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feat(headers): Add Pragma header field
Add the HTTP/1.0 `Pragma` header field used to prevent older Caches, that
do not understand the `Cache-Control` header field from caching the ressource.

Closes #237
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pyfisch committed Jan 24, 2015
1 parent fb92a26 commit 767c95d
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Showing 2 changed files with 63 additions and 1 deletion.
3 changes: 2 additions & 1 deletion src/header/common/mod.rs
Expand Up @@ -23,6 +23,7 @@ pub use self::host::Host;
pub use self::if_modified_since::IfModifiedSince;
pub use self::last_modified::LastModified;
pub use self::location::Location;
pub use self::pragma::Pragma;
pub use self::referer::Referer;
pub use self::server::Server;
pub use self::set_cookie::SetCookie;
Expand Down Expand Up @@ -157,11 +158,11 @@ mod host;
mod last_modified;
mod if_modified_since;
mod location;
mod pragma;
mod referer;
mod server;
mod set_cookie;
mod transfer_encoding;
mod upgrade;
mod user_agent;
mod vary;

61 changes: 61 additions & 0 deletions src/header/common/pragma.rs
@@ -0,0 +1,61 @@
use std::fmt;
use std::ascii::AsciiExt;

use header::{Header, HeaderFormat, parsing};

/// The `Pragma` header defined by HTTP/1.0.
///
/// > The "Pragma" header field allows backwards compatibility with
/// > HTTP/1.0 caches, so that clients can specify a "no-cache" request
/// > that they will understand (as Cache-Control was not defined until
/// > HTTP/1.1). When the Cache-Control header field is also present and
/// > understood in a request, Pragma is ignored.

/// > In HTTP/1.0, Pragma was defined as an extensible field for
/// > implementation-specified directives for recipients. This
/// > specification deprecates such extensions to improve interoperability.
///
/// Spec: https://tools.ietf.org/html/rfc7234#section-5.4
#[derive(Clone, PartialEq, Debug)]
pub enum Pragma {
/// Corresponds to the `no-cache` value.
NoCache,
/// Every value other than `no-cache`.
Ext(String),
}

impl Header for Pragma {
fn header_name() -> &'static str {
"Pragma"
}

fn parse_header(raw: &[Vec<u8>]) -> Option<Pragma> {
parsing::from_one_raw_str(raw).and_then(|s: String| {
let slice = &s.to_ascii_lowercase()[];
match slice {
"" => None,
"no-cache" => Some(Pragma::NoCache),
_ => Some(Pragma::Ext(s)),
}
})
}
}

impl HeaderFormat for Pragma {
fn fmt_header(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Pragma::NoCache => write!(f, "no-cache"),
Pragma::Ext(ref string) => write!(f, "{}", string),
}
}
}

#[test]
fn test_parse_header() {
let a: Pragma = Header::parse_header([b"no-cache".to_vec()].as_slice()).unwrap();
let b = Pragma::NoCache;
assert_eq!(a, b);
let c: Pragma = Header::parse_header([b"FoObar".to_vec()].as_slice()).unwrap();
let d = Pragma::Ext("FoObar".to_string());
assert_eq!(c, d);
}

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