feat/add discv5

[darrenkel]

Summary

• TODO: Add disco metrics

  This PR introduces the modern discv5 (Node Discovery Protocol v5) from the latest go-ethereum alongside the existing legacy discv5 implementation, enabling a transition path for peer discovery.

• See a local docker compose example here: https://github.com/vechain/thor/compare/darren/feat/add-discv5-2...darren/feat/add-discv5-compose?expand=1

Motivation

VeChainThor currently uses an older discv5 implementation from an earlier go-ethereum version. The modern discv5 protocol offers:

• Better NAT traversal
• Improved security (encrypted handshakes)
• ENR (Ethereum Node Records) support for richer node metadata
• Network isolation via the eth ENR entry for filtering nodes by topic

Changes

New Packages

• p2p/discv5/ - Modern discv5 protocol from go-ethereum with subpackages:
  • discover/ - v4 and v5 UDP discovery implementations
  • enode/ - Node representation and local node management
  • v5wire/ - Protocol wire encoding and session handling
  • nat/, netutil/, rlpx/ - Supporting network utilities
• common/ - Common utilities (hexutil, mclock, lru, math, prque, bitutil, etc.)
• rlp/ - RLP encoding/decoding library

Renamed Package

• p2p/discv5/ → p2p/tempdiscv5/ - Legacy discv5 renamed to avoid conflicts

P2P Server Updates (p2psrv/server.go)

• Runs both discv5 versions simultaneously using a shared UDP connection
• New discv5 writes to the socket; unhandled packets forwarded to tempdiscv5
• Node filtering via callback to accept only nodes with matching eth ENR record
• New options: DiscV5 (enable new), TempDiscV5 (enable legacy)

Node Filtering

• Nodes are filtered based on the eth ENR record matching the genesis-based topic
• Ensures nodes only connect to peers on the same VeChain network

New Flags

• --disable-temp-discv5 (hidden) - Disable legacy discv5 for testing

Architecture

                  ┌─────────────────────────┐
                  │     Shared UDP Port     │
                  └───────────┬─────────────┘
                              │
            ┌─────────────────┼─────────────────┐
            │                 │                 │
            ▼                 │                 ▼
  ┌─────────────────┐         │       ┌─────────────────┐
  │  Modern discv5  │         │       │  Temp discv5    │
  │  (v5 protocol)  │ ────────┘       │  (legacy)       │
  │                 │  unhandled      │                 │
  └─────────────────┘  packets        └─────────────────┘
            │                                   │
            └─────────────┬─────────────────────┘
                          │
                          ▼
                ┌─────────────────┐
                │ Discovered Nodes│
                │  (with filter)  │
                └─────────────────┘

Test Plan

• Run thor node with both discovery protocols enabled (default)
• Verify nodes are discovered via both protocols
• Test --disable-temp-discv5 flag disables legacy discovery
• Verify node filtering correctly rejects nodes from different networks
• Run disco bootnode with both protocols
• Test NAT traversal functionality

Breaking Changes

None - existing behavior preserved by default with both protocols running.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• New and existing E2E tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 22.98513% with 4195 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
p2p/discv5/discover/v5_udp.go	0.00%	503 Missing ⚠️
p2p/discv5/discover/v4_udp.go	0.00%	412 Missing ⚠️
p2p/discv5/discover/v5wire/encoding.go	0.00%	332 Missing ⚠️
p2p/discv5/discover/table.go	0.00%	328 Missing ⚠️
p2p/discv5/enode/nodedb.go	0.00%	238 Missing ⚠️
p2p/discv5/enode/iter.go	0.00%	205 Missing ⚠️
p2p/discv5/enode/node.go	0.00%	190 Missing ⚠️
p2p/discv5/msgrate/msgrate.go	0.00%	140 Missing ⚠️
p2p/discv5/enode/localnode.go	0.00%	135 Missing ⚠️
p2p/discv5/discover/table_reval.go	0.00%	111 Missing ⚠️
... and 47 more

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[github-actions]

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