Core-Geth¶

Core-Geth is an Ethereum Classic execution client. It is a downstream of ethereum/go-ethereum that keeps chain configuration as data rather than code, so one geth binary runs the networks in the Supported networks table, private networks among them. The README’s Project history tells where the project came from.

This page lists what Core-Geth adds to go-ethereum, how its chain configuration is built, and what go-ethereum has that Core-Geth does not.

Additional features¶

JSON-RPC API¶

• OpenRPC service discovery. The rpc.discover method returns an OpenRPC document describing the client’s methods, including some the interface it answers on does not serve, with their parameters and results. See OpenRPC discovery.
• The trace module. trace_block, trace_transaction, trace_call and trace_callMany return trace entries in the format of OpenEthereum’s trace module, and trace_filter works only as a subscription. See the trace module overview and the trace method reference.

The JSON-RPC API overview covers the rest of the API.

External EVMs through EVMC¶

Core-Geth implements version 7 of the EVMC connector API as an experimental feature. --vm.evm and --vm.ewasm load an external EVM or ewasm interpreter from a shared library, and neither is supported on Ethereum Classic or Mordor: see Running Geth with an External VM.

Development and testing¶

• --dev.pow starts an ephemeral proof-of-work network with a pre-funded developer account. It switches mining on with no CPU threads, so it seals no block unless --miner.threads is above 0; --fakepow.poisson --miner.threads 2 seals blocks without generating an Ethash DAG.
• --fakepow.poisson disables proof-of-work verification and adds a Poisson mining delay based on --miner.threads.
• make test-coregeth runs the tests specific to Core-Geth, including imports of simulated canonical chains. See Testing.

Ethereum Classic proposals¶

Ethereum Classic’s own proposals, ECIPs and ECBPs, are chain configuration fields of their own, alongside the EIPs. Among them:

• ECIP-1010, the difficulty bomb pause: ECIP1010PauseBlock and ECIP1010Length
• ECIP-1017, the monetary policy: ECIP1017FBlock and ECIP1017EraRounds
• ECIP-1041, the difficulty bomb disposal: DisposalBlock
• ECIP-1099, Etchash: ECIP1099FBlock
• ECBP-1100, MESS (Modified Exponential Subjective Scoring): ECBP1100FBlock

CoreGethChainConfig in params/types/coregeth/chain_config.go defines the fields, and ClassicChainConfig in params/config_classic.go sets Ethereum Classic’s activation blocks.

Divergent design¶

Chain configuration by feature¶

At the code level, Core-Geth and go-ethereum differ in how code asks the chain configuration whether a feature is active.

In go-ethereum, it asks about a named upgrade:

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blockNumber := big.NewInt(0)
config := params.MainnetChainConfig
if config.IsByzantium(blockNumber) {
    // do a special thing for post-Byzantium chains
}

Byzantium is a group of EIPs, and the check does not say which of them the code depends on. Core-Geth asks about the EIP itself:

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blockNumber := big.NewInt(0)
config := params.MainnetChainConfig
if config.IsEnabled(config.GetEIP658Transition, blockNumber) {
    // do a special thing for post-EIP658 chains
}

The ChainConfigurator interface in params/types/ctypes/configurator_iface.go carries a transition getter and setter for each supported feature, in ProtocolSpecifier, and IsEnabled, in Forker.

Because each EIP is a setting of its own, a chain can adopt some of an upgrade’s EIPs and not others. Ethereum Classic runs EIP-658, which embeds a transaction status code in receipts, without EIP-649, Byzantium’s difficulty bomb delay and block reward reduction. TestClassicIs649 in params/config_test.go asserts that ClassicChainConfig has no EIP-649 transition.

Limitations¶

• Release builds keep source file paths. go-ethereum builds with -trimpath; Core-Geth’s build/ci.go does not, and its comment gives the reason: the OpenRPC discovery document relies on reflection and source parsing that break when paths are trimmed. A geth binary therefore contains the source paths of the machine that built it.
• Some go-ethereum features are absent, among them the --vmtrace flag, which records internal VM operations with a named tracer, and the blsync beacon light syncer.
• Ethereum’s networks are not supported. See Networks this client does not support.
• geth version-check checks go-ethereum’s vulnerability feed, not this client’s. See SECURITY.md.