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MoreBC2

Net processing handshake

CategoryDeveloper / Source AtlasStatusReviewed / Runtime-corroborated structuralLast reviewed2026-09-12

Summary

Section titled “Summary”

This page maps the peer handshake and early feature-negotiation portion of BitcoinII Core v31.1.0 src/net_processing.*.

The source review covers version / verack, service/version checks, self-connection handling, relay preferences, and early feature messages such as wtxidrelay, sendaddrv2, compact-block signaling, and optional transaction-reconciliation negotiation.

September v31.1.0 runtime evidence now corroborates successful ordinary outbound handshakes because the isolated mainnet node established multiple outbound peers and began current header synchronization. That does not mean every feature-negotiation branch was instrumented.

Handshake flow

Section titled “Handshake flow”

Reviewed version processing includes:

  • parsing protocol version, services, time, addresses, nonce, subversion, start height, and relay preference;
  • rejecting peers below the minimum supported protocol version;
  • self-connection detection for inbound connections;
  • recording peer services and negotiated common protocol version;
  • disconnecting selected outbound peers that fail expected-service requirements;
  • sending the local version response for inbound peers where appropriate;
  • transitioning toward verack and successful-connection state.

Messages arriving before the expected handshake stage can be ignored or cause disconnect according to their timing requirements.

Early feature negotiation

Section titled “Early feature negotiation”

Source-reviewed early features include:

  • wtxidrelay;
  • sendaddrv2;
  • compact-block signaling;
  • optional transaction reconciliation;
  • address-fetch / getaddr behavior for selected outbound peers.

Some negotiation messages are only valid before successful connection and are treated differently if received after verack.

Runtime evidence — 2026-09-11

Section titled “Runtime evidence — 2026-09-11”

The isolated Windows v31.1.0 mainnet node observed:

  • protocol version 70016;
  • four outbound peers during the first run;
  • six outbound peers after restart;
  • current header acquisition and advancing IBD;
  • no manual peer injection required.

Those facts require successful enough version/verack/peer initialization for normal synchronization to proceed and therefore corroborate the ordinary outbound handshake path.

MoreBC2 did not capture or publish every negotiation message, peer address, service-flag combination, or transport handshake detail.

BitcoinII-specific boundary

Section titled “BitcoinII-specific boundary”

The broad version/verack structure remains Bitcoin-style. Current BitcoinII divergence becomes material after/around connection establishment through chain/network identity and validation rules such as:

  • mainnet message start / P2P port;
  • ShockWave contextual header difficulty;
  • fork-aware header synchronization;
  • replay-protection transaction signatures;
  • consensus data restrictions.

A successful generic Bitcoin-style handshake therefore does not imply full protocol/transaction/mining compatibility.

Privacy boundary

Section titled “Privacy boundary”

Peer diagnostics can reveal public/local network addresses and session details. MoreBC2’s runtime records summarize peer counts/state without publishing an identifiable peer list.

Section titled “Related pages”

Open work

Section titled “Open work”
  • Privacy-safe current v31 capture of selected negotiation/transport properties if needed.
  • Keep address, block/header, transaction relay and peer-health behavior in their dedicated pages.
  • Do not generalize one peer’s negotiated features to the entire network.

Primary sources

Section titled “Primary sources”
  • v31.1.0/src/net_processing.cpp
  • v31.1.0/src/net_processing.h
  • v31.1.0/src/protocol.*

Canonical tag: https://github.com/Bitcoin-II/BitcoinII-Core/tree/v31.1.0

Verification

Section titled “Verification”

Status: Reviewed / Runtime-corroborated structural
Primary evidence: BitcoinII Core v31.1.0 handshake source plus September 11 successful outbound-peer/synchronization runtime evidence
Notes: Ordinary outbound handshake success is corroborated. Exact feature-negotiation, inbound, transport, and failure branches remain uninstrumented.