This commit modifies the existing block selection logic to limit
preferentially by weight instead of serialized block size, and also to
adhere to the new sig-op cost limits which are weighted according to
the witness discount.
The btclog package has been changed to defining its own logging
interface (rather than seelog's) and provides a default implementation
for callers to use.
There are two primary advantages to the new logger implementation.
First, all log messages are created before the call returns. Compared
to seelog, this prevents data races when mutable variables are logged.
Second, the new logger does not implement any kind of artifical rate
limiting (what seelog refers to as "adaptive logging"). Log messages
are outputted as soon as possible and the application will appear to
perform much better when watching standard output.
Because log rotation is not a feature of the btclog logging
implementation, it is handled by the main package by importing a file
rotation package that provides an io.Reader interface for creating
output to a rotating file output. The rotator has been configured
with the same defaults that btcd previously used in the seelog config
(10MB file limits with maximum of 3 rolls) but now compresses newly
created roll files. Due to the high compressibility of log text, the
compressed files typically reduce to around 15-30% of the original
10MB file.
This contains a bit of cleanup and additional logic to improve the
recently-added ability to specify additional checkpoints via the
--addcheckpoint option.
In particular:
- Improve error messages in the checkpoint parsing
- Correct the mergeCheckpoints function to weed out duplicate height
checkpoints while using the most-recently provided one as described by
its comment
- Add an assertion to blockchain.New that the provided checkpoints are
sorted as required
- Keep comments to 80 columns and use two spaces after periods in them to
be consistent with the rest of the code base
- Make the entry in doc.go match the actual btcd -h output
If a host is down and doesn't send a TCP RST, the net.Dial function
blocks until the OS times out the connection. Convert to using
DialTimeout with a 30 second default timeout.
This commit modifies the `ConnManager` to use the `net.Add` interface
through the package instead of a plain string to represent and
manipulate addresses. This change makes the package much more general as
users of the package can possibly utilize custom implementations of the
`net.Addr` interface to establish connections.
More precisely, the `ConnReq` struct has been modified to use a net.Addr
instance explicitly, and the `DialFunc` type has also been modified to
take a `net.Addr` directly. This latter change gives functions that
adhere to the `DialFunc` type more flexibility as to exactly how the
connection is established.
Additionally, the `connmgr.Config.GetNewAddress` configuration option
now directly returns a `net.Addr. This change allows the `connmgr` to be
decoupled from all DNS queries which allows callers to preferentially
select more secure methods like performing DNS lookups over a Tor proxy.
The current max orphan transaction size causes problems with dependent
transaction relay due to its artificially small size in relation to the
max standard transaction size.
Consequently, this modifies the orphan transaction policy by increasing
the max size of each orphan to the same value allowed for standard
non-orphan transactions and reducing the default max allowed number of
orphans to 100.
From a memory usage standpoint, the worst case max mem usage prior to
this change was 5MB plus structure and tracking overhead (1000 max
orphans * 5KB max each). With this, that is raised to 10MB (100 max
orphans * 100KB max each) in the worst case.
It is important to note that the values were originally implemented as a
naive means to control the size of the orphan pool before several of the
recent enhancements which more aggressively remove orphans from the
orphan pool were added, so they needed to be evaluated again.
For a very long time prior to recent changes, the orphan pool would
quickly reach the max allowed worst-case usage and effectively stay
there forever whereas with more recent changes, the actual run-time
orphan pool usage is usually much smaller.
Finally, as another point in favor of this change, as the network has
evolved, nodes have generally become better about orphan management and
as such missing ancestors will typically either be broadcast or mined
fairly quickly resulting in fewer overall orphans.
Avoid compatibility issues with software that relies on the behavior of
bitcoind's JSON-RPC implementation.
The JSON-RPC 1.0 spec defines that notifications must have their "id"
set to null and states that notifications do not have a response.
A JSON-RPC 2.0 notification is a request with "json-rpc":"2.0", and
without an "id" member. The specification states that notifications
must not be responded to. JSON-RPC 2.0 permits the null value as a
valid request id, therefore such requests are not notifications.
