Use BoringSSL/LibreSSL’s CBB and CBS

[DemiMarie]

BoringSSL and LibreSSL have CBB and CBS structures that avoid buffer overflows. OpenSSL should use something similar for all internal buffer management.

[t8m]

We have WPACKET which is basically that. We just need to use it where appropriate.

[DemiMarie]

We have WPACKET which is basically that. We just need to use it where appropriate.

I consider all parsing of untrusted data to be appropriate uses. In particular, this includes the ASN.1 encoder and decoder.

[DemiMarie]

And the punycode implementation.

[nhorman]

marking as inactive, will be closed at the completion of 3.4 dev without further input