conn.go: Only log errors from writing to a connection that aren't net.ErrClosed instead of returning.

Other errors are recoverable through resending and don't need to be propagated into error chains.

Author: Sandertv

conn.go

@@ -537,7 +537,7 @@ func (conn *Conn) sendAcknowledgement(packets []uint24, bitflag byte, buf *bytes
 		// We managed to write n packets in the ACK with this MTU size, write
 		// the next of the packets in a new ACK.
 		ack.packets = ack.packets[n:]
-		if _, err := conn.conn.WriteTo(buf.Bytes(), conn.raddr); err != nil {
+		if err := conn.writeTo(buf.Bytes(), conn.raddr); err != nil {
 			return fmt.Errorf("send acknowlegement: %w", err)
 		}
 		buf.Reset()
@@ -603,15 +603,28 @@ func (conn *Conn) sendDatagram(pk *packet) error {
 	seq := conn.seq.Inc()
 	writeUint24(conn.buf, seq)
 	pk.write(conn.buf)
+	defer conn.buf.Reset()
 
-	// We then send the pk to the connection.
-	if _, err := conn.conn.WriteTo(conn.buf.Bytes(), conn.raddr); err != nil {
-		return fmt.Errorf("send datagram: write to %v: %w", conn.raddr, err)
-	}
 	// We then re-add the pk to the recovery queue in case the new one gets
 	// lost too, in which case we need to resend it again.
 	conn.retransmission.add(seq, pk)
-	conn.buf.Reset()
+
+	if err := conn.writeTo(conn.buf.Bytes(), conn.raddr); err != nil {
+		return fmt.Errorf("send datagram: %w", err)
+	}
+	return nil
+}
+
+// writeTo calls WriteTo on the underlying UDP connection and returns an error
+// only if the error returned is net.ErrClosed. In any other case, the error
+// is logged but not returned. This is done because at this stage, packets
+// being lost to an error can be recovered through resending.
+func (conn *Conn) writeTo(p []byte, raddr net.Addr) error {
+	if _, err := conn.conn.WriteTo(p, raddr); errors.Is(err, net.ErrClosed) {
+		return fmt.Errorf("write to: %w", err)
+	} else if err != nil {
+		conn.handler.log().Error("write to: " + err.Error())
+	}
 	return nil
 }
 

dial.go

@@ -233,7 +233,7 @@ func (dialer Dialer) DialContext(ctx context.Context, address string) (*Conn, er
 // dial finishes the RakNet connection sequence and returns a Conn if
 // successful.
 func (dialer Dialer) connect(ctx context.Context, state *connState) (*Conn, error) {
-	conn := newConn(internal.ConnToPacketConn(state.conn), state.raddr, state.mtu, dialerConnectionHandler{})
+	conn := newConn(internal.ConnToPacketConn(state.conn), state.raddr, state.mtu, dialerConnectionHandler{l: dialer.ErrorLog})
 	if err := conn.send((&message.ConnectionRequest{ClientGUID: state.id, RequestTime: timestamp()})); err != nil {
 		return nil, dialer.error("dial", fmt.Errorf("send connection request: %w", err))
 	}
@@ -259,17 +259,15 @@ func (dialer Dialer) clientListen(rakConn *Conn, conn net.Conn) {
 	b := make([]byte, rakConn.effectiveMTU())
 	for {
 		n, err := conn.Read(b)
+		if err == nil && n != 0 {
+			err = rakConn.receive(b[:n])
+		}
 		if err != nil {
-			if !errors.Is(err, net.ErrClosed) {
-				// Errors reading a packet other than the connection being
-				// may be worth logging.
-				dialer.ErrorLog.Error("client: read packet: " + err.Error())
+			if errors.Is(err, net.ErrClosed) {
+				return
 			}
-			return
-		} else if n == 0 {
-			continue
-		}
-		if err := rakConn.receive(b[:n]); err != nil {
+			// Errors reading a packet other than the connection being
+			// closed may be worth logging.
 			dialer.ErrorLog.Error("client: " + err.Error())
 		}
 	}

handler.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"github.com/sandertv/go-raknet/internal/message"
 	"hash/crc32"
+	"log/slog"
 	"net"
 	"time"
 )
@@ -14,6 +15,7 @@ type connectionHandler interface {
 	handle(conn *Conn, b []byte) (handled bool, err error)
 	limitsEnabled() bool
 	close(conn *Conn)
+	log() *slog.Logger
 }
 
 type listenerConnectionHandler struct {
@@ -26,6 +28,10 @@ var (
 	errUnexpectedAdditionalNIC = errors.New("unexpected additional NEW_INCOMING_CONNECTION packet")
 )
 
+func (h listenerConnectionHandler) log() *slog.Logger {
+	return h.l.conf.ErrorLog
+}
+
 func (h listenerConnectionHandler) limitsEnabled() bool {
 	return true
 }
@@ -185,14 +191,18 @@ func (h listenerConnectionHandler) handleNewIncomingConnection(conn *Conn) error
 	return nil
 }
 
-type dialerConnectionHandler struct{}
+type dialerConnectionHandler struct{ l *slog.Logger }
 
 var (
 	errUnexpectedCR            = errors.New("unexpected CONNECTION_REQUEST packet")
 	errUnexpectedAdditionalCRA = errors.New("unexpected additional CONNECTION_REQUEST_ACCEPTED packet")
 	errUnexpectedNIC           = errors.New("unexpected NEW_INCOMING_CONNECTION packet")
 )
 
+func (h dialerConnectionHandler) log() *slog.Logger {
+	return h.l
+}
+
 func (h dialerConnectionHandler) close(conn *Conn) {
 	_ = conn.conn.Close()
 }

listener.go

@@ -1,6 +1,7 @@
 package raknet
 
 import (
+	"errors"
 	"fmt"
 	"github.com/sandertv/go-raknet/internal"
 	"log/slog"
@@ -182,7 +183,7 @@ func (listener *Listener) listen() {
 		} else if n == 0 || listener.sec.blocked(addr) {
 			continue
 		}
-		if err = listener.handle(b[:n], addr); err != nil {
+		if err = listener.handle(b[:n], addr); err != nil && !errors.Is(err, net.ErrClosed) {
 			listener.conf.ErrorLog.Error("listener: handle packet: "+err.Error(), "address", addr.String(), "block-duration", max(0, listener.conf.BlockDuration))
 			listener.sec.block(addr)
 		}