Address labeling and coin control

[kristapsk]

I would like to suggest two features that could potentially improve on-chain privacy for more advanced users when opening channels - address labeling and coin control.

1. New additional optional "label" parameter for newaddr, that would be also displayed in listunds.
2. New additional optional "address" parameter for fundchannel, where I could specify which funds to use for channel funding. Technically, specifying txid:idx for UTXO would be better, but I think that's too confusing for users, and in case there are multiple UTXO's for that address, it's anyway always a good idea to spend them all.

Idea is that I could have funded my lightning node from various sources previously, even long time ago, but probably I would not like to mix together certain UTXO's in the same on-chain transactions. So, we need labels then to not forget from where funds come and we need coin control features to better control which UTXO's to use.

Also, change outputs. I like Wasabi Wallet's way of auto-labeling them "change of (label)".

Then there is channel closing, need to think about labelling these UTXO's too, but that's another question and the above two would be a good start IMO.

[ZmnSCPxj]

For myself, I would rather that such features remain with onchain wallets, and have a "walletless" Lightning node. I.e. when you open a channel the LN node will give an address the onchain wallet will send to in order to complete the open.

Otherwise we would need to implement every feature every onchain wallet has , in addition to the entire BOLT spec.

[wiredcheetah]

working on a hack to enable this in my own fork of c-lightning. I need to find out if channels always close to an address from dev-listaddrs. In that case, I can add extra parameter to withdraw specifying which indices/addresses/txids to badlist from input selection to make withdraw think they're not available.

[wiredcheetah]

looks like struct utxo **wallet_get_utxos in /wallet/wallet.c queries the database for unspent utxos. I don't know how to safely modify to omit certain utxos from its return value.