Move lightning-invoice deser errors to lib.rs instead of `pub use`
[rust-lightning] / lightning-invoice / src / lib.rs
index 61e394da6dba4ef70979a5dae1d673ce2b483732..5784607dde937b85fa384ed65a630d7af1d3ca3a 100644 (file)
@@ -5,7 +5,10 @@
 #![deny(unused_mut)]
 #![deny(broken_intra_doc_links)]
 
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+
 #![cfg_attr(feature = "strict", deny(warnings))]
+#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
 
 //! This crate provides data structures to represent
 //! [lightning BOLT11](https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md)
 //!   * For parsing use `str::parse::<Invoice>(&self)` (see the docs of `impl FromStr for Invoice`)
 //!   * For constructing invoices use the `InvoiceBuilder`
 //!   * For serializing invoices use the `Display`/`ToString` traits
+
+#[cfg(not(any(feature = "std", feature = "no-std")))]
+compile_error!("at least one of the `std` or `no-std` features must be enabled");
+
+pub mod payment;
 pub mod utils;
 
 extern crate bech32;
 extern crate bitcoin_hashes;
-extern crate lightning;
+#[macro_use] extern crate lightning;
 extern crate num_traits;
 extern crate secp256k1;
+extern crate alloc;
+#[cfg(any(test, feature = "std"))]
+extern crate core;
+
+#[cfg(feature = "std")]
+use std::time::SystemTime;
 
 use bech32::u5;
 use bitcoin_hashes::Hash;
@@ -31,35 +45,100 @@ use lightning::ln::features::InvoiceFeatures;
 #[cfg(any(doc, test))]
 use lightning::routing::network_graph::RoutingFees;
 use lightning::routing::router::RouteHint;
+use lightning::util::invoice::construct_invoice_preimage;
 
 use secp256k1::key::PublicKey;
 use secp256k1::{Message, Secp256k1};
 use secp256k1::recovery::RecoverableSignature;
 
-use std::fmt::{Display, Formatter, self};
-use std::iter::FilterMap;
-use std::ops::Deref;
-use std::slice::Iter;
-use std::time::{SystemTime, Duration, UNIX_EPOCH};
+use core::fmt::{Display, Formatter, self};
+use core::iter::FilterMap;
+use core::num::ParseIntError;
+use core::ops::Deref;
+use core::slice::Iter;
+use core::time::Duration;
+use core::str;
 
 mod de;
 mod ser;
 mod tb;
 
-pub use de::{ParseError, ParseOrSemanticError};
+mod prelude {
+       #[cfg(feature = "hashbrown")]
+       extern crate hashbrown;
+
+       pub use alloc::{vec, vec::Vec, string::String, collections::VecDeque, boxed::Box};
+       #[cfg(not(feature = "hashbrown"))]
+       pub use std::collections::{HashMap, HashSet, hash_map};
+       #[cfg(feature = "hashbrown")]
+       pub use self::hashbrown::{HashMap, HashSet, hash_map};
+
+       pub use alloc::string::ToString;
+}
+
+use prelude::*;
 
-// TODO: fix before 2037 (see rust PR #55527)
-/// Defines the maximum UNIX timestamp that can be represented as `SystemTime`. This is checked by
-/// one of the unit tests, please run them.
-const SYSTEM_TIME_MAX_UNIX_TIMESTAMP: u64 = std::i32::MAX as u64;
+/// Sync compat for std/no_std
+#[cfg(feature = "std")]
+mod sync {
+       pub use ::std::sync::{Mutex, MutexGuard};
+}
+
+/// Sync compat for std/no_std
+#[cfg(not(feature = "std"))]
+mod sync;
+
+/// Errors that indicate what is wrong with the invoice. They have some granularity for debug
+/// reasons, but should generally result in an "invalid BOLT11 invoice" message for the user.
+#[allow(missing_docs)]
+#[derive(PartialEq, Debug, Clone)]
+pub enum ParseError {
+       Bech32Error(bech32::Error),
+       ParseAmountError(ParseIntError),
+       MalformedSignature(secp256k1::Error),
+       BadPrefix,
+       UnknownCurrency,
+       UnknownSiPrefix,
+       MalformedHRP,
+       TooShortDataPart,
+       UnexpectedEndOfTaggedFields,
+       DescriptionDecodeError(str::Utf8Error),
+       PaddingError,
+       IntegerOverflowError,
+       InvalidSegWitProgramLength,
+       InvalidPubKeyHashLength,
+       InvalidScriptHashLength,
+       InvalidRecoveryId,
+       InvalidSliceLength(String),
+
+       /// Not an error, but used internally to signal that a part of the invoice should be ignored
+       /// according to BOLT11
+       Skip,
+}
 