Bitcoin Core serves requests with "id":null or even an absent "id", and
responds to such requests with "id":null in the response.
Btcd does not respond to any request without and "id" or with "id":null,
regardless the indicated JSON-RPC protocol version.
In order to avoid compatibility issues with software relying on
Core's behavior, this commit implements "quirks mode" as follows:
- quirks mode can be enabled via configuration (disabled by default)
- If no JSON-RPC version is indicated in the request, accept and
respond to request with "id":null
- If no JSON-RPC version is indicated in the request, accept and
respond to requests without an "id" member
- In both cases above, use "id":null in the response
- Do not respond to request without an "id" or with "id":null when
JSON-RPC version is indicated in the request (process as notification)
This commit introduces package connmgr which contains connection
management related functionality.
The following is an overview of the features the package provides:
- Maintain fixed number of outbound connections
- Optional connect-only mode
- Retry persistent connections with increasing back-off
- Source peers from DNS seeds
- Use Tor to resolve DNS
- Dynamic ban scores
- Test coverage
In addition, btcd has been refactored to make use of the new package by
extending the connection manager to work with the server to source and
maintain peer connections. The following is a broad overview of the
changes to integrate the package:
- Simplify peer state by removing pending, retry peers
- Refactor to remove retries which are now handled by connmgr
- Use callback to add addresses sourced from the DNS seed
Finally the following connection-related things have been improved as a
part of this refactor:
- Fixes 100% cpu usage when network is down (#129)
- Fixes issues with max peers (#577)
- Simplify outbound peer connections management
This corrects the case where any errors that might have happened when
creating the config file were not being displayed due to the logging
system not being initialized yet.
While here, consistently use fmt.Fprint{f,ln} throughout the loadConfig
function even after the logging system is initialized since it will
help prevent copy/paste errors such as the one that induced this change
to begin with.
This commit adds two new cli flags: one for accepting non-std
transactions, and the other for rejecting non-std transactions.
The two flag are rejected when using concurrently. Config parsing is
set up such that, the desired policy expressed via the config always
overrides the policy set by default for a particular chain.
The doc.go files and the sample-btcd.conf file have been updated to document
the new flags exposing further policy control.
This does the minimum work necessary to refactor the mempool code into
its own package. The idea is that separating this code into its own
package will greatly improve its testability, allow independent
benchmarking and profiling, and open up some interesting opportunities
for future development related to the memory pool.
There are likely some areas related to policy that could be further
refactored, however it is better to do that in future commits in order
to keep the changeset as small as possible during this refactor.
Overview of the major changes:
- Create the new package
- Move several files into the new package:
- mempool.go -> mempool/mempool.go
- mempoolerror.go -> mempool/error.go
- policy.go -> mempool/policy.go
- policy_test.go -> mempool/policy_test.go
- Update mempool logging to use the new mempool package logger
- Rename mempoolPolicy to Policy (so it's now mempool.Policy)
- Rename mempoolConfig to Config (so it's now mempool.Config)
- Rename mempoolTxDesc to TxDesc (so it's now mempool.TxDesc)
- Rename txMemPool to TxPool (so it's now mempool.TxPool)
- Move defaultBlockPrioritySize to the new package and export it
- Export DefaultMinRelayTxFee from the mempool package
- Export the CalcPriority function from the mempool package
- Introduce a new RawMempoolVerbose function on the TxPool and update
the RPC server to use it
- Update all references to the mempool to use the package.
- Add a skeleton README.md
Profiles discovered that lookups into the signature cache included an
expensive comparison to the stored `sigInfo` struct. This lookup had the
potential to be more expensive than directly verifying the signature
itself!
In addition, evictions were rather expensive because they involved
reading from /dev/urandom, or equivalent, for each eviction once the
signature cache was full as well as potentially iterating over every
item in the cache in the worst-case.
