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 |
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flags |
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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.
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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.