core

README

Go Core

Official Golang implementation of the CORE protocol.

Automated builds are available for stable releases and the unstable master branch. Binary archives are published at CORE website > downloads.

Building the source

Building gocore requires both a Go (version 1.13 or later) and a C compiler. You can install them using your favorite package manager. Once the dependencies are installed, run

make gocore

or, to build the full suite of utilities:

make all

ICAN network prefixes

CORE Client implements ICAN-based addresses with following formats:

Name	Prefix	Length	Format
Mainnet	CB	44	hh!kk!hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!
Testnets	AB	44	hh!kk!hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!
Privatenets	CE	44	hh!kk!hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!

Executables

The go-core project comes with several wrappers/executables found in the cmd directory.

Command	Description
gocore	Main Core CLI client. It is the entry point into the CORE network (main-, "testnets" or private net), capable of running as a full node (default), archive node (retaining all historical state), or a light node (retrieving data live). It can be used by other processes as a gateway into the CORE network via JSON RPC endpoints exposed on top of HTTP, WebSocket, and/or IPC transports. Type gocore --help for command-line options.
abigen	Source code generator to convert CORE contract definitions into easy to use, compile-time type-safe Go packages. It operates on plain CORE contract ABIs with expanded functionality if the contract bytecode is also available. However, it also accepts Ylem source files, making development much more streamlined.
bootnode	Stripped down version of our CORE client implementation that only takes part in the network node discovery protocol, but does not run any of the higher-level application protocols. It can be used as a lightweight bootstrap node to aid in finding peers in private networks.
cvm	Developer utility version of the CVM (CORE Virtual Machine) that is capable of running bytecode snippets within a configurable environment and execution mode. Its purpose is to allow isolated, fine-grained debugging of CVM opcodes.
gocorerpctest	Developer utility tool to support our core/rpc-test test suite which validates baseline conformity to the CORE JSON RPC specs.
rlpdump	Developer utility tool to convert binary RLP (Recursive Length Prefix) dumps (data encoding used by the CORE protocol both network as well as consensus wise) to user-friendlier hierarchical representation.

Full node on the main CORE network

By far the most common scenario is people wanting to simply interact with the CORE network: create accounts; transfer funds; deploy and interact with contracts. For this particular use-case the user doesn't care about years-old historical data, so we can fast-sync quickly to the current state of the network. To do so:

$ gocore console

This command will:

• Start gocore in fast sync mode (default, can be changed with the --syncmode flag), causing it to download more data in exchange for avoiding processing the entire history of the CORE network, which is very CPU intensive.
• Startup gocore's built-in interactive JavaScript console, (via the trailing console subcommand) through which you can invoke all official web3 methods as well as gocore's own management APIs. This tool is optional and if you leave it out you can always attach to an already running gocore instance with gocore attach.

A Full node on the Devin network (PoW)

Transitioning towards developers, if you'd like to play around with creating CORE contracts, you almost certainly would like to do that without any real money involved until you get the hang of the entire system. In other words, instead of attaching to the main network, you want to join one of the tests networks (Devin, Koliba) with your node, which is fully equivalent to the main network, but with play-Core only.

$ gocore --devin console

The console subcommand has the exact same meaning as above and they are equally useful on the devin too. Please see above for their explanations if you've skipped here.

Specifying the --devin flag, however, will reconfigure your gocore instance a bit:

• Instead of using the default data directory (~/core on Linux for example), gocore will nest itself one level deeper into a devin subfolder (~/core/devin on Linux). Note, on OSX and Linux this also means that attaching to a running devin node requires the use of a custom endpoint since gocore attach will try to attach to a production node endpoint by default.
• Instead of connecting the main Core network, the client will connect to the test network, which uses different P2P bootnodes, different network IDs, and genesis states.

Full node on the Koliba test network (PoA)

Gocore also supports connecting to a proof-of-authority (PoA) based test network called Koliba (operated by members of the community). This network is lighter, more secure.

