Remote Mailslot Protocol

[MS-MAIL]:

Remote Mailslot Protocol

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Revision Summary

Date / Revision History / Revision Class / Comments /
12/18/2006 / 0.01 / New / Version 0.01 release
3/2/2007 / 1.0 / Major / Version 1.0 release
4/3/2007 / 1.1 / Minor / Version 1.1 release
5/11/2007 / 1.2 / Minor / Version 1.2 release
6/1/2007 / 1.2.1 / Editorial / Changed language and formatting in the technical content.
7/3/2007 / 1.2.2 / Editorial / Changed language and formatting in the technical content.
7/20/2007 / 1.2.3 / Editorial / Changed language and formatting in the technical content.
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Table of Contents

1 Introduction 6

1.1 Glossary 6

1.2 References 6

1.2.1 Normative References 6

1.2.2 Informative References 7

1.3 Overview 7

1.4 Relationship to Other Protocols 7

1.5 Prerequisites/Preconditions 7

1.6 Applicability Statement 7

1.7 Versioning and Capability Negotiation 8

1.8 Vendor-Extensible Fields 8

1.9 Standards Assignments 8

2 Messages 9

2.1 Transport 9

2.2 Message Syntax 9

2.2.1 Mailslot Write Message 9

3 Protocol Details 13

3.1 Client Details 13

3.1.1 Abstract Data Model 13

3.1.2 Timers 13

3.1.3 Initialization 13

3.1.4 Higher-Layer Triggered Events 13

3.1.4.1 Application Writes to a Mailslot 13

3.1.5 Message Processing Events and Sequencing Rules 13

3.1.6 Timer Events 14

3.1.7 Other Local Events 14

3.2 Server Details 14

3.2.1 Abstract Data Model 14

3.2.1.1 Global 14

3.2.1.2 Per Mailslot 14

3.2.2 Timers 14

3.2.3 Initialization 14

3.2.4 Higher-Layer Triggered Events 15

3.2.4.1 Application Creates a Mailslot 15

3.2.4.2 Application Reads from a Mailslot 15

3.2.4.3 Application Closes a Mailslot 16

3.2.5 Message Processing Events and Sequencing Rules 16

3.2.5.1 Server Receives a Mailslot Write 16

3.2.6 Timer Events 16

3.2.7 Other Local Events 17

4 Protocol Examples 18

5 Security 20

5.1 Security Considerations for Implementers 20

5.2 Index of Security Parameters 20

6 Appendix A: Product Behavior 21

7 Change Tracking 24

8 Index 25

1  Introduction

The Remote Mailslot Protocol is a simple, unreliable, insecure, and unidirectional interprocess communications (IPC) protocol between a client and server. A mailslot server creates a mailslot, and a mailslot client writes messages to the mailslot created by the server. The server then reads these messages, thus achieving communication between the client and server. A mailslot is represented locally on the server as a file.

Sections 1.5, 1.8, 1.9, 2, and 3 of this specification are normative. All other sections and examples in this specification are informative.

1.1  Glossary

This document uses the following terms:

little-endian: Multiple-byte values that are byte-ordered with the least significant byte stored in the memory location with the lowest address.

named pipe: A named, one-way, or duplex pipe for communication between a pipe server and one or more pipe clients.

NetBIOS datagram service: An implementation of NetBIOS services in a datagram environment as specified in [RFC1001] section 17.

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.

1.2  References

Links to a document in the Microsoft Open Specifications library point to the correct section in the most recently published version of the referenced document. However, because individual documents in the library are not updated at the same time, the section numbers in the documents may not match. You can confirm the correct section numbering by checking the Errata.

1.2.1  Normative References

We conduct frequent surveys of the normative references to assure their continued availability. If you have any issue with finding a normative reference, please contact . We will assist you in finding the relevant information.

[MS-BRWS] Microsoft Corporation, "Common Internet File System (CIFS) Browser Protocol".

[MS-CIFS] Microsoft Corporation, "Common Internet File System (CIFS) Protocol".

[MS-DTYP] Microsoft Corporation, "Windows Data Types".

[MS-NRPC] Microsoft Corporation, "Netlogon Remote Protocol".

[MS-SMB] Microsoft Corporation, "Server Message Block (SMB) Protocol".

[NETBEUI] IBM Corporation, "LAN Technical Reference: 802.2 and NetBIOS APIs", 1986, http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/BK8P7001/CCONTENTS

[RFC1001] Network Working Group, "Protocol Standard for a NetBIOS Service on a TCP/UDP Transport: Concepts and Methods", RFC 1001, March 1987, http://www.ietf.org/rfc/rfc1001.txt

[RFC1002] Network Working Group, "Protocol Standard for a NetBIOS Service on a TCP/UDP Transport: Detailed Specifications", STD 19, RFC 1002, March 1987, http://www.rfc-editor.org/rfc/rfc1002.txt

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, http://www.rfc-editor.org/rfc/rfc2119.txt

1.2.2  Informative References

[MSLOT] Microsoft Corporation, "Mailslots", http://msdn.microsoft.com/en-us/library/aa365576.aspx

[PIPE] Microsoft Corporation, "Named Pipes", http://msdn.microsoft.com/en-us/library/aa365590.aspx

1.3  Overview

The Remote Mailslot Protocol is a simple, unreliable, insecure, and unidirectional interprocess communications (IPC) protocol between a client and server or among a group of servers that use the NetBIOS datagram service (as specified in [RFC1001] section 17) as the transport protocol. A mailslot server creates a mailslot, and a mailslot client writes messages to the mailslot created by the server. The server then reads these messages, thus achieving communication between the client and server applications. If the server closes the mailslot, the client will no longer be able to send messages to this mailslot.

This protocol specifies a means of carrying SMB_COM_TRANSACTION messages (as specified in section 2.2.1) over a NetBIOS datagram service. The sender of the mailslot message formats the SMB_COM_TRANSACTION message and sends it as a NetBIOS datagram. This protocol is not transported over SMB.

1.4  Relationship to Other Protocols

The Remote Mailslot Protocol relies on the transport mechanisms of the NetBIOS datagram service (as specified in section 2.1).

The Remote Mailslot Protocol is used by the Netlogon Remote Protocol, as described in [MS-NRPC] to locate domain controllers. The Netlogon Remote Protocol uses "\MAILSLOT\NET\NETLOGON".

The Remote Mailslot Protocol is used by the Common Internet File System (CIFS) Browser Protocol, as described in [MS-BRWS] to accomplish inter-machine communication. The Common Internet File System (CIFS) Browser Protocol uses "\MAILSLOT\LANMAN" and "\MAILSLOT\BROWSE".

1.5  Prerequisites/Preconditions

The server needs to have a NetBIOS name registered, as described in [RFC1001] section 15. The higher-layer application that uses the Remote Mailslot Protocol needs to know the NetBIOS name of the server to which it is trying to connect. The higher-layer application needs to also know the name of the mailslot.

1.6  Applicability Statement

Remote mailslot messages are used in scenarios that require sending simple, short messages to one or more computers on the network. Neither the sender nor the receiver can expect reliable or ordered delivery of these messages.

Due to the unordered, unreliable, and unidirectional nature of the Remote Mailslot Protocol, it is recommended that clients that need a more robust or bidirectional communication mechanism with the server use other, more reliable protocols such as named pipes, as specified in [PIPE]. Also, because the Remote Mailslot Protocol has no authentication, it is unsuitable for applications requiring a secure communication between the sender and receiver.<1>