-/// Allow the expiry time to be up to one year. Since this reduces the range of possible timestamps
-/// it should be rather low as long as we still have to support 32bit time representations
-const MAX_EXPIRY_TIME: u64 = 60 * 60 * 24 * 356;
+/// Indicates that something went wrong while parsing or validating the invoice. Parsing errors
+/// should be mostly seen as opaque and are only there for debugging reasons. Semantic errors
+/// like wrong signatures, missing fields etc. could mean that someone tampered with the invoice.
+#[derive(PartialEq, Debug, Clone)]
+pub enum ParseOrSemanticError {
+       /// The invoice couldn't be decoded
+       ParseError(ParseError),
+
+       /// The invoice could be decoded but violates the BOLT11 standard
+       SemanticError(::SemanticError),
+}
+
+/// The number of bits used to represent timestamps as defined in BOLT 11.
+const TIMESTAMP_BITS: usize = 35;
+
+/// The maximum timestamp as [`Duration::as_secs`] since the Unix epoch allowed by [`BOLT 11`].
+///
+/// [BOLT 11]: https://github.com/lightning/bolts/blob/master/11-payment-encoding.md
+pub const MAX_TIMESTAMP: u64 = (1 << TIMESTAMP_BITS) - 1;
 
 /// Default expiry time as defined by [BOLT 11].
 ///
-/// [BOLT 11]: https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md
+/// [BOLT 11]: https://github.com/lightning/bolts/blob/master/11-payment-encoding.md
 pub const DEFAULT_EXPIRY_TIME: u64 = 3600;
 
 /// Default minimum final CLTV expiry as defined by [BOLT 11].
@@ -67,61 +146,10 @@ pub const DEFAULT_EXPIRY_TIME: u64 = 3600;
 /// Note that this is *not* the same value as rust-lightning's minimum CLTV expiry, which is
 /// provided in [`MIN_FINAL_CLTV_EXPIRY`].
 ///
-/// [BOLT 11]: https://github.com/lightningnetwork/lightning-rfc/blob/master/11-payment-encoding.md
+/// [BOLT 11]: https://github.com/lightning/bolts/blob/master/11-payment-encoding.md
 /// [`MIN_FINAL_CLTV_EXPIRY`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY
 pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 
-/// This function is used as a static assert for the size of `SystemTime`. If the crate fails to
-/// compile due to it this indicates that your system uses unexpected bounds for `SystemTime`. You
-/// can remove this functions and run the test `test_system_time_bounds_assumptions`. In any case,
-/// please open an issue. If all tests pass you should be able to use this library safely by just
-/// removing this function till we patch it accordingly.
-fn __system_time_size_check() {
-       // Use 2 * sizeof(u64) as expected size since the expected underlying implementation is storing
-       // a `Duration` since `SystemTime::UNIX_EPOCH`.
-       unsafe { std::mem::transmute_copy::<SystemTime, [u8; 16]>(&UNIX_EPOCH); }
-}
-
-
-/// **Call this function on startup to ensure that all assumptions about the platform are valid.**
-///
-/// Unfortunately we have to make assumptions about the upper bounds of the `SystemTime` type on
-/// your platform which we can't fully verify at compile time and which isn't part of it's contract.
-/// To our best knowledge our assumptions hold for all platforms officially supported by rust, but
-/// since this check is fast we recommend to do it anyway.
-///
-/// If this function fails this is considered a bug. Please open an issue describing your
-/// platform and stating your current system time.
-///
-/// # Panics
-/// If the check fails this function panics. By calling this function on startup you ensure that
-/// this wont happen at an arbitrary later point in time.
-pub fn check_platform() {
-    // The upper and lower bounds of `SystemTime` are not part of its public contract and are
-    // platform specific. That's why we have to test if our assumptions regarding these bounds
-    // hold on the target platform.
-    //
-    // If this test fails on your platform, please don't use the library and open an issue
-    // instead so we can resolve the situation. Currently this library is tested on:
-    //   * Linux (64bit)
-    let fail_date = UNIX_EPOCH + Duration::from_secs(SYSTEM_TIME_MAX_UNIX_TIMESTAMP);
-    let year = Duration::from_secs(60 * 60 * 24 * 365);
-
-    // Make sure that the library will keep working for another year
-    assert!(fail_date.duration_since(SystemTime::now()).unwrap() > year);
-
-    let max_ts = PositiveTimestamp::from_unix_timestamp(
-        SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME
-    ).unwrap();
-    let max_exp = ::ExpiryTime::from_seconds(MAX_EXPIRY_TIME).unwrap();
-
-    assert_eq!(
-        (*max_ts.as_time() + *max_exp.as_duration()).duration_since(UNIX_EPOCH).unwrap().as_secs(),
-        SYSTEM_TIME_MAX_UNIX_TIMESTAMP
-    );
-}
-
-
 /// Builder for `Invoice`s. It's the most convenient and advised way to use this library. It ensures
 /// that only a semantically and syntactically correct Invoice can be built using it.
 ///
@@ -141,6 +169,9 @@ pub fn check_platform() {
 ///
 /// use lightning_invoice::{Currency, InvoiceBuilder};
 ///
+/// # #[cfg(not(feature = "std"))]
+/// # fn main() {}
+/// # #[cfg(feature = "std")]
 /// # fn main() {
 /// let private_key = SecretKey::from_slice(
 ///            &[
@@ -185,11 +216,11 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
        tagged_fields: Vec<TaggedField>,
        error: Option<CreationError>,
 
