bitcoin_units/locktime/
absolute.rs

1// SPDX-License-Identifier: CC0-1.0
2
3//! Provides [`Height`] and [`Time`] types used by the `rust-bitcoin` `absolute::LockTime` type.
4
5#[cfg(feature = "alloc")]
6use alloc::{boxed::Box, string::String};
7use core::fmt;
8
9use internals::write_err;
10
11#[cfg(feature = "alloc")]
12use crate::parse;
13use crate::parse::ParseIntError;
14
15/// The Threshold for deciding whether a lock time value is a height or a time (see [Bitcoin Core]).
16///
17/// `LockTime` values _below_ the threshold are interpreted as block heights, values _above_ (or
18/// equal to) the threshold are interpreted as block times (UNIX timestamp, seconds since epoch).
19///
20/// Bitcoin is able to safely use this value because a block height greater than 500,000,000 would
21/// never occur because it would represent a height in approximately 9500 years. Conversely, block
22/// times under 500,000,000 will never happen because they would represent times before 1986 which
23/// are, for obvious reasons, not useful within the Bitcoin network.
24///
25/// [Bitcoin Core]: https://github.com/bitcoin/bitcoin/blob/9ccaee1d5e2e4b79b0a7c29aadb41b97e4741332/src/script/script.h#L39
26pub const LOCK_TIME_THRESHOLD: u32 = 500_000_000;
27
28/// An absolute block height, guaranteed to always contain a valid height value.
29#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
30pub struct Height(u32);
31
32impl Height {
33    /// Absolute block height 0, the genesis block.
34    pub const ZERO: Self = Height(0);
35
36    /// The minimum absolute block height (0), the genesis block.
37    pub const MIN: Self = Self::ZERO;
38
39    /// The maximum absolute block height.
40    pub const MAX: Self = Height(LOCK_TIME_THRESHOLD - 1);
41
42    /// Creates a [`Height`] from a hex string.
43    ///
44    /// The input string may or may not contain a typical hex prefix e.g., `0x`.
45    pub fn from_hex(s: &str) -> Result<Self, ParseHeightError> {
46        parse_hex(s, Self::from_consensus)
47    }
48
49    /// Constructs a new block height.
50    ///
51    /// # Errors
52    ///
53    /// If `n` does not represent a valid block height value.
54    ///
55    /// # Examples
56    ///
57    /// ```rust
58    /// use bitcoin_units::locktime::absolute::Height;
59    ///
60    /// let h: u32 = 741521;
61    /// let height = Height::from_consensus(h).expect("invalid height value");
62    /// assert_eq!(height.to_consensus_u32(), h);
63    /// ```
64    #[inline]
65    pub const fn from_consensus(n: u32) -> Result<Height, ConversionError> {
66        if is_block_height(n) {
67            Ok(Self(n))
68        } else {
69            Err(ConversionError::invalid_height(n))
70        }
71    }
72
73    /// Converts this [`Height`] to its inner `u32` value.
74    #[inline]
75    pub const fn to_consensus_u32(self) -> u32 { self.0 }
76}
77
78impl fmt::Display for Height {
79    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
80}
81
82crate::impl_parse_str!(Height, ParseHeightError, parser(Height::from_consensus));
83
84/// Error returned when parsing block height fails.
85#[derive(Debug, Clone, Eq, PartialEq)]
86pub struct ParseHeightError(ParseError);
87
88impl fmt::Display for ParseHeightError {
89    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
90        self.0.display(f, "block height", 0, LOCK_TIME_THRESHOLD - 1)
91    }
92}
93
94#[cfg(feature = "std")]
95impl std::error::Error for ParseHeightError {
96    // To be consistent with `write_err` we need to **not** return source in case of overflow
97    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { self.0.source() }
98}
99
100impl From<ParseError> for ParseHeightError {
101    fn from(value: ParseError) -> Self { Self(value) }
102}
103
104#[cfg(feature = "serde")]
105impl<'de> serde::Deserialize<'de> for Height {
106    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
107    where
108        D: serde::Deserializer<'de>,
109    {
110        let u = u32::deserialize(deserializer)?;
