fix: compute hex-dump byte ranges client-side from per-obs raw_hex (#891)

## Symptom The colored byte strip in the packet detail pane is offset from the labeled byte breakdown below it. Off by N bytes where N is the difference between the top-level packet's path length and the displayed observation's path length. ## Root cause Server computes `breakdown.ranges` once from the top-level packet's raw_hex (in `BuildBreakdown`) and ships it in the API response. After #882 we render each observation's own raw_hex, but we keep using the top-level breakdown — so a 7-hop top-level packet shipped "Path: bytes 2-8", and when we rendered an 8-hop observation we coloured 7 of the 8 path bytes and bled into the payload. The labeled rows below (which use `buildFieldTable`) parse the displayed raw_hex on the client, so they were correct — they just didn't match the strip above. ## Fix Port `BuildBreakdown()` to JS as `computeBreakdownRanges()` in `app.js`. Use it in `renderDetail()` from the actually-rendered (per-obs) raw_hex. ## Test Manually verified the JS function output matches the Go implementation for FLOOD/non-transport, transport, ADVERT, and direct-advert (zero hops) cases. Closes nothing (caught in post-tag bug bash). --------- Co-authored-by: you <you@example.com>
2026-08-29 00:18:22 +00:00 · 2026-04-21 22:17:14 -07:00
parent 56ec590bc4
commit 6ca5e86df6
8 changed files with 321 additions and 266 deletions
@@ -443,106 +443,6 @@ func DecodePacket(hexString string, validateSignatures bool) (*DecodedPacket, er
 	}, nil
 }

-// HexRange represents a labeled byte range for the hex breakdown visualization.
-type HexRange struct {
-	Start int    `json:"start"`
-	End   int    `json:"end"`
-	Label string `json:"label"`
-}
-
-// Breakdown holds colored byte ranges returned by the packet detail endpoint.
-type Breakdown struct {
-	Ranges []HexRange `json:"ranges"`
-}
-
-// BuildBreakdown computes labeled byte ranges for each section of a MeshCore packet.
-// The returned ranges are consumed by createColoredHexDump() and buildHexLegend()
-// in the frontend (public/app.js).
-func BuildBreakdown(hexString string) *Breakdown {
-	hexString = strings.ReplaceAll(hexString, " ", "")
-	hexString = strings.ReplaceAll(hexString, "\n", "")
-	hexString = strings.ReplaceAll(hexString, "\r", "")
-	buf, err := hex.DecodeString(hexString)
-	if err != nil || len(buf) < 2 {
-		return &Breakdown{Ranges: []HexRange{}}
-	}
-
-	var ranges []HexRange
-	offset := 0
-
-	// Byte 0: Header
-	ranges = append(ranges, HexRange{Start: 0, End: 0, Label: "Header"})
-	offset = 1
-
-	header := decodeHeader(buf[0])
-
-	// Bytes 1-4: Transport Codes (TRANSPORT_FLOOD / TRANSPORT_DIRECT only)
-	if isTransportRoute(header.RouteType) {
-		if len(buf) < offset+4 {
-			return &Breakdown{Ranges: ranges}
-		}
-		ranges = append(ranges, HexRange{Start: offset, End: offset + 3, Label: "Transport Codes"})
-		offset += 4
-	}
-
-	if offset >= len(buf) {
-		return &Breakdown{Ranges: ranges}
-	}
-
-	// Next byte: Path Length (bits 7-6 = hashSize-1, bits 5-0 = hashCount)
-	ranges = append(ranges, HexRange{Start: offset, End: offset, Label: "Path Length"})
-	pathByte := buf[offset]
-	offset++
-
-	hashSize := int(pathByte>>6) + 1
-	hashCount := int(pathByte & 0x3F)
-	pathBytes := hashSize * hashCount
-
-	// Path hops
-	if hashCount > 0 && offset+pathBytes <= len(buf) {
-		ranges = append(ranges, HexRange{Start: offset, End: offset + pathBytes - 1, Label: "Path"})
-	}
-	offset += pathBytes
-
-	if offset >= len(buf) {
-		return &Breakdown{Ranges: ranges}
-	}
-
-	payloadStart := offset
-
-	// Payload — break ADVERT into named sub-fields; everything else is one Payload range
-	if header.PayloadType == PayloadADVERT && len(buf)-payloadStart >= 100 {
-		ranges = append(ranges, HexRange{Start: payloadStart, End: payloadStart + 31, Label: "PubKey"})
-		ranges = append(ranges, HexRange{Start: payloadStart + 32, End: payloadStart + 35, Label: "Timestamp"})
-		ranges = append(ranges, HexRange{Start: payloadStart + 36, End: payloadStart + 99, Label: "Signature"})
-
-		appStart := payloadStart + 100
-		if appStart < len(buf) {
-			ranges = append(ranges, HexRange{Start: appStart, End: appStart, Label: "Flags"})
-			appFlags := buf[appStart]
-			fOff := appStart + 1
-			if appFlags&0x10 != 0 && fOff+8 <= len(buf) {
-				ranges = append(ranges, HexRange{Start: fOff, End: fOff + 3, Label: "Latitude"})
-				ranges = append(ranges, HexRange{Start: fOff + 4, End: fOff + 7, Label: "Longitude"})
-				fOff += 8
-			}
-			if appFlags&0x20 != 0 && fOff+2 <= len(buf) {
-				fOff += 2
-			}
-			if appFlags&0x40 != 0 && fOff+2 <= len(buf) {
-				fOff += 2
-			}
-			if appFlags&0x80 != 0 && fOff < len(buf) {
-				ranges = append(ranges, HexRange{Start: fOff, End: len(buf) - 1, Label: "Name"})
-			}
-		}
-	} else {
-		ranges = append(ranges, HexRange{Start: payloadStart, End: len(buf) - 1, Label: "Payload"})
-	}
-
-	return &Breakdown{Ranges: ranges}
-}
-
 // ComputeContentHash computes the SHA-256-based content hash (first 16 hex chars).
 // It hashes the payload-type nibble + payload (skipping path bytes) to produce a
 // route-independent identifier for the same logical packet. For TRACE packets,
@@ -97,146 +97,6 @@ func TestDecodePacket_FloodHasNoCodes(t *testing.T) {
 	}
 }