-       phantom_d: std::marker::PhantomData<D>,
-       phantom_h: std::marker::PhantomData<H>,
-       phantom_t: std::marker::PhantomData<T>,
-       phantom_c: std::marker::PhantomData<C>,
-       phantom_s: std::marker::PhantomData<S>,
+       phantom_d: core::marker::PhantomData<D>,
+       phantom_h: core::marker::PhantomData<H>,
+       phantom_t: core::marker::PhantomData<T>,
+       phantom_c: core::marker::PhantomData<C>,
+       phantom_s: core::marker::PhantomData<S>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -279,14 +310,14 @@ pub struct RawDataPart {
        pub tagged_fields: Vec<RawTaggedField>,
 }
 
-/// A timestamp that refers to a date after 1 January 1970 which means its representation as UNIX
-/// timestamp is positive.
+/// A timestamp that refers to a date after 1 January 1970.
 ///
 /// # Invariants
-/// The UNIX timestamp representing the stored time has to be positive and small enough so that
-/// a `EpiryTime` can be added to it without an overflow.
+///
+/// The Unix timestamp representing the stored time has to be positive and no greater than
+/// [`MAX_TIMESTAMP`].
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct PositiveTimestamp(SystemTime);
+pub struct PositiveTimestamp(Duration);
 
 /// SI prefixes for the human readable part
 #[derive(Eq, PartialEq, Debug, Clone, Copy)]
@@ -378,7 +409,8 @@ pub enum TaggedField {
 
 /// SHA-256 hash
 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
-pub struct Sha256(pub sha256::Hash);
+pub struct Sha256(/// (C-not exported) as the native hash types are not currently mapped
+       pub sha256::Hash);
 
 /// Description string
 ///
@@ -393,11 +425,6 @@ pub struct PayeePubKey(pub PublicKey);
 
 /// Positive duration that defines when (relatively to the timestamp) in the future the invoice
 /// expires
-///
-/// # Invariants
-/// The number of seconds this expiry time represents has to be in the range
-/// `0...(SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME)` to avoid overflows when adding it to a
-/// timestamp
 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 pub struct ExpiryTime(Duration);
 
@@ -457,11 +484,11 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
                        tagged_fields: Vec::new(),
                        error: None,
 
-                       phantom_d: std::marker::PhantomData,
-                       phantom_h: std::marker::PhantomData,
-                       phantom_t: std::marker::PhantomData,
-                       phantom_c: std::marker::PhantomData,
-                       phantom_s: std::marker::PhantomData,
+                       phantom_d: core::marker::PhantomData,
+                       phantom_h: core::marker::PhantomData,
+                       phantom_t: core::marker::PhantomData,
+                       phantom_c: core::marker::PhantomData,
+                       phantom_s: core::marker::PhantomData,
                }
        }
 }
@@ -477,11 +504,11 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
                        tagged_fields: self.tagged_fields,
                        error: self.error,
 
