haskoin-core-0.6.0: src/Network/Haskoin/Transaction/Builder.hs
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-|
Module : Network.Haskoin.Transaction.Builder
Copyright : No rights reserved
License : UNLICENSE
Maintainer : xenog@protonmail.com
Stability : experimental
Portability : POSIX
Code to simplify transaction creation, signing, fee calculation and coin
selection.
-}
module Network.Haskoin.Transaction.Builder
( -- * Transaction Creation & Signing
buildAddrTx
, buildTx
, buildInput
, SigInput(..)
, signTx
, signInput
, verifyStdTx
, mergeTxs
, sigKeys
, mergeTxInput
, findSigInput
, verifyStdInput
-- * Coin Selection
, Coin(..)
, chooseCoins
, chooseCoinsSink
, chooseMSCoins
, chooseMSCoinsSink
, countMulSig
, greedyAddSink
, guessTxFee
, guessMSTxFee
, guessTxSize
, guessMSSize
) where
import Control.Arrow (first)
import Control.DeepSeq (NFData, rnf)
import Control.Monad (foldM, mzero, unless, when)
import Control.Monad.Identity (runIdentity)
import Crypto.Secp256k1
import Data.Aeson (FromJSON, ToJSON,
Value (Object), object,
parseJSON, toJSON, (.:),
(.:?), (.=))
import qualified Data.ByteString as B
import Data.Conduit (ConduitT, Void, await,
runConduit, (.|))
import Data.Conduit.List (sourceList)
import Data.List (find, nub)
import Data.Maybe (catMaybes, fromJust,
fromMaybe, isJust,
mapMaybe, maybeToList)
import Data.Serialize (encode)
import Data.String.Conversions (cs)
import Data.Text (Text)
import Data.Word (Word64)
import Network.Haskoin.Address
import Network.Haskoin.Constants
import Network.Haskoin.Crypto.Signature
import Network.Haskoin.Keys.Common
import Network.Haskoin.Network.Common
import Network.Haskoin.Script
import Network.Haskoin.Transaction.Common
import Network.Haskoin.Util
-- | Any type can be used as a Coin if it can provide a value in Satoshi.
-- The value is used in coin selection algorithms.
class Coin c where
coinValue :: c -> Word64
-- | Coin selection algorithm for normal (non-multisig) transactions. This
-- function returns the selected coins together with the amount of change to
-- send back to yourself, taking the fee into account.
chooseCoins :: Coin c
=> Word64 -- ^ value to send
-> Word64 -- ^ fee per byte
-> Int -- ^ number of outputs (including change)
-> Bool -- ^ try to find better solutions
-> [c] -- ^ list of ordered coins to choose from
-> Either String ([c], Word64)
-- ^ coin selection and change
chooseCoins target fee nOut continue coins =
runIdentity . runConduit $
sourceList coins .| chooseCoinsSink target fee nOut continue
-- | Coin selection algorithm for normal (non-multisig) transactions. This
-- function returns the selected coins together with the amount of change to
-- send back to yourself, taking the fee into account. This version uses a Sink
-- for conduit-based coin selection.
chooseCoinsSink :: (Monad m, Coin c)
=> Word64 -- ^ value to send
-> Word64 -- ^ fee per byte
-> Int -- ^ number of outputs (including change)
-> Bool -- ^ try to find better solution
-> ConduitT c Void m (Either String ([c], Word64))
-- ^ coin selection and change
chooseCoinsSink target fee nOut continue
| target > 0 =
maybeToEither err <$>
greedyAddSink target (guessTxFee fee nOut) continue
| otherwise = return $ Left "chooseCoins: Target must be > 0"
where
err = "chooseCoins: No solution found"
-- | Coin selection algorithm for multisig transactions. This function returns
-- the selected coins together with the amount of change to send back to
-- yourself, taking the fee into account. This function assumes all the coins
-- are script hash outputs that send funds to a multisignature address.
chooseMSCoins :: Coin c
=> Word64 -- ^ value to send
-> Word64 -- ^ fee per byte
-> (Int, Int) -- ^ m of n multisig
-> Int -- ^ number of outputs (including change)
-> Bool -- ^ try to find better solution
-> [c]
-> Either String ([c], Word64)
-- ^ coin selection change amount
chooseMSCoins target fee ms nOut continue coins =
runIdentity . runConduit $
sourceList coins .| chooseMSCoinsSink target fee ms nOut continue
-- | Coin selection algorithm for multisig transactions. This function returns
-- the selected coins together with the amount of change to send back to
-- yourself, taking the fee into account. This function assumes all the coins
-- are script hash outputs that send funds to a multisignature address. This
-- version uses a Sink if you need conduit-based coin selection.
