Data structures for per-connection security data

Also tidy up other comments.

Change-Id: I8f0ca07580090a1857e5412d069dd04acd128294
fixup NewClientSecurityObject

Check for allocation failures in both places, not just the first time.

Change-Id: Ic8fa3cf0efb2363ac1fab6137ba197c3517f9866
Include a union for security object privateData

We have client and server versions, but alias them for the first
field, which specifies which type is in use.
The union lets this aliasing be more correct by the standard.

Change-Id: I6581cbdd9ec4aed943b7361b39526727153cb5d5
Create and destroy connections

Destroy the security object on last close.

Change-Id: Iee79f072bccd202db658771cf1e5d29c0c411761
rxgk_server: check auth, get/create challenge

Using a random nonce brings in hcrypto.
We don't check the response (and the client drops it on the floor),
so nothing new yet.

Change-Id: I88905e42c31b70379aaf4a85ac642eb9b6a92ee9
Add copy_rxgkdata

A utility function to allocate and copy data from one RXGK_Data to another.

Change-Id: I13055027fa986158dbce5391f88391f5ba24755a
fixup use RXGK_Data for cprivate token

Don't use C99 variable-length arrays just to be fancy.

Change-Id: I7b6a5e410927b037e32a9d90d98296f0272610f9
The token is just data, not an array of the same

One data blob contains the token.

Change-Id: I479e097a202f96f9df4aea6c120b792d35951ba5
The fixed-length nonce is encoded straightforwardly

Change-Id: I40f17035da77fe8c64c075f5a33745a358272375
Note need to do something with epoch and cid

Change-Id: I18f8a8eaba9c4e2684ed9febed750b0f655613d8
First crack at GetResponse

Lots of memory leaks, and needs to be refactored, but doesn't
seem to crash right away.

Change-Id: Ica44ce9a656f8e79fd033621f4f601d9475cb0f3