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stack.go
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stack.go
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package vif
import (
"context"
"fmt"
"net"
"time"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
"go.opentelemetry.io/otel/trace"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
"gvisor.dev/gvisor/pkg/waiter"
"github.com/datawire/dlib/dlog"
"github.com/telepresenceio/telepresence/v2/pkg/tunnel"
)
func NewStack(ctx context.Context, dev stack.LinkEndpoint, streamCreator tunnel.StreamCreator) (*stack.Stack, error) {
s := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{
ipv4.NewProtocol,
ipv6.NewProtocol,
},
TransportProtocols: []stack.TransportProtocolFactory{
icmp.NewProtocol4,
icmp.NewProtocol6,
tcp.NewProtocol,
udp.NewProtocol,
},
HandleLocal: false,
})
if err := setDefaultOptions(s); err != nil {
return nil, err
}
if err := setNIC(ctx, s, dev); err != nil {
return nil, err
}
setTCPHandler(ctx, s, streamCreator)
setUDPHandler(ctx, s, streamCreator)
return s, nil
}
const (
myWindowScale = 6
maxReceiveWindow = 1 << (myWindowScale + 14) // 1MiB
)
// maxInFlight specifies the max number of in-flight connection attempts.
const maxInFlight = 512
// keepAliveIdle is used as the very first alive interval. Subsequent intervals
// use keepAliveInterval.
const keepAliveIdle = 60 * time.Second
// keepAliveInterval is the interval between sending keep-alive packets.
const keepAliveInterval = 30 * time.Second
// keepAliveCount is the max number of keep-alive probes that can be sent
// before the connection is killed due to lack of response.
const keepAliveCount = 9
type idStringer stack.TransportEndpointID
func (i idStringer) String() string {
return fmt.Sprintf("%s:%d -> %s:%d", i.RemoteAddress, i.RemotePort, i.LocalAddress, i.LocalPort)
}
func setDefaultOptions(s *stack.Stack) error {
// Forwarding
if err := s.SetForwardingDefaultAndAllNICs(ipv4.ProtocolNumber, true); err != nil {
return fmt.Errorf("SetForwardingDefaultAndAllNICs(ipv4, %t): %s", true, err)
}
if err := s.SetForwardingDefaultAndAllNICs(ipv6.ProtocolNumber, true); err != nil {
return fmt.Errorf("SetForwardingDefaultAndAllNICs(ipv6, %t): %s", true, err)
}
ttl := tcpip.DefaultTTLOption(64)
if err := s.SetNetworkProtocolOption(ipv4.ProtocolNumber, &ttl); err != nil {
return fmt.Errorf("SetDefaultTTL(ipv4, %d): %s", ttl, err)
}
if err := s.SetNetworkProtocolOption(ipv6.ProtocolNumber, &ttl); err != nil {
return fmt.Errorf("SetDefaultTTL(ipv6, %d): %s", ttl, err)
}
return nil
}
func setNIC(ctx context.Context, s *stack.Stack, ep stack.LinkEndpoint) error {
nicID := tcpip.NICID(s.UniqueID())
if err := s.CreateNICWithOptions(nicID, ep, stack.NICOptions{Name: "tel", Context: ctx}); err != nil {
return fmt.Errorf("create NIC failed: %s", err)
}
if err := s.SetPromiscuousMode(nicID, true); err != nil {
return fmt.Errorf("SetPromiscuousMode(%d, %t): %s", nicID, true, err)
}
if err := s.SetSpoofing(nicID, true); err != nil {
return fmt.Errorf("SetSpoofing(%d, %t): %s", nicID, true, err)
}
s.SetRouteTable([]tcpip.Route{
{
Destination: header.IPv4EmptySubnet,
NIC: nicID,
},
{
Destination: header.IPv6EmptySubnet,
NIC: nicID,
},
})
return nil
}
func forwardTCP(ctx context.Context, streamCreator tunnel.StreamCreator, fr *tcp.ForwarderRequest) {
var ep tcpip.Endpoint
var err tcpip.Error
id := fr.ID()
ctx, span := otel.GetTracerProvider().Tracer("").Start(ctx, "TCPHandler",
trace.WithNewRoot(),
trace.WithAttributes(
attribute.String("tel2.remote-ip", id.RemoteAddress.To4().String()),
attribute.String("tel2.local-ip", id.LocalAddress.To4().String()),
attribute.Int("tel2.local-port", int(id.LocalPort)),
attribute.Int("tel2.remote-port", int(id.RemotePort)),
