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// SPDX-License-Identifier: CC0-1.0
//! Provides type [`LockTime`] that implements the logic around nSequence/OP_CHECKSEQUENCEVERIFY.
//!
//! There are two types of lock time: lock-by-blockheight and lock-by-blocktime, distinguished by
//! whether bit 22 of the `u32` consensus value is set.
//!
use core::convert::TryFrom;
use core::fmt;
#[cfg(all(test, mutate))]
use mutagen::mutate;
use crate::parse::impl_parse_str_from_int_infallible;
use crate::prelude::*;
#[cfg(doc)]
use crate::relative;
/// A relative lock time value, representing either a block height or time (512 second intervals).
///
/// The `relative::LockTime` type does not have any constructors, this is by design, please use
/// `Sequence::to_relative_lock_time` to create a relative lock time.
///
/// ### Relevant BIPs
///
/// * [BIP 68 Relative lock-time using consensus-enforced sequence numbers](https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki)
/// * [BIP 112 CHECKSEQUENCEVERIFY](https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki)
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub enum LockTime {
/// A block height lock time value.
Blocks(Height),
/// A 512 second time interval value.
Time(Time),
}
impl LockTime {
/// Returns true if this [`relative::LockTime`] is satisfied by either height or time.
///
/// # Examples
///
/// ```rust
/// # use bitcoin::Sequence;
/// # use bitcoin::locktime::relative::{LockTime, Height, Time};
///
/// # let height = 100; // 100 blocks.
/// # let intervals = 70; // Approx 10 hours.
/// # let current_height = || Height::from(height + 10);
/// # let current_time = || Time::from_512_second_intervals(intervals + 10);
/// # let lock = Sequence::from_height(height).to_relative_lock_time().expect("valid height");
///
/// // Users that have chain data can get the current height and time to check against a lock.
/// let height_and_time = (current_time(), current_height()); // tuple order does not matter.
/// assert!(lock.is_satisfied_by(current_height(), current_time()));
/// ```
#[inline]
#[cfg_attr(all(test, mutate), mutate)]
pub fn is_satisfied_by(&self, h: Height, t: Time) -> bool {
if let Ok(true) = self.is_satisfied_by_height(h) {
true
} else {
matches!(self.is_satisfied_by_time(t), Ok(true))
}
}
/// Returns true if satisfaction of `other` lock time implies satisfaction of this
/// [`relative::LockTime`].
///
/// A lock time can only be satisfied by n blocks being mined or n seconds passing. If you have
/// two lock times (same unit) then the larger lock time being satisfied implies (in a
/// mathematical sense) the smaller one being satisfied.
///
/// This function is useful when checking sequence values against a lock, first one checks the
/// sequence represents a relative lock time by converting to `LockTime` then use this function
/// to see if satisfaction of the newly created lock time would imply satisfaction of `self`.
///
/// Can also be used to remove the smaller value of two `OP_CHECKSEQUENCEVERIFY` operations
/// within one branch of the script.
///
/// # Examples
///
/// ```rust
/// # use bitcoin::Sequence;
/// # use bitcoin::locktime::relative::{LockTime, Height, Time};
///
/// # let height = 100; // 100 blocks.
/// # let lock = Sequence::from_height(height).to_relative_lock_time().expect("valid height");
/// # let test_sequence = Sequence::from_height(height + 10);
///
/// let satisfied = match test_sequence.to_relative_lock_time() {
/// None => false, // Handle non-lock-time case.
/// Some(test_lock) => lock.is_implied_by(test_lock),
/// };
/// assert!(satisfied);
/// ```
#[inline]
#[cfg_attr(all(test, mutate), mutate)]
pub fn is_implied_by(&self, other: LockTime) -> bool {
use LockTime::*;
match (*self, other) {
(Blocks(this), Blocks(other)) => this.value() <= other.value(),
(Time(this), Time(other)) => this.value() <= other.value(),
_ => false, // Not the same units.
}
}
/// Returns true if this [`relative::LockTime`] is satisfied by [`Height`].
///
/// # Errors
///
/// Returns an error if this lock is not lock-by-height.
