Seems it was forgotten about when IsPushOnly() and the unittests were
written. A particular oddity is that OP_RESERVED doesn't count towards
the >201 opcode limit unlike every other named opcode.
To fix a minor malleability found by Sergio Lerner (reported here:
https://bitcointalk.org/index.php?topic=8392.msg1245898#msg1245898)
The problem is that if (R,S) is a valid ECDSA signature for a given
message and public key, (R,-S) is also valid. Modulo N (the order
of the secp256k1 curve), this means that both (R,S) and (R,N-S) are
valid. Given that N is odd, S and N-S have a different lowest bit.
We solve the problem by forcing signatures to have an even S value,
excluding one of the alternatives.
This commit just changes the signing code to always produce even S
values, and adds a verification mode to check it. This code is not
enabled anywhere yet. Existing tests in key_tests.cpp verify that
the produced signatures are still valid.
The length of vectors, maps, sets, etc are serialized using
Write/ReadCompactSize -- which, unfortunately, do not use a
unique encoding.
So deserializing and then re-serializing a transaction (for example)
can give you different bits than you started with. That doesn't
cause any problems that we are aware of, but it is exactly the type
of subtle mismatch that can lead to exploits.
With this pull, reading a non-canonical CompactSize throws an
exception, which means nodes will ignore 'tx' or 'block' or
other messages that are not properly encoded.
Please check my logic... but this change is safe with respect to
causing a network split. Old clients that receive
non-canonically-encoded transactions or blocks deserialize
them into CTransaction/CBlock structures in memory, and then
re-serialize them before relaying them to peers.
And please check my logic with respect to causing a blockchain
split: there are no CompactSize fields in the block header, so
the block hash is always canonical. The merkle root in the block
header is computed on a vector<CTransaction>, so
any non-canonical encoding of the transactions in 'tx' or 'block'
messages is erased as they are read into memory by old clients,
and does not affect the block hash. And, as noted above, old
clients re-serialize (with canonical encoding) 'tx' and 'block'
messages before relaying to peers.
Fixes issue#2838; this is a tweaked version of pull#2845 that
should not leak the length of the password and is more generic,
in case we run into other situations where we need
timing-attack-resistant comparisons.
Orphan transactions were stored as a CDataStream pointer;
this changes the mapOrphanTransactions data structures to
store orphans as a CTransaction.
This also fixes CVE-2013-4627 by always re-serializing
transactions before relaying them.
The new class is accessed via the Params() method and holds
most things that vary between main, test and regtest networks.
The regtest mode has two purposes, one is to run the
bitcoind/bitcoinj comparison tool which compares two separate
implementations of the Bitcoin protocol looking for divergence.
The other is that when run, you get a local node which can mine
a single block instantly, which is highly convenient for testing
apps during development as there's no need to wait 10 minutes for
a block on the testnet.
Removed AreInputsStandard from CTransaction, made it a regular function in main.
Moved CTransaction::GetOutputFor to CCoinsViewCache.
Moved GetLegacySigOpCount and GetP2SHSigOpCount out of CTransaction into regular functions in main.
Moved GetValueIn and HaveInputs from CTransaction into CCoinsViewCache.
Moved AllowFree, ClientCheckInputs, CheckInputs, UpdateCoins, and CheckTransaction out of CTransaction and into main.
Moved IsStandard and IsFinal out of CTransaction and put them in main as IsStandardTx and IsFinalTx. Moved GetValueOut out of CTransaction into main. Moved CTxIn, CTxOut, and CTransaction into core.
Added minimum fee parameter to CTxOut::IsDust() temporarily until CTransaction is moved to core.h so that CTxOut needn't know about CTransaction.
- explicitly set the default of all GetBoolArg() calls
- rework getarg_test.cpp and util_tests.cpp to cover this change
- some indentation fixes
- move macdockiconhandler.h include in bitcoin.cpp to the "our headers"
section
This fixes test_bitcoin failures on openbsd reported by dhill on IRC.
On some systems rand() is a simple LCG over 2^31 and so it produces
an even-odd sequence. ApproximateBestSubset was only using the least
significant bit and so every run of the iterative solver would be the
same for some inputs, resulting in some pretty dumb decisions.
Using something other than the least significant bit would paper over
the issue but who knows what other way a system's rand() might get us
here. Instead we use an internal RNG with a period of something like
2^60 which is well behaved. This also makes it possible to make the
selection deterministic for the tests, if we wanted to implement that.
* During block verification (when parallelism is requested), script
check actions are stored instead of being executed immediately.
* After every processed transactions, its signature actions are
pushed to a CScriptCheckQueue, which maintains a queue and some
synchronization mechanism.
* Two or more threads (if enabled) start processing elements from
this queue,
* When the block connection code is finished processing transactions,
it joins the worker pool until the queue is empty.
As cs_main is held the entire time, and all verification must be
finished before the block continues processing, this does not reach
the best possible performance. It is a less drastic change than
some more advanced mechanisms (like doing verification out-of-band
entirely, and rolling back blocks when a failure is detected).
The -par=N flag controls the number of threads (1-16). 0 means auto,
and is the default.
These flags select features to be enabled/disabled during script
evaluation/checking, instead of several booleans passed along.
Currently these flags are defined:
* SCRIPT_VERIFY_P2SH: enable BIP16-style subscript evaluation
* SCRIPT_VERIFY_STRICTENC: enforce strict adherence to pubkey/sig encoding standards.
Peter Todd