-                       phantom_d: std::marker::PhantomData,
-                       phantom_h: std::marker::PhantomData,
-                       phantom_t: std::marker::PhantomData,
-                       phantom_c: std::marker::PhantomData,
-                       phantom_s: std::marker::PhantomData,
+                       phantom_d: core::marker::PhantomData,
+                       phantom_h: core::marker::PhantomData,
+                       phantom_t: core::marker::PhantomData,
+                       phantom_c: core::marker::PhantomData,
+                       phantom_s: core::marker::PhantomData,
                }
        }
 
@@ -505,10 +532,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 
        /// Sets the expiry time
        pub fn expiry_time(mut self, expiry_time: Duration) -> Self {
-        match ExpiryTime::from_duration(expiry_time) {
-            Ok(t) => self.tagged_fields.push(TaggedField::ExpiryTime(t)),
-            Err(e) => self.error = Some(e),
-        };
+               self.tagged_fields.push(TaggedField::ExpiryTime(ExpiryTime::from_duration(expiry_time)));
                self
        }
 
@@ -587,7 +611,8 @@ impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::F
 }
 
 impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
-       /// Sets the timestamp.
+       /// Sets the timestamp to a specific [`SystemTime`].
+       #[cfg(feature = "std")]
        pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
                match PositiveTimestamp::from_system_time(time) {
                        Ok(t) => self.timestamp = Some(t),
@@ -597,7 +622,18 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
                self.set_flags()
        }
 
-       /// Sets the timestamp to the current UNIX timestamp.
+       /// Sets the timestamp to a duration since the Unix epoch.
+       pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+               match PositiveTimestamp::from_duration_since_epoch(time) {
+                       Ok(t) => self.timestamp = Some(t),
+                       Err(e) => self.error = Some(e),
+               }
+
+               self.set_flags()
+       }
+
+       /// Sets the timestamp to the current system time.
+       #[cfg(feature = "std")]
        pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
                let now = PositiveTimestamp::from_system_time(SystemTime::now());
                self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
@@ -616,9 +652,9 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T,
 impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
        /// Sets the payment secret and relevant features.
        pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
-               let features = InvoiceFeatures::empty()
-                       .set_variable_length_onion_required()
-                       .set_payment_secret_required();
+               let mut features = InvoiceFeatures::empty();
+               features.set_variable_length_onion_required();
+               features.set_payment_secret_required();
                self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
                self.tagged_fields.push(TaggedField::Features(features));
                self.set_flags()
@@ -628,13 +664,11 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
        /// Sets the `basic_mpp` feature as optional.
        pub fn basic_mpp(mut self) -> Self {
-               self.tagged_fields = self.tagged_fields
-                       .drain(..)
-                       .map(|field| match field {
-                               TaggedField::Features(f) => TaggedField::Features(f.set_basic_mpp_optional()),
-                               _ => field,
-                       })
-                       .collect();
+               for field in self.tagged_fields.iter_mut() {
+                       if let TaggedField::Features(f) = field {
+                               f.set_basic_mpp_optional();
+                       }
+               }
                self
        }
 }
@@ -774,7 +808,7 @@ impl SignedRawInvoice {
 macro_rules! find_extract {
        ($iter:expr, $enm:pat, $enm_var:ident) => {
                find_all_extract!($iter, $enm, $enm_var).next()
-    };
+       };
 }
 
 /// Finds the all elements of an enum stream of a given variant and extracts one member of the
@@ -797,41 +831,18 @@ macro_rules! find_extract {
 /// ```
 macro_rules! find_all_extract {
        ($iter:expr, $enm:pat, $enm_var:ident) => {
-       $iter.filter_map(|tf| match *tf {
+               $iter.filter_map(|tf| match *tf {
                        $enm => Some($enm_var),
                        _ => None,
                })
-    };
+       };
 }
 
