DESIGN AND VALIDATION OF COMPUTER PROTOCOLS

Transcription

1 DESIGN AND VALIDATION OF COMPUTER PROTOCOLS Gerard J. Holzmann Bell Laboratories Murray Hill, New Jersey PRENTICE-HALL Englewood Cliffs, New Jersey 07632

2 Prentice Hall Software Series Brian W. Kernighan, Advisor Copyright 1991 by Lucent Technologies, Bell Laboratories, Incorporated. This book is typeset in Times Roman by the author, using an Linotronic 200P phototypesetter and a DEC VAX 8550 running the 10th Edition of the UNIX operating system. DEC and VAX are trademarks of Digital Equipment Corporation. UNIX is a registered trademark of AT&T. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America Prentice-Hall International (UK) Limited, London Prentice-Hall of Australia Pty. Limited, Sydney Prentice-Hall Canada Inc., Toronto Prentice-Hall Hispanoamericana, S.A., Mexico Prentice-Hall of India Private Limited, New Delhi Prentice-Hall of Japan, Inc., Tokyo Simon & Schuster Asia Pte. Ltd., Singapore Editora Prentice-Hall do Brasil, Ltda., Rio de Janeiro

3 CONTENTS Foreword Preface ix xi Part I Basics 1. Introduction 1.1 Early Beginnings The First Networks Protocols as Languages Protocol Standardization Summary 15 Exercises 16 Bibliographic Notes Protocol Structure 2.1 Introduction The Five Elements of a Protocol An Example Service and Environment Vocabulary and Format Procedure Rules Structured Protocol Design Ten Rules of Design Summary 39 Exercises 39 Bibliographic Notes Error Control 3.1 Introduction Error Model Types of Transmission Errors Redundancy Types of Codes Parity Check Error Correction A Linear Block Code Cyclic Redundancy Checks 56

4 3.10 Arithmetic Checksum Summary 64 Exercises 64 Bibliographic Notes Flow Control 4.1 Introduction Window Protocols Sequence Numbers Negative Acknowledgments Congestion Avoidance Summary 86 Exercises 87 Bibliographic Notes 88 Part II Specification and Modeling 5. Validation Models 5.1 Introduction Processes, Channels, Variables Executability of Statements Variables and Data Types Process Types Message Channels Control Flow Examples Modeling Procedures and Recursion Message Type Definitions Modeling Timeouts Lynch s Protocol Revisited Summary 107 Exercises 108 Bibliographic Notes Correctness Requirements 6.1 Introduction Reasoning about Behavior Assertions System Invariants Deadlocks Bad Cycles Temporal Claims Summary 125 Exercises 126 Bibliographic Notes Protocol Design 7.1 Introduction 128

5 7.2 Service Specification Assumptions about the Channel Protocol Vocabulary Messsage Format Procedure Rules Summary 160 Exercises 160 Bibliographic Notes Finite State Machines 8.1 Introduction Informal Description Formal Description Execution of Machines Minimization of Machines The Conformance Testing Problem Combining Machines Extended Finite State Machines Generalization of Machines Restricted Models Summary 184 Exercises 185 Bibliographic Notes 185 Part III Conformance Testing, Synthesis and Validation 9. Conformance Testing 9.1 Introduction Functional Testing Structural Testing Deriving UIO Sequences Modified Transition Tours An Alternative Method Summary 199 Exercises 200 Bibliographic Notes Protocol Synthesis 10.1 Introduction Protocol Derivation Derivation Algorithm Incremental Design Place Synchronization Summary 211 Exercises 212 Bibliographic Notes Protocol Validation

6 11.1 Introduction Manual Proof Method Automated Validation Methods The Supertrace Algorithm Detecting Non-Progress Cycles Detecting Acceptance Cycles Checking Temporal Claims Complexity Management Boundedness of PROMELA Models Summary 238 Exercises 239 Bibliographic Notes 240 Part IV Design Tools 12. A Protocol Simulator 12.1 Introduction SPIN Overview Expressions Variables Statements Control Flow Process and Message Types Macro Expansion SPIN Options Summary 294 Exercises 295 Bibliographic Notes A Protocol Validator 13.1 Introduction Structure of the Validator The Validation Kernel The Transition Matrix The Validator-Generator Code Overview of the Code Guided Simulation Some Applications Coverage in Supertrace Mode Summary 316 Exercises 316 Bibliographic Notes 317

7 14. Using the Validator 14.1 Introduction An Optical Telegraph Protocol Dekker s Algorithm A Larger Validation Flow Control Validation Session Layer Validation Summary 349 Exercises 349 Bibliographic Notes 349 Conclusion 351 References 352 Appendices A. Data Transmission 367 B. Flow Chart Language 380 C. PROMELA Language Report 383 D. SPIN Simulator Source 393 E. SPIN Validator Source 436 F. PROMELA File Transfer Protocol 528 Name Index 537 Subject Index 539

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