all: fix golangci-lint issues (#3064)

hscontrol/mapper/batcher_lockfree.go

@@ -2,6 +2,7 @@ package mapper
 
 import (
 	"crypto/rand"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"sync"
@@ -18,7 +19,13 @@ import (
 	"tailscale.com/types/ptr"
 )
 
-var errConnectionClosed = errors.New("connection channel already closed")
+// LockFreeBatcher errors.
+var (
+	errConnectionClosed      = errors.New("connection channel already closed")
+	ErrInitialMapSendTimeout = errors.New("sending initial map: timeout")
+	ErrBatcherShuttingDown   = errors.New("batcher shutting down")
+	ErrConnectionSendTimeout = errors.New("timeout sending to channel (likely stale connection)")
+)
 
 // LockFreeBatcher uses atomic operations and concurrent maps to eliminate mutex contention.
 type LockFreeBatcher struct {
@@ -81,6 +88,7 @@ func (b *LockFreeBatcher) AddNode(id types.NodeID, c chan<- *tailcfg.MapResponse
 	if err != nil {
 		nlog.Error().Err(err).Msg("initial map generation failed")
 		nodeConn.removeConnectionByChannel(c)
+
 		return fmt.Errorf("generating initial map for node %d: %w", id, err)
 	}
 
@@ -90,11 +98,12 @@ func (b *LockFreeBatcher) AddNode(id types.NodeID, c chan<- *tailcfg.MapResponse
 	case c <- initialMap:
 		// Success
 	case <-time.After(5 * time.Second): //nolint:mnd
-		nlog.Error().Err(errors.New("timeout")).Msg("initial map send timeout") //nolint:err113
-		nlog.Debug().Caller().Dur("timeout.duration", 5*time.Second).           //nolint:mnd
-											Msg("initial map send timed out because channel was blocked or receiver not ready")
+		nlog.Error().Err(ErrInitialMapSendTimeout).Msg("initial map send timeout")
+		nlog.Debug().Caller().Dur("timeout.duration", 5*time.Second). //nolint:mnd
+										Msg("initial map send timed out because channel was blocked or receiver not ready")
 		nodeConn.removeConnectionByChannel(c)
-		return fmt.Errorf("sending initial map to node %d: timeout", id)
+
+		return fmt.Errorf("%w for node %d", ErrInitialMapSendTimeout, id)
 	}
 
 	// Update connection status
@@ -135,6 +144,7 @@ func (b *LockFreeBatcher) RemoveNode(id types.NodeID, c chan<- *tailcfg.MapRespo
 		nlog.Debug().Caller().
 			Int("active.connections", nodeConn.getActiveConnectionCount()).
 			Msg("node connection removed but keeping online, other connections remain")
+
 		return true // Node still has active connections
 	}
 
@@ -219,10 +229,12 @@ func (b *LockFreeBatcher) worker(workerID int) {
 			// This is used for synchronous map generation.
 			if w.resultCh != nil {
 				var result workResult
+
 				if nc, exists := b.nodes.Load(w.nodeID); exists {
 					var err error
 
 					result.mapResponse, err = generateMapResponse(nc, b.mapper, w.c)
+
 					result.err = err
 					if result.err != nil {
 						b.workErrors.Add(1)
@@ -235,7 +247,7 @@ func (b *LockFreeBatcher) worker(workerID int) {
 						nc.updateSentPeers(result.mapResponse)
 					}
 				} else {
-					result.err = fmt.Errorf("node %d not found", w.nodeID)
+					result.err = fmt.Errorf("%w: %d", ErrNodeNotFoundMapper, w.nodeID)
 
 					b.workErrors.Add(1)
 					wlog.Error().Err(result.err).
@@ -402,6 +414,7 @@ func (b *LockFreeBatcher) cleanupOfflineNodes() {
 				}
 			}
 		}
+
 		return true
 	})
 
@@ -454,6 +467,7 @@ func (b *LockFreeBatcher) ConnectedMap() *xsync.Map[types.NodeID, bool] {
 		if nodeConn.hasActiveConnections() {
 			ret.Store(id, true)
 		}
+
 		return true
 	})
 
