http_types/conditional/
if_unmodified_since.rs

1use crate::headers::{HeaderName, HeaderValue, Headers, ToHeaderValues, IF_UNMODIFIED_SINCE};
2use crate::utils::{fmt_http_date, parse_http_date};
3
4use std::fmt::Debug;
5use std::option;
6use std::time::SystemTime;
7
8/// Apply the HTTP method if the entity has not been modified after the
9/// given date.
10///
11/// # Specifications
12///
13/// - [RFC 7232, section 3.4: If-Unmodified-Since](https://tools.ietf.org/html/rfc7232#section-3.4)
14///
15/// # Examples
16///
17/// ```
18/// # fn main() -> http_types::Result<()> {
19/// #
20/// use http_types::Response;
21/// use http_types::conditional::IfUnmodifiedSince;
22/// use std::time::{SystemTime, Duration};
23///
24/// let time = SystemTime::now() + Duration::from_secs(5 * 60);
25/// let expires = IfUnmodifiedSince::new(time);
26///
27/// let mut res = Response::new(200);
28/// expires.apply(&mut res);
29///
30/// let expires = IfUnmodifiedSince::from_headers(res)?.unwrap();
31///
32/// // HTTP dates only have second-precision.
33/// let elapsed = time.duration_since(expires.modified())?;
34/// assert_eq!(elapsed.as_secs(), 0);
35/// #
36/// # Ok(()) }
37/// ```
38#[derive(Debug, Ord, PartialOrd, Eq, PartialEq)]
39pub struct IfUnmodifiedSince {
40    instant: SystemTime,
41}
42
43impl IfUnmodifiedSince {
44    /// Create a new instance of `IfUnmodifiedSince`.
45    pub fn new(instant: SystemTime) -> Self {
46        Self { instant }
47    }
48
49    /// Returns the last modification time listed.
50    pub fn modified(&self) -> SystemTime {
51        self.instant
52    }
53
54    /// Create an instance of `IfUnmodifiedSince` from a `Headers` instance.
55    pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
56        let headers = match headers.as_ref().get(IF_UNMODIFIED_SINCE) {
57            Some(headers) => headers,
58            None => return Ok(None),
59        };
60
61        // If we successfully parsed the header then there's always at least one
62        // entry. We want the last entry.
63        let header = headers.iter().last().unwrap();
64
65        let instant = parse_http_date(header.as_str())?;
66        Ok(Some(Self { instant }))
67    }
68
69    /// Insert a `HeaderName` + `HeaderValue` pair into a `Headers` instance.
70    pub fn apply(&self, mut headers: impl AsMut<Headers>) {
71        headers.as_mut().insert(IF_UNMODIFIED_SINCE, self.value());
72    }
73
74    /// Get the `HeaderName`.
75    pub fn name(&self) -> HeaderName {
76        IF_UNMODIFIED_SINCE
77    }
78
79    /// Get the `HeaderValue`.
80    pub fn value(&self) -> HeaderValue {
81        let output = fmt_http_date(self.instant);
82
83        // SAFETY: the internal string is validated to be ASCII.
84        unsafe { HeaderValue::from_bytes_unchecked(output.into()) }
85    }
86}
87
88impl ToHeaderValues for IfUnmodifiedSince {
89    type Iter = option::IntoIter<HeaderValue>;
90    fn to_header_values(&self) -> crate::Result<Self::Iter> {
91        // A HeaderValue will always convert into itself.
92        Ok(self.value().to_header_values().unwrap())
93    }
94}
95
96#[cfg(test)]
97mod test {
98    use super::*;
99    use crate::headers::Headers;
100    use std::time::Duration;
101
102    #[test]
103    fn smoke() -> crate::Result<()> {
104        let time = SystemTime::now() + Duration::from_secs(5 * 60);
105        let expires = IfUnmodifiedSince::new(time);
106
107        let mut headers = Headers::new();
108        expires.apply(&mut headers);
109
110        let expires = IfUnmodifiedSince::from_headers(headers)?.unwrap();
111
112        // HTTP dates only have second-precision
113        let elapsed = time.duration_since(expires.modified())?;
114        assert_eq!(elapsed.as_secs(), 0);
115        Ok(())
116    }
117
118    #[test]
119    fn bad_request_on_parse_error() {
120        let mut headers = Headers::new();
121        headers.insert(IF_UNMODIFIED_SINCE, "<nori ate the tag. yum.>");
122        let err = IfUnmodifiedSince::from_headers(headers).unwrap_err();
123        assert_eq!(err.status(), 400);
124    }
125}
http_types/conditional/if_unmodified_since.rs

http_types/conditional/
if_unmodified_since.rs
