feat(core/forkid): announce forkid via ENR and remove eth/62 #19738

[gzliudan]

Proposed changes

Ref: ethereum#19738

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• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Changes that don't change source code or tests
• docs: Documentation only changes
• feat: A new feature
• fix: A bug fix
• perf: A code change that improves performance
• refactor: A code change that neither fixes a bug nor adds a feature
• revert: Revert something
• style: Changes that do not affect the meaning of the code
• test: Adding missing tests or correcting existing tests

Impacted Components

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• Consensus
• Account
• Network
• Geth
• Smart Contract
• External components
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Checklist

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• This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• Tested on a private network from the genesis block and monitored the chain operating correctly for multiple epochs.
• Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• Tested the backwards compatibility.
• Tested with XDC nodes running this version co-exist with those running the previous version.
• Relevant documentation has been updated as part of this PR
• N/A

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[Copilot]

Pull request overview

This PR adds an eth ENR entry to advertise the chain fork ID (EIP-2124) via discovery and refactors the eth protocol configuration to stop announcing eth/62 during capability negotiation.

Changes:

• Expose p2p.Server.LocalNode() so services can update the local ENR record.
• Add an eth ENR entry containing forkid.ID and update it on chain head events.
• Update eth protocol configuration/refactor protocol construction and remove eth/62 from the advertised ProtocolVersions.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
p2p/server.go	Adds LocalNode() accessor to retrieve the server’s local ENR node record.
p2p/enr/enr_test.go	Updates a test comment to match the UDP ENR key being tested.
eth/protocol.go	Refactors protocol constants/vars and removes eth/62 from advertised versions.
eth/peer.go	Updates message size checks to use the renamed max message size constant.
eth/handler.go	Refactors protocol construction and replaces cached chain config usage with blockchain.Config().
eth/handler_test.go	Removes the protocol compatibility test (fast sync vs versions).
eth/enr_entry.go	Introduces the eth ENR entry (forkid) and a goroutine to refresh it on head updates.
eth/backend.go	Attaches the eth ENR entry to protocols and starts the ENR update loop on service start.
core/blockchain_reader.go	Updates the comment on BlockChain.Config().

Comments suppressed due to low confidence (1)

eth/handler_test.go:45

• ProtocolVersions no longer advertises eth/62, but this file still runs eth/62 variants (e.g. TestGetBlockHeaders62). If eth/62 support is truly being removed, these eth/62-specific tests should be removed/updated; otherwise, ProtocolVersions/docs should clarify that eth/62 is still supported (just not announced).

// Tests that block headers can be retrieved from a remote chain based on user queries.
func TestGetBlockHeaders62(t *testing.T) { testGetBlockHeaders(t, 62) }

// TestGetBlockHeaders63 tests get block headers 63.
func TestGetBlockHeaders63(t *testing.T) { testGetBlockHeaders(t, 63) }