Hi list,
A few days ago, I asked the user list about a "wrong sequence number" error
that I randomly get using SMPP
(http://www.mail-archive.com/[email protected]/msg15479.html). I have now
investigated this further and I have it tracked down to the way that
send_messages() interacts with unlocked_try_write().
On the one hand:
send_messages() only considers a return code of 0 to be an OK return code for
send_pdu() [line 1011 of smsc_smpp.c in version 1.4.3].
This return code of send_pdu() comes, via conn_write(), from
unlocked_try_write().
On the other hand:
unlocked_try_write() has three possible return codes: "Return 0 for success, 1
if there is still data left in the buffer, and -1 for errors." [lines 280-281
of conn.c in version 1.4.3].
So, according to the comment, -1 is definitely an error. But is 1 also to be
considered as an error (which is what send_messages() does)? Is it really an
error if the buffer is not yet completely flushed?
We've noticed that when bearerbox sends PDUs in quick succession, we sometimes
get unlocked_try_write() returning 1. On the SMSC side (using the sctt SMSC
simulator), we see that the PDU arrives correctly. But since send_messages()
considers this 1 as an error, it does not register the sequence number, so
bearerbox doesn't recognize the submit_sm_resp, and later resubmits the message.
=> Any thoughts? Should send_messages() be made less strict, and consider
send_pdu() >= 0 as OK, rather than send_pdu() == 0?
Regards,
Raf
