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

Assisted-by: GLM 5.3 Flash

internal/nfs4server/migration_test.go

@@ -0,0 +1,93 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package nfs4server
+
+import (
+	"testing"
+
+	"sourcedock.dev/petrbalvin/nfs/internal/nfs4"
+	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
+)
+
+// A configured referral answers LOOKUP with a stub, GETATTR with the
+// location attributes, and everything that touches the backend with
+// NFS4ERR_MOVED, RFC 5661 sections 8.4.2 and 11.9.
+func TestReferralAndMoved(t *testing.T) {
+	h := testTree(t)
+	h.SetReferral("migrated", Referral{
+		Servers:  []string{"10.0.0.9.8.1", "10.0.0.9.8.2"},
+		RootPath: []string{"exports", "data"},
+	})
+	sid, seq := newSession(t, h)
+	run := func(s uint32, ops [][]byte) (nfs4.CompoundRes, [][]byte) {
+		t.Helper()
+		all := append([][]byte{nfs4.AppendSequenceArgs(nil, sid, s, 0, defaultSlots-1, true)}, ops...)
+		payload := nfs4.AppendCompoundArgs(nil, "ref", nfs4.MinorVersion, all)
+		body, ok := h.compound(payload, cred{uid: 0, gid: 0})
+		if !ok {
+			t.Fatal("garbage")
+		}
+		r, bodies, derr := nfs4.DecodeCompoundResBodies(body)
+		if derr != nil {
+			t.Fatalf("decode: %v", derr)
+		}
+		return r, bodies[1:]
+	}
+
+	// LOOKUP lands on the stub and GETATTR carries the locations.
+	seq++
+	res, bodies := run(seq, [][]byte{
+		nfs4.AppendPutRootfh(nil),
+		nfs4.AppendLookup(nil, "migrated"),
+		// The blob carries only the one attribute: attributes encode in
+		// numeric order, so the test reads them one call at a time.
+		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrFsLocations)),
+	})
+	if res.Status != nfs4.ErrOK {
+		t.Fatalf("lookup stub: status %d", res.Status)
+	}
+	ad := xdr.NewDecoder(bodies[2])
+	words, aerr := ad.Uint32() // the response bitmap: count then words
+	if aerr != nil {
+		t.Fatal(aerr)
+	}
+	if _, rerr := ad.Raw(int(words) * 4); rerr != nil {
+		t.Fatal(rerr)
+	}
+	blob, aerr := ad.VarOpaque()
+	if aerr != nil {
+		t.Fatal(aerr)
+	}
+	fsRoot, locations, err := nfs4.DecodeFsLocations(blob)
+	if err != nil {
+		t.Fatalf("decode fs_locations: %v", err)
+	}
+	if len(locations) != 1 || len(locations[0].Servers) != 2 ||
+		locations[0].Servers[1] != "10.0.0.9.8.2" {
+		t.Fatalf("locations %+v", locations)
+	}
+	if len(fsRoot) != 1 || fsRoot[0] != "" {
+		t.Fatalf("fs root %v", fsRoot)
+	}
+
+	// A write against the stub is MOVED.
+	seq++
+	res, _ = run(seq, [][]byte{
+		nfs4.AppendPutRootfh(nil),
+		nfs4.AppendLookup(nil, "migrated"),
+		nfs4.AppendWriteArgs(nil, nfs4.Stateid{}, 0, nfs4.StableFileSync, []byte("x")),
+	})
+	if res.Status != nfs4.ErrMoved {
+		t.Fatalf("write on stub: status %d, want MOVED", res.Status)
+	}
+
+	// The real tree still serves files under their own names.
+	seq++
+	res, _ = run(seq, [][]byte{
+		nfs4.AppendPutRootfh(nil),
+		nfs4.AppendLookup(nil, "a.txt"),
+		nfs4.AppendGetattr(nil, nfs4.OfBits(nfs4.AttrSize)),
+	})
+	wantStatus(t, "real file", res.Status, nfs4.ErrOK)
+}