segwitv0.rs

// SPDX-License-Identifier: CC0-1.0

//! # Segwit Output Descriptors
//!
//! Implementation of Segwit Descriptors. Contains the implementation
//! of wsh, wpkh and sortedmulti inside wsh.

use core::fmt;

use bitcoin::{Address, Network, ScriptBuf, Weight};

use super::checksum::verify_checksum;
use super::SortedMultiVec;
use crate::descriptor::{write_descriptor, DefiniteDescriptorKey};
use crate::expression::{self, FromTree};
use crate::miniscript::context::{ScriptContext, ScriptContextError};
use crate::miniscript::satisfy::{Placeholder, Satisfaction, Witness};
use crate::plan::AssetProvider;
use crate::policy::{semantic, Liftable};
use crate::prelude::*;
use crate::util::varint_len;
use crate::{
    Error, ForEachKey, FromStrKey, Miniscript, MiniscriptKey, Satisfier, Segwitv0, ToPublicKey,
    TranslateErr, TranslatePk, Translator,
};
/// A Segwitv0 wsh descriptor
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct Wsh<Pk: MiniscriptKey> {
    /// underlying miniscript
    inner: WshInner<Pk>,
}

impl<Pk: MiniscriptKey> Wsh<Pk> {
    /// Get the Inner
    pub fn into_inner(self) -> WshInner<Pk> { self.inner }

    /// Get a reference to inner
    pub fn as_inner(&self) -> &WshInner<Pk> { &self.inner }

    /// Create a new wsh descriptor
    pub fn new(ms: Miniscript<Pk, Segwitv0>) -> Result<Self, Error> {
        // do the top-level checks
        Segwitv0::top_level_checks(&ms)?;
        Ok(Self { inner: WshInner::Ms(ms) })
    }

    /// Create a new sortedmulti wsh descriptor
    pub fn new_sortedmulti(k: usize, pks: Vec<Pk>) -> Result<Self, Error> {
        // The context checks will be carried out inside new function for
        // sortedMultiVec
        Ok(Self { inner: WshInner::SortedMulti(SortedMultiVec::new(k, pks)?) })
    }

    /// Get the descriptor without the checksum
    #[deprecated(since = "8.0.0", note = "use format!(\"{:#}\") instead")]
    pub fn to_string_no_checksum(&self) -> String { format!("{:#}", self) }

    /// Checks whether the descriptor is safe.
    pub fn sanity_check(&self) -> Result<(), Error> {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.sanity_check()?,
            WshInner::Ms(ref ms) => ms.sanity_check()?,
        }
        Ok(())
    }

    /// Computes an upper bound on the difference between a non-satisfied
    /// `TxIn`'s `segwit_weight` and a satisfied `TxIn`'s `segwit_weight`
    ///
    /// Assumes all ECDSA signatures are 73 bytes, including push opcode and
    /// sighash suffix.
    ///
    /// # Errors
    /// When the descriptor is impossible to safisfy (ex: sh(OP_FALSE)).
    pub fn max_weight_to_satisfy(&self) -> Result<Weight, Error> {
        let (redeem_script_size, max_sat_elems, max_sat_size) = match self.inner {
            WshInner::SortedMulti(ref smv) => (
                smv.script_size(),
                smv.max_satisfaction_witness_elements(),
                smv.max_satisfaction_size(),
            ),
            WshInner::Ms(ref ms) => (
                ms.script_size(),
                ms.max_satisfaction_witness_elements()?,
                ms.max_satisfaction_size()?,
            ),
        };
        // stack size varint difference between non-satisfied (0) and satisfied
        // `max_sat_elems` is inclusive of the "witness script" (redeem script)
        let stack_varint_diff = varint_len(max_sat_elems) - varint_len(0);

        Ok(Weight::from_wu(
            (stack_varint_diff + varint_len(redeem_script_size) + redeem_script_size + max_sat_size)
                as u64,
        ))
    }

