Root cause: Merkle verification failures (error 659) and peer bans occurred
because protocol TX was not consistently present in m_transactions[1].
Parser fix (pool_block_parser.inl):
- Skip dummy transactions[0] entry when populating m_transactions
- Add protocol TX computation after parsing for Carrot v1 blocks
Block template fix (block_template.cpp):
- Insert protocol TX at position [1] during block creation in update()
- Insert protocol TX during select_mempool_transactions()
get_pow_hash fix (pool_block.cpp):
- Ensure protocol TX is populated before serialize_mainchain_data()
The protocol TX must be at m_transactions[1] before ANY serialization
occurs, otherwise sender and receiver compute different merkle roots.
Tested: Multiple restart cycles with two nodes, no bans, chains stay synced.
Problem: P2Pool nodes starting at different times or experiencing network
issues would create independent genesis blocks, resulting in incompatible
chains. Nodes would ban each other for invalid blocks that were actually
valid on a different chain. Cache resume after restart frequently failed
due to genesis mismatch between nodes.
Solution: Oldest compatible genesis wins protocol that coordinates
genesis selection across peers before mining begins.
New P2P message GENESIS_INFO exchanges:
- Genesis block hash
- Genesis timestamp
- Genesis mainchain height
- Protocol version
Startup behavior:
- Wait up to 90 seconds for peer genesis info (with progress logging)
- Adopt oldest genesis from compatible peers
- Only create own genesis if no peers respond
Late joiner reconciliation:
- Running nodes that receive older genesis from new peer will purge
their sidechain and re-sync to the older chain
- Cache files deleted on purge to prevent reload of stale blocks
Protocol versioning:
- PROTOCOL_VERSION constant at top of side_chain.h
- Increment only on consensus-breaking changes
- Version mismatch logs warning, prevents genesis adoption
Tiebreaker: When timestamps match, lexicographically lower hash wins.
- Add dev fee output in get_outputs_blob() for sidechain validation
- Fix extra nonce size calculation to account for dev fee weight
- Fix size estimation in busy mempool handler to account for dev fee
- Add debug logging for mainchain data serialization
- Fixes peer banning due to sidechain ID mismatch (error 502)
P2Pool-main: 8.2 MB saved
P2Pool-mini: 66 MB saved
P2Pool-nano: 25.2 MB saved
The feature is available only when building from source and is intended for use on low-memory systems (for example, a VPS server with < 1 GB RAM).
It only makes sense to use with `--no-cache --no-randomx` in the command line because cache and RandomX hasher take much more memory.
Matt Hess