chooseMSCoinsSink :: (Monad m, Coin c)
=> Word64 -- ^ value to send
-> Word64 -- ^ fee per byte
-> (Int, Int) -- ^ m of n multisig
-> Int -- ^ number of outputs (including change)
-> Bool -- ^ try to find better solution
-> ConduitT c Void m (Either String ([c], Word64))
-- ^ coin selection and change
chooseMSCoinsSink target fee ms nOut continue
| target > 0 =
maybeToEither err <$>
greedyAddSink target (guessMSTxFee fee ms nOut) continue
| otherwise = return $ Left "chooseMSCoins: Target must be > 0"
where
err = "chooseMSCoins: No solution found"
-- | Select coins greedily by starting from an empty solution. If the 'continue'
-- flag is set, the algorithm will try to find a better solution in the stream
-- after a solution is found. If the next solution found is not strictly better
-- than the previously found solution, the algorithm stops and returns the
-- previous solution. If the continue flag is not set, the algorithm will return
-- the first solution it finds in the stream.
greedyAddSink :: (Monad m, Coin c)
=> Word64 -- ^ value to send
-> (Int -> Word64) -- ^ coin count to fee function
-> Bool -- ^ try to find better solutions
-> ConduitT c Void m (Maybe ([c], Word64))
-- ^ coin selection and change
greedyAddSink target guessFee continue =
go [] 0 [] 0
where
-- The goal is the value we must reach (including the fee) for a certain
-- amount of selected coins.
goal c = target + guessFee c
go acc aTot ps pTot = await >>= \case
-- A coin is available in the stream
Just coin -> do
let val = coinValue coin
-- We have reached the goal using this coin
if val + aTot >= goal (length acc + 1)
-- If we want to continue searching for better solutions
then if continue
-- This solution is the first one or
-- This solution is better than the previous one
then if pTot == 0 || val + aTot < pTot
-- Continue searching for better solutions in the stream
then go [] 0 (coin:acc) (val + aTot)
-- Otherwise, we stop here and return the previous
-- solution
else return $ Just (ps, pTot - goal (length ps))
-- Otherwise, return this solution
else return $
Just (coin : acc, val + aTot - goal (length acc + 1))
-- We have not yet reached the goal. Add the coin to the
-- accumulator
else go (coin:acc) (val + aTot) ps pTot
-- We reached the end of the stream
Nothing ->
return $ if null ps
-- If no solution was found, return Nothing
then Nothing
-- If we have a solution, return it
else Just (ps, pTot - goal (length ps))
-- | Estimate tranasction fee to pay based on transaction size estimation.
guessTxFee :: Word64 -> Int -> Int -> Word64
guessTxFee byteFee nOut nIn =
byteFee * fromIntegral (guessTxSize nIn [] nOut 0)
-- | Same as 'guessTxFee' but for multisig transactions.
guessMSTxFee :: Word64 -> (Int, Int) -> Int -> Int -> Word64
guessMSTxFee byteFee ms nOut nIn =
byteFee * fromIntegral (guessTxSize 0 (replicate nIn ms) nOut 0)
-- | Computes an upper bound on the size of a transaction based on some known
-- properties of the transaction.
guessTxSize :: Int -- ^ number of regular transaction inputs
-> [(Int,Int)] -- ^ multisig m of n for each input
-> Int -- ^ number of P2PKH outputs
-> Int -- ^ number of P2SH outputs
-> Int -- ^ upper bound on transaction size
guessTxSize pki msi pkout msout =
8 + inpLen + inp + outLen + out
where
inpLen = B.length $ encode $ VarInt $ fromIntegral $ length msi + pki
outLen = B.length $ encode $ VarInt $ fromIntegral $ pkout + msout
inp = pki * 148 + sum (map guessMSSize msi)
-- (20: hash160) + (5: opcodes) +
-- (1: script len) + (8: Word64)
out =
pkout * 34 +
-- (20: hash160) + (3: opcodes) +
-- (1: script len) + (8: Word64)
msout * 32
-- | Size of a multisig P2SH input.
