SMB_COM_READ_ANDX MaxCount != filesize

Christopher R. Hertel crh at ubiqx.mn.org
Wed Mar 16 20:12:40 GMT 2005


Hmmm...

So if I understand this correctly, the clients (Windows clients, I
presume) are never asking for as many bytes as they could actually read.  
Is the difference consistent?  That is, for small files is MaxCount
always, say, 8 bytes less than you'd expect?

My guess is that some parameter in the initial negotiation is off by a
fixed number of bytes.  If that guess is correct, it's probably a result
of not counting soe field that un-obviously needs to be counted.  SMB
field offsets and such are sometimes a little weird that way.

Chris -)----

On Wed, Mar 16, 2005 at 02:49:35PM -0500, Sailaja Josyula wrote:
> Hi,
> 
> I have written my own SMBserver to run as a VFS.  I have question 
> regarding SMB_COM_READ_ANDX command.
> 
> The MaxCount parameter in the command SMB_COM_READ_ANDX is never set to 
> the filesize. Even though I am setting 
> the End_Of_File parameter correctly in the response to NT_CREATE_ANDX 
> command. 
> 
> In the windows SMB I see that the SMB_COM_READ_ANDX requests come with the 
> Count set to the Filesize specified
> in the NT_CREATE_ANDX command.  The MaxCount field not being set correctly 
> is causing multiple SMB_COM_READ_ANDX
> commands to be triggered with different offset and Count values, even if 
> the filesize is as small as 8 bytes.
> 
> Is there something I am missing or not setting prior to the 
> SMB_COM_READ_ANDX? How does this parameter get set in
> the SMB_COM_READ_ANDX command.
> 
> The protocol I have negotiated is NT LM 0.12. 
> 
> Thanks
> 
> Sailaja Josyula
> Websphere Portal
> IBM Software Group
> Phone: 914-784-5472 Tie Line: 863-5472 Fax: 914-784-3833
> sailaja at us.ibm.com

-- 
"Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org


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