Add proxy package

This package includes the proxy which translates the unix socket to the
vsock. This proxy could be dropped in the future if podman will support
natively the vsock protocol.

Signed-off-by: Alice Frosi <[email protected]>

Author: alicefr

pkg/vsock/proxy.go

@@ -0,0 +1,143 @@
+package proxy
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"os"
+
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+const podmanVMProxyDefault = "/tmp/podman-bootc-proxy.sock"
+
+type Proxy struct {
+	cid    uint
+	port   uint
+	socket string
+	done   chan struct{}
+}
+
+func NewProxy(cid, port uint, socket string) *Proxy {
+	if socket == "" {
+		socket = podmanVMProxyDefault
+	}
+	return &Proxy{
+		cid:    cid,
+		port:   port,
+		socket: socket,
+		done:   make(chan struct{}),
+	}
+}
+
+func (proxy *Proxy) GetSocket() string {
+	return proxy.socket
+}
+
+func (proxy *Proxy) Stop() {
+	select {
+	case <-proxy.done:
+		// already closed
+	default:
+		close(proxy.done)
+	}
+	os.Remove(proxy.socket)
+	logrus.Debugf("Stopped proxy")
+}
+
+func (proxy *Proxy) Start() error {
+	_ = os.Remove(proxy.socket)
+
+	unixListener, err := net.Listen("unix", proxy.socket)
+	if err != nil {
+		return fmt.Errorf("Failed to listen on unix socket: %v", err)
+	}
+	go func() {
+		defer unixListener.Close()
+
+		for {
+			select {
+			case <-proxy.done:
+				return
+			default:
+				unixConn, err := unixListener.Accept()
+				if err != nil {
+					logrus.Warnf("Accept error: %v", err)
+					continue
+				}
+
+				go proxy.handleConnection(unixConn)
+			}
+		}
+	}()
+
+	logrus.Debugf("Started proxy at: %s", proxy.socket)
+
+	return nil
+}
+
+func (proxy *Proxy) handleConnection(unixConn net.Conn) {
+	defer unixConn.Close()
+
+	fd, err := unix.Socket(unix.AF_VSOCK, unix.SOCK_STREAM, 0)
+	if err != nil {
+		logrus.Errorf("vsock socket error: %v", err)
+		return
+	}
+
+	sa := &unix.SockaddrVM{CID: uint32(proxy.cid), Port: uint32(proxy.port)}
+	if err := unix.Connect(fd, sa); err != nil {
+		logrus.Debugf("Failed to connect error: %v", err)
+		return
+	}
+
+	vconnFile := os.NewFile(uintptr(fd), "vsock")
+	if vconnFile == nil {
+		logrus.Error("Failed to create os.File from fd")
+		unix.Close(fd)
+		return
+	}
+	defer vconnFile.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	errCh := make(chan error, 2)
+	go proxy.proxyFileToConn(ctx, vconnFile, unixConn, errCh)
+	go proxy.proxyConnToFile(ctx, unixConn, vconnFile, errCh)
+
+	// Wait for the first error or cancellation
+	select {
+	case <-proxy.done:
+	case err := <-errCh:
+		if err != nil && err != io.EOF {
+			logrus.Errorf("proxy error: %v", err)
+		}
+	}
+}
+
+func (proxy *Proxy) proxyFileToConn(ctx context.Context, file *os.File, conn net.Conn, errCh chan error) {
+	go func() {
+		_, err := io.Copy(conn, file)
+		errCh <- err
+	}()
+	select {
+	case <-ctx.Done():
+	case <-proxy.done:
+	case <-errCh:
+	}
+}
+
+func (proxy *Proxy) proxyConnToFile(ctx context.Context, conn net.Conn, file *os.File, errCh chan error) {
+	go func() {
+		_, err := io.Copy(file, conn)
+		errCh <- err
+	}()
+	select {
+	case <-ctx.Done():
+	case <-proxy.done:
+	case <-errCh:
+	}
+}