))
defer func() {
if err != nil {
msg := fmt.Sprintf("forward TCP %s: %s", idStringer(id), err)
span.SetStatus(codes.Error, msg)
dlog.Errorf(ctx, msg)
}
span.End()
}()
wq := waiter.Queue{}
if ep, err = fr.CreateEndpoint(&wq); err != nil {
fr.Complete(true)
return
}
defer fr.Complete(false)
so := ep.SocketOptions()
so.SetKeepAlive(true)
idle := tcpip.KeepaliveIdleOption(keepAliveIdle)
if err = ep.SetSockOpt(&idle); err != nil {
return
}
ivl := tcpip.KeepaliveIntervalOption(keepAliveInterval)
if err = ep.SetSockOpt(&ivl); err != nil {
return
}
if err = ep.SetSockOptInt(tcpip.KeepaliveCountOption, keepAliveCount); err != nil {
return
}
dispatchToStream(ctx, newConnID(header.TCPProtocolNumber, id), gonet.NewTCPConn(&wq, ep), streamCreator)
}
func setTCPHandler(ctx context.Context, s *stack.Stack, streamCreator tunnel.StreamCreator) {
if err := s.SetTransportProtocolOption(tcp.ProtocolNumber,
&tcpip.TCPSendBufferSizeRangeOption{
Min: tcp.MinBufferSize,
Default: tcp.DefaultSendBufferSize,
Max: tcp.MaxBufferSize,
}); err != nil {
return
}
if err := s.SetTransportProtocolOption(tcp.ProtocolNumber,
&tcpip.TCPReceiveBufferSizeRangeOption{
Min: tcp.MinBufferSize,
Default: tcp.DefaultSendBufferSize,
Max: tcp.MaxBufferSize,
}); err != nil {
return
}
sa := tcpip.TCPSACKEnabled(true)
s.SetTransportProtocolOption(tcp.ProtocolNumber, &sa)
// Enable Receive Buffer Auto-Tuning, see:
// https://github.com/google/gvisor/issues/1666
mo := tcpip.TCPModerateReceiveBufferOption(true)
s.SetTransportProtocolOption(tcp.ProtocolNumber, &mo)
f := tcp.NewForwarder(s, maxReceiveWindow, maxInFlight, func(fr *tcp.ForwarderRequest) {
forwardTCP(ctx, streamCreator, fr)
})
s.SetTransportProtocolHandler(tcp.ProtocolNumber, f.HandlePacket)
}
var blockedUDPPorts = map[uint16]bool{ //nolint:gochecknoglobals // constant
137: true, // NETBIOS Name Service
138: true, // NETBIOS Datagram Service
139: true, // NETBIOS
}
func forwardUDP(ctx context.Context, s *stack.Stack, streamCreator tunnel.StreamCreator, fr *udp.ForwarderRequest) {
id := fr.ID()
ctx, span := otel.GetTracerProvider().Tracer("").Start(ctx, "UDPHandler",
trace.WithNewRoot(),
trace.WithAttributes(
attribute.String("tel2.remote-ip", id.RemoteAddress.To4().String()),
attribute.String("tel2.local-ip", id.LocalAddress.To4().String()),
attribute.Int("tel2.local-port", int(id.LocalPort)),
attribute.Int("tel2.remote-port", int(id.RemotePort)),
attribute.Bool("tel2.port-blocked", false),
))
defer span.End()
if _, ok := blockedUDPPorts[id.LocalPort]; ok {
span.SetAttributes(attribute.Bool("tel2.port-blocked", true))
return
}
wq := waiter.Queue{}
ep, err := fr.CreateEndpoint(&wq)
if err != nil {
msg := fmt.Sprintf("forward UDP %s: %s", idStringer(id), err)
span.SetStatus(codes.Error, msg)
dlog.Errorf(ctx, msg)
return
}
dispatchToStream(ctx, newConnID(udp.ProtocolNumber, id), gonet.NewUDPConn(s, &wq, ep), streamCreator)
}
func setUDPHandler(ctx context.Context, s *stack.Stack, streamCreator tunnel.StreamCreator) {
f := udp.NewForwarder(s, func(fr *udp.ForwarderRequest) {
forwardUDP(ctx, s, streamCreator, fr)
})
s.SetTransportProtocolHandler(udp.ProtocolNumber, f.HandlePacket)
}
func newConnID(proto tcpip.TransportProtocolNumber, id stack.TransportEndpointID) tunnel.ConnID {
return tunnel.NewConnID(int(proto), ([]byte)(id.RemoteAddress), ([]byte)(id.LocalAddress), id.RemotePort, id.LocalPort)
}
func dispatchToStream(ctx context.Context, id tunnel.ConnID, conn net.Conn, streamCreator tunnel.StreamCreator) {
ctx, cancel := context.WithCancel(ctx)
stream, err := streamCreator(ctx, id)
if err != nil {
dlog.Errorf(ctx, "forward %s: %s", id, err)
cancel()
return
}
ep := tunnel.NewConnEndpoint(stream, conn, cancel, nil, nil)
ep.Start(ctx)
}