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Implement BIP 66 validation rules and switchover logic

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This commit is contained in:
Pieter Wuille 2015-02-05 20:56:10 -08:00 committed by Ross Nicoll
parent cdb81cec3f
commit 53a49c0246
3 changed files with 116 additions and 13 deletions
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39
src/main.cpp
View file

@ -1966,6 +1966,12 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
unsigned int flags = SCRIPT_VERIFY_NOCACHE |
(fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE);
if (block.nVersion >= 3 &&
((!TestNet() && CBlockIndex::IsSuperMajority(3, pindex->pprev, 750, 1000)) ||
(TestNet() && CBlockIndex::IsSuperMajority(3, pindex->pprev, 51, 100)))) {
flags |= SCRIPT_VERIFY_DERSIG;
}
CBlockUndo blockundo;
CCheckQueueControl<CScriptCheck> control(fScriptChecks && nScriptCheckThreads ? &scriptcheckqueue : NULL);
@ -2755,21 +2761,30 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
REJECT_INVALID, "bad-txns-nonfinal");
}
// Enforce block.nVersion=2 rule that the coinbase starts with serialized block height
if (block.nVersion >= 2)
{
// if 750 of the last 1,000 blocks are version 2 or greater (51/100 if testnet):
if ((!TestNet() && CBlockIndex::IsSuperMajority(2, pindex->pprev, 750, 1000)) ||
(TestNet() && CBlockIndex::IsSuperMajority(2, pindex->pprev, 51, 100)))
// Reject block.nVersion=2 blocks when 95% (75% on testnet) of the network has upgraded:
if (block.nVersion < 3)
{
CScript expect = CScript() << nHeight;
if (block.vtx[0].vin[0].scriptSig.size() < expect.size() ||
!std::equal(expect.begin(), expect.end(), block.vtx[0].vin[0].scriptSig.begin())) {
pindex->nStatus |= BLOCK_FAILED_VALID;
return state.DoS(100, error("AcceptBlock() : block height mismatch in coinbase"),
REJECT_INVALID, "bad-cb-height");
if ((!TestNet() && CBlockIndex::IsSuperMajority(3, pindexPrev, 950, 1000)) ||
(TestNet() && CBlockIndex::IsSuperMajority(3, pindexPrev, 75, 100)))
{
return state.Invalid(error("AcceptBlock() : rejected nVersion=2 block"),
REJECT_OBSOLETE, "bad-version");
}
}
// Enforce block.nVersion=2 rule that the coinbase starts with serialized block height
if (block.nVersion >= 2)
{
// if 750 of the last 1,000 blocks are version 2 or greater (51/100 if testnet):
if ((!TestNet() && CBlockIndex::IsSuperMajority(2, pindex->pprev, 750, 1000)) ||
(TestNet() && CBlockIndex::IsSuperMajority(2, pindex->pprev, 51, 100)))
CScript expect = CScript() << nHeight;
if (block.vtx[0].vin[0].scriptSig.size() < expect.size() ||
!std::equal(expect.begin(), expect.end(), block.vtx[0].vin[0].scriptSig.begin())) {
pindex->nStatus |= BLOCK_FAILED_VALID;
return state.DoS(100, error("AcceptBlock() : block height mismatch in coinbase"),
REJECT_INVALID, "bad-cb-height");
}
}
}
// Write block to history file

