urbit/lib/btc-wallet-store.hoon
2021-05-26 18:30:13 -07:00

166 lines
4.1 KiB
Plaintext

::
::
/- *btc-wallet-store
/+ bip32, btc
=, secp:crypto
=+ ecc=secp256k1
|%
++ defaults
|%
++ max-gap 20
++ confs 6
--
::
++ from-xpub
|= [=xpub:btc scan-to=(unit scon) max-gap=(unit @ud) confs=(unit @ud)]
^- walt
:* (from-extended:bip32 (trip xpub))
(xpub-type:btc xpub)
*wach
[0 0]
%.n
(fall scan-to *scon)
(fall max-gap max-gap:defaults)
(fall confs confs:defaults)
==
:: wad: door for processing walts (wallets)
:: parameterized on a walt and it's chyg account
::
++ wad
|_ [w=walt =chyg]
++ mk-address
|= =idx
^- address:btc
=/ pubkey=@ux
%- compress-point:ecc
pub:(derive-public:(derive-public:wilt.w (@ chyg)) idx)
?: ?=(%bip84 bipt.w)
(need (encode-pubkey:bech32:btc %main pubkey))
~|("legacy addresses not supported yet " !!)
:: generates and watches the next available address
::
++ gen-address
^- (pair address:btc walt)
=/ addr (mk-address nixt-idx)
:- addr
(update-address addr [chyg nixt-idx *(set utxo:btc)])
:: insert a new address; update "nixt" free address if this one was it
::
++ update-address
|= [a=address:btc =addi]
^- walt
?> =(chyg chyg.addi)
?> =(a (mk-address idx.addi))
=? nixt.w (is-nixt addi)
new:bump-nixt
w(wach (~(put by wach.w) a addi))
::
++ is-nixt
|= =addi ^- ?
?: ?=(%0 chyg.addi)
=(idx.addi p.nixt.w)
=(idx.addi q.nixt.w)
++ nixt-idx
?:(?=(%0 chyg) p.nixt.w q.nixt.w)
:: Returns: the prior idx in the account
:: nixt with account idx bumped
:: Increments idx until an unwatched address is found
:: Crashes if max-index is passed
::
++ bump-nixt
|^ ^- [old=idx new=nixt]
:- nixt-idx
=/ new-idx=idx +(nixt-idx)
|- ?> (lte new-idx max-index)
?. (~(has by wach.w) (mk-address new-idx))
(set-nixt new-idx)
$(new-idx +(new-idx))
::
++ set-nixt
|= idx=@ ^- nixt
?:(?=(%0 chyg) [idx q.nixt.w] [p.nixt.w idx])
--
--
:: sut: door to select utxos
::
++ sut
|_ [w=walt eny=@uvJ =feyb txos=(list txo)]
++ meta-weight 10
++ output-weight 31
::
++ target-value
^- sats
%+ roll (turn txos |=(=txo value.txo))
|=([a=sats b=sats] (add a b))
::
++ base-weight
^- vbytes
%+ add meta-weight
(mul (lent txos) output-weight)
::
++ input-weight
^- vbytes
?. ?=(%bip84 bipt.w)
~|("Only bech32 wallets supported" !!)
102
::
++ total-vbytes
|= selected=(list input)
^- vbytes
%+ add base-weight
(mul input-weight (lent selected))
:: value of an input after fee
:: 0 if net is <= 0
::
++ net-value
|= val=sats ^- sats
=/ cost (mul input-weight feyb)
?: (lte val cost) 0
(sub val cost)
:: Uses naive random selection. Should switch to branch-and-bound later.
::
++ select-utxos
|^ ^- (unit =txbu)
=/ uis=(unit (list input))
%- single-random-draw
%- zing
(turn ~(val by wach.w) to-inputs)
?~(uis ~ `(inputs-to-txbu u.uis))
::
++ to-inputs
|= =addi ^- (list input)
%+ turn ~(tap in utxos.addi)
|=(=utxo:btc [utxo chyg.addi idx.addi])
++ inputs-to-txbu
|= is=(list input) ^- txbu
:* (total-vbytes is)
%+ turn is
|=(i=input [utxo.i ~ [bipt.w chyg.i idx.i]])
txos
==
--
:: single-random-draw
:: randomly choose utxos until target is hit
:: only use an input if its net-value > 0
::
++ single-random-draw
|= is=(list input)
^- (unit (list input))
=/ rng ~(. og eny)
=/ target (add target-value (mul feyb base-weight)) :: add base fees to target
=| [select=(list input) total=sats:btc]
|- ?: =(~ is) ~
=^ n rng (rads:rng (lent is))
=/ i=input (snag n is)
=/ net-val (net-value value.utxo.i)
=? select (gth net-val 0) [i select] :: select if net-value > 0
=/ new-total (add total net-val)
?: (gte new-total target) `select
%= $
is (oust [n 1] is)
total new-total
==
::
--
--