 #[allow(missing_docs)]
 impl RawInvoice {
-       /// Construct the invoice's HRP and signatureless data into a preimage to be hashed.
-       pub(crate) fn construct_invoice_preimage(hrp_bytes: &[u8], data_without_signature: &[u5]) -> Vec<u8> {
-               use bech32::FromBase32;
-
-               let mut preimage = Vec::<u8>::from(hrp_bytes);
-
-               let mut data_part = Vec::from(data_without_signature);
-               let overhang = (data_part.len() * 5) % 8;
-               if overhang > 0 {
-                       // add padding if data does not end at a byte boundary
-                       data_part.push(u5::try_from_u8(0).unwrap());
-
-                       // if overhang is in (1..3) we need to add u5(0) padding two times
-                       if overhang < 3 {
-                               data_part.push(u5::try_from_u8(0).unwrap());
-                       }
-               }
-
-               preimage.extend_from_slice(&Vec::<u8>::from_base32(&data_part)
-                       .expect("No padding error may occur due to appended zero above."));
-               preimage
-       }
-
        /// Hash the HRP as bytes and signatureless data part.
        fn hash_from_parts(hrp_bytes: &[u8], data_without_signature: &[u5]) -> [u8; 32] {
-               let preimage = RawInvoice::construct_invoice_preimage(hrp_bytes, data_without_signature);
+               let preimage = construct_invoice_preimage(hrp_bytes, data_without_signature);
                let mut hash: [u8; 32] = Default::default();
                hash.copy_from_slice(&sha256::Hash::hash(&preimage)[..]);
                hash
@@ -940,56 +951,57 @@ impl RawInvoice {
 }
 
 impl PositiveTimestamp {
-       /// Create a new `PositiveTimestamp` from a unix timestamp in the Range
-       /// `0...SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME`, otherwise return a
-       /// `CreationError::TimestampOutOfBounds`.
+       /// Creates a `PositiveTimestamp` from a Unix timestamp in the range `0..=MAX_TIMESTAMP`.
+       ///
+       /// Otherwise, returns a [`CreationError::TimestampOutOfBounds`].
        pub fn from_unix_timestamp(unix_seconds: u64) -> Result<Self, CreationError> {
-               if unix_seconds > SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME {
-                       Err(CreationError::TimestampOutOfBounds)
-               } else {
-                       Ok(PositiveTimestamp(UNIX_EPOCH + Duration::from_secs(unix_seconds)))
-               }
+               Self::from_duration_since_epoch(Duration::from_secs(unix_seconds))
        }
 
-       /// Create a new `PositiveTimestamp` from a `SystemTime` with a corresponding unix timestamp in
-       /// the Range `0...SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME`, otherwise return a
-       /// `CreationError::TimestampOutOfBounds`.
+       /// Creates a `PositiveTimestamp` from a [`SystemTime`] with a corresponding Unix timestamp in
+       /// the range `0..=MAX_TIMESTAMP`.
+       ///
+       /// Otherwise, returns a [`CreationError::TimestampOutOfBounds`].
+       #[cfg(feature = "std")]
        pub fn from_system_time(time: SystemTime) -> Result<Self, CreationError> {
-               if time
-                       .duration_since(UNIX_EPOCH)
-                       .map(|t| t.as_secs() <= SYSTEM_TIME_MAX_UNIX_TIMESTAMP - MAX_EXPIRY_TIME)
-                       .unwrap_or(true)
-                       {
-                               Ok(PositiveTimestamp(time))
-                       } else {
+               time.duration_since(SystemTime::UNIX_EPOCH)
+                       .map(Self::from_duration_since_epoch)
+                       .unwrap_or(Err(CreationError::TimestampOutOfBounds))
+       }
+
+       /// Creates a `PositiveTimestamp` from a [`Duration`] since the Unix epoch in the range
+       /// `0..=MAX_TIMESTAMP`.
+       ///
+       /// Otherwise, returns a [`CreationError::TimestampOutOfBounds`].
+       pub fn from_duration_since_epoch(duration: Duration) -> Result<Self, CreationError> {
+               if duration.as_secs() <= MAX_TIMESTAMP {
+                       Ok(PositiveTimestamp(duration))
+               } else {
                        Err(CreationError::TimestampOutOfBounds)
                }
        }
 
-       /// Returns the UNIX timestamp representing the stored time
+       /// Returns the Unix timestamp representing the stored time
        pub fn as_unix_timestamp(&self) -> u64 {
-               self.0.duration_since(UNIX_EPOCH)
-                       .expect("ensured by type contract/constructors")
-                       .as_secs()
+               self.0.as_secs()
        }
 
