# Table of contents:

• Introduction
• Client/Request
• Server/Response
  • From filename
  • Asynchronously
    • Policies
      • Policy
• Examples
  • Downloading shields
    • By filename
    • Automatically
  • By filename after removal
• Known changes

# Introduction

GCF is a command introduced with MSNP11.

It is a Notification Server command, without a request payload and WITH a response payload.

It gets configuration data from a file on the server.

# Client/Request

Only in MSNP11 and MSNP12.

GCF TrID filename

Where filename is the file to retrieve. Only Shields.xml is known to be this parameter.

# Server/Response

# From filename

GCF TrID filename length
payload

Where length is the size (in bytes) of the payload.

Where payload is the data for this file.

# Asynchronously

GCF 0 length
payload

Being an asynchronous command, the Transaction ID is set to 0.

# Policies

This element contains one or multiple <Policy> elements.

# Policy

This element has two attributes:

• type: The type of policy:
  • `SHIELDS": The Shields Configuration Data.
  • ABCH: Address Book Service policies.
  • ERRORRESPONSETABLE: The same as the Messenger Config's <ErrorResponseTable>.
  • P2P: Peer-to-peer policies.
• checksum: A capitalized MD5 hash of the inner contents of this element.

# Examples

# Downloading shields

For more information read the Shields Configuration Data article.

# By filename

Only in MSNP11 and MSNP12.

C: GCF 1 Shields.xml
S: GCF 1 Shields.xml 145
<?xml version="1.0" encoding="utf-8" ?><config><shield><cli maj="7" min="0" minbld="0" maxbld="9999" deny=" " /></shield><block></block></config>

# Automatically

Since MSNP13.

C: USR 2 TWN I example@hotmail.com
S: GCF 0 203
<Policies><Policy type="SHIELDS" checksum="94A347C122C483F8BEAD525832DB2F71"><config><shield><cli maj="7" min="0" minbld="0" maxbld="9999" deny=" " /></shield><block></block></config></Policy></Policies>
S: USR 2 TWN S passport=parameters,neat=huh,lc=1033,id=507

# By filename after removal

NOTE: I don't know if this is correct.

C: GCF 3 Shields.xml

Server disconnects client.

# Known changes

• MSNP13: Dropped support for getting a response via filenames, and changed how the Shields configuration data is contained.