Update the "send scsi command" fucntion to honour
"FirstBurstLength" so that we only send this many bytes as unsolicited data.
The wait for a train of R2T from the target to clock out additional
busrts of data until the full task data has been sent to the Target.
We should now honour, and handle the case of
ImmediateData=No
InitialR2T=No
correctly for targets that are limited on receiveing data too fast.
Update the send pdu command to trap when we need to send data to the target
but we are not allowed to send using immediate data.
For this case, send the data as a separate DATAOUT pdu instead.
Twiddle the flags and other fields to now manage that we send the data
as two separate PDUs.
This function can allocate a new pdu using a specific itt value
and specific flags instead of using the defaults of, next iff, no flags set.
This can be used when we need to allocate additional PDUs in a chain,
for commands that span across multiple PDUs and where all need to keep
the same itt value.
For example
->WRITE10 cdb
->DATAOUT
-<RESPONSE
Here the DATAOUT PDU belongs to the same task that was started by write10
so it need to use the same itt value.
Input processing used to keep all data in one single input buffer, which
makes it hard to handle nested events as well as reading directly from the
socket into the application buffer without an extra copy.
Create a new iscsi_in_pdu structure where we store the header, and any data
for the recevied pdu and store them in a proper input queue.
Change the signature for all processing functions to tahe a iscsi_in_pdu
structure for the received pdu instead of just a pointer to a buffer.
