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3.2.5.3.7 Processing MCS Attach User Confirm PDU

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The structure and fields of the MCS Attach User Confirm PDU are specified in section 2.2.1.7.

If Enhanced RDP Security (section 5.4) is in effect, the External Security Protocol (section 5.4.5) MUST be used to decrypt and verify the integrity of the entire PDU prior to any processing taking place.

The embedded length fields within the tpktHeader field ([T123] section 8) MUST be examined for consistency with the received data. If there is any discrepancy, the connection SHOULD be dropped.

The MCS Attach User Confirm PDU (embedded within the mcsAUcf field) is specified in [T125] section 7, parts 5 and 10. If the result field is not set to rt-successful (0), the client SHOULD drop the connection. If the result field is set to rt-successful (0) but the initiator field is not present, the client SHOULD drop the connection. If the initiator field is present, the client stores the value of the initiator in the User Channel ID store (section 3.2.1.5), because the initiator specifies the User Channel ID.

Once the User Channel ID has been extracted, the client MUST send an MCS Channel Join Request PDU for the user channel (section 3.2.5.3.8).