111        Ok(Height::from_consensus(u).map_err(serde::de::Error::custom)?)
112    }
113}
114
115#[cfg(feature = "serde")]
116impl serde::Serialize for Height {
117    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
118    where
119        S: serde::Serializer,
120    {
121        self.to_consensus_u32().serialize(serializer)
122    }
123}
124
125/// A UNIX timestamp, seconds since epoch, guaranteed to always contain a valid time value.
126///
127/// Note that there is no manipulation of the inner value during construction or when using
128/// `to_consensus_u32()`. Said another way, `Time(x)` means 'x seconds since epoch' _not_ '(x -
129/// threshold) seconds since epoch'.
130#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
131pub struct Time(u32);
132
133impl Time {
134    /// The minimum absolute block time (Tue Nov 05 1985 00:53:20 GMT+0000).
135    pub const MIN: Self = Time(LOCK_TIME_THRESHOLD);
136
137    /// The maximum absolute block time (Sun Feb 07 2106 06:28:15 GMT+0000).
138    pub const MAX: Self = Time(u32::MAX);
139
140    /// Creates a [`Time`] from a hex string.
141    ///
142    /// The input string may or may not contain a typical hex prefix e.g., `0x`.
143    pub fn from_hex(s: &str) -> Result<Self, ParseTimeError> { parse_hex(s, Self::from_consensus) }
144
145    /// Constructs a new block time.
146    ///
147    /// # Errors
148    ///
149    /// If `n` does not encode a valid UNIX time stamp.
150    ///
151    /// # Examples
152    ///
153    /// ```rust
154    /// use bitcoin_units::locktime::absolute::Time;
155    ///
156    /// let t: u32 = 1653195600; // May 22nd, 5am UTC.
157    /// let time = Time::from_consensus(t).expect("invalid time value");
158    /// assert_eq!(time.to_consensus_u32(), t);
159    /// ```
160    #[inline]
161    pub const fn from_consensus(n: u32) -> Result<Time, ConversionError> {
162        if is_block_time(n) {
163            Ok(Self(n))
164        } else {
165            Err(ConversionError::invalid_time(n))
166        }
167    }
168
169    /// Converts this [`Time`] to its inner `u32` value.
170    #[inline]
171    pub const fn to_consensus_u32(self) -> u32 { self.0 }
172}
173
174impl fmt::Display for Time {
175    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
176}
177
178crate::impl_parse_str!(Time, ParseTimeError, parser(Time::from_consensus));
179
180#[cfg(feature = "serde")]
181impl<'de> serde::Deserialize<'de> for Time {
182    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
183    where
184        D: serde::Deserializer<'de>,
185    {
186        let u = u32::deserialize(deserializer)?;
187        Ok(Time::from_consensus(u).map_err(serde::de::Error::custom)?)
188    }
189}
190
191#[cfg(feature = "serde")]
192impl serde::Serialize for Time {
193    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
194    where
195        S: serde::Serializer,
196    {
197        self.to_consensus_u32().serialize(serializer)
198    }
199}
200
201/// Error returned when parsing block time fails.
