3.2.5.3.11 Sending Client Info PDU

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The structure and fields of the Client Info PDU are specified in section 2.2.1.11.

The tpktHeader field is initialized as specified in [T123] section 8, while the x224Data field (which contains an X.224 Class 0 Data TPDU) is initialized as specified in [X224] section 13.7.

The mcsSDrq field is initialized as specified in [T125] section 11.32. The embedded initiator field MUST be set to the User Channel ID (held in the User Channel ID store (section 3.2.1.5)) and the embedded channelId field MUST be set to the MCS I/O channel ID (held in the I/O Channel ID (section 3.2.1.3)). The embedded userData field contains the remaining fields of the Client Info PDU.

If Enhanced RDP Security (section 5.4) is in effect, the External Security Protocol (section 5.4.5) MUST be used to encrypt the entire PDU and generate a verification digest. The securityHeader field MUST be present; however, it will contain a Basic Security Header structure (section 2.2.8.1.1.2.1).

If Standard RDP Security mechanisms (section 5.3) are in effect, the PDU data following the securityHeader field can be encrypted and signed (depending on the values of the Encryption Level (section 5.3.1) and Encryption Method selected by the server as part of the negotiation specified in section 5.3.2) using the methods and techniques described in 5.3.6. The format of the securityHeader field is selected as described in the section detailing the PDU structure and fields (section 2.2) and the fields populated with appropriate security data. If the data is to be encrypted, the embedded flags field of the securityHeader field MUST contain the SEC_ENCRYPT (0x0008) flag.

The embedded flags field of the securityHeader field (which is always present) MUST contain the SEC_INFO_PKT (0x0040) flag (specified in section 2.2.8.1.1.2.1) to indicate the PDU type.

If the client is in the process of attempting an automatic reconnection operation using a cookie stored in the Automatic Reconnection Cookie store (section 3.2.1.9), then it MUST populate the autoReconnectCookie field of the Extended Info Structure (section 2.2.1.11.1.1.1) with the contents of the cookie. The remainder of the PDU MUST be populated with client settings according to the structure and type definition in section 2.2.1.11.1.1.