SMB meaning of trans2 max_xmit

Urban Widmark urban at
Mon Oct 16 22:12:39 GMT 2000

How is the trans2 max_xmit value and the Max{Parameter,Data,Setup}Count
values related?

Some recent (well, more old and familiar) smbfs problems seems to have
been caused by smbfs allowing to large values for max parameters and max
data (combined, 4079+4079 vs the buffer size of 4356). Making the sum of
these <= the negotiated buffer size seems to make the servers happy.

cifs6.txt says
"MaxBufferSize is the size of the largest message which the client can
 legitimately send to the server"
and it has a similar paragraph on the client buffer size.

So I would assume that the Max.*Count values should add up to the buffer
size, or the buffer size minus the header size. The question is which.

Is message defined as the "contents" of the SMB (the parameters, data and
setup) or does it include the headers? I would assume the later from
reading the "specs" and I think that is what the smbd code does too.

However, smbclient allows for more than max_xmit bytes to be returned,
apparently without causing problems on the server side. In cli_list when
doing TRANSACT2_FINDFIRST/FINDNEXT it asks for max_xmit data + 10 bytes
param. Is this known to be correct or does it just happen to work?

Any pointers on the correct interpretation of this ...


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