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synced 2024-09-20 06:46:11 +08:00
Fix UDP listener on IPv4-only Linux (#787)
On some systems, IPv6 is disabled (for example, CIS benchmark recommends to disable it when not used), but currently all UDP connections are using AF_INET6 sockets. When we are binding AF_INET6 socket to an address like ::ffff:1.2.3.4 (IPv4 addresses are parsed by net.ParseIP this way), we can't send or receive IPv6 packets anyway, so this will not break any scenarios. --------- Co-authored-by: Wade Simmons <wsimmons@slack-corp.com>
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parent
c5a403b7a8
commit
0f0534d739
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@ -22,6 +22,7 @@ import (
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type StdConn struct {
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sysFd int
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isV4 bool
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l *logrus.Logger
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batch int
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}
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@ -45,9 +46,22 @@ const (
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type _SK_MEMINFO [_SK_MEMINFO_VARS]uint32
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func maybeIPV4(ip net.IP) (net.IP, bool) {
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ip4 := ip.To4()
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if ip4 != nil {
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return ip4, true
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}
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return ip, false
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}
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func NewListener(l *logrus.Logger, ip net.IP, port int, multi bool, batch int) (Conn, error) {
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ipV4, isV4 := maybeIPV4(ip)
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af := unix.AF_INET6
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if isV4 {
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af = unix.AF_INET
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}
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syscall.ForkLock.RLock()
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fd, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
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fd, err := unix.Socket(af, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
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if err == nil {
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unix.CloseOnExec(fd)
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}
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@ -58,9 +72,6 @@ func NewListener(l *logrus.Logger, ip net.IP, port int, multi bool, batch int) (
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return nil, fmt.Errorf("unable to open socket: %s", err)
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}
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var lip [16]byte
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copy(lip[:], ip.To16())
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if multi {
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if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
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return nil, fmt.Errorf("unable to set SO_REUSEPORT: %s", err)
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@ -68,7 +79,17 @@ func NewListener(l *logrus.Logger, ip net.IP, port int, multi bool, batch int) (
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}
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//TODO: support multiple listening IPs (for limiting ipv6)
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if err = unix.Bind(fd, &unix.SockaddrInet6{Addr: lip, Port: port}); err != nil {
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var sa unix.Sockaddr
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if isV4 {
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sa4 := &unix.SockaddrInet4{Port: port}
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copy(sa4.Addr[:], ipV4)
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sa = sa4
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} else {
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sa6 := &unix.SockaddrInet6{Port: port}
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copy(sa6.Addr[:], ip.To16())
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sa = sa6
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}
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if err = unix.Bind(fd, sa); err != nil {
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return nil, fmt.Errorf("unable to bind to socket: %s", err)
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}
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@ -77,7 +98,7 @@ func NewListener(l *logrus.Logger, ip net.IP, port int, multi bool, batch int) (
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//v, err := unix.GetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_INCOMING_CPU)
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//l.Println(v, err)
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return &StdConn{sysFd: fd, l: l, batch: batch}, err
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return &StdConn{sysFd: fd, isV4: isV4, l: l, batch: batch}, err
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}
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func (u *StdConn) Rebind() error {
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@ -143,7 +164,11 @@ func (u *StdConn) ListenOut(r EncReader, lhf LightHouseHandlerFunc, cache *firew
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//metric.Update(int64(n))
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for i := 0; i < n; i++ {
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udpAddr.IP = names[i][8:24]
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if u.isV4 {
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udpAddr.IP = names[i][4:8]
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} else {
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udpAddr.IP = names[i][8:24]
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}
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udpAddr.Port = binary.BigEndian.Uint16(names[i][2:4])
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r(udpAddr, plaintext[:0], buffers[i][:msgs[i].Len], h, fwPacket, lhf, nb, q, cache.Get(u.l))
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}
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@ -192,13 +217,18 @@ func (u *StdConn) ReadMulti(msgs []rawMessage) (int, error) {
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}
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func (u *StdConn) WriteTo(b []byte, addr *Addr) error {
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if u.isV4 {
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return u.writeTo4(b, addr)
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}
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return u.writeTo6(b, addr)
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}
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func (u *StdConn) writeTo6(b []byte, addr *Addr) error {
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var rsa unix.RawSockaddrInet6
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rsa.Family = unix.AF_INET6
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p := (*[2]byte)(unsafe.Pointer(&rsa.Port))
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p[0] = byte(addr.Port >> 8)
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p[1] = byte(addr.Port)
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copy(rsa.Addr[:], addr.IP)
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// Little Endian -> Network Endian
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rsa.Port = (addr.Port >> 8) | ((addr.Port & 0xff) << 8)
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copy(rsa.Addr[:], addr.IP.To16())
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for {
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_, _, err := unix.Syscall6(
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@ -221,6 +251,39 @@ func (u *StdConn) WriteTo(b []byte, addr *Addr) error {
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}
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}
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func (u *StdConn) writeTo4(b []byte, addr *Addr) error {
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addrV4, isAddrV4 := maybeIPV4(addr.IP)
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if !isAddrV4 {
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return fmt.Errorf("Listener is IPv4, but writing to IPv6 remote")
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}
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var rsa unix.RawSockaddrInet4
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rsa.Family = unix.AF_INET
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// Little Endian -> Network Endian
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rsa.Port = (addr.Port >> 8) | ((addr.Port & 0xff) << 8)
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copy(rsa.Addr[:], addrV4)
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for {
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_, _, err := unix.Syscall6(
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unix.SYS_SENDTO,
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uintptr(u.sysFd),
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uintptr(unsafe.Pointer(&b[0])),
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uintptr(len(b)),
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uintptr(0),
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uintptr(unsafe.Pointer(&rsa)),
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uintptr(unix.SizeofSockaddrInet4),
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)
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if err != 0 {
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return &net.OpError{Op: "sendto", Err: err}
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}
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//TODO: handle incomplete writes
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return nil
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}
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}
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func (u *StdConn) ReloadConfig(c *config.C) {
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b := c.GetInt("listen.read_buffer", 0)
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if b > 0 {
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