///
/// # Examples
///
/// ```rust
/// # use bitcoin::Sequence;
/// # use bitcoin::locktime::relative::{LockTime, Height, Time};
///
/// let height: u16 = 100;
/// let lock = Sequence::from_height(height).to_relative_lock_time().expect("valid height");
/// assert!(lock.is_satisfied_by_height(Height::from(height+1)).expect("a height"));
/// ```
#[inline]
#[cfg_attr(all(test, mutate), mutate)]
pub fn is_satisfied_by_height(&self, h: Height) -> Result<bool, Error> {
use LockTime::*;
match *self {
Blocks(ref height) => Ok(height.value() <= h.value()),
Time(ref time) => Err(Error::IncompatibleTime(*self, *time)),
}
}
/// Returns true if this [`relative::LockTime`] is satisfied by [`Time`].
///
/// # Errors
///
/// Returns an error if this lock is not lock-by-time.
///
/// # Examples
///
/// ```rust
/// # use bitcoin::Sequence;
/// # use bitcoin::locktime::relative::{LockTime, Height, Time};
///
/// let intervals: u16 = 70; // approx 10 hours;
/// let lock = Sequence::from_512_second_intervals(intervals).to_relative_lock_time().expect("valid time");
/// assert!(lock.is_satisfied_by_time(Time::from_512_second_intervals(intervals + 10)).expect("a time"));
/// ```
#[inline]
#[cfg_attr(all(test, mutate), mutate)]
pub fn is_satisfied_by_time(&self, t: Time) -> Result<bool, Error> {
use LockTime::*;
match *self {
Time(ref time) => Ok(time.value() <= t.value()),
Blocks(ref height) => Err(Error::IncompatibleHeight(*self, *height)),
}
}
}
impl From<Height> for LockTime {
#[inline]
fn from(h: Height) -> Self { LockTime::Blocks(h) }
}
impl From<Time> for LockTime {
#[inline]
fn from(t: Time) -> Self { LockTime::Time(t) }
}
impl fmt::Display for LockTime {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use LockTime::*;
if f.alternate() {
match *self {
Blocks(ref h) => write!(f, "block-height {}", h),
Time(ref t) => write!(f, "block-time {} (512 second intervals)", t),
}
} else {
match *self {
Blocks(ref h) => fmt::Display::fmt(h, f),
Time(ref t) => fmt::Display::fmt(t, f),
}
}
}
}
/// A relative lock time lock-by-blockheight value.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct Height(u16);
impl Height {
/// Relative block height 0, can be included in any block.
pub const ZERO: Self = Height(0);
/// The minimum relative block height (0), can be included in any block.
pub const MIN: Self = Self::ZERO;
/// The maximum relative block height.
pub const MAX: Self = Height(u16::max_value());
/// The minimum relative block height (0), can be included in any block.
///
/// This is provided for consistency with Rust 1.41.1, newer code should use [`Height::MIN`].
#[deprecated(since = "0.31.0", note = "Use Self::MIN instead")]
pub const fn min_value() -> Self { Self::MIN }
/// The maximum relative block height.
///
/// This is provided for consistency with Rust 1.41.1, newer code should use [`Height::MAX`].
#[deprecated(since = "0.31.0", note = "Use Self::MAX instead")]
pub const fn max_value() -> Self { Self::MAX }
/// Returns the inner `u16` value.
#[inline]
pub fn value(self) -> u16 { self.0 }
}
impl From<u16> for Height {
#[inline]
fn from(value: u16) -> Self { Height(value) }
}
impl_parse_str_from_int_infallible!(Height, u16, from);
impl fmt::Display for Height {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
}
/// A relative lock time lock-by-blocktime value.
///
/// For BIP 68 relative lock-by-blocktime locks, time is measure in 512 second intervals.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(crate = "actual_serde"))]
pub struct Time(u16);
impl Time {
/// Relative block time 0, can be included in any block.
pub const ZERO: Self = Time(0);
/// The minimum relative block time (0), can be included in any block.
pub const MIN: Self = Time::ZERO;
/// The maximum relative block time (33,554,432 seconds or approx 388 days).
pub const MAX: Self = Time(u16::max_value());
/// The minimum relative block time.
///
/// This is provided for consistency with Rust 1.41.1, newer code should use [`Time::MIN`].
