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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use chrono::{DateTime, Utc};
use std::time::Duration;
use viaduct::{header_names, Response};
/// How old a response already was when it was received, from its `Age` and
/// `Date` headers (RFC 9111 ยง4.2.3). A missing or unreadable header counts
/// as zero.
pub(super) struct ResponseAge {
age: Duration,
date: Option<DateTime<Utc>>,
}
impl From<&Response> for ResponseAge {
fn from(response: &Response) -> Self {
Self {
age: response
.headers
.get(header_names::AGE)
.and_then(|value| value.trim().parse().ok())
.map(Duration::from_secs)
.unwrap_or_default(),
date: response
.headers
.get(header_names::DATE)
.and_then(|value| DateTime::parse_from_rfc2822(value.trim()).ok())
.map(|date| date.to_utc()),
}
}
}
impl ResponseAge {
/// The larger of `Age` and the time elapsed since `Date`, as of `now`.
pub(super) fn at(&self, now: DateTime<Utc>) -> Duration {
let since_date = self
.date
.and_then(|date| (now - date).to_std().ok())
.unwrap_or_default();
self.age.max(since_date)
}
}
#[cfg(test)]
mod tests {
use super::*;
use viaduct::{Headers, Method};
fn age_at_now(headers: &[(&str, &str)]) -> Duration {
let mut map = Headers::new();
for (name, value) in headers {
map.insert(name.to_string(), *value).unwrap();
}
let response = Response {
body: vec![],
headers: map,
request_method: Method::Get,
status: 200,
};
let now = "2025-11-06T08:49:37Z".parse().unwrap();
ResponseAge::from(&response).at(now)
}
#[test]
fn no_age_or_date_is_zero() {
assert_eq!(age_at_now(&[]), Duration::ZERO);
}
#[test]
fn uses_age_header() {
assert_eq!(age_at_now(&[("age", "72000")]), Duration::from_secs(72000));
}
#[test]
fn uses_time_since_date_header() {
assert_eq!(
age_at_now(&[("date", "Thu, 06 Nov 2025 07:49:37 GMT")]),
Duration::from_secs(3600)
);
}
#[test]
fn takes_the_larger_of_age_and_date() {
let date = ("date", "Thu, 06 Nov 2025 07:49:37 GMT");
assert_eq!(
age_at_now(&[("age", "60"), date]),
Duration::from_secs(3600)
);
assert_eq!(
age_at_now(&[("age", "7200"), date]),
Duration::from_secs(7200)
);
}
#[test]
fn date_in_the_future_is_zero() {
assert_eq!(
age_at_now(&[("date", "Thu, 06 Nov 2025 09:49:37 GMT")]),
Duration::ZERO
);
}
#[test]
fn unreadable_headers_are_ignored() {
assert_eq!(
age_at_now(&[("age", "-5"), ("date", "yesterday")]),
Duration::ZERO
);
}
}