To remedy this poor performance several changes have been made:
* Change the lookup key to the fixed sized 32-byte signature hash
* Perform a full equality check only if there is a cache hit which
results in a significant speed up for both insertions and existence
checks
* Override entries in the case of a colliding hash on insert Add an
* .IsEqual() method to the Signature and PublicKey types in the
btcec package to facilitate easy equivalence testing
* Allocate the signature cache map with the max number of entries in
order to avoid unnecessary map re-sizes/allocations
* Optimize evictions from the signature cache Delete the first entry
* seen which is safe from manipulation due to
the pre image resistance of the hash function
* Double the default maximum number of entries within the signature
cache due to the reduction in the size of a cache entry
* With this eviction scheme, removals are effectively O(1)
Fixes#575.
This introduces a new indexing infrastructure for supporting optional
indexes using the new database and blockchain infrastructure along with
two concrete indexer implementations which provide both a
transaction-by-hash and a transaction-by-address index.
The new infrastructure is mostly separated into a package named indexers
which is housed under the blockchain package. In order to support this,
a new interface named IndexManager has been introduced in the blockchain
package which provides methods to be notified when the chain has been
initialized and when blocks are connected and disconnected from the main
chain. A concrete implementation of an index manager is provided by the
new indexers package.
The new indexers package also provides a new interface named Indexer
which allows the index manager to manage concrete index implementations
which conform to the interface.
The following is high level overview of the main index infrastructure
changes:
- Define a new IndexManager interface in the blockchain package and
modify the package to make use of the interface when specified
- Create a new indexers package
- Provides an Index interface which allows concrete indexes to plugin
to an index manager
- Provides a concrete IndexManager implementation
- Handles the lifecycle of all indexes it manages
- Tracks the index tips
- Handles catching up disabled indexes that have been reenabled
- Handles reorgs while the index was disabled
- Invokes the appropriate methods for all managed indexes to allow
them to index and deindex the blocks and transactions
- Implement a transaction-by-hash index
- Makes use of internal block IDs to save a significant amount of
space and indexing costs over the old transaction index format
- Implement a transaction-by-address index
- Makes use of a leveling scheme in order to provide a good tradeoff
between space required and indexing costs
- Supports enabling and disabling indexes at will
- Support the ability to drop indexes if they are no longer desired
The following is an overview of the btcd changes:
- Add a new index logging subsystem
- Add new options --txindex and --addrindex in order to enable the
optional indexes
- NOTE: The transaction index will automatically be enabled when the
address index is enabled because it depends on it
- Add new options --droptxindex and --dropaddrindex to allow the indexes
to be removed
- NOTE: The address index will also be removed when the transaction
index is dropped because it depends on it
- Update getrawtransactions RPC to make use of the transaction index
- Reimplement the searchrawtransaction RPC that makes use of the address
index
- Update sample-btcd.conf to include sample usage for the new optional
index flags
This commit is the first stage of several that are planned to convert
the blockchain package into a concurrent safe package that will
ultimately allow support for multi-peer download and concurrent chain
processing. The goal is to update btcd proper after each step so it can
take advantage of the enhancements as they are developed.
In addition to the aforementioned benefit, this staged approach has been
chosen since it is absolutely critical to maintain consensus.
Separating the changes into several stages makes it easier for reviewers
to logically follow what is happening and therefore helps prevent
consensus bugs. Naturally there are significant automated tests to help
prevent consensus issues as well.
The main focus of this stage is to convert the blockchain package to use
the new database interface and implement the chain-related functionality
which it no longer handles. It also aims to improve efficiency in
various areas by making use of the new database and chain capabilities.
