Coinbaser #569

Allow customizing what addresses are paid by generation, with failover to the standard "50 BTC to me" behaviour; also adds the "setworkaux" JSON-RPC call to add arbitrary data to the coinbase, which can be used to implement merged-mining (has safeguards against creating invalid coinbases)

The internal code changes for "setworkaux" can also be used to put "feature flags" in coinbases, to enable upgrades (like OP_EVAL) when X% of the last Y blocks advertise support (after which, they should stop advertising the flag to make room for future content).

Eligius has tested this changeset quite a bit under the 0.3.23 codebase.

The "setauxwork" JSON-RPC method has support for addition: https://bitcointalk.org/index.php?topic=46927.0

I support the principal of coinbaser however I don't understand why setworkaux is part of this patch. It would appear to have quite a different purpose and my concerns about it are outlined here: https://bitcointalk.org/index.php?topic=46927.msg559622#msg559622

It would appear to be an incomplete solution for merged mining. It does provide one of the operations necessary to make mm work but to my knowledge there's no complete solution based on this. vinced's mm patches include a complete solution but the 'setworkaux' part is not exposed. merging setworkaux with the vinced solution would seem to be best of both worlds option but since that's not what's being proposed I can't support setworkaux as a standalone patch.

The coinbaser part of this patch needs to be explained. What output is expected from the coinbaser command? In what format? It's no use pulling a patch if luke is the only one that knows how to use it.

setworkaux is part of Coinbaser because it affects the coinbase transaction. I'm not ready to declare the other (non-coinbase-related) component required for merged mining "done" until there are some actual specs for MM with which to make a complete implementation.

I agree the coinbaser output format should probably be documented. I'll see if I can get that added to this soon, unless someone else wants to pitch in. Eligius probably won't be using bitcoind much longer, FYI.

edit: This comment was originally a fairly off topic rant about merged mining in general and only slightly relevant to the patch in question. I've moved the rant to a more appropriate place:

https://bitcointalk.org/index.php?topic=47136.0

Wrote up some docs on the wiki: https://en.bitcoin.it/wiki/Coinbaser

GitHub fail. Moved to #708