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Add comprehensive spec audit results and pyMC_core issue reports

- CHANGELOG.md: Full audit findings organized by severity
- PYMC_CORE_ISSUES.md: 7 evidence-based bug reports for pyMC_core
  (wrong constants, broken path_len decoding, wrong TRACE hash,
  wrong SNR calculation)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Add comprehensive spec audit results and pyMC_core issue reports

- CHANGELOG.md: Full audit findings organized by severity
- PYMC_CORE_ISSUES.md: 7 evidence-based bug reports for pyMC_core
  (wrong constants, broken path_len decoding, wrong TRACE hash,
  wrong SNR calculation)
- Remove ERRATA.md: contents already covered by audit findings

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2026-04-01 21:37:57 -06:00

1.9 KiB

Raw Blame History

MeshCore Protocol Specification

Section 12: Payload — Control

Overview

The CONTROL payload carries control and discovery data. Control packets are raw byte payloads whose structure is determined by the first byte. A subset of control packets (those with bit 7 of the first byte set) are restricted to zero-hop delivery only.

Payload Type

Header payload type field: 0x0B (CONTROL)

Wire Format

 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Control Byte |  Data...      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Fields

Field	Offset	Size	Type	Description
control_byte	0	1 byte	uint8	Control type identifier
data	1	variable	raw	Control-specific data

Zero-Hop Restriction

When bit 7 (0x80) of the control byte is set, the packet is restricted to zero-hop delivery only. The reference implementation enforces this:

If (payload[0] & 0x80) != 0 AND the packet is direct-routed:
- It is processed only if getPathHashCount() == 0.
- It is NOT forwarded to other nodes.

Discovery Protocols

Control packets are commonly used for node discovery. The specific sub-protocol formats are application-defined, but typically include:

Discovery Request: Sent zero-hop to find nearby nodes
Discovery Response: Contains node type, name, SNR, and other metadata

Encoding

Construct the raw control data bytes.
If the control packet should be zero-hop only, set bit 7 of the first byte.
Copy data to payload, set payload_len.

Constraints

Payload MUST be at least 1 byte (the control byte).
Maximum payload: 184 bytes (MAX_PACKET_PAYLOAD).

Cross-References

Section 17: Routing — Zero-hop delivery
Test vectors: corpus/payloads/control/

Reference Implementation

Mesh::createControlData() in src/Mesh.cpp — Encoding
Mesh::onRecvPacket(), CONTROL handling — Zero-hop check and delivery

1.9 KiB Raw Blame History