$ gocore --koliba console

Configuration

As an alternative to passing the numerous flags to the gocore binary, you can also pass a configuration file via:

$ gocore --config /path/to/your_config.toml

To get an idea of how the file should look like you can use the dumpconfig subcommand to export your existing configuration:

$ gocore --your-favourite-flags dumpconfig

Docker quick start

One of the quickest ways to get Core up and running on your machine is by using Docker:

docker run -d --name core-node -v /Users/robocop/core-coin:/root \
           -p 8545:8545 -p 30300:30300 \
           core-coin/client-go

This will start gocore in fast-sync mode with a DB memory allowance of 1GB just as the above command does. It will also create a persistent volume in your home directory for saving your blockchain as well as map the default ports.

Do not forget --rpcaddr 0.0.0.0, if you want to access RPC from other containers and/or hosts. By default, gocore binds to the local interface, and RPC endpoints are not accessible from the outside.

Programmatically interfacing gocore nodes

As a developer, sooner rather than later you'll want to start interacting with gocore and the CORE network via your own programs and not manually through the console. To aid this, gocore has built-in support for JSON-RPC based APIs and gocore specific APIs. These can be exposed via HTTP, WebSockets, and IPC (UNIX sockets on UNIX based platforms, and named pipes on Windows).

The IPC interface is enabled by default and exposes all the APIs supported by gocore, whereas the HTTP and WS interfaces need to manually be enabled and only expose a subset of APIs due to security reasons. These can be turned on/off and configured as you'd expect.

HTTP based JSON-RPC API options:

• --rpc Enable the HTTP-RPC server
• --rpcaddr HTTP-RPC server listening interface (default: localhost)
• --rpcport HTTP-RPC server listening port (default: 8545)
• --rpcapi API's offered over the HTTP-RPC interface (default: xcb,net,web3)
• --rpccorsdomain Comma separated list of domains from which to accept cross origin requests (browser enforced)
• --ws Enable the WS-RPC server
• --wsaddr WS-RPC server listening interface (default: localhost)
• --wsport WS-RPC server listening port (default: 8546)
• --wsapi API's offered over the WS-RPC interface (default: xcb,net,web3)
• --wsorigins Origins from which to accept websockets requests
• --ipcdisable Disable the IPC-RPC server
• --ipcapi API's offered over the IPC-RPC interface (default: admin,debug,xcb,miner,net,personal,shh,txpool,web3)
• --ipcpath Filename for IPC socket/pipe within the datadir (explicit paths escape it)

You'll need to use your own programming environments' capabilities (libraries, tools, etc) to connect via HTTP, WS, or IPC to a gocore node configured with the above flags and you'll need to speak JSON-RPC on all transports. You can reuse the same connection for multiple requests!

Note: Please understand the security implications of opening up an HTTP/WS based transport before doing so! Hackers on the internet are actively trying to subvert CORE nodes with exposed APIs! Further, all browser tabs can access locally running web servers, so malicious web pages could try to subvert locally available APIs!

Operating a private network

Maintaining your own private network is more involved as a lot of configurations taken for granted in the official networks need to be manually set up.

Defining the private genesis state

First, you'll need to create the genesis state of your networks, which all nodes need to be aware of and agree upon. This consists of a small JSON file (e.g. call it genesis.json):

{
  "config": {
    "chainId": "<arbitrary positive integer>"
  },
  "alloc": {},
  "corebase": "ce450000000000000000000000000000000000000000",
  "difficulty": "0x20000",
  "extraData": "",
  "energyLimit": "0x2fefd8",
  "nonce": "0x0000000000000042",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "timestamp": "0x00"
}

The above fields should be fine for most purposes, although we'd recommend changing the nonce to some random value so you prevent unknown remote nodes from being able to connect to you. If you'd like to pre-fund some accounts for easier testing, create the accounts and populate the alloc field with their addresses.

