Public Access
twislaandClaude Opus 5.5
3242475699
The 16-byte clear header (hops away, channel hash, relay node), the EU_868 presets and their frequency slots, and the channel hash, all checked against Meshtastic's source. Captures are pcap with LoRaTap v0, read back with TShark 4.2.5; packet RSSI is plain dBm, as Wireshark reads it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT
37 lines
1.3 KiB
C++
37 lines
1.3 KiB
C++
#pragma once
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#include <cstddef>
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#include <cstdint>
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#include <string>
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namespace roro::meshtastic {
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constexpr uint32_t kBroadcast = 0xFFFFFFFF;
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// The 16 bytes every Meshtastic packet starts with, sent in clear (little-endian). The payload
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// after it is encrypted with the Channel's key.
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struct PacketHeader {
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uint32_t to = 0, from = 0, id = 0;
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uint8_t flags = 0;
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uint8_t channelHash = 0; // the Channel's name and key folded into a byte (see channelHash())
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uint8_t nextHop = 0; // last byte of the Node meant to relay it next; 0 when flooding
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uint8_t relayNode = 0; // last byte of the Node that relayed it to us
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uint8_t hopLimit() const { return flags & 0x07; }
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bool wantAck() const { return flags & 0x08; }
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bool viaMqtt() const { return flags & 0x10; }
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uint8_t hopStart() const { return flags >> 5; }
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bool broadcast() const { return to == kBroadcast; }
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// How many times it was relayed before we heard it; -1 when the sender didn't say (hop start 0).
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int hopsAway() const { return hopStart() == 0 ? -1 : hopStart() - hopLimit(); }
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};
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constexpr size_t kHeaderSize = 16;
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bool parseHeader(const uint8_t* data, size_t len, PacketHeader& out);
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// "!12345678", as Meshtastic writes node numbers; "all" for broadcast.
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std::string nodeId(uint32_t node);
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} // namespace roro::meshtastic
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