PluGeth

PluGeth is a fork of the Go Ethereum Client (Geth) that implements a plugin architecture, allowing developers to extend Geth's capabilities in a number of different ways using plugins, rather than having to create additional, new forks of Geth.

Design Goals

The upstream Geth client exists primarily to serve as a client for the Ethereum mainnet, though it also supports a number of popular testnets. Supporting the Ethereum mainnet is a big enough challenge in its own right that the Geth team generally avoids changes to support other networks, or to provide features only a small handful of users would be interested in.

The result is that many projects have forked Geth. Some implement their own consensus protocols or alter the behavior of the EVM to support other networks. Others are designed to extract information from the Ethereum mainnet in ways the standard Geth client does not support.

Creating numerous different forks to fill a variety of different needs comes with a number of drawbacks. Forks tend to drift apart from each other. Many networks that forked from Geth long ago have stopped merging updates from Geth; this makes some sense, given that those networks have moved in different directions than Geth and merging upstream changes while properly maintaining consensus rules of an existing network could prove quite challenging. But not merging changes from upstream can mean that security updates are easily missed, especially when the upstream team obscures security updates as optimizations as a matter of process.

PluGeth aims to provide a single Geth fork that developers can choose to extend rather than forking the Geth project. Out of the box, PluGeth behaves exactly like upstream Geth, but by installing plugins written in Golang, developers can extend its functionality in a wide variety of way.

Anatomy of a Plugin

Plugins for Plugeth use Golang's Native Plugin System. Plugin modules must export variables using specific names and types. These will be processed by the plugin loader, and invoked at certain points during Geth's operations.

API

Flags

Name: Flags
Type: flag.FlagSet
Behavior: This FlagSet will be parsed and your plugin will be able to access the resulting flags. Note that if any flags are provided, certain checks are disabled within Geth to avoid failing due to unexpected flags.

Subcommands

Name: Subcommands
Type: map[string]func(ctx *cli.Context, args []string) error
Behavior: If Geth is invoked with geth YOUR_COMMAND, the plugin loader will look for YOUR_COMMAND within this map, and invoke the corresponding function. This can be useful for certain behaviors like manipulating Geth's database without having to build a separate binary.

Tracers

Name: Tracer
Type: map[string]TracerResult
Behavior: When calling debug.traceX functions (such as debug_traceCall and debug_traceTransaction) the tracer can be specified as a key to this map and the tracer used will be the TracerResult specified here. TracerResult objects must match the interface:

// CaptureStart is called at the start of each transaction
CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
// CaptureState is called for each opcode
CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
// CaptureFault is called when an error occurs in the EVM
CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, depth int, err error) {
// CaptureEnd is called at the end of each transaction
CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) {
// GetResult should return a JSON serializable result object to respond to the trace call
GetResult() (interface{}, error) {

Caution: Modifying of the values passed into tracer functions can alter the results of the EVM execution in unpredictable ways. Additionally, some objects may be reused across calls, so data you wish to capture should be copied rather than retained by reference.

LiveTracer

Name: LiveTracer
Type: vm.Tracer
Behavior: This tracer is used for tracing transactions as they are processed within blocks. Note that if a block does not validate, some transactions may be processed that don't end up in blocks, so be sure to check transactions against finalized blocks.

The interface for a vm.Tracer is similar to a TracerResult (above), but does not require a GetResult() function.

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