{
  "alloc": {
    "ce180000000000000000000000000000000000000001": {
      "balance": "111111111"
    },
    "ce880000000000000000000000000000000000000002": {
      "balance": "222222222"
    }
  }
}

With the genesis state defined in the above JSON file, you'll need to initialize every gocore node with it prior to starting it up to ensure all blockchain parameters are correctly set:

$ gocore init path/to/genesis.json

Creating the rendezvous point

With all nodes that you want to run initialized to the desired genesis state, you'll need to start a bootstrap node that others can use to find each other in your network and/or over the internet. The clean way is to configure and run a dedicated bootnode:

$ bootnode --genkey=boot.key
$ bootnode --nodekey=boot.key

With the bootnode online, it will display an enode URL that other nodes can use to connect to it and exchange peer information. Make sure to replace the displayed IP address information (most probably [::]) with your externally accessible IP to get the actual enode URL.

Note: You could also use a full-fledged gocore node as a bootnode, but it's the less recommended way.

Starting up your member nodes

With the bootnode operational and externally reachable (you can try telnet <ip> <port> to ensure it's indeed reachable), start every subsequent gocore node pointed to the bootnode for peer discovery via the --bootnodes flag. It will probably also be desirable to keep the data directory of your private network separated, so do also specify a custom --datadir flag.

$ gocore --datadir=path/to/custom/data/folder --bootnodes=<bootnode-enode-url-from-above>

Note: Since your network will be completely cut off from the main and test networks, you'll also need to configure a miner to process transactions and create new blocks for you.

Running a private miner

In a private network setting, however, a single CPU miner instance is more than enough for practical purposes as it can produce a stable stream of blocks at the correct intervals without needing heavy resources (consider running on a single thread, no need for multiple ones either). To start a gocore instance for mining, run it with all your usual flags, extended by:

$ gocore <usual-flags> --mine --miner.threads=1 --corebase=ce450000000000000000000000000000000000000000

Which will start mining blocks and transactions on a single CPU thread, crediting all proceedings to the account specified by --corebase. You can further tune the mining by changing the default energy limit blocks converge to (--targetenergylimit) and the price transactions are accepted at (--energyprice).

Issue Labels

Priority

Label	Meaning (SLA)
P1 Urgent	The current release + potentially immediate hotfix
P2 High	The next release
P3 Medium	Within the next 3 releases
P4 Low	Anything outside the next 3 releases

Severity

Label	Impact
S1 Critical	Outage, broken feature with no workaround
S2 High	Broken feature, workaround too complex & unacceptable
S3 Moderate	Broken feature, workaround acceptable
S4 Low	Functionality inconvenience or cosmetic issue
S5 Note	Note about feature and/or code

Contribution

Thank you for considering helping out with the source code! We welcome contributions from anyone on the internet, and are grateful for even the smallest of fixes!

If you'd like to contribute to go-core, please fork, fix, commit and send a pull request for the maintainers to review and merge into the main codebase. If you wish to submit more complex changes though, please check up with the core devs first on the Core ◆ Talk to ensure those changes are in line with the general philosophy of the project and/or get some early feedback which can make both your efforts much lighter as well as our review and merge procedures quick and simple.

Please make sure your contributions adhere to our coding guidelines:

• Code must adhere to the official Go formatting guidelines (i.e. uses gofmt).
• Code must be documented adhering to the official Go commentary guidelines.
• Pull requests need to be based on and opened against the master branch.
• Commit messages should be prefixed with the package(s) they modify.
  • E.g. "xcb, rpc: make trace configs optional"

Security vulnerability disclosure

Please report suspected security vulnerabilities in private following the Security manual. Do NOT create publicly viewable issues for suspected security vulnerabilities.

License

The go-core library (i.e. all code outside of the cmd directory) is licensed under the GNU Lesser General Public License v3.0, also included in our repository in the COPYING.LESSER file.

The go-core binaries (i.e. all code inside of the cmd directory) are licensed under the GNU General Public License v3.0, also included in our repository in the COPYING file.

Community

Documentation

Overview

Package core defines interfaces for interacting with Core.

