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2.2.4.22.2 Response

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The server MUST not return the typical response data when responding to this request. The server MUST respond with one message containing the raw data being read from the file or named pipe. The server relies on the transport layer to provide the client with the length, in bytes, of the received message. This enables the client to request up to 65,535 bytes of data and receive it directly into an arbitrary buffer space. The amount of data requested is expected to be larger than the negotiated buffer size for this session. If the client request is to read more bytes than the file or named pipe contains, the size of the returned server message MUST be the number of bytes actually read from the file or named pipe. When the number of bytes returned to the client in the unformatted raw message is less than the bytes requested, this outcome indicates to the client that the end of file (EOF) has been reached.

Because the server does not return the typical response data, the SMB Protocol cannot guarantee that the client can associate the server response data (message) with the correct corresponding client request. Therefore, the client MUST guarantee that there are and will be no other requests from the client to the server for the duration of the SMB_COM_READ_RAW (section 2.2.4.22) command's processing.

Because the server does not provide the typical response data, it cannot provide error information when an error occurs. In the event of an error, the server MUST return zero bytes to the client. The client is then responsible for issuing an alternative file I/O command request that provides the typical server response data. The client SHOULD send SMB_COM_READ_ANDX (section 2.2.4.42) to determine the cause of the error. The server MUST then respond with the appropriate status and error information. It is up to the client to take appropriate action to recover from the error. Care needs to be taken when interpreting the server returning 0 bytes to the client, because this condition is also used to indicate that the EOF has been reached.