2.2.7.1.10 Virtual Channel Capability Set (TS_VIRTUALCHANNEL_CAPABILITYSET)

The TS_VIRTUALCHANNEL_CAPABILITYSET structure is used to advertise virtual channel support characteristics. This capability is sent by both client and server.


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capabilitySetType

lengthCapability

flags

VCChunkSize (optional)

capabilitySetType (2 bytes): A 16-bit, unsigned integer. The type of the capability set. This field MUST be set to CAPSTYPE_VIRTUALCHANNEL (20).

lengthCapability (2 bytes): A 16-bit, unsigned integer. The length in bytes of the capability data, including the size of the capabilitySetType and lengthCapability fields.

flags (4 bytes): A 32-bit, unsigned integer. Virtual channel compression flags.

Flag

Meaning

VCCAPS_NO_COMPR

0x00000000

Virtual channel compression is not supported.

VCCAPS_COMPR_SC

0x00000001

Indicates to the server that virtual channel compression is supported by the client for server-to-client traffic. The highest compression level supported by the client is advertised in the Client Info PDU (section 2.2.1.11).

VCCAPS_COMPR_CS_8K

0x00000002

Indicates to the client that virtual channel compression is supported by the server for client-to-server traffic (the compression level is limited to RDP 4.0 bulk compression).

VCChunkSize (4 bytes): A 32-bit unsigned integer. When sent from server to client, this field contains the maximum allowed size of a virtual channel chunk. When sent from client to server, the value in this field is ignored by the server; the server determines the maximum virtual channel chunk size. This value MUST be greater than or equal to CHANNEL_CHUNK_LENGTH and less than or equal to 16256.

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