2.2.2.3.2 Client Offscreen Bitmap Cache Error PDU

The Offscreen Bitmap Cache Error PDU is sent by clients that support offscreen bitmap caching and encounter caching errors.


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tpktHeader

x224Data

mcsSDrq (variable)

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securityHeader (variable)

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offscreenBitmapCacheErrorPduData (22 bytes)

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tpktHeader (4 bytes): A TPKT Header as specified in [T123] section 8.

x224Data (3 bytes): An X.224 Class 0 Data TPDU, as specified in [X224] section 13.7.

mcsSDrq (variable): Variable-length PER-encoded MCS Domain PDU (DomainMCSPDU) that encapsulates an MCS Send Data Request structure (SDrq, choice 25 from DomainMCSPDU), as specified in [T125] section 11.32 (the ASN.1 structure definitions are specified in [T125] section 7, parts 7 and 10). The userData field of the MCS Send Data Request PDU contains a Security Header and an Offscreen Bitmap Cache Error PDU Data (section 2.2.2.3.2.1) structure.

securityHeader (variable): Optional security header. The presence and format of the security header depends on the Encryption Level and Encryption Method selected by the server ([MS-RDPBCGR] sections 5.3.2 and 2.2.1.4.3). If the Encryption Level selected by the server is greater than ENCRYPTION_LEVEL_NONE (0) and the Encryption Method selected by the server is greater than ENCRYPTION_METHOD_NONE (0), then this field MUST contain one of the following headers:

  • Non-FIPS Security Header ([MS-RDPBCGR] section 2.2.8.1.1.2.2) if the Encryption Method selected by the server is ENCRYPTION_METHOD_40BIT (0x00000001), ENCRYPTION_METHOD_56BIT (0x00000008), or ENCRYPTION_METHOD_128BIT (0x00000002).

  • FIPS Security Header ([MS-RDPBCGR] section 2.2.8.1.1.2.3) if the Encryption Level selected by the server is ENCRYPTION_METHOD_FIPS (0x00000010).

If the Encryption Level selected by the server is ENCRYPTION_LEVEL_NONE (0) and the Encryption Method selected by the server is ENCRYPTION_METHOD_NONE (0), then this header MUST NOT be included in the PDU.

offscreenBitmapCacheErrorPduData (22 bytes): The actual contents of the Offscreen Bitmap Cache Error PDU, as specified in section 2.2.2.3.2.1.