diff --git a/sys_conn_df.go b/sys_conn_df.go index a21894122..b90a13da7 100644 --- a/sys_conn_df.go +++ b/sys_conn_df.go @@ -1,4 +1,4 @@ -//go:build !linux && !windows +//go:build !linux && !windows && !darwin package quic diff --git a/sys_conn_df_darwin.go b/sys_conn_df_darwin.go new file mode 100644 index 000000000..e3a9b77f5 --- /dev/null +++ b/sys_conn_df_darwin.go @@ -0,0 +1,72 @@ +//go:build darwin + +package quic + +import ( + "errors" + "strconv" + "strings" + "syscall" + + "golang.org/x/sys/unix" + + "github.com/quic-go/quic-go/internal/utils" +) + +func setDF(rawConn syscall.RawConn) (bool, error) { + // Setting DF bit is only supported from macOS11 + // https://github.com/chromium/chromium/blob/117.0.5881.2/net/socket/udp_socket_posix.cc#L555 + if supportsDF, err := isAtLeastMacOS11(); !supportsDF || err != nil { + return false, err + } + + // Enabling IP_DONTFRAG 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_DONTFRAG, 1) + errDFIPv6 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_DONTFRAG, 1) + }); 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.") + // On macOS, the syscall for setting DF bit for IPv4 fails on dual-stack listeners. + // Treat the connection as not having DF enabled, even though the DF bit will be set + // when used for IPv6. + // See https://github.com/quic-go/quic-go/issues/3793 for details. + return false, nil + case errDFIPv4 != nil && errDFIPv6 != nil: + return false, errors.New("setting DF failed for both IPv4 and IPv6") + } + return true, nil +} + +func isMsgSizeErr(err error) bool { + return errors.Is(err, unix.EMSGSIZE) +} + +func isAtLeastMacOS11() (bool, error) { + uname := &unix.Utsname{} + err := unix.Uname(uname) + if err != nil { + return false, err + } + + release := string(uname.Release[:]) + if idx := strings.Index(release, "."); idx != -1 { + version, err := strconv.Atoi(release[:idx]) + if err != nil { + return false, err + } + // Darwin version 20 is macOS version 11 + // https://en.wikipedia.org/wiki/Darwin_(operating_system)#Darwin_20_onwards + return version >= 20, nil + } + return false, nil +}