#[deprecated(since = "0.31.0", note = "Use Self::MIN instead")]
pub const fn min_value() -> Self { Self::MIN }
/// The maximum relative block time.
///
/// This is provided for consistency with Rust 1.41.1, newer code should use [`Time::MAX`].
#[deprecated(since = "0.31.0", note = "Use Self::MAX instead")]
pub const fn max_value() -> Self { Self::MAX }
/// Create a [`Time`] using time intervals where each interval is equivalent to 512 seconds.
///
/// Encoding finer granularity of time for relative lock-times is not supported in Bitcoin.
#[inline]
pub fn from_512_second_intervals(intervals: u16) -> Self { Time(intervals) }
/// Create a [`Time`] from seconds, converting the seconds into 512 second interval with ceiling
/// division.
///
/// # Errors
///
/// Will return an error if the input cannot be encoded in 16 bits.
#[inline]
pub fn from_seconds_ceil(seconds: u32) -> Result<Self, Error> {
if let Ok(interval) = u16::try_from((seconds + 511) / 512) {
Ok(Time::from_512_second_intervals(interval))
} else {
Err(Error::IntegerOverflow(seconds))
}
}
/// Returns the inner `u16` value.
#[inline]
pub fn value(self) -> u16 { self.0 }
}
impl_parse_str_from_int_infallible!(Time, u16, from_512_second_intervals);
impl fmt::Display for Time {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
}
/// Errors related to relative lock times.
#[derive(Debug, Clone, PartialEq, Eq)]
#[non_exhaustive]
pub enum Error {
/// Input time in seconds was too large to be encoded to a 16 bit 512 second interval.
IntegerOverflow(u32),
/// Tried to satisfy a lock-by-blocktime lock using a height value.
IncompatibleHeight(LockTime, Height),
/// Tried to satisfy a lock-by-blockheight lock using a time value.
IncompatibleTime(LockTime, Time),
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use Error::*;
match *self {
IntegerOverflow(val) => write!(
f,
"{} seconds is too large to be encoded to a 16 bit 512 second interval",
val
),
IncompatibleHeight(lock, height) =>
write!(f, "tried to satisfy lock {} with height: {}", lock, height),
IncompatibleTime(lock, time) =>
write!(f, "tried to satisfy lock {} with time: {}", lock, time),
}
}
}
#[cfg(feature = "std")]
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
use Error::*;
match *self {
IntegerOverflow(_) | IncompatibleHeight(_, _) | IncompatibleTime(_, _) => None,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn satisfied_by_height() {
let height = Height::from(10);
let time = Time::from_512_second_intervals(70);
let lock = LockTime::from(height);
assert!(!lock.is_satisfied_by(Height::from(9), time));
assert!(lock.is_satisfied_by(Height::from(10), time));
assert!(lock.is_satisfied_by(Height::from(11), time));
}
#[test]
fn satisfied_by_time() {
let height = Height::from(10);
let time = Time::from_512_second_intervals(70);
let lock = LockTime::from(time);
assert!(!lock.is_satisfied_by(height, Time::from_512_second_intervals(69)));
assert!(lock.is_satisfied_by(height, Time::from_512_second_intervals(70)));
assert!(lock.is_satisfied_by(height, Time::from_512_second_intervals(71)));
}
#[test]
fn height_correctly_implies() {
let height = Height::from(10);
let lock = LockTime::from(height);
assert!(!lock.is_implied_by(LockTime::from(Height::from(9))));
assert!(lock.is_implied_by(LockTime::from(Height::from(10))));
assert!(lock.is_implied_by(LockTime::from(Height::from(11))));
}
#[test]
fn time_correctly_implies() {
let time = Time::from_512_second_intervals(70);
let lock = LockTime::from(time);
assert!(!lock.is_implied_by(LockTime::from(Time::from_512_second_intervals(69))));
assert!(lock.is_implied_by(LockTime::from(Time::from_512_second_intervals(70))));
assert!(lock.is_implied_by(LockTime::from(Time::from_512_second_intervals(71))));
}
#[test]
fn incorrect_units_do_not_imply() {
let time = Time::from_512_second_intervals(70);
let height = Height::from(10);
let lock = LockTime::from(time);
assert!(!lock.is_implied_by(LockTime::from(height)));
}
}