swaitsandClaude Opus 4.6
9db901088e
- 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>
58 lines
1.7 KiB
Markdown
58 lines
1.7 KiB
Markdown
# MeshCore Protocol Specification
|
|
|
|
## Section 4: Payload — ACK
|
|
|
|
### Overview
|
|
|
|
The ACK (acknowledgment) payload is the simplest payload type. It consists of a
|
|
single 4-byte CRC value used to confirm receipt of a previously sent message.
|
|
The CRC is computed by the sender from the original message's timestamp, text,
|
|
and sender public key.
|
|
|
|
### Payload Type
|
|
|
|
Header payload type field: `0x03` (ACK)
|
|
|
|
### Wire Format
|
|
|
|
```
|
|
0 1 2 3
|
|
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| ACK CRC (uint32_le) |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
```
|
|
|
|
### Fields
|
|
|
|
| Field | Offset | Size | Type | Description |
|
|
|-------|--------|------|------|-------------|
|
|
| ack_crc | 0 | 4 bytes | uint32_le | CRC identifying the acknowledged message |
|
|
|
|
### Encoding
|
|
|
|
1. Compute the 4-byte CRC value for the message being acknowledged.
|
|
2. Write the CRC as a little-endian 32-bit unsigned integer.
|
|
3. Set payload_len to 4.
|
|
|
|
### Decoding
|
|
|
|
1. Read 4 bytes from the payload as a little-endian uint32.
|
|
2. If fewer than 4 bytes are available, the packet is INVALID.
|
|
|
|
### Constraints
|
|
|
|
- The payload MUST be exactly 4 bytes.
|
|
- Implementations SHOULD log or discard ACK packets with payload_len < 4.
|
|
|
|
### Cross-References
|
|
|
|
- [Section 1: Wire Format](01-wire-format.md) — Packet framing
|
|
- [Section 11: Multipart](11-payload-multipart.md) — Multipart ACK encoding
|
|
- Test vectors: `corpus/payloads/ack/`
|
|
|
|
### Reference Implementation
|
|
|
|
- `Mesh::createAck()` in `src/Mesh.cpp`
|
|
- ACK reception in `Mesh::onRecvPacket()`, case `PAYLOAD_TYPE_ACK`
|