GnuTLS considered harmful

[Howard Chu <hyc@symas.com>]

The recent trouble in ITS#5361 prompted me to look into the GnuTLS code a 
little deeper. It turns out that their corresponding set_subject_alt_name() 
API only takes a char * pointer as input, without a corresponding length. As 
such, this API will only work for string-form alternative names, and will 
typically break with IP addresses and other alternatives.

Looking across more of their APIs, I see that the code makes liberal use of 
strlen and strcat, when it needs to be using counted-length data blobs 
everywhere. In short, the code is fundamentally broken; most of its external 
and internal APIs are incapable of passing binary data without mangling it. 
The code is completely unsafe for handling binary data, and yet the nature of 
TLS processing is almost entirely dependent on secure handling of binary data.

I strongly recommend that GnuTLS not be used. All of its APIs would need to be 
overhauled to correct its flaws and it's clear that the developers there are 
too naive and inexperienced to even understand that it's broken.
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/