-       /// Returns a reference to the internal `SystemTime` time representation
-       pub fn as_time(&self) -> &SystemTime {
-               &self.0
+       /// Returns the duration of the stored time since the Unix epoch
+       pub fn as_duration_since_epoch(&self) -> Duration {
+               self.0
        }
-}
 
-impl Into<SystemTime> for PositiveTimestamp {
-       fn into(self) -> SystemTime {
-               self.0
+       /// Returns the [`SystemTime`] representing the stored time
+       #[cfg(feature = "std")]
+       pub fn as_time(&self) -> SystemTime {
+               SystemTime::UNIX_EPOCH + self.0
        }
 }
 
-impl Deref for PositiveTimestamp {
-       type Target = SystemTime;
-
-       fn deref(&self) -> &Self::Target {
-               &self.0
+#[cfg(feature = "std")]
+impl Into<SystemTime> for PositiveTimestamp {
+       fn into(self) -> SystemTime {
+               SystemTime::UNIX_EPOCH + self.0
        }
 }
 
@@ -1130,11 +1142,17 @@ impl Invoice {
                Ok(invoice)
        }
 
-       /// Returns the `Invoice`'s timestamp (should equal it's creation time)
-       pub fn timestamp(&self) -> &SystemTime {
+       /// Returns the `Invoice`'s timestamp (should equal its creation time)
+       #[cfg(feature = "std")]
+       pub fn timestamp(&self) -> SystemTime {
                self.signed_invoice.raw_invoice().data.timestamp.as_time()
        }
 
+       /// Returns the `Invoice`'s timestamp as a duration since the Unix epoch
+       pub fn duration_since_epoch(&self) -> Duration {
+               self.signed_invoice.raw_invoice().data.timestamp.0
+       }
+
        /// Returns an iterator over all tagged fields of this Invoice.
        ///
        /// (C-not exported) As there is not yet a manual mapping for a FilterMap
@@ -1187,6 +1205,29 @@ impl Invoice {
                        .unwrap_or(Duration::from_secs(DEFAULT_EXPIRY_TIME))
        }
 
+       /// Returns whether the invoice has expired.
+       #[cfg(feature = "std")]
+       pub fn is_expired(&self) -> bool {
+               Self::is_expired_from_epoch(&self.timestamp(), self.expiry_time())
+       }
+
+       /// Returns whether the expiry time from the given epoch has passed.
+       #[cfg(feature = "std")]
+       pub(crate) fn is_expired_from_epoch(epoch: &SystemTime, expiry_time: Duration) -> bool {
+               match epoch.elapsed() {
+                       Ok(elapsed) => elapsed > expiry_time,
+                       Err(_) => false,
+               }
+       }
+
+       /// Returns whether the expiry time would pass at the given point in time.
+       /// `at_time` is the timestamp as a duration since the Unix epoch.
+       pub fn would_expire(&self, at_time: Duration) -> bool {
+               self.duration_since_epoch()
+                       .checked_add(self.expiry_time())
+                       .unwrap_or_else(|| Duration::new(u64::max_value(), 1_000_000_000 - 1)) < at_time
+       }
+
        /// Returns the invoice's `min_final_cltv_expiry` time, if present, otherwise
        /// [`DEFAULT_MIN_FINAL_CLTV_EXPIRY`].
        pub fn min_final_cltv_expiry(&self) -> u64 {
@@ -1208,10 +1249,10 @@ impl Invoice {
        }
 
        /// Returns a list of all routes included in the invoice as the underlying hints
-       pub fn route_hints(&self) -> Vec<&RouteHint> {
+       pub fn route_hints(&self) -> Vec<RouteHint> {
                find_all_extract!(
                        self.signed_invoice.known_tagged_fields(), TaggedField::PrivateRoute(ref x), x
-               ).map(|route| &**route).collect()
+               ).map(|route| (**route).clone()).collect()
        }
 
        /// Returns the currency for which the invoice was issued
@@ -1219,8 +1260,13 @@ impl Invoice {
                self.signed_invoice.currency()
        }
 