-func TestBuildBreakdown_InvalidHex(t *testing.T) {
-	b := BuildBreakdown("not-hex!")
-	if len(b.Ranges) != 0 {
-		t.Errorf("expected empty ranges for invalid hex, got %d", len(b.Ranges))
-	}
-}
-
-func TestBuildBreakdown_TooShort(t *testing.T) {
-	b := BuildBreakdown("11") // 1 byte — no path byte
-	if len(b.Ranges) != 0 {
-		t.Errorf("expected empty ranges for too-short packet, got %d", len(b.Ranges))
-	}
-}
-
-func TestBuildBreakdown_FloodNonAdvert(t *testing.T) {
-	// Header 0x15: route=1/FLOOD, payload=5/GRP_TXT
-	// PathByte 0x01: 1 hop, 1-byte hash
-	// PathHop: AA
-	// Payload: FF0011
-	b := BuildBreakdown("1501AAFFFF00")
-	labels := rangeLabels(b.Ranges)
-	expect := []string{"Header", "Path Length", "Path", "Payload"}
-	if !equalLabels(labels, expect) {
-		t.Errorf("expected labels %v, got %v", expect, labels)
-	}
-	// Verify byte positions
-	assertRange(t, b.Ranges, "Header", 0, 0)
-	assertRange(t, b.Ranges, "Path Length", 1, 1)
-	assertRange(t, b.Ranges, "Path", 2, 2)
-	assertRange(t, b.Ranges, "Payload", 3, 5)
-}
-
-func TestBuildBreakdown_TransportFlood(t *testing.T) {
-	// Header 0x14: route=0/TRANSPORT_FLOOD, payload=5/GRP_TXT
-	// TransportCodes: AABBCCDD (4 bytes)
-	// PathByte 0x01: 1 hop, 1-byte hash
-	// PathHop: EE
-	// Payload: FF00
-	b := BuildBreakdown("14AABBCCDD01EEFF00")
-	assertRange(t, b.Ranges, "Header", 0, 0)
-	assertRange(t, b.Ranges, "Transport Codes", 1, 4)
-	assertRange(t, b.Ranges, "Path Length", 5, 5)
-	assertRange(t, b.Ranges, "Path", 6, 6)
-	assertRange(t, b.Ranges, "Payload", 7, 8)
-}
-
-func TestBuildBreakdown_FloodNoHops(t *testing.T) {
-	// Header 0x15: FLOOD/GRP_TXT; PathByte 0x00: 0 hops; Payload: AABB
-	b := BuildBreakdown("150000AABB")
-	assertRange(t, b.Ranges, "Header", 0, 0)
-	assertRange(t, b.Ranges, "Path Length", 1, 1)
-	// No Path range since hashCount=0
-	for _, r := range b.Ranges {
-		if r.Label == "Path" {
-			t.Error("expected no Path range for zero-hop packet")
-		}
-	}
-	assertRange(t, b.Ranges, "Payload", 2, 4)
-}
-
-func TestBuildBreakdown_AdvertBasic(t *testing.T) {
-	// Header 0x11: FLOOD/ADVERT
-	// PathByte 0x01: 1 hop, 1-byte hash
-	// PathHop: AA
-	// Payload: 100 bytes (PubKey32 + Timestamp4 + Signature64) + Flags=0x02 (repeater, no extras)
-	pubkey := repeatHex("AB", 32)
-	ts := "00000000" // 4 bytes
-	sig := repeatHex("CD", 64)
-	flags := "02"
-	hex := "1101AA" + pubkey + ts + sig + flags
-	b := BuildBreakdown(hex)
-	assertRange(t, b.Ranges, "Header", 0, 0)
-	assertRange(t, b.Ranges, "Path Length", 1, 1)
-	assertRange(t, b.Ranges, "Path", 2, 2)
-	assertRange(t, b.Ranges, "PubKey", 3, 34)
