fix: crash when stopping LLDP receiver

internal/lldp/lldp.go

@@ -26,7 +26,6 @@ type LLDP struct {
 	enableRx bool
 	enableTx bool
 
-	packets          chan gopacket.Packet
 	interfaceName    string
 	advertiseOptions *AdvertiseOptions
 	onChange         func(neighbors []Neighbor)

internal/lldp/rx.go

@@ -3,7 +3,10 @@ package lldp
 import (
 	"context"
 	"fmt"
+	"io"
 	"net"
+	"strings"
+	"syscall"
 	"time"
 
 	"github.com/google/gopacket"
@@ -42,13 +45,6 @@ func (l *LLDP) setUpCapture() error {
 	}
 	logger.Info().Msg("created TPacketRx")
 
-	// Double-check: another goroutine might have set it up while we were creating
-	if l.tPacketRx != nil {
-		// Another goroutine already set it up, close our instance
-		tPacketRx.Close()
-		return nil
-	}
-
 	// set up multicast addresses
 	// otherwise the kernel might discard the packets
 	// another workaround would be to enable promiscuous mode but that's too tricky
@@ -98,23 +94,44 @@ func (l *LLDP) doCapture(logger *zerolog.Logger, rxCtx context.Context) {
 		l.mu.Unlock()
 	}()
 
-	packetChan := l.pktSourceRx.Packets()
-	for {
-		select {
-		case packet, ok := <-packetChan:
-			if !ok {
-				logger.Info().Msg("packet source closed")
-				return
-			}
-			if err := l.handlePacket(packet, logger); err != nil {
+	// TODO: use a channel to handle the packets
+	// PacketSource.Packets() is not reliable and can cause panics and the upstream hasn't fixed it yet
+	for rxCtx.Err() == nil {
+		if l.pktSourceRx == nil || l.tPacketRx == nil {
+			logger.Error().Msg("packet source or TPacketRx not initialized")
+			break
+		}
+
+		packet, err := l.pktSourceRx.NextPacket()
+		if err == nil {
+			if handleErr := l.handlePacket(packet, logger); handleErr != nil {
 				logger.Error().
-					Err(err).
+					Err(handleErr).
 					Msg("error handling packet")
 			}
-		case <-rxCtx.Done():
-			logger.Info().Msg("LLDP receiver stopped")
-			return
+			continue
 		}
+
+		// Immediately retry for temporary network errors and EAGAIN
+		// temporary has been deprecated and most cases are timeouts
+		if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+			continue
+		}
+		if err == syscall.EAGAIN {
+			continue
+		}
+
+		// Immediately break for known unrecoverable errors
+		if err == io.EOF || err == io.ErrUnexpectedEOF ||
+			err == io.ErrNoProgress || err == io.ErrClosedPipe || err == io.ErrShortBuffer ||
+			err == syscall.EBADF ||
+			strings.Contains(err.Error(), "use of closed file") {
+			break
+		}
+
+		logger.Error().
+			Err(err).
+			Msg("error receiving LLDP packet")
 	}
 }
 
@@ -348,17 +365,21 @@ func (l *LLDP) stopCapture() error {
 	if rxCancel != nil {
 		rxCancel()
 		l.rxCancel = nil
+
+		logger.Info().Msg("cancelled RX context, waiting for goroutine to finish")
 	}
 
 	// Wait a bit for goroutine to finish
-	time.Sleep(1000 * time.Millisecond)
+	time.Sleep(500 * time.Millisecond)
 
 	if l.tPacketRx != nil {
+		logger.Info().Msg("closing TPacketRx")
 		l.tPacketRx.Close()
 		l.tPacketRx = nil
 	}
 
 	if l.pktSourceRx != nil {
+		logger.Info().Msg("closing packet source")
 		l.pktSourceRx = nil
 	}
 

internal/network/types/config.go

@@ -54,7 +54,8 @@ type NetworkConfig struct {
 }
 
 func (c *NetworkConfig) ShouldEnableLLDPTransmit() bool {
-	return c.LLDPMode.String != "rx_only" && c.LLDPMode.String != "disabled"
+	// backwards compatibility: `basic` mode will be `rx_only` due to privacy concerns
+	return c.LLDPMode.String != "rx_only" && c.LLDPMode.String != "disabled" && c.LLDPMode.String != "basic"
 }
 
 func (c *NetworkConfig) ShouldEnableLLDPReceive() bool {

network.go

@@ -179,6 +179,7 @@ func initNetwork() error {
 		EnableTx:         nc.ShouldEnableLLDPTransmit(),
 		AdvertiseOptions: advertiseOptions,
 		OnChange: func(neighbors []lldp.Neighbor) {
+			// TODO: send deltas instead of the whole list
 			writeJSONRPCEvent("lldpNeighbors", neighbors, currentSession)
 		},
 		Logger: networkLogger,

ui/src/routes/devices.$id.settings.network.tsx

@@ -6,7 +6,7 @@ import dayjs from "dayjs";
 import relativeTime from "dayjs/plugin/relativeTime";
 import validator from "validator";
 
-import { LLDPNeighbor, NetworkSettings, NetworkState, useNetworkStateStore, useRTCStore } from "@hooks/stores";
+import { NetworkSettings, NetworkState, useLLDPNeighborsStore, useNetworkStateStore, useRTCStore } from "@hooks/stores";
 import { useJsonRpc } from "@hooks/useJsonRpc";
 import AutoHeight from "@components/AutoHeight";
 import { Button } from "@components/Button";
@@ -98,11 +98,12 @@ export default function SettingsNetworkRoute() {
     { label: string; from: string; to: string }[]
   >([]);
 
-  const [lldpNeighbors, setLldpNeighbors] = useState<LLDPNeighbor[]>([]);
+  const setLLDPNeighbors = useLLDPNeighborsStore(state => state.setNeighbors);
+  const lldpNeighbors = useLLDPNeighborsStore(state => state.neighbors);
   const fetchLLDPNeighbors = useCallback(async () => {
     const neighbors = await getLLDPNeighbors();
-    setLldpNeighbors(neighbors);
-  }, [setLldpNeighbors]);
+    setLLDPNeighbors(neighbors);
+  }, [setLLDPNeighbors]);
 
   useEffect(() => {
     fetchLLDPNeighbors();
@@ -572,9 +573,9 @@ export default function SettingsNetworkRoute() {
                         />
                       </SettingsItem>
                     </div>
-                    <AutoHeight>
+                    {lldpNeighbors.length > 0 && <AutoHeight>
                       <LLDPNeighborsCard neighbors={lldpNeighbors} />
-                    </AutoHeight>
+                    </AutoHeight>}
                   </div>
                 )
               }