guessMSSize :: (Int,Int) -> Int
guessMSSize (m, n)
-- OutPoint (36) + Sequence (4) + Script
= 40 + fromIntegral (B.length $ encode $ VarInt $ fromIntegral scp) + scp
-- OP_M + n*PubKey + OP_N + OP_CHECKMULTISIG
where
rdm =
fromIntegral $
B.length $ encode $ opPushData $ B.replicate (n * 34 + 3) 0
-- Redeem + m*sig + OP_0
scp = rdm + m * 73 + 1
{- Build a new Tx -}
-- | Build a transaction by providing a list of outpoints as inputs
-- and a list of recipient addresses and amounts as outputs.
buildAddrTx :: Network -> [OutPoint] -> [(Text, Word64)] -> Either String Tx
buildAddrTx net xs ys = buildTx xs =<< mapM f ys
where
f (s, v) =
maybe (Left ("buildAddrTx: Invalid address " ++ cs s)) Right $ do
a <- stringToAddr net s
let o = addressToOutput a
return (o, v)
-- | Build a transaction by providing a list of outpoints as inputs
-- and a list of 'ScriptOutput' and amounts as outputs.
buildTx :: [OutPoint] -> [(ScriptOutput, Word64)] -> Either String Tx
buildTx xs ys =
mapM fo ys >>= \os -> return $ Tx 1 (map fi xs) os [] 0
where
fi outPoint = TxIn outPoint B.empty maxBound
fo (o, v)
| v <= 2100000000000000 = return $ TxOut v $ encodeOutputBS o
| otherwise =
Left $ "buildTx: Invalid amount " ++ show v
-- | Data type used to specify the signing parameters of a transaction input.
-- To sign an input, the previous output script, outpoint and sighash are
-- required. When signing a pay to script hash output, an additional redeem
-- script is required.
data SigInput = SigInput
{ sigInputScript :: !ScriptOutput -- ^ output script to spend
, sigInputValue :: !Word64 -- ^ output script value
, sigInputOP :: !OutPoint -- ^ outpoint to spend
, sigInputSH :: !SigHash -- ^ signature type
, sigInputRedeem :: !(Maybe RedeemScript) -- ^ sedeem script
} deriving (Eq, Show)
instance NFData SigInput where
rnf (SigInput o v p h b) =
rnf o `seq` rnf v `seq` rnf p `seq` rnf h `seq` rnf b
instance ToJSON SigInput where
toJSON (SigInput so val op sh rdm) = object $
[ "pkscript" .= so
, "value" .= val
, "outpoint" .= op
, "sighash" .= sh
] ++ [ "redeem" .= r | r <- maybeToList rdm ]
instance FromJSON SigInput where
parseJSON (Object o) = do
so <- o .: "pkscript"
val <- o .: "value"
op <- o .: "outpoint"
sh <- o .: "sighash"
rdm <- o .:? "redeem"
return $ SigInput so val op sh rdm
parseJSON _ = mzero
-- | Sign a transaction by providing the 'SigInput' signing parametres and a
-- list of private keys. The signature is computed deterministically as defined
-- in RFC-6979.
signTx :: Network
-> Tx -- ^ transaction to sign
-> [SigInput] -- ^ signing parameters
-> [SecKey] -- ^ private keys to sign with
-> Either String Tx -- ^ signed transaction
signTx net otx sigis allKeys
| null ti = Left "signTx: Transaction has no inputs"
| otherwise = foldM go otx $ findSigInput sigis ti
where
ti = txIn otx
go tx (sigi@(SigInput so _ _ _ rdmM), i) = do
keys <- sigKeys net so rdmM allKeys
foldM (\t k -> signInput net t i sigi k) tx keys
-- | Sign a single input in a transaction deterministically (RFC-6979).
signInput :: Network -> Tx -> Int -> SigInput -> SecKeyI -> Either String Tx
signInput net tx i (SigInput so val _ sh rdmM) key = do
let sig = TxSignature (signHash (secKeyData key) m) sh
si <- buildInput net tx i so val rdmM sig $ derivePubKeyI key
let ins = updateIndex i (txIn tx) (f si)
return $ Tx (txVersion tx) ins (txOut tx) [] (txLockTime tx)
where
f si x = x {scriptInput = encodeInputBS si}
m = txSigHash net tx (encodeOutput $ fromMaybe so rdmM) val i sh
-- | Order the 'SigInput' with respect to the transaction inputs. This allows
-- the user to provide the 'SigInput' in any order. Users can also provide only
-- a partial set of 'SigInput' entries.
