disable GSO if sending fails for a particular remote address

sys_conn_df_linux.go

@@ -4,11 +4,7 @@ package quic
 
 import (
 	"errors"
-	"log"
-	"os"
-	"strconv"
 	"syscall"
-	"unsafe"
 
 	"golang.org/x/sys/unix"
 
@@ -38,43 +34,9 @@ func setDF(rawConn syscall.RawConn) (bool, error) {
 	return true, nil
 }
 
-func maybeSetGSO(rawConn syscall.RawConn) bool {
-	enable, _ := strconv.ParseBool(os.Getenv("QUIC_GO_ENABLE_GSO"))
-	if !enable {
-		return false
-	}
-
-	var setErr error
-	if err := rawConn.Control(func(fd uintptr) {
-		setErr = unix.SetsockoptInt(int(fd), syscall.IPPROTO_UDP, unix.UDP_SEGMENT, 1)
-	}); err != nil {
-		setErr = err
-	}
-	if setErr != nil {
-		log.Println("failed to enable GSO")
-		return false
-	}
-	return true
-}
-
 func isSendMsgSizeErr(err error) bool {
 	// https://man7.org/linux/man-pages/man7/udp.7.html
 	return errors.Is(err, unix.EMSGSIZE)
 }
 
-func isRecvMsgSizeErr(err error) bool { return false }
-
-func appendUDPSegmentSizeMsg(b []byte, size uint16) []byte {
-	startLen := len(b)
-	const dataLen = 2 // payload is a uint16
-	b = append(b, make([]byte, unix.CmsgSpace(dataLen))...)
-	h := (*unix.Cmsghdr)(unsafe.Pointer(&b[startLen]))
-	h.Level = syscall.IPPROTO_UDP
-	h.Type = unix.UDP_SEGMENT
-	h.SetLen(unix.CmsgLen(dataLen))
-
-	// UnixRights uses the private `data` method, but I *think* this achieves the same goal.
-	offset := startLen + unix.CmsgSpace(0)
-	*(*uint16)(unsafe.Pointer(&b[offset])) = size
-	return b
-}
+func isRecvMsgSizeErr(error) bool { return false }