SASL property for compression layer

Julien ÉLIE julien at
Sun Nov 1 15:17:04 EST 2015


I am currently working on implementing the NNTP COMPRESS command in the 
InternetNetNews news server.  This commands permits to start a 
compression layer (like the COMPRESS command for IMAP).

I have a question about a possible already active compression layer 
after the use of SASL authentication.  Is there a way to check whether a 
compression layer has been negotiated during SASL authentication?

With OpenSSL, we can use the SSL_get_current_compression() function to 
see whether a compression layer has been negotiated at the same time of 
the TLS encryption layer.  A similar function could be useful in Cyrus 
SASL if it does not already exist.  (Maybe current or future SASL 
mechanisms can or will negotiate a compression layer.)

Note:  it could be a property like SASL_SSF that InternetNewsNews 
already checks after SASL authentication to see whether an encryption 
layer has been negotiated.  If the value of that property is >0, the use 
of STARTTLS is disabled as an encryption layer already exists.

Julien ÉLIE

« If your dog is barking at the back door and your wife yelling at the
   frontdoor, who do you let in first?  The dog of course…  at least
   he'll shut up after you let him in! »

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