findSigInput :: [SigInput] -> [TxIn] -> [(SigInput, Int)]
findSigInput si ti =
mapMaybe g $ zip (matchTemplate si ti f) [0..]
where
f s txin = sigInputOP s == prevOutput txin
g (Just s, i) = Just (s,i)
g (Nothing, _) = Nothing
-- | Find from the list of provided private keys which one is required to sign
-- the 'ScriptOutput'.
sigKeys ::
Network
-> ScriptOutput
-> Maybe RedeemScript
-> [SecKey]
-> Either String [SecKeyI]
sigKeys net so rdmM keys =
case (so, rdmM) of
(PayPK p, Nothing) ->
return . map fst . maybeToList $ find ((== p) . snd) zipKeys
(PayPKHash h, Nothing) ->
return . map fst . maybeToList $
find ((== h) . getAddrHash160 . pubKeyAddr net . snd) zipKeys
(PayMulSig ps r, Nothing) ->
return $ map fst $ take r $ filter ((`elem` ps) . snd) zipKeys
(PayScriptHash _, Just rdm) -> sigKeys net rdm Nothing keys
_ -> Left "sigKeys: Could not decode output script"
where
zipKeys =
[ (prv, pub)
| k <- keys
, t <- [True, False]
, let prv = wrapSecKey t k
, let pub = derivePubKeyI prv
]
-- | Construct an input for a transaction given a signature, public key and data
-- about the previous output.
buildInput ::
Network
-> Tx -- ^ transaction where input will be added
-> Int -- ^ input index where signature will go
-> ScriptOutput -- ^ output script being spent
-> Word64 -- ^ amount of previous output
-> Maybe RedeemScript -- ^ redeem script if pay-to-script-hash
-> TxSignature
-> PubKeyI
-> Either String ScriptInput
buildInput net tx i so val rdmM sig pub = do
when (i >= length (txIn tx)) $ Left "buildInput: Invalid input index"
case (so, rdmM) of
(PayPK _, Nothing) -> return $ RegularInput $ SpendPK sig
(PayPKHash _, Nothing) -> return $ RegularInput $ SpendPKHash sig pub
(PayMulSig msPubs r, Nothing) -> do
let mSigs = take r $ catMaybes $ matchTemplate allSigs msPubs f
return $ RegularInput $ SpendMulSig mSigs
(PayScriptHash _, Just rdm) -> do
inp <- buildInput net tx i rdm val Nothing sig pub
return $ ScriptHashInput (getRegularInput inp) rdm
_ -> Left "buildInput: Invalid output/redeem script combination"
where
scp = scriptInput $ txIn tx !! i
allSigs =
nub $
sig :
case decodeInputBS net scp of
Right (ScriptHashInput (SpendMulSig xs) _) -> xs
Right (RegularInput (SpendMulSig xs)) -> xs
_ -> []
out = encodeOutput so
f (TxSignature x sh) p =
verifyHashSig (txSigHash net tx out val i sh) x (pubKeyPoint p)
f TxSignatureEmpty _ = False
{- Merge multisig transactions -}
-- | Merge partially-signed multisig transactions.
mergeTxs :: Network -> [Tx] -> [(ScriptOutput, Word64, OutPoint)] -> Either String Tx
mergeTxs net txs os
| null txs = error "Transaction list is empty"
| length (nub emptyTxs) /= 1 = Left "Transactions do not match"
| length txs == 1 = return $ head txs
| otherwise = foldM (mergeTxInput net txs) (head emptyTxs) outs
where
zipOp = zip (matchTemplate os (txIn $ head txs) f) [0..]
outs = map (first $ (\(o,v,_) -> (o,v)) . fromJust) $ filter (isJust . fst) zipOp
f (_, _, o) txin = o == prevOutput txin
emptyTxs = map (\tx -> foldl clearInput tx outs) txs
ins is i = updateIndex i is (\ti -> ti{ scriptInput = B.empty })
clearInput tx (_, i) =
Tx (txVersion tx) (ins (txIn tx) i) (txOut tx) [] (txLockTime tx)
-- | Merge input from partially-signed multisig transactions.
