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Merge pull request #4365 from gavinandresen/relax_isstandard

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Relax IsStandard rules for pay-to-script-hash transactions
This commit is contained in:
Gavin Andresen
2014-06-27 10:53:24 -04:00
parent 4684c883bb 7f3b4e9569
commit 6259937388
3 changed files with 95 additions and 64 deletions
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43
src/main.cpp
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@@ -583,15 +583,13 @@ bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
}
//
// Check transaction inputs, and make sure any
// pay-to-script-hash transactions are evaluating IsStandard scripts
// Check transaction inputs to mitigate two
// potential denial-of-service attacks:
//
// Why bother? To avoid denial-of-service attacks; an attacker
// can submit a standard HASH... OP_EQUAL transaction,
// which will get accepted into blocks. The redemption
// script can be anything; an attacker could use a very
// expensive-to-check-upon-redemption script like:
// DUP CHECKSIG DROP ... repeated 100 times... OP_1
// 1. scriptSigs with extra data stuffed into them,
// not consumed by scriptPubKey (or P2SH script)
// 2. P2SH scripts with a crazy number of expensive
// CHECKSIG/CHECKMULTISIG operations
//
bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
{
@@ -615,8 +613,9 @@ bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
// Transactions with extra stuff in their scriptSigs are
// non-standard. Note that this EvalScript() call will
// be quick, because if there are any operations
// beside "push data" in the scriptSig the
// IsStandard() call returns false
// beside "push data" in the scriptSig
// IsStandard() will have already returned false
// and this method isn't called.
vector<vector<unsigned char> > stack;
if (!EvalScript(stack, tx.vin[i].scriptSig, tx, i, false, 0))
return false;
@@ -628,16 +627,20 @@ bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
CScript subscript(stack.back().begin(), stack.back().end());
vector<vector<unsigned char> > vSolutions2;
txnouttype whichType2;
if (!Solver(subscript, whichType2, vSolutions2))
return false;
if (whichType2 == TX_SCRIPTHASH)
return false;
int tmpExpected;
tmpExpected = ScriptSigArgsExpected(whichType2, vSolutions2);
if (tmpExpected < 0)
return false;
nArgsExpected += tmpExpected;
if (Solver(subscript, whichType2, vSolutions2))
{
int tmpExpected = ScriptSigArgsExpected(whichType2, vSolutions2);
if (tmpExpected < 0)
return false;
nArgsExpected += tmpExpected;
}
else
{
// Any other Script with less than 15 sigops OK:
unsigned int sigops = subscript.GetSigOpCount(true);
// ... extra data left on the stack after execution is OK, too:
return (sigops <= MAX_P2SH_SIGOPS);
}
}
if (stack.size() != (unsigned int)nArgsExpected)