fix: filter garbage channel names from /api/channels, fixes #201

Channels with garbage-decrypted names (pre-#197 data still in DB) are now
filtered at the API level using the same non-printable character heuristic
from #197. Applied in both Node.js server.js and Go server (store.go, db.go).
No data is deleted — only filtered from API responses.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

cmd/server/db.go

@@ -1218,6 +1218,12 @@ func (db *DB) GetChannels() ([]map[string]interface{}, error) {
 		if dtype != "CHAN" {
 			continue
 		}
+		// Filter out garbage-decrypted channel names/messages (pre-#197 data still in DB)
+		chanStr, _ := decoded["channel"].(string)
+		textStr, _ := decoded["text"].(string)
+		if hasGarbageChars(chanStr) || hasGarbageChars(textStr) {
+			continue
+		}
 		channelName, _ := decoded["channel"].(string)
 		if channelName == "" {
 			channelName = "unknown"

cmd/server/store.go

@@ -12,6 +12,7 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+	"unicode/utf8"
 )
 
 // payloadTypeNames maps payload_type int → human-readable name (firmware-standard).
@@ -1538,6 +1539,25 @@ func filterTxSlice(s []*StoreTx, fn func(*StoreTx) bool) []*StoreTx {
 	return result
 }
 
+// countNonPrintable counts characters that are non-printable (< 0x20 except \n, \t)
+// or invalid UTF-8 replacement characters. Mirrors the heuristic from #197.
+func countNonPrintable(s string) int {
+	count := 0
+	for _, r := range s {
+		if r < 0x20 && r != '\n' && r != '\t' {
+			count++
+		} else if r == utf8.RuneError {
+			count++
+		}
+	}
+	return count
+}
+
+// hasGarbageChars returns true if the string contains garbage (non-printable) data.
+func hasGarbageChars(s string) bool {
+	return s != "" && (!utf8.ValidString(s) || countNonPrintable(s) > 2)
+}
+
 // GetChannels returns channel list from in-memory packets (payload_type 5, decoded type CHAN).
 func (s *PacketStore) GetChannels(region string) []map[string]interface{} {
 	s.mu.RLock()
@@ -1588,6 +1608,10 @@ func (s *PacketStore) GetChannels(region string) []map[string]interface{} {
 		if decoded.Type != "CHAN" {
 			continue
 		}
+		// Filter out garbage-decrypted channel names/messages (pre-#197 data still in DB)
+		if hasGarbageChars(decoded.Channel) || hasGarbageChars(decoded.Text) {
+			continue
+		}
 
 		channelName := decoded.Channel
 		if channelName == "" {

decoder.js

@@ -360,7 +360,7 @@ function validateAdvert(advert) {
   return { valid: true };
 }
 
-module.exports = { decodePacket, validateAdvert, ROUTE_TYPES, PAYLOAD_TYPES, VALID_ROLES };
+module.exports = { decodePacket, validateAdvert, hasNonPrintableChars, ROUTE_TYPES, PAYLOAD_TYPES, VALID_ROLES };
 
 // --- Tests ---
 if (require.main === module) {

test-server-routes.js

@@ -121,6 +121,28 @@ function seedTestData() {
   try { pktStore.insert(chanPkt2); } catch {}
   try { db.insertTransmission(chanPkt2); } catch {}
 
+  // Seed a CHAN packet with garbage-decrypted name (pre-#197 data) — should be filtered out
+  const garbageChanPkt = {
+    raw_hex: 'GARBAGE0CHANNEL1',
+    timestamp: now, observer_id: 'test-obs-1', observer_name: 'TestObs', snr: 2, rssi: -95,
+    hash: 'test-hash-garbage-chan', route_type: 0, payload_type: 5, payload_version: 1,
+    path_json: JSON.stringify([]),
+    decoded_json: JSON.stringify({ type: 'CHAN', channel: 'garb\x01\x02\x03age', text: 'SomeUser: hello\x04\x05\x06', sender: 'SomeUser' }),
+  };
+  try { pktStore.insert(garbageChanPkt); } catch {}
+  try { db.insertTransmission(garbageChanPkt); } catch {}
+
+  // Seed a CHAN packet with clean name but garbage text — should also be filtered out
+  const garbageTextPkt = {
+    raw_hex: 'GARBAGE0TEXT0001',
+    timestamp: now, observer_id: 'test-obs-1', observer_name: 'TestObs', snr: 2, rssi: -95,
+    hash: 'test-hash-garbage-text', route_type: 0, payload_type: 5, payload_version: 1,
+    path_json: JSON.stringify([]),
+    decoded_json: JSON.stringify({ type: 'CHAN', channel: 'cleanChan', text: '\x00\x01\x02\x03garbage binary', sender: 'User' }),
+  };
+  try { pktStore.insert(garbageTextPkt); } catch {}
+  try { db.insertTransmission(garbageTextPkt); } catch {}
+
   // Packet with sender_key/recipient_key for peer interaction coverage in db.getNodeAnalytics
   const peerPkt = {
     raw_hex: 'DEADBEEF00112233',
@@ -436,6 +458,17 @@ seedTestData();
     assert(typeof r.body === 'object', 'should return channels');
   });
 
+  await t('GET /api/channels filters garbage channel names', async () => {
+    cache.clear();
+    const r = await request(app).get('/api/channels').expect(200);
+    const names = r.body.channels.map(c => c.name);
+    assert(!names.some(n => n.includes('\x01') || n.includes('\x02') || n.includes('\x03')),
+      'garbage channel names should be filtered out');
+    assert(!names.includes('cleanChan'),
+      'channels with garbage text should be filtered out');
+    assert(names.includes('ch01'), 'valid channel ch01 should still be present');
+  });
+
   await t('GET /api/channels with region', async () => {
     await request(app).get('/api/channels?region=SFO').expect(200);
   });