    /// Computes an upper bound on the weight of a satisfying witness to the
    /// transaction.
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix. Includes the weight of the VarInts encoding the
    /// scriptSig and witness stack length.
    ///
    /// # Errors
    /// When the descriptor is impossible to safisfy (ex: sh(OP_FALSE)).
    #[deprecated(
        since = "10.0.0",
        note = "Use max_weight_to_satisfy instead. The method to count bytes was redesigned and the results will differ from max_weight_to_satisfy. For more details check rust-bitcoin/rust-miniscript#476."
    )]
    pub fn max_satisfaction_weight(&self) -> Result<usize, Error> {
        let (script_size, max_sat_elems, max_sat_size) = match self.inner {
            WshInner::SortedMulti(ref smv) => (
                smv.script_size(),
                smv.max_satisfaction_witness_elements(),
                smv.max_satisfaction_size(),
            ),
            WshInner::Ms(ref ms) => (
                ms.script_size(),
                ms.max_satisfaction_witness_elements()?,
                ms.max_satisfaction_size()?,
            ),
        };
        Ok(4 +  // scriptSig length byte
            varint_len(script_size) +
            script_size +
            varint_len(max_sat_elems) +
            max_sat_size)
    }
}

impl<Pk: MiniscriptKey + ToPublicKey> Wsh<Pk> {
    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn script_pubkey(&self) -> ScriptBuf { self.inner_script().to_p2wsh() }

    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn address(&self, network: Network) -> Address {
        match self.inner {
            WshInner::SortedMulti(ref smv) => Address::p2wsh(&smv.encode(), network),
            WshInner::Ms(ref ms) => Address::p2wsh(&ms.encode(), network),
        }
    }

    /// Obtains the underlying miniscript for this descriptor.
    pub fn inner_script(&self) -> ScriptBuf {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.encode(),
            WshInner::Ms(ref ms) => ms.encode(),
        }
    }

    /// Obtains the pre bip-340 signature script code for this descriptor.
    pub fn ecdsa_sighash_script_code(&self) -> ScriptBuf { self.inner_script() }

    /// Returns satisfying non-malleable witness and scriptSig with minimum
    /// weight to spend an output controlled by the given descriptor if it is
    /// possible to construct one using the `satisfier`.
    pub fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, ScriptBuf), Error>
    where
        S: Satisfier<Pk>,
    {
        let mut witness = match self.inner {
            WshInner::SortedMulti(ref smv) => smv.satisfy(satisfier)?,
            WshInner::Ms(ref ms) => ms.satisfy(satisfier)?,
        };
        let witness_script = self.inner_script();
        witness.push(witness_script.into_bytes());
        let script_sig = ScriptBuf::new();
        Ok((witness, script_sig))
    }

    /// Returns satisfying, possibly malleable, witness and scriptSig with
    /// minimum weight to spend an output controlled by the given descriptor if
    /// it is possible to construct one using the `satisfier`.
    pub fn get_satisfaction_mall<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, ScriptBuf), Error>
    where
        S: Satisfier<Pk>,
    {
        let mut witness = match self.inner {
            WshInner::SortedMulti(ref smv) => smv.satisfy(satisfier)?,
            WshInner::Ms(ref ms) => ms.satisfy_malleable(satisfier)?,
        };
        witness.push(self.inner_script().into_bytes());
        let script_sig = ScriptBuf::new();
        Ok((witness, script_sig))
    }
}

impl Wsh<DefiniteDescriptorKey> {
    /// Returns a plan if the provided assets are sufficient to produce a non-malleable satisfaction
    pub fn plan_satisfaction<P>(
        &self,
        provider: &P,
    ) -> Satisfaction<Placeholder<DefiniteDescriptorKey>>
    where
        P: AssetProvider<DefiniteDescriptorKey>,
    {
        match &self.inner {
            WshInner::SortedMulti(sm) => sm.build_template(provider),
            WshInner::Ms(ms) => ms.build_template(provider),
        }
    }

