Prune some dead quirks and document the SSL_OP_ALL ones.

Update SSL_OP_ALL to account for SSL_OP_CRYPTOPRO_TLSEXT_BUG being gone,
and update ssl3_setup_write_buffer to account for SSL_MODE_CBC_RECORD_SPLITTING
rather than the now defunct SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.

Also remove SSL_OP_TLS_BLOCK_PADDING_BUG. This is to allow for a buggy peer
which pads CBC with N bytes of value N rather than N+1 bytes of value N. This
quirk has been broken since CBC padding checks became constant-time, as
demonstrated by this attempt at a test. (Instead of just decrementing
padding_length, it needs to also keep track of a separate padding_value and not
decrement that one.)

https://boringssl-review.googlesource.com/#/c/1690/

(The quirk would also fall over anyway if the buggy client ever did a session
resumption; then the server speaks first rather than the client, and the quirk
triggered on reading the first encrypted record from the peer.)

Change-Id: I19942dc629a47832aead77a46bb50e0b0a9780b3
Reviewed-on: https://boringssl-review.googlesource.com/1694
Reviewed-by: Adam Langley <agl@google.com>
7 files changed