202#[derive(Debug, Clone, Eq, PartialEq)]
203pub struct ParseTimeError(ParseError);
204
205impl fmt::Display for ParseTimeError {
206    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
207        self.0.display(f, "block height", LOCK_TIME_THRESHOLD, u32::MAX)
208    }
209}
210
211#[cfg(feature = "std")]
212impl std::error::Error for ParseTimeError {
213    // To be consistent with `write_err` we need to **not** return source in case of overflow
214    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { self.0.source() }
215}
216
217impl From<ParseError> for ParseTimeError {
218    fn from(value: ParseError) -> Self { Self(value) }
219}
220
221fn parser<T, E, S, F>(f: F) -> impl FnOnce(S) -> Result<T, E>
222where
223    E: From<ParseError>,
224    S: AsRef<str> + Into<String>,
225    F: FnOnce(u32) -> Result<T, ConversionError>,
226{
227    move |s| {
228        let n = s.as_ref().parse::<i64>().map_err(ParseError::invalid_int(s))?;
229        let n = u32::try_from(n).map_err(|_| ParseError::Conversion(n))?;
230        f(n).map_err(ParseError::from).map_err(Into::into)
231    }
232}
233
234fn parse_hex<T, E, S, F>(s: S, f: F) -> Result<T, E>
235where
236    E: From<ParseError>,
237    S: AsRef<str> + Into<String>,
238    F: FnOnce(u32) -> Result<T, ConversionError>,
239{
240    let n = i64::from_str_radix(parse::hex_remove_optional_prefix(s.as_ref()), 16)
241        .map_err(ParseError::invalid_int(s))?;
242    let n = u32::try_from(n).map_err(|_| ParseError::Conversion(n))?;
243    f(n).map_err(ParseError::from).map_err(Into::into)
244}
245
246/// Returns true if `n` is a block height i.e., less than 500,000,000.
247pub const fn is_block_height(n: u32) -> bool { n < LOCK_TIME_THRESHOLD }
248
249/// Returns true if `n` is a UNIX timestamp i.e., greater than or equal to 500,000,000.
250pub const fn is_block_time(n: u32) -> bool { n >= LOCK_TIME_THRESHOLD }
251
252/// An error that occurs when converting a `u32` to a lock time variant.
253#[derive(Debug, Clone, PartialEq, Eq)]
254#[non_exhaustive]
255pub struct ConversionError {
256    /// The expected timelock unit, height (blocks) or time (seconds).
257    unit: LockTimeUnit,
258    /// The invalid input value.
259    input: u32,
260}
261
262impl ConversionError {
263    /// Constructs a `ConversionError` from an invalid `n` when expecting a height value.
264    const fn invalid_height(n: u32) -> Self { Self { unit: LockTimeUnit::Blocks, input: n } }
265
266    /// Constructs a `ConversionError` from an invalid `n` when expecting a time value.
267    const fn invalid_time(n: u32) -> Self { Self { unit: LockTimeUnit::Seconds, input: n } }
268}
269
270impl fmt::Display for ConversionError {
271    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
272        write!(f, "invalid lock time value {}, {}", self.input, self.unit)
273    }
274}
275
276#[cfg(feature = "std")]
277impl std::error::Error for ConversionError {
278    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { None }
279}
280
281/// Describes the two types of locking, lock-by-blockheight and lock-by-blocktime.
282#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
283enum LockTimeUnit {
284    /// Lock by blockheight.
285    Blocks,
286    /// Lock by blocktime.
287    Seconds,
288}
289
290impl fmt::Display for LockTimeUnit {
291    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
292        use LockTimeUnit::*;
293
294        match *self {
295            Blocks => write!(f, "expected lock-by-blockheight (must be < {})", LOCK_TIME_THRESHOLD),
296            Seconds => write!(f, "expected lock-by-blocktime (must be >= {})", LOCK_TIME_THRESHOLD),
297        }
298    }
299}
300
301/// Internal - common representation for height and time.