@@ -469,6 +483,7 @@ func (b *LockFreeBatcher) ConnectedMap() *xsync.Map[types.NodeID, bool] {
 				ret.Store(id, false)
 			}
 		}
+
 		return true
 	})
 
@@ -488,7 +503,7 @@ func (b *LockFreeBatcher) MapResponseFromChange(id types.NodeID, ch change.Chang
 	case result := <-resultCh:
 		return result.mapResponse, result.err
 	case <-b.done:
-		return nil, fmt.Errorf("batcher shutting down while generating map response for node %d", id)
+		return nil, fmt.Errorf("%w while generating map response for node %d", ErrBatcherShuttingDown, id)
 	}
 }
 
@@ -523,8 +538,9 @@ type multiChannelNodeConn struct {
 // generateConnectionID generates a unique connection identifier.
 func generateConnectionID() string {
 	bytes := make([]byte, 8)
-	rand.Read(bytes)
-	return fmt.Sprintf("%x", bytes)
+	_, _ = rand.Read(bytes)
+
+	return hex.EncodeToString(bytes)
 }
 
 // newMultiChannelNodeConn creates a new multi-channel node connection.
@@ -557,7 +573,9 @@ func (mc *multiChannelNodeConn) addConnection(entry *connectionEntry) {
 		Msg("addConnection: waiting for mutex - POTENTIAL CONTENTION POINT")
 
 	mc.mutex.Lock()
+
 	mutexWaitDur := time.Since(mutexWaitStart)
+
 	defer mc.mutex.Unlock()
 
 	mc.connections = append(mc.connections, entry)
@@ -579,9 +597,11 @@ func (mc *multiChannelNodeConn) removeConnectionByChannel(c chan<- *tailcfg.MapR
 			mc.log.Debug().Caller().Str(zf.Chan, fmt.Sprintf("%p", c)).
 				Int("remaining_connections", len(mc.connections)).
 				Msg("successfully removed connection")
+
 			return true
 		}
 	}
+
 	return false
 }
 
@@ -615,6 +635,7 @@ func (mc *multiChannelNodeConn) send(data *tailcfg.MapResponse) error {
 		// This is not an error - the node will receive a full map when it reconnects
 		mc.log.Debug().Caller().
 			Msg("send: skipping send to node with no active connections (likely rapid reconnection)")
+
 		return nil // Return success instead of error
 	}
 
@@ -623,7 +644,9 @@ func (mc *multiChannelNodeConn) send(data *tailcfg.MapResponse) error {
 		Msg("send: broadcasting to all connections")
 
 	var lastErr error
+
 	successCount := 0
+
 	var failedConnections []int // Track failed connections for removal
 
 	// Send to all connections
@@ -632,8 +655,10 @@ func (mc *multiChannelNodeConn) send(data *tailcfg.MapResponse) error {
 			Str(zf.ConnID, conn.id).Int(zf.ConnectionIndex, i).
 			Msg("send: attempting to send to connection")
 
-		if err := conn.send(data); err != nil {
+		err := conn.send(data)
+		if err != nil {
 			lastErr = err
+
 			failedConnections = append(failedConnections, i)
 			mc.log.Warn().Err(err).Str(zf.Chan, fmt.Sprintf("%p", conn.c)).
 				Str(zf.ConnID, conn.id).Int(zf.ConnectionIndex, i).
@@ -695,7 +720,7 @@ func (entry *connectionEntry) send(data *tailcfg.MapResponse) error {
 	case <-time.After(50 * time.Millisecond):
 		// Connection is likely stale - client isn't reading from channel
 		// This catches the case where Docker containers are killed but channels remain open
-		return fmt.Errorf("connection %s: timeout sending to channel (likely stale connection)", entry.id)
+		return fmt.Errorf("connection %s: %w", entry.id, ErrConnectionSendTimeout)
 	}
 }
 
@@ -805,6 +830,7 @@ func (b *LockFreeBatcher) Debug() map[types.NodeID]DebugNodeInfo {
 			Connected:         connected,
 			ActiveConnections: activeConnCount,
 		}
+
 		return true
 	})
 
@@ -819,6 +845,7 @@ func (b *LockFreeBatcher) Debug() map[types.NodeID]DebugNodeInfo {
 				ActiveConnections: 0,
 			}
 		}
+
 		return true
 	})