88
src/script.cpp
View file

@ -297,6 +297,86 @@ bool IsCanonicalSignature(const valtype &vchSig, unsigned int flags) {
return true;
}
// BIP 66 defined signature encoding check. This largely overlaps with
// IsCanonicalSignature above, but lacks hashtype constraints, and uses the
// exact implementation code from BIP 66.
bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
// * total-length: 1-byte length descriptor of everything that follows,
// excluding the sighash byte.
// * R-length: 1-byte length descriptor of the R value that follows.
// * R: arbitrary-length big-endian encoded R value. It must use the shortest
// possible encoding for a positive integers (which means no null bytes at
// the start, except a single one when the next byte has its highest bit set).
// * S-length: 1-byte length descriptor of the S value that follows.
// * S: arbitrary-length big-endian encoded S value. The same rules apply.
// * sighash: 1-byte value indicating what data is hashed (not part of the DER
// signature)
// Minimum and maximum size constraints.
if (sig.size() < 9) return false;
if (sig.size() > 73) return false;
// A signature is of type 0x30 (compound).
if (sig[0] != 0x30) return false;
// Make sure the length covers the entire signature.
if (sig[1] != sig.size() - 3) return false;
// Extract the length of the R element.
unsigned int lenR = sig[3];
// Make sure the length of the S element is still inside the signature.
if (5 + lenR >= sig.size()) return false;
// Extract the length of the S element.
unsigned int lenS = sig[5 + lenR];
// Verify that the length of the signature matches the sum of the length
// of the elements.
if ((size_t)(lenR + lenS + 7) != sig.size()) return false;
// Check whether the R element is an integer.
if (sig[2] != 0x02) return false;
// Zero-length integers are not allowed for R.
if (lenR == 0) return false;
// Negative numbers are not allowed for R.
if (sig[4] & 0x80) return false;
// Null bytes at the start of R are not allowed, unless R would
// otherwise be interpreted as a negative number.
if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
// Check whether the S element is an integer.
if (sig[lenR + 4] != 0x02) return false;
// Zero-length integers are not allowed for S.
if (lenS == 0) return false;
// Negative numbers are not allowed for S.
if (sig[lenR + 6] & 0x80) return false;
// Null bytes at the start of S are not allowed, unless S would otherwise be
// interpreted as a negative number.
if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
return true;
}
bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags) {
// Empty signature. Not strictly DER encoded, but allowed to provide a
// compact way to provide an invalid signature for use with CHECK(MULTI)SIG
if (vchSig.size() == 0) {
return true;
}
if ((flags & SCRIPT_VERIFY_DERSIG) != 0 && !IsValidSignatureEncoding(vchSig)) {
return false;
}
return true;
}
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags, int nHashType)
{
CScript::const_iterator pc = script.begin();
@ -849,6 +929,10 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
// Drop the signature, since there's no way for a signature to sign itself
scriptCode.FindAndDelete(CScript(vchSig));
if (!CheckSignatureEncoding(vchSig, flags)) {
return false;
}
bool fSuccess = IsCanonicalSignature(vchSig, flags) && IsCanonicalPubKey(vchPubKey, flags) &&
CheckSig(vchSig, vchPubKey, scriptCode, txTo, nIn, nHashType, flags);
@ -909,6 +993,10 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
valtype& vchSig = stacktop(-isig);
valtype& vchPubKey = stacktop(-ikey);
if (!CheckSignatureEncoding(vchSig, flags)) {
return false;
}
// Check signature
bool fOk = IsCanonicalSignature(vchSig, flags) && IsCanonicalPubKey(vchPubKey, flags) &&
CheckSig(vchSig, vchPubKey, scriptCode, txTo, nIn, nHashType, flags);

2
src/script.h
View file

@ -190,7 +190,7 @@ enum
SCRIPT_VERIFY_STRICTENC = (1U << 1), // enforce strict conformance to DER and SEC2 for signatures and pubkeys
SCRIPT_VERIFY_LOW_S = (1U << 2), // enforce low S values (<n/2) in signatures (depends on STRICTENC)
SCRIPT_VERIFY_NOCACHE = (1U << 3), // do not store results in signature cache (but do query it)
SCRIPT_VERIFY_NULLDUMMY = (1U << 4), // verify dummy stack item consumed by CHECKMULTISIG is of zero-length
SCRIPT_VERIFY_DERSIG = (1U << 4), // enforce signature encodings as defined by BIP 66 (which is a softfork, while STRICTENC is not)
};
// Mandatory script verification flags that all new blocks must comply with for