WRITE_ANDX packet [Protocol]

CIFS Protocol

WRITE_ANDX

The WRITE_ANDX packet defines the data portion of the CIFS client request and server response packets for the command code WRITE_ANDX. The data portion follows immediately on the packet header, the first field, WordCount, being the same field as WordCount in the packet header SMB_Header.

               Field name      Displacement     Length
                                  (bytes)       (bytes)
Client_Request
               WordCount             0             1
               ANDXCommand           1             1
               ANDXReserved          2             1
               ANDXOffset            3             2
               Fid                   5             2
               Offset                7             4
               Reserved             11             4
               WriteMode            15             2
               CountBytesRemai      17             2
               DataLengthHigh       19             2
               DataLength           21             2
               DataOffset           23             2
               OffsetHigh           25             4
               ByteCount            29             2
               Pad[]                31         Variable
               Data[ DataLengt       *         Variable
Server_Response
               WordCount             0             1
               ANDXCommand           1             1
               ANDXReserved          2             1
               ANDXOffset            3             2
               Count                 5             2
               Remaining             7             2
               CountHigh             9             2
               Reserved             11             2
               ByteCount            13             2

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1

Fields

Write_AndX

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
Server_Response

Data type: union

Data portions for client request and server response.

Client_Request

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
WordCount								ANDXCommand																ANDXReserved								ANDXOffset																Fid																Offset																																Reserved																																WriteMode																CountBytesRemaining																DataLengthHigh																DataLength																DataOffset																OffsetHigh																																ByteCount																Pad[]																																Data[ DataLength ]

Data type: struct

Client request data portion.

WordCount

Data type: UCHAR

Count of parameter words.

ANDXCommand

Data type: UCHAR

Secondary command. If no secondary command exists, the value is 0xFF.

0XFF
SMB_COM_CLOSE
SMB_COM_LOCK_AND_READ
SMB_COM_READ
SMB_COM_READ_ANDX
SMB_COM_WRITE_ANDX

ANDXReserved

Data type: UCHAR

Reserved. This value must be 0 (zero).

ANDXOffset

Data type: USHORT

Offset to the WordCount location of the following command.

Fid

Data type: USHORT

File identifier or handle.

Offset

Data type: ULONG

Offset in bytes of write start position in the file.

Reserved

Data type: ULONG

Reserved. This value must be 0 (zero).

WriteMode

Data type: USHORT

Write mode bits. Set to 0 (zero) for writethrough.

CountBytesRemaining

Data type: USHORT

Count of bytes remaining to satisfy the client request.

DataLengthHigh

Data type: USHORT

If CAP_LARGE_WRITEX, the value is set to the high 16 bits of DataLength. Otherwise, the value must be 0 (zero).

DataLength

Data type: USHORT

Number of data bytes in buffer. The value is greater than 0 (zero).

DataOffset

Data type: USHORT

Offset to data bytes.

OffsetHigh

Data type: ULONG

High 32 bits of offset. This value is set if WordCount is 14.

ByteCount

Data type: USHORT

Count of data bytes.

Pad[]

Data type: UCHAR

Pad to SHORT or LONG.

Data[ DataLength ]

Data type: UCHAR

Array of data bytes to write.

Server_Response

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
WordCount								ANDXCommand								ANDXReserved								ANDXOffset																Count																Remaining																CountHigh																Reserved																ByteCount

Data type: struct

Server response data portion.

WordCount: Data type: UCHAR
Count of parameter words.
ANDXCommand: Data type: UCHAR
Secondary command. If no secondary command exists, the value is 0xFF.
ANDXReserved: Data type: UCHAR
Reserved. Must be 0 (zero).
ANDXOffset: Data type: USHORT
Offset to the WordCount location of the following command.
Count: Data type: USHORT
Count of bytes written.
Remaining: Data type: USHORT
Reserved.
CountHigh: Data type: USHORT
High 16 bits of Count.
Reserved: Data type: USHORT
Reserved.
ByteCount: Data type: USHORT
Count of data bytes. The value is 0 (zero).

Remarks

A ByteCount value of 0 (zero) transfers 0 bytes of data to the file, but does not truncate the file. To truncate a file, use a client request such as SMB_COM_WRITE.

In the client request, if the WriteMode bit0 is set and the Fid value refers to a disk file, the server response is sent after the data is on stable storage.

If the negotiated dialect is NTLM 0.12 or later, the 14-word format of this SMB may be used to access portions of files requiring offsets expressed as 64 bits. Otherwise, the OffsetHigh field must be omitted from the request.

If CAP_LARGE_WRITEX was indicated by the server in the NEGOTIATE response, the client request DataLength field is combined with DataLengthHigh to form a 32-bit value which may exceed the negotiated buffer size. In the server response, Count is combined with CountHigh.

The following error codes may be returned:

ERRDOS/ERRnoaccess
ERRDOS/ERRbadfid
ERRDOS/ERRlock
ERRDOS/ERRbadaccess
ERRSRV/ERRinvid
ERRSRV/ERRbaduid

Fields

Remarks

See Also