    /// Returns a plan if the provided assets are sufficient to produce a malleable satisfaction
    pub fn plan_satisfaction_mall<P>(
        &self,
        provider: &P,
    ) -> Satisfaction<Placeholder<DefiniteDescriptorKey>>
    where
        P: AssetProvider<DefiniteDescriptorKey>,
    {
        match &self.inner {
            WshInner::SortedMulti(sm) => sm.build_template(provider),
            WshInner::Ms(ms) => ms.build_template_mall(provider),
        }
    }
}

/// Wsh Inner
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub enum WshInner<Pk: MiniscriptKey> {
    /// Sorted Multi
    SortedMulti(SortedMultiVec<Pk, Segwitv0>),
    /// Wsh Miniscript
    Ms(Miniscript<Pk, Segwitv0>),
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Wsh<Pk> {
    fn lift(&self) -> Result<semantic::Policy<Pk>, Error> {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.lift(),
            WshInner::Ms(ref ms) => ms.lift(),
        }
    }
}

impl<Pk: FromStrKey> crate::expression::FromTree for Wsh<Pk> {
    fn from_tree(top: &expression::Tree) -> Result<Self, Error> {
        if top.name == "wsh" && top.args.len() == 1 {
            let top = &top.args[0];
            if top.name == "sortedmulti" {
                return Ok(Wsh { inner: WshInner::SortedMulti(SortedMultiVec::from_tree(top)?) });
            }
            let sub = Miniscript::from_tree(top)?;
            Segwitv0::top_level_checks(&sub)?;
            Ok(Wsh { inner: WshInner::Ms(sub) })
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wsh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
}

impl<Pk: MiniscriptKey> fmt::Debug for Wsh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.inner {
            WshInner::SortedMulti(ref smv) => write!(f, "wsh({:?})", smv),
            WshInner::Ms(ref ms) => write!(f, "wsh({:?})", ms),
        }
    }
}

impl<Pk: MiniscriptKey> fmt::Display for Wsh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.inner {
            WshInner::SortedMulti(ref smv) => write_descriptor!(f, "wsh({})", smv),
            WshInner::Ms(ref ms) => write_descriptor!(f, "wsh({})", ms),
        }
    }
}

impl<Pk: FromStrKey> core::str::FromStr for Wsh<Pk> {
    type Err = Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let desc_str = verify_checksum(s)?;
        let top = expression::Tree::from_str(desc_str)?;
        Wsh::<Pk>::from_tree(&top)
    }
}

impl<Pk: MiniscriptKey> ForEachKey<Pk> for Wsh<Pk> {
    fn for_each_key<'a, F: FnMut(&'a Pk) -> bool>(&'a self, pred: F) -> bool {
        match self.inner {
            WshInner::SortedMulti(ref smv) => smv.for_each_key(pred),
            WshInner::Ms(ref ms) => ms.for_each_key(pred),
        }
    }
}

impl<P, Q> TranslatePk<P, Q> for Wsh<P>
where
    P: MiniscriptKey,
    Q: MiniscriptKey,
{
    type Output = Wsh<Q>;

    fn translate_pk<T, E>(&self, t: &mut T) -> Result<Self::Output, TranslateErr<E>>
    where
        T: Translator<P, Q, E>,
    {
        let inner = match self.inner {
            WshInner::SortedMulti(ref smv) => WshInner::SortedMulti(smv.translate_pk(t)?),
            WshInner::Ms(ref ms) => WshInner::Ms(ms.translate_pk(t)?),
        };
        Ok(Wsh { inner })
    }
}

/// A bare Wpkh descriptor at top level
#[derive(Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct Wpkh<Pk: MiniscriptKey> {
    /// underlying publickey
    pk: Pk,
}

impl<Pk: MiniscriptKey> Wpkh<Pk> {
    /// Create a new Wpkh descriptor
    pub fn new(pk: Pk) -> Result<Self, ScriptContextError> {
        // do the top-level checks
        match Segwitv0::check_pk(&pk) {
            Ok(_) => Ok(Wpkh { pk }),
            Err(e) => Err(e),
        }
    }

