remove time dep from actix-http (#2383)

actix-http/src/header/shared/http_date.rs

@@ -0,0 +1,82 @@
+use std::{fmt, io::Write, str::FromStr, time::SystemTime};
+
+use bytes::BytesMut;
+use http::header::{HeaderValue, InvalidHeaderValue};
+
+use crate::{
+    config::DATE_VALUE_LENGTH, error::ParseError, header::IntoHeaderValue,
+    helpers::MutWriter,
+};
+
+/// A timestamp with HTTP formatting and parsing.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct HttpDate(SystemTime);
+
+impl FromStr for HttpDate {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<HttpDate, ParseError> {
+        match httpdate::parse_http_date(s) {
+            Ok(sys_time) => Ok(HttpDate(sys_time)),
+            Err(_) => Err(ParseError::Header),
+        }
+    }
+}
+
+impl fmt::Display for HttpDate {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let date_str = httpdate::fmt_http_date(self.0);
+        f.write_str(&date_str)
+    }
+}
+
+impl IntoHeaderValue for HttpDate {
+    type Error = InvalidHeaderValue;
+
+    fn try_into_value(self) -> Result<HeaderValue, Self::Error> {
+        let mut buf = BytesMut::with_capacity(DATE_VALUE_LENGTH);
+        let mut wrt = MutWriter(&mut buf);
+
+        // unwrap: date output is known to be well formed and of known length
+        write!(wrt, "{}", httpdate::fmt_http_date(self.0)).unwrap();
+
+        HeaderValue::from_maybe_shared(buf.split().freeze())
+    }
+}
+
+impl From<SystemTime> for HttpDate {
+    fn from(sys_time: SystemTime) -> HttpDate {
+        HttpDate(sys_time)
+    }
+}
+
+impl From<HttpDate> for SystemTime {
+    fn from(HttpDate(sys_time): HttpDate) -> SystemTime {
+        sys_time
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::time::Duration;
+
+    use super::*;
+
+    #[test]
+    fn date_header() {
+        macro_rules! assert_parsed_date {
+            ($case:expr, $exp:expr) => {
+                assert_eq!($case.parse::<HttpDate>().unwrap(), $exp);
+            };
+        }
+
+        // 784198117 = SystemTime::from(datetime!(1994-11-07 08:48:37).assume_utc()).duration_since(SystemTime::UNIX_EPOCH));
+        let nov_07 = HttpDate(SystemTime::UNIX_EPOCH + Duration::from_secs(784198117));
+
+        assert_parsed_date!("Mon, 07 Nov 1994 08:48:37 GMT", nov_07);
+        assert_parsed_date!("Monday, 07-Nov-94 08:48:37 GMT", nov_07);
+        assert_parsed_date!("Mon Nov  7 08:48:37 1994", nov_07);
+
+        assert!("this-is-no-date".parse::<HttpDate>().is_err());
+    }
+}