feat: monitor connected Wi-Fi signal per interface (#2367)

agent/wifi/wifi_linux.go

@@ -0,0 +1,78 @@
+//go:build linux
+
+package wifi
+
+import (
+	"bytes"
+	"context"
+	"time"
+
+	"github.com/henrygd/beszel/internal/entities/system"
+	native "github.com/mdlayher/wifi"
+)
+
+type linuxClient interface {
+	Interfaces() ([]*native.Interface, error)
+	BSS(*native.Interface) (*native.BSS, error)
+	StationInfo(*native.Interface) ([]*native.StationInfo, error)
+	SetDeadline(time.Time) error
+	Close() error
+}
+
+func collect(ctx context.Context) map[string]system.WiFi {
+	client, err := native.New()
+	if err != nil {
+		return nil
+	}
+	defer client.Close()
+	return collectLinux(ctx, client)
+}
+
+func collectLinux(ctx context.Context, client linuxClient) map[string]system.WiFi {
+	result := make(map[string]system.WiFi)
+	if ctx.Err() != nil {
+		return result
+	}
+	if deadline, ok := ctx.Deadline(); ok {
+		if client.SetDeadline(deadline) != nil {
+			return result
+		}
+	}
+	interfaces, err := client.Interfaces()
+	if err != nil {
+		return result
+	}
+	for _, iface := range interfaces {
+		if ctx.Err() != nil {
+			break
+		}
+		if iface == nil || iface.Type != native.InterfaceTypeStation || iface.Name == "" {
+			continue
+		}
+		// GET_SCAN reads the kernel's BSS cache, without triggering a scan.
+		// Only the explicit associated status proves a current connection.
+		bss, err := client.BSS(iface)
+		if err != nil || bss == nil || bss.Status != native.BSSStatusAssociated {
+			continue
+		}
+		reading := system.WiFi{SSID: validSSID(bss.SSID)}
+		// Station statistics may require permissions unavailable in default
+		// containers. Keep association even when RSSI cannot be read. Do not
+		// substitute cached scan signal, which may be arbitrarily old.
+		stations, err := client.StationInfo(iface)
+		if err == nil {
+			for _, station := range stations {
+				if station == nil || len(bss.BSSID) == 0 || !bytes.Equal(station.HardwareAddr, bss.BSSID) {
+					continue
+				}
+				signal := float64(station.Signal)
+				if signal >= -150 && signal < 0 {
+					reading.Signal = &signal
+				}
+				break
+			}
+		}
+		result[iface.Name] = reading
+	}
+	return result
+}