feat: full NFSv4.2 server and client in pure Go

Assisted-by: GLM 5.3 Flash

internal/nfsclient/gss_test.go

@@ -0,0 +1,73 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package nfsclient
+
+import (
+	"net"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/nfs/internal/krb5"
+	"sourcedock.dev/petrbalvin/nfs/internal/nfs4"
+	"sourcedock.dev/petrbalvin/nfs/internal/nfs4server"
+	"sourcedock.dev/petrbalvin/nfs/internal/nfsfs"
+	"sourcedock.dev/petrbalvin/nfs/internal/rpc"
+	"sourcedock.dev/petrbalvin/nfs/internal/server"
+)
+
+// The RPCSEC_GSS integrity and privacy levels of this client round trip
+// against the real server over TCP.
+func TestGSSRoundTrip(t *testing.T) {
+	root := t.TempDir()
+	if err := os.WriteFile(filepath.Join(root, "k.txt"), []byte("kerberos"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	backend, err := nfsfs.NewLocal(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+	key := make([]byte, 32)
+	for i := range key {
+		key[i] = byte(i + 3)
+	}
+	h := &nfs4server.Handler{FS: backend, ServerKey: key, ServiceName: "nfs"}
+
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	srv := &server.Server{Handle: h.HandleConn}
+	go srv.Serve(t.Context(), ln)
+	defer ln.Close()
+
+	for _, svc := range []uint32{rpc.SvcIntegrity, rpc.SvcPrivacy} {
+		cl, err := Dial(ln.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := cl.Establish("gss-client"); err != nil {
+			t.Fatalf("establish: %v", err)
+		}
+		if err := cl.EnableGSS(krb5.EtypeAES128, key, "EXAMPLE.ORG", "nfs",
+			"petr@EXAMPLE.ORG", svc); err != nil {
+			t.Fatalf("enable gss: %v", err)
+		}
+		res, _, err := cl.Compound("gss", [][]byte{
+			nfs4.AppendPutRootfh(nil),
+			nfs4.AppendLookup(nil, "k.txt"),
+			nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrSize)),
+		})
+		if err != nil {
+			t.Fatalf("compound: %v", err)
+		}
+		if res.Status != nfs4.ErrOK {
+			t.Fatalf("compound: status %d", res.Status)
+		}
+		if err := cl.DisableGSS(); err != nil {
+			t.Fatalf("disable: %v", err)
+		}
+		cl.Close()
+	}
+}