+       /// Returns the amount if specified in the invoice as millisatoshis.
+       pub fn amount_milli_satoshis(&self) -> Option<u64> {
+               self.signed_invoice.amount_pico_btc().map(|v| v / 10)
+       }
+
        /// Returns the amount if specified in the invoice as pico <currency>.
-       pub fn amount_pico_btc(&self) -> Option<u64> {
+       fn amount_pico_btc(&self) -> Option<u64> {
                self.signed_invoice.amount_pico_btc()
        }
 }
@@ -1300,26 +1346,14 @@ impl Deref for PayeePubKey {
 }
 
 impl ExpiryTime {
-       /// Construct an `ExpiryTime` from seconds. If there exists a `PositiveTimestamp` which would
-       /// overflow on adding the `EpiryTime` to it then this function will return a
-       /// `CreationError::ExpiryTimeOutOfBounds`.
-       pub fn from_seconds(seconds: u64) -> Result<ExpiryTime, CreationError> {
-               if seconds <= MAX_EXPIRY_TIME {
-                       Ok(ExpiryTime(Duration::from_secs(seconds)))
-               } else {
-                       Err(CreationError::ExpiryTimeOutOfBounds)
-               }
+       /// Construct an `ExpiryTime` from seconds.
+       pub fn from_seconds(seconds: u64) -> ExpiryTime {
+               ExpiryTime(Duration::from_secs(seconds))
        }
 
-       /// Construct an `ExpiryTime` from a `Duration`. If there exists a `PositiveTimestamp` which
-       /// would overflow on adding the `EpiryTime` to it then this function will return a
-       /// `CreationError::ExpiryTimeOutOfBounds`.
-       pub fn from_duration(duration: Duration) -> Result<ExpiryTime, CreationError> {
-               if duration.as_secs() <= MAX_EXPIRY_TIME {
-                       Ok(ExpiryTime(duration))
-               } else {
-                       Err(CreationError::ExpiryTimeOutOfBounds)
-               }
+       /// Construct an `ExpiryTime` from a `Duration`.
+       pub fn from_duration(duration: Duration) -> ExpiryTime {
+               ExpiryTime(duration)
        }
 
        /// Returns the expiry time in seconds
@@ -1388,11 +1422,17 @@ pub enum CreationError {
        /// The specified route has too many hops and can't be encoded
        RouteTooLong,
 
-       /// The unix timestamp of the supplied date is <0 or can't be represented as `SystemTime`
+       /// The Unix timestamp of the supplied date is less than zero or greater than 35-bits
        TimestampOutOfBounds,
 
-       /// The supplied expiry time could cause an overflow if added to a `PositiveTimestamp`
-       ExpiryTimeOutOfBounds,
+       /// The supplied millisatoshi amount was greater than the total bitcoin supply.
+       InvalidAmount,
+
+       /// Route hints were required for this invoice and were missing. Applies to
+       /// [phantom invoices].
+       ///
+       /// [phantom invoices]: crate::utils::create_phantom_invoice
+       MissingRouteHints,
 }
 
 impl Display for CreationError {
@@ -1400,12 +1440,14 @@ impl Display for CreationError {
                match self {
                        CreationError::DescriptionTooLong => f.write_str("The supplied description string was longer than 639 bytes"),
                        CreationError::RouteTooLong => f.write_str("The specified route has too many hops and can't be encoded"),
-                       CreationError::TimestampOutOfBounds => f.write_str("The unix timestamp of the supplied date is <0 or can't be represented as `SystemTime`"),
-                       CreationError::ExpiryTimeOutOfBounds => f.write_str("The supplied expiry time could cause an overflow if added to a `PositiveTimestamp`"),
+                       CreationError::TimestampOutOfBounds => f.write_str("The Unix timestamp of the supplied date is less than zero or greater than 35-bits"),
+                       CreationError::InvalidAmount => f.write_str("The supplied millisatoshi amount was greater than the total bitcoin supply"),
+                       CreationError::MissingRouteHints => f.write_str("The invoice required route hints and they weren't provided"),
                }
        }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for CreationError { }
 
 /// Errors that may occur when converting a `RawInvoice` to an `Invoice`. They relate to the
@@ -1461,6 +1503,7 @@ impl Display for SemanticError {
        }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for SemanticError { }
 
 /// When signing using a fallible method either an user-supplied `SignError` or a `CreationError`
@@ -1490,17 +1533,10 @@ mod test {
 
