mirror of
https://github.com/MeshCore-Beacon/beacon-server.git
synced 2026-10-20 07:31:56 +00:00
97 lines
2.6 KiB
Go
97 lines
2.6 KiB
Go
// Copyright 2026 Beacon Contributors
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// SPDX-License-Identifier: AGPL-3.0-or-later
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// Package tracequality checks TRACE structure, not authenticity or RF plausibility.
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package tracequality
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import "encoding/hex"
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type Quality struct {
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Status string `json:"status"` // supported, suspect, or ambiguous; supported is not authenticated
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Reasons []string `json:"reasons"`
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}
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func (q *Quality) Add(reason string) {
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for _, r := range q.Reasons {
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if r == reason {
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return
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}
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}
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q.Reasons = append(q.Reasons, reason)
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if reason == "ambiguous_prefix" && q.Status != "suspect" {
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q.Status = "ambiguous"
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} else if reason != "ambiguous_prefix" {
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q.Status = "suspect"
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}
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}
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// Assess uses TRACE's power-of-two payload hash widths, NOT the ordinary
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// packet path's 1/2/3-byte widths. The path field contains consumed-hop SNRs.
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// -1 means a header/path field is unavailable in a retained summary.
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// Mesh.cpp onRecvPacket/sendDirect: a trace uses direct routing, flags bits
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// 0..1, and fewer than 64 SNR bytes. Partial probes and return loops are valid.
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func Assess(raw []byte, version, route, pathLength int) Quality {
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q := Quality{Status: "supported", Reasons: []string{}}
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if version > 0 {
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q.Add("unsupported_version")
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}
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if route >= 0 && route != 2 && route != 3 {
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q.Add("non_direct_trace")
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}
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if len(raw) < 9 {
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q.Add("incomplete_payload")
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return q
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}
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if len(raw) > 184 {
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q.Add("payload_too_large")
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}
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if raw[8]&0xfc != 0 {
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q.Add("unsupported_flags")
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}
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size := 1 << (raw[8] & 3)
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if (len(raw)-9)%size != 0 {
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q.Add("misaligned_hashes")
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}
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count := (len(raw) - 9) / size
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if count > 63 {
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q.Add("too_many_hops")
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}
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if pathLength > 63 || pathLength > count {
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q.Add("invalid_snr_path")
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}
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return q
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}
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// Stored also checks old parsed rows, without rewriting or deleting the evidence.
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func Stored(raw string, flags byte, hashes []string, snrs []float32) Quality {
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b, err := hex.DecodeString(raw)
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if err != nil {
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return Quality{Status: "suspect", Reasons: []string{"incomplete_payload"}}
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}
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if raw == "" { // Older exports may contain only decoded fields.
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b = make([]byte, 9)
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b[8] = flags
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for _, h := range hashes {
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v, e := hex.DecodeString(h)
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if e != nil {
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return Quality{Status: "suspect", Reasons: []string{"misaligned_hashes"}}
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}
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b = append(b, v...)
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}
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}
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q := Assess(b, -1, -1, len(snrs))
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size := 1 << (flags & 3)
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if len(b) >= 9 && b[8] != flags {
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q.Add("misaligned_hashes")
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}
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for _, h := range hashes {
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if len(h) != 2*size {
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q.Add("misaligned_hashes")
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}
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}
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if len(b) >= 9 && len(hashes) != (len(b)-9)/size {
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q.Add("misaligned_hashes")
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}
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return q
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}
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