RE: [openssl.org #3512] SSL_MODE_ENABLE_PARTIAL_WRITE does not work in DTLS

2014-09-01 Thread Salz, Rich
You can't use partial writes.

The size of your UDP packet depends on the MTU supported by everyone along the 
path.  (BTW, that's what heartbeat was created.)

I suggest you get your program working properly for your definition of what 
properly means, without DTLS.  Then add DTLS.

And have you read the paper I pointed you to?
/r$


Re: [openssl.org #3512] SSL_MODE_ENABLE_PARTIAL_WRITE does not work in DTLS

2014-09-01 Thread Iñaki Baz Castillo
2014-09-01 15:42 GMT+02:00 Salz, Rich rs...@akamai.com:
 The size of your UDP packet depends on the MTU supported by everyone along 
 the path.  (BTW, that's what heartbeat was created.)

Yes, it is understood now. But, given that DTLS provides reliability
and message order, it makes sense IMHO that SSL_write(long size) would
produce chunks of the desired size (previously set somehow). I'm not
asking for it anyhow as the common usage of DLTS for carrying
encrypted application data usually involve their own message framing
and each datagram must contain a single or multiple (but entire)
frames.



 I suggest you get your program working properly for your definition of what 
 properly means, without DTLS.  Then add DTLS.

The fact is that I need DTLS in order to establish a secure UDP
channel for SRTP keys sharing (which is done in the DTLS handshake
with the use_srtp extension). This is done and working. Sending
encrypted application data using DTLS records is a future step that I
do not need right now (I was just testing that). Anyhow I fully
understand now that the application is responsible of detecting the
MTU and writing the correct size into SSL_write().



 And have you read the paper I pointed you to?

Yes, thanks a lot.


-- 
Iñaki Baz Castillo
i...@aliax.net
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