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Revamp GRPC Port forwarding tunnels to use existing proxy #2985

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merged 1 commit into from
Dec 24, 2024
Merged

Revamp GRPC Port forwarding tunnels to use existing proxy #2985

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151 changes: 62 additions & 89 deletions pkg/portfwd/client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,20 +2,18 @@ package portfwd

import (
"context"
"errors"
"fmt"
"io"
"net"
"time"

"github.com/containers/gvisor-tap-vsock/pkg/services/forwarder"
"github.com/lima-vm/lima/pkg/bicopy"
"github.com/lima-vm/lima/pkg/guestagent/api"
guestagentclient "github.com/lima-vm/lima/pkg/guestagent/api/client"
"github.com/sirupsen/logrus"
"golang.org/x/sync/errgroup"
)

func HandleTCPConnection(ctx context.Context, client *guestagentclient.GuestAgentClient, conn net.Conn, guestAddr string) {
defer conn.Close()

id := fmt.Sprintf("tcp-%s-%s", conn.LocalAddr().String(), conn.RemoteAddr().String())

stream, err := client.Tunnel(ctx)
Expand All @@ -24,26 +22,17 @@ func HandleTCPConnection(ctx context.Context, client *guestagentclient.GuestAgen
return
}

g, _ := errgroup.WithContext(ctx)

rw := &GrpcClientRW{stream: stream, id: id, addr: guestAddr}
g.Go(func() error {
_, err := io.Copy(rw, conn)
return err
})
g.Go(func() error {
_, err := io.Copy(conn, rw)
return err
})

if err := g.Wait(); err != nil {
logrus.Debugf("error in tcp tunnel for id: %s error:%v", id, err)
// Handshake message to start tunnel
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if err := stream.Send(&api.TunnelMessage{Id: id, Protocol: "tcp", GuestAddr: guestAddr}); err != nil {
logrus.Errorf("could not start tcp tunnel for id: %s error:%v", id, err)
return
}

rw := &GrpcClientRW{stream: stream, id: id, addr: guestAddr, protocol: "tcp"}
bicopy.Bicopy(rw, conn, nil)
}

func HandleUDPConnection(ctx context.Context, client *guestagentclient.GuestAgentClient, conn net.PacketConn, guestAddr string) {
defer conn.Close()

id := fmt.Sprintf("udp-%s", conn.LocalAddr().String())

stream, err := client.Tunnel(ctx)
Expand All @@ -52,98 +41,82 @@ func HandleUDPConnection(ctx context.Context, client *guestagentclient.GuestAgen
return
}

g, _ := errgroup.WithContext(ctx)

g.Go(func() error {
buf := make([]byte, 65507)
for {
n, addr, err := conn.ReadFrom(buf)
// We must handle n > 0 bytes before considering the error.
// https://pkg.go.dev/net#PacketConn
if n > 0 {
msg := &api.TunnelMessage{
Id: id + "-" + addr.String(),
Protocol: "udp",
GuestAddr: guestAddr,
Data: buf[:n],
UdpTargetAddr: addr.String(),
}
if err := stream.Send(msg); err != nil {
return err
}
}
if err != nil {
// https://pkg.go.dev/net#PacketConn does not mention io.EOF semantics.
if errors.Is(err, io.EOF) {
return nil
}
return err
}
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}
})
// Handshake message to start tunnel
if err := stream.Send(&api.TunnelMessage{Id: id, Protocol: "udp", GuestAddr: guestAddr}); err != nil {
logrus.Errorf("could not start udp tunnel for id: %s error:%v", id, err)
return
}

g.Go(func() error {
for {
// Not documented: when err != nil, in is always nil.
in, err := stream.Recv()
if err != nil {
if errors.Is(err, io.EOF) {
return nil
}
return err
}
addr, err := net.ResolveUDPAddr("udp", in.UdpTargetAddr)
if err != nil {
return err
}
_, err = conn.WriteTo(in.Data, addr)
if err != nil {
return err
}
}
proxy, err := forwarder.NewUDPProxy(conn, func() (net.Conn, error) {
rw := &GrpcClientRW{stream: stream, id: id, addr: guestAddr, protocol: "udp"}
return rw, nil
})

