This commit provides a new interface, MedianTimeSource, along with a
concrete implementation which allows improved accuracy of time by making
use of the median network time as calculated from multiple time samples.
The time samples are to be provided by callers and are intended to come
from remote clients.
The calculations performed in this implementation exactly mirror those in
Bitcoin Core because time calculations are part of the consensus rules and
hence need to match exactly.
This commit splits the two rule validation errors related to the timestamp
being too old into two distince errors rather than grouping them under the
same one. Thus there is now a new ErrCheckpointTimeTooNew in addition to
the existing ErrTimeTooNew error.
This allows the caller to detect the when a block is rejected due to a
time-related checkpoint failure whereas before the combined error did not.
This commit moves the ProcessBlock example to a test file so it integrates
nicely with Go's example tooling.
This allows the example output to be tested as a part of running the
normal Go tests to help ensure it doesn't get out of date with the code.
It is also nice to have the example in one place rather than repeating it
in doc.go and README.md.
Links and information about the example have been incldued in doc.go and
README.md in place of the example.
Since the underlying database driver can now return an error when looking
up if blocks and transactions exist, the HaveBlock function now includes
an error return to allow any underlying errors to be exposed.
This commit creates and exports a new constant, MaxTimeOffsetSeconds,
which is the maximum number of seconds a block timestamp is allowed to be
ahead of the current time.
Previously this value was hard coded into the consensus rule path, however
it is useful better to have it defined as a constant and exported so other
callers can access it.
No consensus rules have been changed with this commit.
This commit adds a new behavior flag, BFDryRun which allows the caller
to indicate all checks should be performed against the block as normal
except it will not modify any state. This is useful to test that a block
is valid without actually modifying the current chain or memory state.
This commit also adds a few additional checks which were elided before
since they are implicitly handled by btcwire. However, with the ability
to propose blocks which didn't necessarily come through the btcwire path,
these checks need to be enforced in the chain code as well.
As a part of adding the checks, three new error codes named
ErrBlockTooBig, ErrTooManyTransactions, and ErrTxTooBig have been
introduced.
Closes#5.
This commit modifies the error return type for errors during script
validation to use the RuleError so they are consistent with the rest of
the errors. This also helps the calling code differentiate blocks
rejected due to script parsing and validation errors as opposed to
internal issues such as inability to read from the disk.
To accomplish this, two new two new RuleErrors, ErrScriptMalformed and
ErrScriptValidation, have been added.
Also, the errors for script parsing issues and script validation errors
have been improved to include both transaction hashes and indexes involved
in the validation effort. Previously script parsing issues had almost no
additional information as to which transaction input/outputs the failing
script came from.
This commit adds a new behavior flag, BFNoPoWCheck which allows the caller
to indicate the check which ensures a block hashes to a value less than
required target should not be performed.
This commit change the ProcessBlock function to accept a new type named
BehaviorFlags in place of the current fastAdd parameter.
This has been done to pave the way for adding more control over the checks
that are performed such as avoiding the proof of work checks which will be
in an upcoming commit. A bitmask was chosen because it will allow the
ProcessBlock API to remain a little more stable since new flag additions
that change the behavior are only likely to be used by new code because
adding flags does not change the existing behavior.
ok @jrick
This commit changes the way that orphan blocks are identified by adding a
new boolean return value on ProcessBlock and removing the notification for
NTOrphanBlock.
This allows the calling code to identify orphan blocks immediately instead
of having to setup a seperate callback handler and implementing some type
of state tracking. This, in turn, allows cleaner code for handling them.
In addition, the tests have been updated for the new function signature
and also now check that each block is or is not an orphan as expected
which makes the tests more robust.
ok @jrick
This commit changes the RuleError type to a struct which consists of an
error code and human-readable description.
From a usage perspective, existing code should not break since type
asserting an error to a RuleError still works in the same manner. The
difference is the caller can now take that type asserted RuleError and
access the .ErrorCode field on it to programmatically identify the
specific rule that was violated.
ok @jrick
This commit refactors the code to make use of the btcnet package for
network-specific parameters instead of switching on the specific network.
For example, the percentage of the network that needs to run version 2
blocks is different between testnet and mainnet. Previously the code was
using a switch to choose these values. With this refactor, those
parameters are part of the network parameters provided when creating a new
chain instance.
Another example is checkpoints, which have been moved to btcnet so they
can be specified by the caller instead of hard coded into this package.
As a result, the checkpoints for the standard networks are now specified
in the btcnet package.
This makes it easier to add new networks such as a testnet4 should it
become needed. It also allows callers to define their own custom network
parameters without having to modify the code of the package to add new
switch cases for the custom network.
This commit corrects the debug log print to use the hash of referenced
coinbase transaction instead of the hash of the current transation when a
coinbase maturity is not met.
Rather than using the deprecated TxShas function on a btcutil.Block,
convert the checkBIP0030 to use the newer preferred method of ranging over
the Transactions to obtain the cached hash of each transaction.
This is also a little more efficient since it can avoid creating and
caching an extra slice to keep the hashes in addition to having the hash
cached with each transaction.
This commit makes a slight variant of the existing calcPastMedianTime
function available to external callers. The new exported version
calculates the past median time from the end of the current main chain
versus an arbitrary block node.
This commit makes a slight variant of the existing checkConnectBlock
function available to external callers. The new exported version checks
if the passed block will connect to the end of the current main chain.
In order to support this, a few other small modifications have been made
to the initial index generation and the existing checkConnectBlock since
it previously made some assumptions about the state of genesis block which
can no longer be assumed due accepting blocks from callers directly.
Also, add a quick test to ensure the new function fails when checking if
the genesis block will connect again when it's already inserted.
This commit exports a new variant of the existing internal
calcNextRequiredDifficulty function which calculates and returns the next
required difficulty for a block after the end of the current best chain
based on the difficulty retarget rules.
In order to support the exported function the internal one was slightly
modified to accept the block timestamp instead of an entire block since
the timestamp is all that is needed and the caller of the exported
function might next have a full block yet.
This commit modifies the BuildMerkleTreeStore function to accept a slice
of btcutil.Tx transactions as opposed to a full block. This allows more
flexibility when calculating merkle roots since a full block may not be
created yet (particularly when generating blocks that need to be solved in
mining).
Previously, the BuildMerkleTreeStore function accepted a btcutil.Block
because originally the block itself cached the transaction hashes and it
was necessary to have access to the block to make use of the cached
transactions. However, the code has since been improved such that it
caches transaction hashes directly in each btcutil.Tx. This means the
code can remain as efficient as before while allowing the individual
transacitons to be passed.
This commit adds an additional sanity check to ensure the block that is
being processed does not contain a timestamp with a precision higher than
one second. This is necessary because the consensus rules only deal with
whole seconds in the time comparisons whereas the internal data structures
make use of Go time.Time values which support up to nanosecond precision.
Also, add a test to ensure the new functionality works as expected.
ok @owainga
