mirror of
https://github.com/MeshCore-Beacon/beacon-server.git
synced 2026-10-17 22:20:12 +00:00
MrAlders0n
52fc3e1e48
A short topic pubkey panicked a lane worker and killed the process; keys must now be 32 bytes and lane workers recover. Also reject non-finite radio values before airtime, strip NULs from advert names and neighbour scopes, guard the MQTT client pointer, and never stream a broker copy of a hearing as a repeat.
61 lines
1.7 KiB
Go
61 lines
1.7 KiB
Go
// Copyright 2026 Beacon Contributors
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// SPDX-License-Identifier: AGPL-3.0-or-later
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// Package lora computes LoRa airtime for MeshCore frames, so an observation
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// can be costed in milliseconds of channel occupancy.
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package lora
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import "math"
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const (
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minSF = 7
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maxSF = 12
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minCR = 5
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maxCR = 8
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// MinBWKHz and MaxBWKHz bracket every LoRa bandwidth (7.8 kHz sub-GHz to 1625 kHz SX128x).
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MinBWKHz = 7
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MaxBWKHz = 1625
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)
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// PreambleSymbols mirrors MeshCore's preambleLengthForSF: 32 symbols at SF<=8, 16 above.
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func PreambleSymbols(sf int) int {
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if sf <= 8 {
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return 32
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}
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return 16
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}
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// FrameLength is the on-air byte count of a MeshCore frame rebuilt from its stored parts.
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func FrameLength(transportCodes bool, pathLen, payloadLen int) int {
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n := 1 + 1 + pathLen + payloadLen // header byte + path length byte
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if transportCodes {
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n += 4
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}
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return n
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}
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// TimeOnAirMs is the Semtech LoRa time-on-air (RadioLib getTimeOnAir: CRC on, explicit header,
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// LDRO auto at t_sym >= 16 ms). ok is false when any parameter is outside the costable range.
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func TimeOnAirMs(frameLen, sf int, bwKHz float64, cr int) (ms float64, ok bool) {
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if frameLen <= 0 || sf < minSF || sf > maxSF || !(bwKHz >= MinBWKHz && bwKHz <= MaxBWKHz) || cr < minCR || cr > maxCR {
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return 0, false
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}
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tSym := math.Exp2(float64(sf)) / bwKHz
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de := 0
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if tSym >= 16 {
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de = 1
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}
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n := float64(PreambleSymbols(sf)) + 4.25 + float64(symbols(frameLen, sf, cr, de))
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return n * tSym, true
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}
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// symbols is the Semtech payload symbol count with explicit header and CRC on.
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func symbols(frameLen, sf, cr, de int) int {
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n := math.Ceil(float64(8*frameLen-4*sf+44)/float64(4*(sf-2*de))) * float64(cr)
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if n < 0 {
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n = 0
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}
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return 8 + int(n)
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}
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