Recovery: reindex interrupted sessions and fix packet counts; actionable AP activation error

cmd/pilens-helper/main.go

@@ -309,7 +309,7 @@ func activate(ctx context.Context, n config.Network, files map[string][]byte, st
 	}
 	if n.AP.Enabled {
 		if _, err := run(ctx, 60*time.Second, "nmcli", "--wait", "45", "connection", "up", netgen.ConnName); err != nil {
-			return err
+			return fmt.Errorf("the access point did not start. Likely causes: the band/channel is not permitted for country %s or not supported by this radio, or the radio does not support %s in AP mode (%w)", n.AP.Country, strings.ToUpper(n.AP.Security), err)
 		}
 		step("access point %q activated", n.AP.SSID)
 		if _, err := run(ctx, 30*time.Second, "systemctl", "restart", "pilens-dnsmasq.service"); err != nil {

cmd/pilens/main.go

@@ -130,7 +130,9 @@ func serve(args []string) error {
 	lim := capture.DefaultLimits()
 	db.GetJSON("capture_limits", &lim)
 	eng.SetLimits(lim)
-	recoverSessions(db, *caps)
+	for _, id := range recoverSessions(db, *caps) {
+		go eng.Reindex(id)
+	}
 
 	cert, fp, err := ensureCert(*data)
 	if err != nil {
@@ -178,7 +180,8 @@ func serve(args []string) error {
 }
 
 // recoverSessions finalises sessions left running by a crash or power loss.
-func recoverSessions(db *store.Store, dir string) {
+// It returns the IDs of the sessions it marked interrupted.
+func recoverSessions(db *store.Store, dir string) (ids []string) {
 	rows, err := db.Query(`SELECT s.id, g.seq, g.file, g.format FROM segments g JOIN capture_sessions s ON s.id=g.session_id WHERE g.complete=0 AND g.deleted=0`)
 	if err == nil {
 		type seg struct {
@@ -216,7 +219,16 @@ func recoverSessions(db *store.Store, dir string) {
 			slog.Warn("recovered interrupted segment", "session", s.id, "segment", s.seq, "packets", n, "truncated_tail", scanErr != nil)
 		}
 	}
+	if r, err := db.Query(`SELECT id FROM capture_sessions WHERE state IN ('running','importing')`); err == nil {
+		for r.Next() {
+			var id string
+			r.Scan(&id)
+			ids = append(ids, id)
+		}
+		r.Close()
+	}
 	db.Exec(`UPDATE capture_sessions SET state='failed', error='interrupted: the service stopped unexpectedly (power loss or crash); segments were finalised on restart and summaries may be incomplete', ended_at=? WHERE state IN ('running','importing')`, time.Now().UnixMilli())
+	return ids
 }
 
 func sdNotify(state string) {

internal/capture/query.go

@@ -502,3 +502,59 @@ func (e *Engine) indexImport(id, path, format string) {
 	data, _ := json.Marshal(map[string]string{"session": id})
 	e.Hub.Publish(Event{Type: "resync", Data: data})
 }
+
+// Reindex fills in summary rows missing for complete segments (after a crash or
+// power loss the index can lag behind what reached the capture file).
+func (e *Engine) Reindex(id string) error {
+	segs, err := e.Segments(id)
+	if err != nil {
+		return err
+	}
+	var total int64
+	for _, s := range segs {
+		if s.Deleted || !s.Complete {
+			continue
+		}
+		total += s.Count
+		var have int64
+		e.DB.QueryRow(`SELECT COUNT(*) FROM packets WHERE session_id=? AND num>=? AND num<?`, id, s.Base, s.Base+s.Count).Scan(&have)
+		if have >= s.Count {
+			continue
+		}
+		path := filepath.Join(e.sessionDir(id), s.File)
+		var offs []int64
+		pcapfile.Scan(path, s.Format, func(_ int, off int64, _ []byte) error { offs = append(offs, off); return nil }) // truncated tail tolerated
+		ctx, cancel := context.WithTimeout(context.Background(), time.Hour)
+		cmd := e.Tools.Command(ctx, 3600, e.Tools.SummaryArgs(path)...)
+		out, err := cmd.StdoutPipe()
+		if err == nil {
+			err = cmd.Start()
+		}
+		if err != nil {
+			cancel()
+			return err
+		}
+		var batch []Row
+		flush := func() {
+			if tx, err := e.DB.Begin(); err == nil {
+				insertRows(tx, id, batch)
+				tx.Commit()
+			}
+			batch = batch[:0]
+		}
+		ReadSummaries(out, func(r Row) {
+			if r.Num < 1 || r.Num > int64(len(offs)) {
+				return
+			}
+			r.Off, r.Seg, r.Num = offs[r.Num-1], s.Seq, s.Base+r.Num-1
+			if batch = append(batch, r); len(batch) >= 2000 {
+				flush()
+			}
+		})
+		flush()
+		cmd.Wait()
+		cancel()
+	}
+	e.DB.Exec(`UPDATE capture_sessions SET packets=? WHERE id=? AND packets<?`, total, id, total)
+	return nil
+}

internal/netgen/netgen.go

@@ -91,7 +91,7 @@ func DnsmasqConf(n config.Network) string {
 	w := func(f string, v ...any) { fmt.Fprintf(&b, f+"\n", v...) }
 	w("# Managed by PiLens. Changes are overwritten; use the PiLens UI.")
 	w("interface=%s", n.AP.Interface)
-	w("bind-dynamic") // only the AP interface; survives the address appearing late
+	w("bind-dynamic")        // only the AP interface; survives the address appearing late
 	w("except-interface=lo") // dnsmasq otherwise adds loopback implicitly
 	w("no-hosts")
 	w("domain-needed")