openpgp: Add two new types, Timestamp and Duration.

  - Timestamp and Duration represent dates and durations with the
    range and resolution that OpenPGP can represent.  By using these
    types to store dates and durations, we enforce correct
    canonicalization.

1 files changed, 168 insertions, 0 deletions

diff --git a/openpgp/src/types/timestamp.rs b/openpgp/src/types/timestamp.rs
new file mode 100644
index 00000000..318a6ba9
--- /dev/null
+++ b/openpgp/src/types/timestamp.rs
@@ -0,0 +1,168 @@
+use std::convert::{TryFrom, TryInto};
+use std::fmt;
+use std::time::{SystemTime, Duration as SystemDuration, UNIX_EPOCH};
+use quickcheck::{Arbitrary, Gen};
+
+use crate::{
+    Error,
+    Result,
+};
+
+/// A timestamp representable by OpenPGP.
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Timestamp(u32);
+
+impl From<Timestamp> for u32 {
+    fn from(t: Timestamp) -> Self {
+        t.0
+    }
+}
+
+impl From<u32> for Timestamp {
+    fn from(t: u32) -> Self {
+        Timestamp(t)
+    }
+}
+
+impl TryFrom<SystemTime> for Timestamp {
+    type Error = failure::Error;
+
+    fn try_from(t: SystemTime) -> Result<Self> {
+        match t.duration_since(std::time::UNIX_EPOCH) {
+            Ok(d) if d.as_secs() <= std::u32::MAX as u64 =>
+                Ok(Timestamp(d.as_secs() as u32)),
+            _ => Err(Error::InvalidArgument(
+                format!("Time exceeds u32 epoch: {:?}", t))
+                     .into()),
+        }
+    }
+}
+
+impl From<Timestamp> for SystemTime {
+    fn from(t: Timestamp) -> Self {
+        UNIX_EPOCH + SystemDuration::new(t.0 as u64, 0)
+    }
+}
+
+impl fmt::Debug for Timestamp {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}", SystemTime::from(*self))
+    }
+}
+
+impl Timestamp {
+    /// Returns the current time.
+    pub fn now() -> Timestamp {
+        SystemTime::now().try_into()
+            .expect("representable for the next hundred years")
+    }
+}
+
+impl Arbitrary for Timestamp {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        Timestamp(u32::arbitrary(g))
+    }
+}
+
+/// A duration representable by OpenPGP.
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Duration(u32);
+
+impl From<Duration> for u32 {
+    fn from(d: Duration) -> Self {
+        d.0
+    }
+}
+
+impl From<u32> for Duration {
+    fn from(d: u32) -> Self {
+        Duration(d)
+    }
+}
+
+impl TryFrom<SystemDuration> for Duration {
+    type Error = failure::Error;
+
+    fn try_from(d: SystemDuration) -> Result<Self> {
+        if d.as_secs() <= std::u32::MAX as u64 {
+            Ok(Duration(d.as_secs() as u32))
+        } else {
+            Err(Error::InvalidArgument(
+                format!("Duration exceeds u32: {:?}", d))
+                     .into())
+        }
+    }
+}
+
+impl From<Duration> for SystemDuration {
+    fn from(d: Duration) -> Self {
+        SystemDuration::new(d.0 as u64, 0)
+    }
+}
+
+impl fmt::Debug for Duration {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}", SystemDuration::from(*self))
+    }
+}
+
+impl Duration {
+    /// Returns a `Duration` with the given number of seconds.
+    pub fn seconds(n: u32) -> Duration {
+        n.into()
+    }
+
+    /// Returns a `Duration` with the given number of minutes, if
+    /// representable.
+    pub fn minutes(n: u32) -> Result<Duration> {
+        60u32.checked_mul(n).ok_or(())
+            .map(Self::seconds)
+            .map_err(|_| Error::InvalidArgument(
+                format!("Not representable: {} minutes in seconds exceeds u32",
+                        n)).into())
+    }
+
+    /// Returns a `Duration` with the given number of hours, if
+    /// representable.
+    pub fn hours(n: u32) -> Result<Duration> {
+        60u32.checked_mul(n)
+            .ok_or(Error::InvalidArgument("".into()).into())
+            .and_then(Self::minutes)
+            .map_err(|_| Error::InvalidArgument(
+                format!("Not representable: {} hours in seconds exceeds u32",
+                        n)).into())
+    }
+
+    /// Returns a `Duration` with the given number of days, if
+    /// representable.
+    pub fn days(n: u32) -> Result<Duration> {
+        24u32.checked_mul(n)
+            .ok_or(Error::InvalidArgument("".into()).into())
+            .and_then(Self::hours)
+            .map_err(|_| Error::InvalidArgument(
+                format!("Not representable: {} days in seconds exceeds u32",
+                        n)).into())
+    }
+
+    /// Returns a `Duration` with the given number of weeks, if
+    /// representable.
+    pub fn weeks(n: u32) -> Result<Duration> {
+        7u32.checked_mul(n)
+            .ok_or(Error::InvalidArgument("".into()).into())
+            .and_then(Self::days)
+            .map_err(|_| Error::InvalidArgument(
+                format!("Not representable: {} weeks in seconds exceeds u32",
+                        n)).into())
+    }
+
+    /// Returns the duration as seconds.
+    pub fn as_secs(self) -> u64 {
+        self.0 as u64
+    }
+}
+
+impl Arbitrary for Duration {
+    fn arbitrary<G: Gen>(g: &mut G) -> Self {
+        Duration(u32::arbitrary(g))
+    }
+}