if err := g.Wait(); err != nil {
logrus.Debugf("error in udp tunnel for id: %s error:%v", id, err)
if err != nil {
logrus.Errorf("error in udp tunnel proxy for id: %s error:%v", id, err)
return
}

defer func() {
err := proxy.Close()
if err != nil {
logrus.Errorf("error in closing udp tunnel proxy for id: %s error:%v", id, err)
}
}()
proxy.Run()
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}

type GrpcClientRW struct {
id string
addr string
stream api.GuestService_TunnelClient
id string
addr string

protocol string
stream api.GuestService_TunnelClient
}

var _ io.ReadWriter = (*GrpcClientRW)(nil)
var _ net.Conn = (*GrpcClientRW)(nil)

func (g GrpcClientRW) Write(p []byte) (n int, err error) {
if len(p) == 0 {
return 0, nil
}
func (g *GrpcClientRW) Write(p []byte) (n int, err error) {
err = g.stream.Send(&api.TunnelMessage{
Id: g.id,
GuestAddr: g.addr,
Data: p,
Protocol: "tcp",
Protocol: g.protocol,
})
if err != nil {
return 0, err
}
return len(p), nil
}

func (g GrpcClientRW) Read(p []byte) (n int, err error) {
// Not documented: when err != nil, in is always nil.
func (g *GrpcClientRW) Read(p []byte) (n int, err error) {
in, err := g.stream.Recv()
if err != nil {
if errors.Is(err, io.EOF) {
return 0, nil
}
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return 0, err
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}
if len(in.Data) == 0 {
return 0, nil
}
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copy(p, in.Data)
return len(in.Data), nil
}

func (g *GrpcClientRW) Close() error {
return g.stream.CloseSend()
}

func (g *GrpcClientRW) LocalAddr() net.Addr {
return &net.UnixAddr{Name: "grpc", Net: "unixpacket"}
}

func (g *GrpcClientRW) RemoteAddr() net.Addr {
return &net.UnixAddr{Name: "grpc", Net: "unixpacket"}
}

func (g *GrpcClientRW) SetDeadline(_ time.Time) error {
return nil
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Why we don't implement it? should we log a warning to make the issue visible?

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Too much logging will become a noise since these are connections. It will be called multiple times and its doesn't help much. SetDeadline is not even usecul in our case as ours is a grpc stream

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Or just panic. If these functions don't do what they're supposed to (and are never called) a panic would be proof of that.

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We cannot panic on all cases.

These are left as NO-OP wantedly. These methods may / will be called but its of no value to us as its a grpc tunnel wrapped conn

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no-op on SetDeadline is not a reasonable thing to do. It should return an error.

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@tamird Please understand the full flow before commenting. All left like that for a reason.

UDP Proxy internally will call SetReadDeadline so we cannot throw error. It will be no-op only. That's why all SetDeadline like methods are returning null.

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no-op on SetDeadline is not a reasonable thing to do. It should return an error.

I think you are talking past each other. SetDeadline() must exist to implement the interface, but there is not actual implementation of that concept for this particular implementation (there is no deadline). Therefore the method does nothing. It doesn't mean it is an error; just a vestigial method that is not being used.