Index

• Variables
• type CallMsg
• type ChainReader
• type ChainStateReader
• type ChainSyncReader
• type ContractCaller
• type EnergyEstimator
• type EnergyPricer
• type FilterQuery
• type LogFilterer
• type PendingContractCaller
• type PendingStateEventer
• type PendingStateReader
• type Subscription
• type SyncProgress
• type TransactionReader
• type TransactionSender

Variables

var NotFound = errors.New("not found")

NotFound is returned by API methods if the requested item does not exist.

Types

type CallMsg

type CallMsg struct {
	From        common.Address  // the sender of the 'transaction'
	To          *common.Address // the destination contract (nil for contract creation)
	Energy      uint64          // if 0, the call executes with near-infinite energy
	EnergyPrice *big.Int        // ore <-> energy exchange ratio
	Value       *big.Int        // amount of ore sent along with the call
	Data        []byte          // input data, usually an ABI-encoded contract method invocation
}

CallMsg contains parameters for contract calls.

type ChainReader

type ChainReader interface {
	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
	BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error)
	HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error)
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
	TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error)
	TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error)

	// This method subscribes to notifications about changes of the head block of
	// the canonical chain.
	SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (Subscription, error)
}

ChainReader provides access to the blockchain. The methods in this interface access raw data from either the canonical chain (when requesting by block number) or any blockchain fork that was previously downloaded and processed by the node. The block number argument can be nil to select the latest canonical block. Reading block headers should be preferred over full blocks whenever possible.

The returned error is NotFound if the requested item does not exist.

type ChainStateReader

type ChainStateReader interface {
	BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error)
	StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error)
	CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error)
	NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error)
}

ChainStateReader wraps access to the state trie of the canonical blockchain. Note that implementations of the interface may be unable to return state values for old blocks. In many cases, using CallContract can be preferable to reading raw contract storage.

type ChainSyncReader

type ChainSyncReader interface {
	SyncProgress(ctx context.Context) (*SyncProgress, error)
}

ChainSyncReader wraps access to the node's current sync status. If there's no sync currently running, it returns nil.

type ContractCaller

type ContractCaller interface {
	CallContract(ctx context.Context, call CallMsg, blockNumber *big.Int) ([]byte, error)
}

A ContractCaller provides contract calls, essentially transactions that are executed by the CVM but not mined into the blockchain. ContractCall is a low-level method to execute such calls. For applications which are structured around specific contracts, the abigen tool provides a nicer, properly typed way to perform calls.

type EnergyEstimator

type EnergyEstimator interface {
	EstimateEnergy(ctx context.Context, call CallMsg) (uint64, error)
}

EnergyEstimator wraps EstimateEnergy, which tries to estimate the energy needed to execute a specific transaction based on the pending state. There is no guarantee that this is the true energy limit requirement as other transactions may be added or removed by miners, but it should provide a basis for setting a reasonable default.

type EnergyPricer

type EnergyPricer interface {
	SuggestEnergyPrice(ctx context.Context) (*big.Int, error)
}

EnergyPricer wraps the energy price oracle, which monitors the blockchain to determine the optimal energy price given current fee market conditions.

type FilterQuery

type FilterQuery struct {
	BlockHash *common.Hash     // used by xcb_getLogs, return logs only from block with this hash
	FromBlock *big.Int         // beginning of the queried range, nil means genesis block
	ToBlock   *big.Int         // end of the range, nil means latest block
	Addresses []common.Address // restricts matches to events created by specific contracts

	// The Topic list restricts matches to particular event topics. Each event has a list
	// of topics. Topics matches a prefix of that list. An empty element slice matches any
	// topic. Non-empty elements represent an alternative that matches any of the
	// contained topics.
	//
	// Examples:
	// {} or nil          matches any topic list
	// {{A}}              matches topic A in first position
	// {{}, {B}}          matches any topic in first position AND B in second position
	// {{A}, {B}}         matches topic A in first position AND B in second position
	// {{A, B}, {C, D}}   matches topic (A OR B) in first position AND (C OR D) in second position
	Topics [][]common.Hash
}

FilterQuery contains options for contract log filtering.

type LogFilterer

type LogFilterer interface {
	FilterLogs(ctx context.Context, q FilterQuery) ([]types.Log, error)
	SubscribeFilterLogs(ctx context.Context, q FilterQuery, ch chan<- types.Log) (Subscription, error)
}

LogFilterer provides access to contract log events using a one-off query or continuous event subscription.

