move UDP receive buffer size manipulation to a separate file

sys_conn_buffers.go

@@ -0,0 +1,48 @@
+package quic
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+
+	"github.com/quic-go/quic-go/internal/protocol"
+	"github.com/quic-go/quic-go/internal/utils"
+)
+
+func setReceiveBuffer(c net.PacketConn, logger utils.Logger) error {
+	conn, ok := c.(interface{ SetReadBuffer(int) error })
+	if !ok {
+		return errors.New("connection doesn't allow setting of receive buffer size. Not a *net.UDPConn?")
+	}
+	size, err := inspectReadBuffer(c)
+	if err != nil {
+		return fmt.Errorf("failed to determine receive buffer size: %w", err)
+	}
+	if size >= protocol.DesiredReceiveBufferSize {
+		logger.Debugf("Conn has receive buffer of %d kiB (wanted: at least %d kiB)", size/1024, protocol.DesiredReceiveBufferSize/1024)
+		return nil
+	}
+	// Ignore the error. We check if we succeeded by querying the buffer size afterward.
+	_ = conn.SetReadBuffer(protocol.DesiredReceiveBufferSize)
+	newSize, err := inspectReadBuffer(c)
+	if newSize < protocol.DesiredReceiveBufferSize {
+		// Try again with RCVBUFFORCE on Linux
+		_ = forceSetReceiveBuffer(c, protocol.DesiredReceiveBufferSize)
+		newSize, err = inspectReadBuffer(c)
+		if err != nil {
+			return fmt.Errorf("failed to determine receive buffer size: %w", err)
+		}
+	}
+	if err != nil {
+		return fmt.Errorf("failed to determine receive buffer size: %w", err)
+	}
+	if newSize == size {
+		return fmt.Errorf("failed to increase receive buffer size (wanted: %d kiB, got %d kiB)", protocol.DesiredReceiveBufferSize/1024, newSize/1024)
+	}
+	if newSize < protocol.DesiredReceiveBufferSize {
+		return fmt.Errorf("failed to sufficiently increase receive buffer size (was: %d kiB, wanted: %d kiB, got: %d kiB)", size/1024, protocol.DesiredReceiveBufferSize/1024, newSize/1024)
+	}
+	logger.Debugf("Increased receive buffer size to %d kiB", newSize/1024)
+	return nil
+}

transport.go

@@ -5,7 +5,6 @@ import (
 	"crypto/rand"
 	"crypto/tls"
 	"errors"
-	"fmt"
 	"log"
 	"net"
 	"os"
@@ -167,46 +166,6 @@ func (t *Transport) DialEarly(ctx context.Context, addr net.Addr, tlsConf *tls.C
 	return dial(ctx, newSendConn(t.conn, addr, nil), t.connIDGenerator, t.handlerMap, tlsConf, conf, onClose, true)
 }
 
-func setReceiveBuffer(c net.PacketConn, logger utils.Logger) error {
-	conn, ok := c.(interface{ SetReadBuffer(int) error })
-	if !ok {
-		return errors.New("connection doesn't allow setting of receive buffer size. Not a *net.UDPConn?")
-	}
-	size, err := inspectReadBuffer(c)
-	if err != nil {
-		return fmt.Errorf("failed to determine receive buffer size: %w", err)
-	}
-	if size >= protocol.DesiredReceiveBufferSize {
-		logger.Debugf("Conn has receive buffer of %d kiB (wanted: at least %d kiB)", size/1024, protocol.DesiredReceiveBufferSize/1024)
-		return nil
-	}
-	// Ignore the error. We check if we succeeded by querying the buffer size afterward.
-	_ = conn.SetReadBuffer(protocol.DesiredReceiveBufferSize)
-	newSize, err := inspectReadBuffer(c)
-	if newSize < protocol.DesiredReceiveBufferSize {
-		// Try again with RCVBUFFORCE on Linux
-		_ = forceSetReceiveBuffer(c, protocol.DesiredReceiveBufferSize)
-		newSize, err = inspectReadBuffer(c)
-		if err != nil {
-			return fmt.Errorf("failed to determine receive buffer size: %w", err)
-		}
-	}
-	if err != nil {
-		return fmt.Errorf("failed to determine receive buffer size: %w", err)
-	}
-	if newSize == size {
-		return fmt.Errorf("failed to increase receive buffer size (wanted: %d kiB, got %d kiB)", protocol.DesiredReceiveBufferSize/1024, newSize/1024)
-	}
-	if newSize < protocol.DesiredReceiveBufferSize {
-		return fmt.Errorf("failed to sufficiently increase receive buffer size (was: %d kiB, wanted: %d kiB, got: %d kiB)", size/1024, protocol.DesiredReceiveBufferSize/1024, newSize/1024)
-	}
-	logger.Debugf("Increased receive buffer size to %d kiB", newSize/1024)
-	return nil
-}
-
-// only print warnings about the UDP receive buffer size once
-var receiveBufferWarningOnce sync.Once
-
 func (t *Transport) init(isServer bool) error {
 	t.initOnce.Do(func() {
 		getMultiplexer().AddConn(t.Conn)
@@ -310,6 +269,9 @@ func (t *Transport) close(e error) {
 	t.closed = true
 }
 
+// only print warnings about the UDP receive buffer size once
+var receiveBufferWarningOnce sync.Once
+
 func (t *Transport) listen(conn rawConn) {
 	defer close(t.listening)
 	defer getMultiplexer().RemoveConn(t.Conn)