The following is an overview of the chain changes:
- Update to use the new database interface
- Add chain-related functionality that the old database used to handle
- Main chain structure and state
- Transaction spend tracking
- Implement a new pruned unspent transaction output (utxo) set
- Provides efficient direct access to the unspent transaction outputs
- Uses a domain specific compression algorithm that understands the
standard transaction scripts in order to significantly compress them
- Removes reliance on the transaction index and paves the way toward
eventually enabling block pruning
- Modify the New function to accept a Config struct instead of
inidividual parameters
- Replace the old TxStore type with a new UtxoViewpoint type that makes
use of the new pruned utxo set
- Convert code to treat the new UtxoViewpoint as a rolling view that is
used between connects and disconnects to improve efficiency
- Make best chain state always set when the chain instance is created
- Remove now unnecessary logic for dealing with unset best state
- Make all exported functions concurrent safe
- Currently using a single chain state lock as it provides a straight
forward and easy to review path forward however this can be improved
with more fine grained locking
- Optimize various cases where full blocks were being loaded when only
the header is needed to help reduce the I/O load
- Add the ability for callers to get a snapshot of the current best
chain stats in a concurrent safe fashion
- Does not block callers while new blocks are being processed
- Make error messages that reference transaction outputs consistently
use <transaction hash>:<output index>
- Introduce a new AssertError type an convert internal consistency
checks to use it
- Update tests and examples to reflect the changes
- Add a full suite of tests to ensure correct functionality of the new
code
The following is an overview of the btcd changes:
- Update to use the new database and chain interfaces
- Temporarily remove all code related to the transaction index
- Temporarily remove all code related to the address index
- Convert all code that uses transaction stores to use the new utxo
view
- Rework several calls that required the block manager for safe
concurrency to use the chain package directly now that it is
concurrent safe
- Change all calls to obtain the best hash to use the new best state
snapshot capability from the chain package
- Remove workaround for limits on fetching height ranges since the new
database interface no longer imposes them
- Correct the gettxout RPC handler to return the best chain hash as
opposed the hash the txout was found in
- Optimize various RPC handlers:
- Change several of the RPC handlers to use the new chain snapshot
capability to avoid needlessly loading data
- Update several handlers to use new functionality to avoid accessing
the block manager so they are able to return the data without
blocking when the server is busy processing blocks
- Update non-verbose getblock to avoid deserialization and
serialization overhead
- Update getblockheader to request the block height directly from
chain and only load the header
- Update getdifficulty to use the new cached data from chain
- Update getmininginfo to use the new cached data from chain
- Update non-verbose getrawtransaction to avoid deserialization and
serialization overhead
- Update gettxout to use the new utxo store versus loading
full transactions using the transaction index
The following is an overview of the utility changes:
- Update addblock to use the new database and chain interfaces
- Update findcheckpoint to use the new database and chain interfaces
- Remove the dropafter utility which is no longer supported
NOTE: The transaction index and address index will be reimplemented in
another commit.
mempoolPolicy contains the values that configure the mempool policy.
This decouples the values from the internals of btcd to move closer
to a mempool package.
The --blocksonly configuration option disables accepting transactions
from remote peers. It will still accept, relay, and rebroadcast
valid transactions sent via RPC or websockets.
Dynamic ban scores consist of a persistent and a decaying component. The
persistent score can be used to create simple additive banning policies
simlar to those found in other bitcoin node implementations. The
decaying score enables the creation of evasive logic which handles
misbehaving peers (especially application layer DoS attacks) gracefully
by disconnecting and banning peers attempting various kinds of flooding.
Dynamic ban scores allow these two approaches to be used in tandem.
This pull request includes the following:
- Dynamic ban score type & functions, with tests for core functionality
- Ban score of connected peers can be queried via rpc (getpeerinfo)
- Example policy with decaying score increments on mempool and getdata
- Logging of misbehavior once half of the ban threshold is reached
- Banning logic can be disabled via configuration (enabled by default)
- User defined ban threshold can be set via configuration
This commit introduces package peer which contains peer related features
refactored from peer.go.
The following is an overview of the features the package provides:
- Provides a basic concurrent safe bitcoin peer for handling bitcoin
communications via the peer-to-peer protocol
- Full duplex reading and writing of bitcoin protocol messages
- Automatic handling of the initial handshake process including protocol
version negotiation
- Automatic periodic keep-alive pinging and pong responses
- Asynchronous message queueing of outbound messages with optional
channel for notification when the message is actually sent
- Inventory message batching and send trickling with known inventory
detection and avoidance
- Ability to wait for shutdown/disconnect
- Flexible peer configuration
- Caller is responsible for creating outgoing connections and listening
for incoming connections so they have flexibility to establish
connections as they see fit (proxies, etc.)