        #[test]
        fn test_system_time_bounds_assumptions() {
-               ::check_platform();
-
-        assert_eq!(
-            ::PositiveTimestamp::from_unix_timestamp(::SYSTEM_TIME_MAX_UNIX_TIMESTAMP + 1),
-            Err(::CreationError::TimestampOutOfBounds)
-        );
-
-        assert_eq!(
-            ::ExpiryTime::from_seconds(::MAX_EXPIRY_TIME + 1),
-            Err(::CreationError::ExpiryTimeOutOfBounds)
-        );
+               assert_eq!(
+                       ::PositiveTimestamp::from_unix_timestamp(::MAX_TIMESTAMP + 1),
+                       Err(::CreationError::TimestampOutOfBounds)
+               );
        }
 
        #[test]
@@ -1703,7 +1739,7 @@ mod test {
                let builder = InvoiceBuilder::new(Currency::Bitcoin)
                        .description("Test".into())
                        .payment_hash(sha256::Hash::from_slice(&[0;32][..]).unwrap())
-                       .current_timestamp();
+                       .duration_since_epoch(Duration::from_secs(1234567));
 
                let invoice = builder.clone()
                        .amount_milli_satoshis(1500)
@@ -1732,7 +1768,7 @@ mod test {
 
                let builder = InvoiceBuilder::new(Currency::Bitcoin)
                        .payment_hash(sha256::Hash::from_slice(&[0;32][..]).unwrap())
-                       .current_timestamp()
+                       .duration_since_epoch(Duration::from_secs(1234567))
                        .min_final_cltv_expiry(144);
 
                let too_long_string = String::from_iter(
@@ -1848,7 +1884,7 @@ mod test {
 
                let builder = InvoiceBuilder::new(Currency::BitcoinTestnet)
                        .amount_milli_satoshis(123)
-                       .timestamp(UNIX_EPOCH + Duration::from_secs(1234567))
+                       .duration_since_epoch(Duration::from_secs(1234567))
                        .payee_pub_key(public_key.clone())
                        .expiry_time(Duration::from_secs(54321))
                        .min_final_cltv_expiry(144)
@@ -1867,8 +1903,10 @@ mod test {
                assert!(invoice.check_signature().is_ok());
                assert_eq!(invoice.tagged_fields().count(), 10);
 
+               assert_eq!(invoice.amount_milli_satoshis(), Some(123));
                assert_eq!(invoice.amount_pico_btc(), Some(1230));
                assert_eq!(invoice.currency(), Currency::BitcoinTestnet);
+               #[cfg(feature = "std")]
                assert_eq!(
                        invoice.timestamp().duration_since(UNIX_EPOCH).unwrap().as_secs(),
                        1234567
@@ -1900,7 +1938,7 @@ mod test {
                        .description("Test".into())
                        .payment_hash(sha256::Hash::from_slice(&[0;32][..]).unwrap())
                        .payment_secret(PaymentSecret([0; 32]))
-                       .current_timestamp()
+                       .duration_since_epoch(Duration::from_secs(1234567))
                        .build_raw()
                        .unwrap()
                        .sign::<_, ()>(|hash| {
@@ -1913,5 +1951,30 @@ mod test {
 
                assert_eq!(invoice.min_final_cltv_expiry(), DEFAULT_MIN_FINAL_CLTV_EXPIRY);
                assert_eq!(invoice.expiry_time(), Duration::from_secs(DEFAULT_EXPIRY_TIME));
+               assert!(!invoice.would_expire(Duration::from_secs(1234568)));
+       }
+
+       #[test]
+       fn test_expiration() {
+               use ::*;
+               use secp256k1::Secp256k1;
+               use secp256k1::key::SecretKey;
+
+               let signed_invoice = InvoiceBuilder::new(Currency::Bitcoin)
+                       .description("Test".into())
+                       .payment_hash(sha256::Hash::from_slice(&[0;32][..]).unwrap())
+                       .payment_secret(PaymentSecret([0; 32]))
+                       .duration_since_epoch(Duration::from_secs(1234567))
+                       .build_raw()
+                       .unwrap()
+                       .sign::<_, ()>(|hash| {
+                               let privkey = SecretKey::from_slice(&[41; 32]).unwrap();
+                               let secp_ctx = Secp256k1::new();
+                               Ok(secp_ctx.sign_recoverable(hash, &privkey))
+                       })
+                       .unwrap();
+               let invoice = Invoice::from_signed(signed_invoice).unwrap();
+
+               assert!(invoice.would_expire(Duration::from_secs(1234567 + DEFAULT_EXPIRY_TIME + 1)));
        }
 }