
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SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS | |
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SCRIPT_VERIFY_CLEANSTACK | |
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SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY; |
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/** For convenience, standard but not mandatory verify flags. */ |
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static const unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS; |
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bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType); |
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/**
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* Check for standard transaction types |
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* @return True if all outputs (scriptPubKeys) use only standard transaction forms |
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*/ |
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bool IsStandardTx(const CTransaction& tx, std::string& reason); |
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/**
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* Check for standard transaction types |
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* @param[in] mapInputs Map of previous transactions that have outputs we're spending |
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* @return True if all inputs (scriptSigs) use only standard transaction forms |
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*/ |
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bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs); |
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#endif // BITCOIN_POLICY_H
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