mergeTxInput ::
Network
-> [Tx]
-> Tx
-> ((ScriptOutput, Word64), Int)
-> Either String Tx
mergeTxInput net txs tx ((so, val), i)
-- Ignore transactions with empty inputs
= do
let ins = map (scriptInput . (!! i) . txIn) txs
sigRes <- mapM extractSigs $ filter (not . B.null) ins
let rdm = snd $ head sigRes
unless (all (== rdm) $ map snd sigRes) $ Left "Redeem scripts do not match"
si <- encodeInputBS <$> go (nub $ concatMap fst sigRes) so rdm
let ins' = updateIndex i (txIn tx) (\ti -> ti {scriptInput = si})
return $ Tx (txVersion tx) ins' (txOut tx) [] (txLockTime tx)
where
go allSigs out rdmM =
case out of
PayMulSig msPubs r ->
let sigs =
take r $
catMaybes $ matchTemplate allSigs msPubs $ f out
in return $ RegularInput $ SpendMulSig sigs
PayScriptHash _ ->
case rdmM of
Just rdm -> do
si <- go allSigs rdm Nothing
return $ ScriptHashInput (getRegularInput si) rdm
_ -> Left "Invalid output script type"
_ -> Left "Invalid output script type"
extractSigs si =
case decodeInputBS net si of
Right (RegularInput (SpendMulSig sigs)) -> Right (sigs, Nothing)
Right (ScriptHashInput (SpendMulSig sigs) rdm) ->
Right (sigs, Just rdm)
_ -> Left "Invalid script input type"
f out (TxSignature x sh) p =
verifyHashSig
(txSigHash net tx (encodeOutput out) val i sh)
x
(pubKeyPoint p)
f _ TxSignatureEmpty _ = False
{- Tx verification -}
-- | Verify if a transaction is valid and all of its inputs are standard.
verifyStdTx :: Network -> Tx -> [(ScriptOutput, Word64, OutPoint)] -> Bool
verifyStdTx net tx xs =
not (null (txIn tx)) && all go (zip (matchTemplate xs (txIn tx) f) [0 ..])
where
f (_, _, o) txin = o == prevOutput txin
go (Just (so, val, _), i) = verifyStdInput net tx i so val
go _ = False
-- | Verify if a transaction input is valid and standard.
verifyStdInput :: Network -> Tx -> Int -> ScriptOutput -> Word64 -> Bool
verifyStdInput net tx i = go (scriptInput $ txIn tx !! i)
where
dec = decodeInputBS net
go inp so val =
case dec inp of
Right (RegularInput (SpendPK (TxSignature sig sh))) ->
case so of
PayPK pub ->
verifyHashSig
(txSigHash net tx out val i sh)
sig
(pubKeyPoint pub)
_ -> False
Right (RegularInput (SpendPKHash (TxSignature sig sh) pub)) ->
case so of
PayPKHash h ->
pubKeyAddr net pub == p2pkhAddr net h &&
verifyHashSig
(txSigHash net tx out val i sh)
sig
(pubKeyPoint pub)
_ -> False
Right (RegularInput (SpendMulSig sigs)) ->
case so of
PayMulSig pubs r ->
countMulSig net tx out val i (map pubKeyPoint pubs) sigs ==
r
_ -> False
Right (ScriptHashInput si rdm) ->
case so of
PayScriptHash h ->
payToScriptAddress net rdm == p2shAddr net h &&
go (encodeInputBS $ RegularInput si) rdm val
_ -> False
_ -> False
where
out = encodeOutput so
-- | Count the number of valid signatures for a multi-signature transaction.
countMulSig ::
Network
-> Tx
-> Script
-> Word64
-> Int
-> [PubKey]
-> [TxSignature]
-> Int
countMulSig _ _ _ _ _ [] _ = 0
countMulSig _ _ _ _ _ _ [] = 0
countMulSig net tx out val i (_:pubs) (TxSignatureEmpty:rest) =
countMulSig net tx out val i pubs rest
countMulSig net tx out val i (pub:pubs) sigs@(TxSignature sig sh:rest)
| verifyHashSig (txSigHash net tx out val i sh) sig pub =
1 + countMulSig net tx out val i pubs rest
| otherwise = countMulSig net tx out val i pubs sigs