    /// Get the inner key
    pub fn into_inner(self) -> Pk { self.pk }

    /// Get the inner key
    pub fn as_inner(&self) -> &Pk { &self.pk }

    /// Get the descriptor without the checksum
    #[deprecated(since = "8.0.0", note = "use format!(\"{:#}\") instead")]
    pub fn to_string_no_checksum(&self) -> String { format!("{:#}", self) }

    /// Checks whether the descriptor is safe.
    pub fn sanity_check(&self) -> Result<(), Error> {
        if self.pk.is_uncompressed() {
            Err(Error::ContextError(ScriptContextError::CompressedOnly(self.pk.to_string())))
        } else {
            Ok(())
        }
    }

    /// Computes an upper bound on the difference between a non-satisfied
    /// `TxIn`'s `segwit_weight` and a satisfied `TxIn`'s `segwit_weight`
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix.
    pub fn max_weight_to_satisfy(&self) -> Weight {
        // stack items: <varint(sig+sigHash)> <sig(71)+sigHash(1)> <varint(pubkey)> <pubkey>
        let stack_items_size = 73 + Segwitv0::pk_len(&self.pk);
        // stackLen varint difference between non-satisfied (0) and satisfied
        let stack_varint_diff = varint_len(2) - varint_len(0);
        Weight::from_wu((stack_varint_diff + stack_items_size) as u64)
    }

    /// Computes an upper bound on the weight of a satisfying witness to the
    /// transaction.
    ///
    /// Assumes all ec-signatures are 73 bytes, including push opcode and
    /// sighash suffix. Includes the weight of the VarInts encoding the
    /// scriptSig and witness stack length.
    #[deprecated(
        since = "10.0.0",
        note = "Use max_weight_to_satisfy instead. The method to count bytes was redesigned and the results will differ from max_weight_to_satisfy. For more details check rust-bitcoin/rust-miniscript#476."
    )]
    pub fn max_satisfaction_weight(&self) -> usize { 4 + 1 + 73 + Segwitv0::pk_len(&self.pk) }
}

impl<Pk: MiniscriptKey + ToPublicKey> Wpkh<Pk> {
    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn script_pubkey(&self) -> ScriptBuf {
        use core::convert::TryFrom;
        let pk = self.pk.to_public_key();
        let compressed = bitcoin::key::CompressedPublicKey::try_from(pk)
            .expect("wpkh descriptors have compressed keys");

        let addr = Address::p2wpkh(&compressed, Network::Bitcoin);
        addr.script_pubkey()
    }

    /// Obtains the corresponding script pubkey for this descriptor.
    pub fn address(&self, network: Network) -> Address {
        use core::convert::TryFrom;
        let pk = self.pk.to_public_key();
        let compressed = bitcoin::key::CompressedPublicKey::try_from(pk)
            .expect("Rust Miniscript types don't allow uncompressed pks in segwit descriptors");

        Address::p2wpkh(&compressed, network)
    }

    /// Obtains the underlying miniscript for this descriptor.
    pub fn inner_script(&self) -> ScriptBuf { self.script_pubkey() }

    /// Obtains the pre bip-340 signature script code for this descriptor.
    pub fn ecdsa_sighash_script_code(&self) -> ScriptBuf {
        // For SegWit outputs, it is defined by bip-0143 (quoted below) and is different from
        // the previous txo's scriptPubKey.
        // The item 5:
        //     - For P2WPKH witness program, the scriptCode is `0x1976a914{20-byte-pubkey-hash}88ac`.
        let addr = Address::p2pkh(self.pk.to_public_key(), Network::Bitcoin);
        addr.script_pubkey()
    }

    /// Returns satisfying non-malleable witness and scriptSig with minimum
    /// weight to spend an output controlled by the given descriptor if it is
    /// possible to construct one using the `satisfier`.
    pub fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, ScriptBuf), Error>
    where
        S: Satisfier<Pk>,
    {
        if let Some(sig) = satisfier.lookup_ecdsa_sig(&self.pk) {
            let sig_vec = sig.to_vec();
            let script_sig = ScriptBuf::new();
            let witness = vec![sig_vec, self.pk.to_public_key().to_bytes()];
            Ok((witness, script_sig))
        } else {
            Err(Error::MissingSig(self.pk.to_public_key()))
        }
    }

