Hello David,
Thank you for this explanation.
I've a good book from Eric Rescorla, but may be I jumped too quickly to
the API and didn't learn enough the concepts!
So If I correctly understand, I must try to read a MAX_RECORD_SIZE
buffer (16383 bytes) when select says "There is something ready to be
read", and I'll receive the error "SSL_WANT READ" until the complete
record will be processed by SSL. And only then, the SSL_read will return
the record and its real length.
It looks like if SSL says to the system "I've something ready" when it
begins to receive a new record. So if I read only the beginning of the
record because I use a too small buffer, I'll never be notified for the
remaining bytes.
Am I right or did I missed something.
Thanks anyway.
Best regards,
--
Francis GASCHET / NUMLOG
http://www.numlog.fr
Tel.: +33 (0) 130 791 616
Fax.: +33 (0) 130 819 286
Le 03/27/2009 06:29 AM David Schwartz a écrit :
the application read the first
1500 bytes, then "select(...)" no more indicates that something has to
be read on the fd. So the OFTP application behind the gateway doesn't
send the new "credit authorisation" because it didn't receive the
complete previous credit. And the sender waits until its inactivity
timer (more or less 2 minutes) triggers.
You cannot call 'select' to wait for data to be received if that data has
already been received. You should not ever assume that OpenSSL is waiting
for data to arrive on the socket unless it tells you this.
You have broken the fundamental rule of OpenSSL. You *assumed* that
encrypted data received over the wire would mean decrypted data received
from OpenSSL. So because you wanted decrypted data from OpenSSL, you waited
for encrypted data on the wire.
Now this is *sometimes* true. But in this case, it was not true. So your
assumption was false.
Do not ever, ever, ever assume that you know what OpenSSL needs to make
further progress. Because if you assume wrong, you are screwed. There is no
reason you should ever need to make this assumption, since OpenSSL will tell
you what it needs.
DS
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