84 lines
2.2 KiB
Go
84 lines
2.2 KiB
Go
//go:build linux
|
|
|
|
package quic
|
|
|
|
import (
|
|
"errors"
|
|
"log"
|
|
"os"
|
|
"strconv"
|
|
"syscall"
|
|
"unsafe"
|
|
|
|
"golang.org/x/sys/unix"
|
|
|
|
"github.com/quic-go/quic-go/internal/utils"
|
|
)
|
|
|
|
// UDP_SEGMENT controls GSO (Generic Segmentation Offload)
|
|
//
|
|
//nolint:stylecheck
|
|
const UDP_SEGMENT = 103
|
|
|
|
func setDF(rawConn syscall.RawConn) (bool, error) {
|
|
// Enabling IP_MTU_DISCOVER will force the kernel to return "sendto: message too long"
|
|
// and the datagram will not be fragmented
|
|
var errDFIPv4, errDFIPv6 error
|
|
if err := rawConn.Control(func(fd uintptr) {
|
|
errDFIPv4 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_MTU_DISCOVER, unix.IP_PMTUDISC_DO)
|
|
errDFIPv6 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_MTU_DISCOVER, unix.IPV6_PMTUDISC_DO)
|
|
}); err != nil {
|
|
return false, err
|
|
}
|
|
switch {
|
|
case errDFIPv4 == nil && errDFIPv6 == nil:
|
|
utils.DefaultLogger.Debugf("Setting DF for IPv4 and IPv6.")
|
|
case errDFIPv4 == nil && errDFIPv6 != nil:
|
|
utils.DefaultLogger.Debugf("Setting DF for IPv4.")
|
|
case errDFIPv4 != nil && errDFIPv6 == nil:
|
|
utils.DefaultLogger.Debugf("Setting DF for IPv6.")
|
|
case errDFIPv4 != nil && errDFIPv6 != nil:
|
|
return false, errors.New("setting DF failed for both IPv4 and IPv6")
|
|
}
|
|
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, UDP_SEGMENT, 1)
|
|
}); err != nil {
|
|
setErr = err
|
|
}
|
|
if setErr != nil {
|
|
log.Println("failed to enable GSO")
|
|
return false
|
|
}
|
|
return true
|
|
}
|
|
|
|
func isMsgSizeErr(err error) bool {
|
|
// https://man7.org/linux/man-pages/man7/udp.7.html
|
|
return errors.Is(err, unix.EMSGSIZE)
|
|
}
|
|
|
|
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 = 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
|
|
}
|