Logs received through a streaming query subscription may have Removed set to true, indicating that the log was reverted due to a chain reorganisation.

type PendingContractCaller

type PendingContractCaller interface {
	PendingCallContract(ctx context.Context, call CallMsg) ([]byte, error)
}

PendingContractCaller can be used to perform calls against the pending state.

type PendingStateEventer

type PendingStateEventer interface {
	SubscribePendingTransactions(ctx context.Context, ch chan<- *types.Transaction) (Subscription, error)
}

A PendingStateEventer provides access to real time notifications about changes to the pending state.

type PendingStateReader

type PendingStateReader interface {
	PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error)
	PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error)
	PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error)
	PendingNonceAt(ctx context.Context, account common.Address) (uint64, error)
	PendingTransactionCount(ctx context.Context) (uint, error)
}

A PendingStateReader provides access to the pending state, which is the result of all known executable transactions which have not yet been included in the blockchain. It is commonly used to display the result of ’unconfirmed’ actions (e.g. wallet value transfers) initiated by the user. The PendingNonceAt operation is a good way to retrieve the next available transaction nonce for a specific account.

type Subscription

type Subscription interface {
	// Unsubscribe cancels the sending of events to the data channel
	// and closes the error channel.
	Unsubscribe()
	// Err returns the subscription error channel. The error channel receives
	// a value if there is an issue with the subscription (e.g. the network connection
	// delivering the events has been closed). Only one value will ever be sent.
	// The error channel is closed by Unsubscribe.
	Err() <-chan error
}

Subscription represents an event subscription where events are delivered on a data channel.

type SyncProgress

type SyncProgress struct {
	StartingBlock uint64 // Block number where sync began
	CurrentBlock  uint64 // Current block number where sync is at
	HighestBlock  uint64 // Highest alleged block number in the chain
	PulledStates  uint64 // Number of state trie entries already downloaded
	KnownStates   uint64 // Total number of state trie entries known about
}

SyncProgress gives progress indications when the node is synchronising with the Core network.

type TransactionReader

type TransactionReader interface {
	// TransactionByHash checks the pool of pending transactions in addition to the
	// blockchain. The isPending return value indicates whether the transaction has been
	// mined yet. Note that the transaction may not be part of the canonical chain even if
	// it's not pending.
	TransactionByHash(ctx context.Context, txHash common.Hash) (tx *types.Transaction, isPending bool, err error)
	// TransactionReceipt returns the receipt of a mined transaction. Note that the
	// transaction may not be included in the current canonical chain even if a receipt
	// exists.
	TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
}

TransactionReader provides access to past transactions and their receipts. Implementations may impose arbitrary restrictions on the transactions and receipts that can be retrieved. Historic transactions may not be available.

Avoid relying on this interface if possible. Contract logs (through the LogFilterer interface) are more reliable and usually safer in the presence of chain reorganisations.

The returned error is NotFound if the requested item does not exist.

type TransactionSender

type TransactionSender interface {
	SendTransaction(ctx context.Context, tx *types.Transaction) error
}

TransactionSender wraps transaction sending. The SendTransaction method injects a signed transaction into the pending transaction pool for execution. If the transaction was a contract creation, the TransactionReceipt method can be used to retrieve the contract address after the transaction has been mined.

The transaction must be signed and have a valid nonce to be included. Consumers of the API can use package accounts to maintain local private keys and need can retrieve the next available nonce using PendingNonceAt.