-	assertRange(t, b.Ranges, "Timestamp", 35, 38)
-	assertRange(t, b.Ranges, "Signature", 39, 102)
-	assertRange(t, b.Ranges, "Flags", 103, 103)
-}
-
-func TestBuildBreakdown_AdvertWithLocation(t *testing.T) {
-	// flags=0x12: hasLocation bit set
-	pubkey := repeatHex("00", 32)
-	ts := "00000000"
-	sig := repeatHex("00", 64)
-	flags := "12" // 0x10 = hasLocation
-	latBytes := "00000000"
-	lonBytes := "00000000"
-	hex := "1101AA" + pubkey + ts + sig + flags + latBytes + lonBytes
-	b := BuildBreakdown(hex)
-	assertRange(t, b.Ranges, "Latitude", 104, 107)
-	assertRange(t, b.Ranges, "Longitude", 108, 111)
-}
-
-func TestBuildBreakdown_AdvertWithName(t *testing.T) {
-	// flags=0x82: hasName bit set
-	pubkey := repeatHex("00", 32)
-	ts := "00000000"
-	sig := repeatHex("00", 64)
-	flags := "82" // 0x80 = hasName
-	name := "4E6F6465" // "Node" in hex
-	hex := "1101AA" + pubkey + ts + sig + flags + name
-	b := BuildBreakdown(hex)
-	assertRange(t, b.Ranges, "Name", 104, 107)
-}
-
-// helpers
-
-func rangeLabels(ranges []HexRange) []string {
-	out := make([]string, len(ranges))
-	for i, r := range ranges {
-		out[i] = r.Label
-	}
-	return out
-}
-
-func equalLabels(a, b []string) bool {
-	if len(a) != len(b) {
-		return false
-	}
-	for i := range a {
-		if a[i] != b[i] {
-			return false
-		}
-	}
-	return true
-}
-
-func assertRange(t *testing.T, ranges []HexRange, label string, wantStart, wantEnd int) {
-	t.Helper()
-	for _, r := range ranges {
-		if r.Label == label {
-			if r.Start != wantStart || r.End != wantEnd {
-				t.Errorf("range %q: want [%d,%d], got [%d,%d]", label, wantStart, wantEnd, r.Start, r.End)
-			}
-			return
-		}
-	}
-	t.Errorf("range %q not found in %v", label, rangeLabels(ranges))
-}

 func TestZeroHopDirectHashSize(t *testing.T) {
 	// DIRECT (RouteType=2) + REQ (PayloadType=0) → header byte = 0x02
@@ -958,11 +958,9 @@ func (s *Server) handlePacketDetail(w http.ResponseWriter, r *http.Request) {
 		pathHops = []interface{}{}
 	}

-	rawHex, _ := packet["raw_hex"].(string)
 	writeJSON(w, PacketDetailResponse{
 		Packet:           packet,
 		Path:             pathHops,
-		Breakdown:        BuildBreakdown(rawHex),
 		ObservationCount: observationCount,
 		Observations:     mapSliceToObservations(observations),
 	})
@@ -315,7 +315,6 @@ type PacketTimestampsResponse struct {
 type PacketDetailResponse struct {
 	Packet           interface{}       `json:"packet"`
 	Path             []interface{}     `json:"path"`
-	Breakdown        *Breakdown        `json:"breakdown"`
 	ObservationCount int               `json:"observation_count"`
 	Observations     []ObservationResp `json:"observations,omitempty"`
 }