only warn on ready for handshake errors

spikecurtis · spikecurtis · commit befa9cb52e2f · 2025-04-21T06:55:34.000Z
diff --git a/enterprise/tailnet/connio.go b/enterprise/tailnet/connio.go
@@ -221,7 +221,7 @@ func (c *connIO) handleRequest(req *proto.CoordinateRequest) error {
 					slog.F("dst", dst.String()),
 				)
 				_ = c.Enqueue(&proto.CoordinateResponse{
-					Error: fmt.Sprintf("you do not share a tunnel with %q", dst.String()),
+					Error: fmt.Sprintf("%s: you do not share a tunnel with %q", agpl.ReadyForHandshakeError, dst.String()),
 				})
 				return nil
 			}
diff --git a/tailnet/controllers.go b/tailnet/controllers.go
@@ -285,8 +285,14 @@ func (c *BasicCoordination) respLoop() {
 		}
 
 		if resp.Error != "" {
-			c.logger.Error(context.Background(),
-				"coordination protocol error", slog.F("error", resp.Error))
+			// ReadyForHandshake error can occur during race conditions, where we send a ReadyForHandshake message,
+			// but the source has already disconnected from the tunnel by the time we do. So, just log at warning.
+			if strings.HasPrefix(resp.Error, ReadyForHandshakeError) {
+				c.logger.Warn(context.Background(), "coordination warning", slog.F("msg", resp.Error))
+			} else {
+				c.logger.Error(context.Background(),
+					"coordination protocol error", slog.F("error", resp.Error))
+			}
 		}
 
 		err = c.coordinatee.UpdatePeers(resp.GetPeerUpdates())
diff --git a/tailnet/coordinator.go b/tailnet/coordinator.go
@@ -27,6 +27,7 @@ const (
 	RequestBufferSize        = 32
 	CloseErrOverwritten      = "peer ID overwritten by new connection"
 	CloseErrCoordinatorClose = "coordinator closed"
+	ReadyForHandshakeError   = "ready for handshake error"
 )
 
 // Coordinator exchanges nodes with agents to establish connections.
@@ -316,7 +317,7 @@ func (c *core) handleReadyForHandshakeLocked(src *peer, rfhs []*proto.Coordinate
 			// don't want to kill its connection.
 			select {
 			case src.resps <- &proto.CoordinateResponse{
-				Error: fmt.Sprintf("you do not share a tunnel with %q", dstID.String()),
+				Error: fmt.Sprintf("%s: you do not share a tunnel with %q", ReadyForHandshakeError, dstID.String()),
 			}:
 			default:
 				return ErrWouldBlock

Original file line number	Diff line number	Diff line change
`@@ -221,7 +221,7 @@ func (c connIO) handleRequest(req proto.CoordinateRequest) error {`
`221`	`221`	`slog.F("dst", dst.String()),`
`222`	`222`	`)`
`223`	`223`	`_ = c.Enqueue(&proto.CoordinateResponse{`
`224`		`- Error: fmt.Sprintf("you do not share a tunnel with %q", dst.String()),`
	`224`	`+ Error: fmt.Sprintf("%s: you do not share a tunnel with %q", agpl.ReadyForHandshakeError, dst.String()),`
`225`	`225`	`})`
`226`	`226`	`return nil`
`227`	`227`	`}`