    /// Returns satisfying, possibly malleable, witness and scriptSig with
    /// minimum weight to spend an output controlled by the given descriptor if
    /// it is possible to construct one using the `satisfier`.
    pub fn get_satisfaction_mall<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, ScriptBuf), Error>
    where
        S: Satisfier<Pk>,
    {
        self.get_satisfaction(satisfier)
    }
}

impl Wpkh<DefiniteDescriptorKey> {
    /// Returns a plan if the provided assets are sufficient to produce a non-malleable satisfaction
    pub fn plan_satisfaction<P>(
        &self,
        provider: &P,
    ) -> Satisfaction<Placeholder<DefiniteDescriptorKey>>
    where
        P: AssetProvider<DefiniteDescriptorKey>,
    {
        let stack = if provider.provider_lookup_ecdsa_sig(&self.pk) {
            let stack = vec![
                Placeholder::EcdsaSigPk(self.pk.clone()),
                Placeholder::Pubkey(self.pk.clone(), Segwitv0::pk_len(&self.pk)),
            ];
            Witness::Stack(stack)
        } else {
            Witness::Unavailable
        };

        Satisfaction { stack, has_sig: true, relative_timelock: None, absolute_timelock: None }
    }

    /// Returns a plan if the provided assets are sufficient to produce a malleable satisfaction
    pub fn plan_satisfaction_mall<P>(
        &self,
        provider: &P,
    ) -> Satisfaction<Placeholder<DefiniteDescriptorKey>>
    where
        P: AssetProvider<DefiniteDescriptorKey>,
    {
        self.plan_satisfaction(provider)
    }
}

impl<Pk: MiniscriptKey> fmt::Debug for Wpkh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "wpkh({:?})", self.pk) }
}

impl<Pk: MiniscriptKey> fmt::Display for Wpkh<Pk> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write_descriptor!(f, "wpkh({})", self.pk)
    }
}

impl<Pk: MiniscriptKey> Liftable<Pk> for Wpkh<Pk> {
    fn lift(&self) -> Result<semantic::Policy<Pk>, Error> {
        Ok(semantic::Policy::Key(self.pk.clone()))
    }
}

impl<Pk: FromStrKey> crate::expression::FromTree for Wpkh<Pk> {
    fn from_tree(top: &expression::Tree) -> Result<Self, Error> {
        if top.name == "wpkh" && top.args.len() == 1 {
            Ok(Wpkh::new(expression::terminal(&top.args[0], |pk| Pk::from_str(pk))?)?)
        } else {
            Err(Error::Unexpected(format!(
                "{}({} args) while parsing wpkh descriptor",
                top.name,
                top.args.len(),
            )))
        }
    }
}

impl<Pk: FromStrKey> core::str::FromStr for Wpkh<Pk> {
    type Err = Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let desc_str = verify_checksum(s)?;
        let top = expression::Tree::from_str(desc_str)?;
        Self::from_tree(&top)
    }
}

impl<Pk: MiniscriptKey> ForEachKey<Pk> for Wpkh<Pk> {
    fn for_each_key<'a, F: FnMut(&'a Pk) -> bool>(&'a self, mut pred: F) -> bool { pred(&self.pk) }
}

impl<P, Q> TranslatePk<P, Q> for Wpkh<P>
where
    P: MiniscriptKey,
    Q: MiniscriptKey,
{
    type Output = Wpkh<Q>;

    fn translate_pk<T, E>(&self, t: &mut T) -> Result<Self::Output, TranslateErr<E>>
    where
        T: Translator<P, Q, E>,
    {
        let res = Wpkh::new(t.pk(&self.pk)?);
        match res {
            Ok(pk) => Ok(pk),
            Err(e) => Err(TranslateErr::OuterError(Error::from(e))),
        }
    }
}