Currently the only source for amount_asset is the value getter on a tx output,
and we don't hand it too far around (mainly ignoring it if it isn't the
chain's main currency). Eventually we could bubble them up to the wallet, use
them to select outputs or actually support assets in the channels.
Since we don't hand them around too widely I thought it was ok for them to be
pass-by-value rather than having to allocate them and pass them around by
reference. They're just 41 bytes currently so the overhead should be ok.
Signed-off-by: Christian Decker <@cdecker>
The fundchannel plugin needs to know how to build a transaction, so we need to
tell it which chainparams to use. Also adds `chainparams` as a global, since
that seems to be the way to do things in plugins.
in order to preserve current behavior, we cap at max if specified 'all';
otherwise we fail since the amount requested is larger than the
channel max capacity
Previously, we'd fail on 'all'. `fundchannel_start` needs an amount
in order to start a funding transaction.
The way that we approach this is to first call `txprepare` with a
placeholder address and the 'all' amount; this will return the maximum
amount available. We then clamp this to the max_funding (currently
hardcoded, in the future we'd want to consult our/the peer's features) and
then use the amount on the output in the prepared transaction as the
funding amount. We then pass this amount to fundchannel_start,
after we've started it successfully we cancel the held placeholder
transaction and prepare a second transaction for the exact amount,
using the funding address that fundchannel_start passed back.
