Large Write_Andx messages

[Michael B Allen]

On 10/29/07, Mikael Klamra <mklamra at gmail.com> wrote:
> I was asking about chained WRITE_ANDX messages.

Hi Mikael,

I played around a lot with chaining in the early days. JCIFS can
actually chain any messages together to any degree provided that it
makes sense to do so. But aside from chaining the
SMB_COM_SESSION_SETUP_ANDX with SMB_COM_TREE_CONNECT_ANDX it was all a
useless exercise as it was found that Windows servers do not support
chaining much at all. There are a few other messages that can be
chained but I have never seen more that two messages in a chain work.

However, there's a much more compelling reason not to mess around with
chaining. I follow a general rule when working with MS
implementations: Do not do anything you do not see Windows do. The
rationale is that MS is not known for third party support through
strict conformance to standards and as such your implementation may
yield inconsistent results with different server versions. Or support
for it could completely disappear in a future version. If you mimic MS
behavior precisely, you know that your implementation will work as
long as MS needs to support the implementation you are mimicking. Or,
in this particular case, ever worse you could corrupt data on the
server trying to chain or pipeline writes.

I get a WireShark capture of a Win32 or .NET test program and copy
that exactly. Anything else is unsafe.

Mike