- User agent name and version
- Bitcoin network
- Service support signalling (full nodes, bloom filters, etc.)
- Maximum supported protocol version
- Ability to register callbacks for handling bitcoin protocol messages
- Proper handling of bloom filter related commands when the caller does
not specify the related flag to signal support
- Disconnects the peer when the protocol version is high enough
- Does not invoke the related callbacks for older protocol versions
- Snapshottable peer statistics such as the total number of bytes read
and written, the remote address, user agent, and negotiated protocol
version
- Helper functions for pushing addresses, getblocks, getheaders, and
reject messages
- These could all be sent manually via the standard message output
function, but the helpers provide additional nice functionality such
as duplicate filtering and address randomization
- Full documentation with example usage
- Test coverage
In addition to the addition of the new package, btcd has been refactored
to make use of the new package by extending the basic peer it provides to
work with the blockmanager and server to act as a full node. The
following is a broad overview of the changes to integrate the package:
- The server is responsible for all connection management including
persistent peers and banning
- Callbacks for all messages that are required to implement a full node
are registered
- Logic necessary to serve data and behave as a full node is now in the
callback registered with the peer
Finally, the following peer-related things have been improved as a part
of this refactor:
- Don't log or send reject message due to peer disconnects
- Remove trace logs that aren't particularly helpful
- Finish an old TODO to switch the queue WaitGroup over to a channel
- Improve various comments and fix some code consistency cases
- Improve a few logging bits
- Implement a most-recently-used nonce tracking for detecting self
connections and generate a unique nonce for each peer
Introduce an ECDSA signature verification into btcd in order to
mitigate a certain DoS attack and as a performance optimization.
The benefits of SigCache are two fold. Firstly, usage of SigCache
mitigates a DoS attack wherein an attacker causes a victim's client to
hang due to worst-case behavior triggered while processing attacker
crafted invalid transactions. A detailed description of the mitigated
DoS attack can be found here: https://bitslog.wordpress.com/2013/01/23/fixed-bitcoin-vulnerability-explanation-why-the-signature-cache-is-a-dos-protection/
Secondly, usage of the SigCache introduces a signature verification
optimization which speeds up the validation of transactions within a
block, if they've already been seen and verified within the mempool.
The server itself manages the sigCache instance. The blockManager and
txMempool respectively now receive pointers to the created sigCache
instance. All read (sig triplet existence) operations on the sigCache
will not block unless a separate goroutine is adding an entry (writing)
to the sigCache. GetBlockTemplate generation now also utilizes the
sigCache in order to avoid unnecessarily double checking signatures
when generating a template after previously accepting a txn to the
mempool. Consequently, the CPU miner now also employs the same
optimization.
The maximum number of entries for the sigCache has been introduced as a
config parameter in order to allow users to configure the amount of
memory consumed by this new additional caching.
SFNodeBloom is a new service flag that a node is required to use to
indicate that it supports bloom filtering. This includes a protocol
version bump to 70011 and a wire version bump to 0.3.0.
btcd:
The SFNodeBloom flag is set by default. A new configuration option
--nopeerbloomfilters has been added to to disable bloom filtering.
Any node advertising a version greater than or equal to 70011 that
attempts to use bloom filtering will be disconnected if bloom
filtering is disabled.
This mimics Bitcoin Core commit afb0ccaf9c9e4e8fac7db3564c4e19c9218c6b03
The configured onion proxy was not being used due to checking if the
passed string had suffix '.onion', which never matched because the
port number is part of the string.
Tor stream isolation randomizes proxy user credentials resulting in
Tor creating a new circuit for each connection. This makes it more
difficult to correlate connections.
Idea from Wladimir J. van der Laan via Bitcoin Core.
The option -maxorphantx allows the user to specify the number of
orphan transactions to keep in memory.
Also, lower the default max orphan count from 10000 to 1000.
