Accuracy improvements:
1. We assumed the output was a p2wpkh, but it can be user-supplied now.
2. We assumed we always had change; remove this for wallet_select_all.
Calculation out-by-one fixes:
1. We need to add 1 byte (4 sipa) for the input count.
2. We need to add 1 byte (4 sipa) for the output count.
3. We need to add 1 byte (4 sipa) for the output script length for each output.
4. We need to add 1 byte (4 sipa) for the input script length for each input.
5. We need to add 1 byte (4 sipa) for the PUSH optcode for each P2SH input.
The results are now a slight overestimate (due to guessing 73 bytes
for signature, whereas they're 71 or 72 in practice).
Fixes: #458
Reported-by: Jonas Nick @jonasnick
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We'll re-use them a few times so having them at a central location is
nice. We also fix a bug that was unreserving UTXO entries upon free,
instead of promoting them to being spent.
This is a bit tricky: for our signing code, we don't want scriptsigs,
but to calculate the txid, we need them. For most transactions in lightning,
they're pure segwit so it doesn't matter, but funding transactions can
have P2SH-wrapped P2WPKH inputs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
built_utxos needs to calculate fees for figuring out how many utxos to
use, so fix that logic and rely on it.
We make build_utxos return a pointer array, so funding_tx can simply hand
that to permute_inputs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Unless the transaction is confirmed, the UTXOs should be released if
something happens to the peer.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