}

func (g *GrpcClientRW) SetReadDeadline(_ time.Time) error {
return nil
}

func (g *GrpcClientRW) SetWriteDeadline(_ time.Time) error {
return nil
}
97 changes: 55 additions & 42 deletions pkg/portfwdserver/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,66 +4,79 @@ import (
"errors"
"io"
"net"
"time"

"github.com/lima-vm/lima/pkg/bicopy"
"github.com/lima-vm/lima/pkg/guestagent/api"
)

type TunnelServer struct {
Conns map[string]net.Conn
}
type TunnelServer struct{}

func NewTunnelServer() *TunnelServer {
return &TunnelServer{
Conns: make(map[string]net.Conn),
}
return &TunnelServer{}
}

func (s *TunnelServer) Start(stream api.GuestService_TunnelServer) error {
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for {
in, err := stream.Recv()
// Receive the handshake message to start tunnel
in, err := stream.Recv()
if err != nil {
if errors.Is(err, io.EOF) {
return nil
}
if err != nil {
return err
}
if len(in.Data) == 0 {
continue
}
return err
}
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conn, ok := s.Conns[in.Id]
if !ok {
conn, err = net.Dial(in.Protocol, in.GuestAddr)
if err != nil {
return err
}
s.Conns[in.Id] = conn

writer := &GRPCServerWriter{id: in.Id, udpAddr: in.UdpTargetAddr, stream: stream}
go func() {
_, _ = io.Copy(writer, conn)
delete(s.Conns, writer.id)
}()
}
_, err = conn.Write(in.Data)
if err != nil {
return err
}
// We simply forward data form GRPC stream to net.Conn for both tcp and udp. So simple proxy is sufficient
conn, err := net.Dial(in.Protocol, in.GuestAddr)
if err != nil {
return err
}
rw := &GRPCServerRW{stream: stream, id: in.Id}
bicopy.Bicopy(rw, conn, nil)
return nil
}

type GRPCServerWriter struct {
id string
udpAddr string
stream api.GuestService_TunnelServer
type GRPCServerRW struct {
id string
stream api.GuestService_TunnelServer
}

var _ io.Writer = (*GRPCServerWriter)(nil)
var _ net.Conn = (*GRPCServerRW)(nil)

func (g GRPCServerWriter) Write(p []byte) (n int, err error) {
if len(p) == 0 {
return 0, nil
}
err = g.stream.Send(&api.TunnelMessage{Id: g.id, Data: p, UdpTargetAddr: g.udpAddr})
func (g *GRPCServerRW) Write(p []byte) (n int, err error) {
err = g.stream.Send(&api.TunnelMessage{Id: g.id, Data: p})
return len(p), err
}

func (g *GRPCServerRW) Read(p []byte) (n int, err error) {
in, err := g.stream.Recv()
if err != nil {
return 0, err
}
copy(p, in.Data)
return len(in.Data), nil
}

func (g *GRPCServerRW) Close() error {
return nil
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Why this does nothing?

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Server doesn't have any stream closing methods. So it doesn't do anything

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So this is implemented only to satisfy the net.Conn interface? Should we log a debug message when about ignoring Close?

This code can be integrated in other code expecting that Close() does something. If doing nothing breaks something, the debug log will help to diagnose the issue.

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debug logs are useful only in dev side, also grpc server doesn't provide close, its purely handled on client itself. I don't think adding debug is anywhere useful.

I don't want to spam it in our guestagent logs which doesn't give much value.

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Returning nil on Close is fine if there is nothing to do. SetDeadline should return an error if it is not implemented.

}

func (g *GRPCServerRW) LocalAddr() net.Addr {
return &net.UnixAddr{Name: "grpc", Net: "unixpacket"}
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This seems like the right way to support good logging, better than the NamedReadWriter added in #2944.

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This is a pointless comment. The purpose of LocalAddr is to identify the connection (which this doesn't do) while the NamedReadWriter in #2944 is identifying the purpose of the connection.

This implementation here is a lie, it doesn't identify the connection and the address it returns cannot be used in any of the normal ways that net.Addr is used.

}

func (g *GRPCServerRW) RemoteAddr() net.Addr {
return &net.UnixAddr{Name: "grpc", Net: "unixpacket"}
}

func (g *GRPCServerRW) SetDeadline(_ time.Time) error {
return nil
}

func (g *GRPCServerRW) SetReadDeadline(_ time.Time) error {
return nil
}

func (g *GRPCServerRW) SetWriteDeadline(_ time.Time) error {
return nil
}
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