302#[derive(Debug, Clone, Eq, PartialEq)]
303enum ParseError {
304    InvalidInteger { source: core::num::ParseIntError, input: String },
305    // unit implied by outer type
306    // we use i64 to have nicer messages for negative values
307    Conversion(i64),
308}
309
310internals::impl_from_infallible!(ParseError);
311
312impl ParseError {
313    fn invalid_int<S: Into<String>>(s: S) -> impl FnOnce(core::num::ParseIntError) -> Self {
314        move |source| Self::InvalidInteger { source, input: s.into() }
315    }
316
317    fn display(
318        &self,
319        f: &mut fmt::Formatter<'_>,
320        subject: &str,
321        lower_bound: u32,
322        upper_bound: u32,
323    ) -> fmt::Result {
324        use core::num::IntErrorKind;
325
326        use ParseError::*;
327
328        match self {
329            InvalidInteger { source, input } if *source.kind() == IntErrorKind::PosOverflow => {
330                write!(f, "{} {} is above limit {}", subject, input, upper_bound)
331            }
332            InvalidInteger { source, input } if *source.kind() == IntErrorKind::NegOverflow => {
333                write!(f, "{} {} is below limit {}", subject, input, lower_bound)
334            }
335            InvalidInteger { source, input } => {
336                write_err!(f, "failed to parse {} as {}", input, subject; source)
337            }
338            Conversion(value) if *value < i64::from(lower_bound) => {
339                write!(f, "{} {} is below limit {}", subject, value, lower_bound)
340            }
341            Conversion(value) => {
342                write!(f, "{} {} is above limit {}", subject, value, upper_bound)
343            }
344        }
345    }
346
347    // To be consistent with `write_err` we need to **not** return source in case of overflow
348    #[cfg(feature = "std")]
349    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
350        use core::num::IntErrorKind;
351
352        use ParseError::*;
353
354        match self {
355            InvalidInteger { source, .. } if *source.kind() == IntErrorKind::PosOverflow => None,
356            InvalidInteger { source, .. } if *source.kind() == IntErrorKind::NegOverflow => None,
357            InvalidInteger { source, .. } => Some(source),
358            Conversion(_) => None,
359        }
360    }
361}
362
363impl From<ParseIntError> for ParseError {
364    fn from(value: ParseIntError) -> Self {
365        Self::InvalidInteger { source: value.source, input: value.input }
366    }
367}
368
369impl From<ConversionError> for ParseError {
370    fn from(value: ConversionError) -> Self { Self::Conversion(value.input.into()) }
371}
372
373#[cfg(test)]
374mod tests {
375    #[cfg(feature = "serde")]
376    use internals::serde_round_trip;
377
378    use super::*;
379
380    #[test]
381    fn time_from_str_hex_happy_path() {
382        let actual = Time::from_hex("0x6289C350").unwrap();
383        let expected = Time::from_consensus(0x6289C350).unwrap();
384        assert_eq!(actual, expected);
385    }
386
387    #[test]
388    fn time_from_str_hex_no_prefix_happy_path() {
389        let time = Time::from_hex("6289C350").unwrap();
390        assert_eq!(time, Time(0x6289C350));
391    }
392
393    #[test]
394    fn time_from_str_hex_invalid_hex_should_err() {
395        let hex = "0xzb93";
396        let result = Time::from_hex(hex);
397        assert!(result.is_err());
398    }
399
400    #[test]
401    fn height_from_str_hex_happy_path() {
402        let actual = Height::from_hex("0xBA70D").unwrap();
403        let expected = Height(0xBA70D);
404        assert_eq!(actual, expected);
405    }
406
407    #[test]
408    fn height_from_str_hex_no_prefix_happy_path() {
409        let height = Height::from_hex("BA70D").unwrap();
410        assert_eq!(height, Height(0xBA70D));
411    }
412
413    #[test]
414    fn height_from_str_hex_invalid_hex_should_err() {
415        let hex = "0xzb93";
416        let result = Height::from_hex(hex);
417        assert!(result.is_err());
418    }
419
420    #[test]
421    #[cfg(feature = "serde")]
422    pub fn encode_decode_height() {
423        serde_round_trip!(Height::ZERO);
424        serde_round_trip!(Height::MIN);
425        serde_round_trip!(Height::MAX);
426    }
427
428    #[test]
429    #[cfg(feature = "serde")]
430    pub fn encode_decode_time() {
431        serde_round_trip!(Time::MIN);
432        serde_round_trip!(Time::MAX);
433    }
434}
bitcoin_units/locktime/absolute.rs

bitcoin_units/locktime/
absolute.rs
