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

Assisted-by: GLM 5.3 Flash

internal/nfs4/dirdeleg.go

@@ -0,0 +1,179 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+// Directory delegations and the notification family: the wire codecs of
+// GET_DIR_DELEGATION (RFC 8881 section 18.39), CB_NOTIFY and
+// CB_NOTIFY_LOCK (RFC 8881 section 20), with the shapes taken from the
+// XDR of RFC 7863.
+
+package nfs4
+
+import (
+	"sourcedock.dev/petrbalvin/nfs/internal/xdr"
+)
+
+// Notification types of the notify_type4 enum.
+const (
+	NotifyChangeChildAttrs = 0
+	NotifyChangeDirAttrs   = 1
+	NotifyRemoveEntry      = 2
+	NotifyAddEntry         = 3
+	NotifyRenameEntry      = 4
+	NotifyChangeCookieVerf = 5
+)
+
+// Statuses of the gddrnf4_status union.
+const (
+	GddOK      = 0
+	GddUnavail = 1
+)
+
+// A Notify4 is one notify4: the kind of the change and the encoded
+// change body.
+type Notify4 struct {
+	Mask Bitmap
+	Vals []byte
+}
+
+// A CBNotify is the decoded CB_NOTIFY4args.
+type CBNotify struct {
+	Stateid Stateid
+	FH      []byte
+	Changes []Notify4
+}
+
+// A CBNotifyLock is the decoded CB_NOTIFY_LOCK4args.
+type CBNotifyLock struct {
+	FH       []byte
+	Clientid uint64
+	Owner    []byte
+}
+
+// AppendGetDirDelegationArgs encodes the GET_DIR_DELEGATION4args: the
+// signal flag, the notification types, the attr delay hints and the
+// requested attribute bitmaps.
+func AppendGetDirDelegationArgs(b []byte, signalAvail bool, notifyTypes Bitmap, childDelay, dirDelay NfsTime, childAttrs, dirAttrs Bitmap) []byte {
+	b = xdr.AppendUint32(b, OpGetDirDelegation)
+	b = xdr.AppendBool(b, signalAvail)
+	b = notifyTypes.AppendTo(b)
+	b = appendNfsTime(b, childDelay)
+	b = appendNfsTime(b, dirDelay)
+	b = childAttrs.AppendTo(b)
+	return dirAttrs.AppendTo(b)
+}
+
+// AppendGetDirDelegationResOK encodes the delegation granted: the
+// verifier, the stateid, the supported notifications and the attribute
+// bitmaps the server promises.
+func AppendGetDirDelegationResOK(b []byte, cookieverf [8]byte, st Stateid, notification, childAttrs, dirAttrs Bitmap) []byte {
+	b = xdr.AppendUint32(b, GddOK)
+	b = append(b, cookieverf[:]...)
+	b = st.Append(b)
+	b = notification.AppendTo(b)
+	b = childAttrs.AppendTo(b)
+	return dirAttrs.AppendTo(b)
+}
+
+// AppendGetDirDelegationResUnavail encodes the no delegation answer: the
+// server promises to signal when one becomes available.
+func AppendGetDirDelegationResUnavail(b []byte, willSignal bool) []byte {
+	b = xdr.AppendUint32(b, GddUnavail)
+	return xdr.AppendBool(b, willSignal)
+}
+
+// appendNotifyEntry encodes one notify_entry4: the name and the full
+// attribute list, which this build carries empty.
+func appendNotifyEntry(b []byte, name string) []byte {
+	b = xdr.AppendString(b, name)
+	return AppendFattr(b, Bitmap{}, Attrs{})
+}
+
+// AppendNotifyAdd encodes the notify_add4 body: the optional removed
+// source of a rename, the new entry, its cookie, the optional previous
+// entry and the end of page flag.
+func AppendNotifyAdd(b []byte, name string, cookie uint64, lastEntry bool) []byte {
+	b = xdr.AppendUint32(b, 0) // nad_old_entry<1>: none
+	b = appendNotifyEntry(b, name)
+	b = xdr.AppendUint32(b, 0) // nad_new_entry_cookie<1>: none
+	b = xdr.AppendUint32(b, 0) // nad_prev_entry<1>: none
+	return xdr.AppendBool(b, lastEntry)
+}
+
+// AppendNotifyRemove encodes the notify_remove4 body: the removed entry
+// and the cookie the client resumes past it from.
+func AppendNotifyRemove(b []byte, name string, cookie uint64) []byte {
+	b = appendNotifyEntry(b, name)
+	return xdr.AppendUint64(b, cookie)
+}
+
+// AppendNotify4 encodes one notify4: the mask and the encoded body.
+func AppendNotify4(b []byte, mask Bitmap, vals []byte) []byte {
+	b = mask.AppendTo(b)
+	return xdr.AppendVarOpaque(b, vals)
+}
+
+// AppendCBNotifyArgs encodes the CB_NOTIFY4args: the delegation stateid,
+// the directory and the changes.
+func AppendCBNotifyArgs(b []byte, st Stateid, fh []byte, changes []Notify4) []byte {
+	b = xdr.AppendUint32(b, OpCBNotify)
+	b = st.Append(b)
+	b = xdr.AppendVarOpaque(b, fh)
+	b = xdr.AppendUint32(b, uint32(len(changes)))
+	for _, c := range changes {
+		b = AppendNotify4(b, c.Mask, c.Vals)
+	}
+	return b
+}
+
+// DecodeCBNotifyArgs decodes the CB_NOTIFY4args the client receives.
+func DecodeCBNotifyArgs(d *xdr.Decoder) (CBNotify, error) {
+	var out CBNotify
+	raw, err := d.Raw(16)
+	if err != nil {
+		return out, err
+	}
+	copy(out.Stateid[:], raw)
+	if out.FH, err = d.VarOpaque(); err != nil {
+		return out, err
+	}
+	n, err := d.Uint32()
+	if err != nil {
+		return out, err
+	}
+	for range n {
+		var c Notify4
+		if c.Mask, err = ReadBitmap(d); err != nil {
+			return out, err
+		}
+		if c.Vals, err = d.VarOpaque(); err != nil {
+			return out, err
+		}
+		out.Changes = append(out.Changes, c)
+	}
+	return out, nil
+}
+
+// AppendCBNotifyLockArgs encodes the CB_NOTIFY_LOCK4args: the file and
+// the lock owner whose denied lock may be available again.
+func AppendCBNotifyLockArgs(b []byte, fh []byte, clientid uint64, owner []byte) []byte {
+	b = xdr.AppendUint32(b, OpCBNotifyLock)
+	b = xdr.AppendVarOpaque(b, fh)
+	b = xdr.AppendUint64(b, clientid)
+	return xdr.AppendVarOpaque(b, owner)
+}
+
+// DecodeCBNotifyLockArgs decodes the CB_NOTIFY_LOCK4args the client
+// receives.
+func DecodeCBNotifyLockArgs(d *xdr.Decoder) (CBNotifyLock, error) {
+	var out CBNotifyLock
+	fh, err := d.VarOpaque()
+	if err != nil {
+		return out, err
+	}
+	out.FH = fh
+	if out.Clientid, err = d.Uint64(); err != nil {
+		return out, err
+	}
+	out.Owner, err = d.VarOpaque()
+	return out, err
+}