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

Assisted-by: GLM 5.3 Flash

internal/rpc/fuzz_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package rpc
+
+import (
+	"bytes"
+	"testing"
+)
+
+// FuzzReadRecord feeds arbitrary fragment streams into the reassembler:
+// no input may panic, allocate without bound or return anything but a
+// record, io.EOF, ErrRecordTooLarge or a truncation error.
+func FuzzReadRecord(f *testing.F) {
+	f.Add([]byte{0x80, 0, 0, 4, 'a', 'b', 'c', 'd'})
+	f.Add([]byte{0, 0, 0, 4, 'a', 'b', 'c', 'd', 0x80, 0, 0, 0})
+	f.Add([]byte{0xff, 0xff, 0xff, 0xff})
+	f.Add([]byte{0, 0, 0, 1})
+	f.Fuzz(func(t *testing.T, data []byte) {
+		rec, err := ReadRecord(bytes.NewReader(data), 1<<16)
+		if err == nil && len(rec) > 1<<16 {
+			t.Fatalf("a record of %d bytes against a limit of %d", len(rec), 1<<16)
+		}
+	})
+}
+
+// FuzzDecodeMessage feeds arbitrary records through the call and reply
+// decoders: no input may panic, and every failure arrives as an error.
+func FuzzDecodeMessage(f *testing.F) {
+	call, err := AppendCall(nil, Call{XID: 1, Program: 100003, Version: 4, Procedure: 1,
+		Cred: Auth{Flavor: FlavorSys, Body: []byte{1, 2}}})
+	if err != nil {
+		f.Fatal(err)
+	}
+	reply, err := AppendAcceptedReply(nil, 1, AuthNull, AcceptSuccess, Mismatch{})
+	if err != nil {
+		f.Fatal(err)
+	}
+	reply = append(reply, 0, 0, 0, 42)
+	f.Add(call)
+	f.Add(reply)
+	f.Add(AppendRejectedReply(nil, 2, AuthBadVerf))
+	f.Add([]byte{0, 0, 0, 1, 0, 0, 0, 1})
+	f.Add([]byte{0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 2})
+	f.Fuzz(func(t *testing.T, data []byte) {
+		// The property under test is that none of these panics; every
+		// malformed input must arrive as an ordinary error.
+		_, _, _ = DecodeCall(data)
+		_, _ = DecodeReply(data)
+		_, _, _ = PeekHeader(data)
+		_, _ = DecodeAuthSysBody(data)
+		_, _ = DecodeGSSCred(data)
+		_, _, _, _, _, _ = DecodeGSSInitRes(data)
+	})
+}