fix(js): probe SMBv1 support after SMB2 negotiation

pkg/js/libs/smb/smb.go

@@ -3,6 +3,7 @@ package smb
 import (
 	"context"
 	"fmt"
+	"net"
 	"time"
 
 	"github.com/praetorian-inc/fingerprintx/pkg/plugins"
@@ -49,19 +50,24 @@ func connectSMBInfoMode(ctx context.Context, executionId string, host string, po
 	if dialer == nil {
 		return nil, fmt.Errorf("dialers not initialized for %s", executionId)
 	}
-	conn, err := dialer.Fastdialer.Dial(ctx, "tcp", fmt.Sprintf("%s:%d", host, port))
+	address := net.JoinHostPort(host, fmt.Sprintf("%d", port))
+	dialSMBInfo := func(ctx context.Context) (net.Conn, error) {
+		return dialer.Fastdialer.Dial(ctx, "tcp", address)
+	}
+	conn, err := dialSMBInfo(ctx)
 	if err != nil {
 		return nil, err
 	}
 	// try to get SMBv2/v3 info
 	result, err := getSMBInfo(conn, true, false)
 	_ = conn.Close() // close regardless of error
 	if err == nil {
+		updateSMBv1Support(ctx, result, dialSMBInfo)
 		return result, nil
 	}
 
 	// try to negotiate SMBv1
-	conn, err = dialer.Fastdialer.Dial(ctx, "tcp", fmt.Sprintf("%s:%d", host, port))
+	conn, err = dialSMBInfo(ctx)
 	if err != nil {
 		return nil, err
 	}

pkg/js/libs/smb/smb_private.go

@@ -12,6 +12,8 @@ import (
 	zgrabsmb "github.com/zmap/zgrab2/lib/smb/smb"
 )
 
+type smbInfoDialFunc func(context.Context) (net.Conn, error)
+
 // ==== private helper functions/methods ====
 
 // collectSMBv2Metadata collects metadata for SMBv2 services.
@@ -53,3 +55,23 @@ func getSMBInfo(conn net.Conn, setupSession, v1 bool) (*zgrabsmb.SMBLog, error)
 	}
 	return result, nil
 }
+
+func updateSMBv1Support(ctx context.Context, result *zgrabsmb.SMBLog, dial smbInfoDialFunc) {
+	if result == nil || result.SupportV1 {
+		return
+	}
+
+	conn, err := dial(ctx)
+	if err != nil {
+		return
+	}
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	v1Result, err := getSMBInfo(conn, false, true)
+	if err != nil || v1Result == nil || !v1Result.SupportV1 {
+		return
+	}
+	result.SupportV1 = true
+}

pkg/js/libs/smb/smb_test.go

@@ -0,0 +1,87 @@
+package smb
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	zgrabsmb "github.com/zmap/zgrab2/lib/smb/smb"
+)
+
+func TestUpdateSMBv1SupportPreservesNegotiatedSMB2Version(t *testing.T) {
+	version := &zgrabsmb.SMBVersions{
+		Major:     2,
+		Minor:     1,
+		VerString: "SMB 2.1",
+	}
+	result := &zgrabsmb.SMBLog{
+		Version: version,
+	}
+	dial, done := newSMBv1ProbeDialer()
+
+	updateSMBv1Support(context.Background(), result, dial)
+
+	require.True(t, result.SupportV1)
+	require.Same(t, version, result.Version)
+	select {
+	case err := <-done:
+		require.NoError(t, err)
+	case <-time.After(time.Second):
+		t.Fatal("SMBv1 probe was not performed")
+	}
+}
+
+func TestUpdateSMBv1SupportIgnoresProbeErrors(t *testing.T) {
+	result := &zgrabsmb.SMBLog{}
+
+	updateSMBv1Support(context.Background(), result, func(context.Context) (net.Conn, error) {
+		return nil, errors.New("dial failed")
+	})
+
+	require.False(t, result.SupportV1)
+}
+
+func newSMBv1ProbeDialer() (smbInfoDialFunc, <-chan error) {
+	done := make(chan error, 1)
+	return func(context.Context) (net.Conn, error) {
+		clientConn, serverConn := net.Pipe()
+		go func() {
+			defer close(done)
+			done <- serveSMBv1Probe(serverConn)
+		}()
+		return clientConn, nil
+	}, done
+}
+
+func serveSMBv1Probe(conn net.Conn) error {
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	var requestSize uint32
+	if err := binary.Read(conn, binary.BigEndian, &requestSize); err != nil {
+		return err
+	}
+	request := make([]byte, requestSize)
+	if _, err := io.ReadFull(conn, request); err != nil {
+		return err
+	}
+	if len(request) < 4 {
+		return io.ErrUnexpectedEOF
+	}
+	if string(request[:4]) != zgrabsmb.ProtocolSmb {
+		return errors.New("expected SMBv1 negotiate request")
+	}
+
+	response := []byte(zgrabsmb.ProtocolSmb)
+	if err := binary.Write(conn, binary.BigEndian, uint32(len(response))); err != nil {
+		return err
+	}
+	_, err := conn.Write(response)
+	return err
+}