2.2.4.3.1 Request

 SMB_Parameters
   {
   UCHAR  WordCount;
   Words
     {
     USHORT              AccessMode;
     SMB_FILE_ATTRIBUTES SearchAttributes;
     }
   }
 SMB_Data
   {
   USHORT ByteCount;
   Bytes
     {
     UCHAR      BufferFormat;
     SMB_STRING FileName;
     }
   }
  

SMB_Header:

Flags (1 byte):

Name and bitmask	Description
SMB_FLAGS_OPLOCK 0x20	If set, the client is requesting an Exclusive Opportunistic Lock (OpLock) on the file.
SMB_FLAGS_OPBATCH 0x40	If set, the client is requesting a Batch Exclusive OpLock on the file. The SMB_FLAGS_OPLOCK bit MUST be set if this bit is set.

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SMB_Parameters
...								SMB_Data (variable)
...

SMB_Parameters (5 bytes):

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WordCount								Words
...

WordCount (1 byte): This field MUST be 0x02.

Words (4 bytes): The message-specific parameters structure.

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AccessMode																SearchAttributes

AccessMode (2 bytes): A 16-bit field for encoding the requested access mode. See section 3.2.4.5.1 for a discussion on sharing modes.

Name and bitmask	Values	Meaning
AccessMode 0x0007	0	Open for reading
	1	Open for writing
	2	Open for reading and writing
	3	Open for execution
	4-7	Reserved. For compatibility with older dialects, the server MUST return STATUS_OS2_INVALID_ACCESS (ERRDOS/ERRbadaccess) if these values are requested.
0x0008	Reserved. MUST be ignored by the server.
SharingMode 0x0070	0	Compatibility mode
	1	Deny read/write/execute to others (exclusive use requested)
	2	Deny write to others
	3	Deny read/execute to others
	4	Deny nothing to others
0x0080	Reserved
ReferenceLocality 0x0700	0	Unknown locality of reference
	1	Mainly sequential access
	2	Mainly random access
	3	Random access with some locality
	4-7	Undefined
0x0800	Reserved
CacheMode 0x1000	0	Perform caching on file
	1	Do not cache the file
0x2000	Reserved
WritethroughMode 0x4000	0	Write-through mode. If this bit is set, no read ahead or write behind is allowed on this file or device. When the response is returned, data is expected to be on the disk or device.
	1
0x8000	Reserved

SearchAttributes (2 bytes): Specifies the type of file. This field is used as a search mask. Both the FileName and the SearchAttributes of a file MUST match in order for the file to be opened.<28>

SMB_Data (variable):

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ByteCount																Bytes (variable)
...

ByteCount (2 bytes): This field MUST be greater than or equal to 0x0002.

Bytes (variable): The message-specific data structure, which follows.

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BufferFormat								FileName (variable)
...

BufferFormat (1 byte): A buffer format identifier. The value of this field MUST be 0x04.

FileName (variable): A null-terminated string containing the file name of the file to be opened.