feat(headers): Add Referrer-Policy header

Author: aravind-pg

src/header/common/mod.rs

@@ -48,6 +48,7 @@ pub use self::prefer::{Prefer, Preference};
 pub use self::preference_applied::PreferenceApplied;
 pub use self::range::{Range, ByteRangeSpec};
 pub use self::referer::Referer;
+pub use self::referrer_policy::ReferrerPolicy;
 pub use self::server::Server;
 pub use self::set_cookie::SetCookie;
 pub use self::strict_transport_security::StrictTransportSecurity;
@@ -410,6 +411,7 @@ mod prefer;
 mod preference_applied;
 mod range;
 mod referer;
+mod referrer_policy;
 mod server;
 mod set_cookie;
 mod strict_transport_security;

src/header/common/referrer_policy.rs

@@ -0,0 +1,94 @@
+use std::fmt;
+use std::ascii::AsciiExt;
+
+use header::{Header, HeaderFormat, parsing};
+
+/// `Referrer-Policy` header, part of
+/// [Referrer Policy](https://www.w3.org/TR/referrer-policy/#referrer-policy-header)
+///
+/// The `Referrer-Policy` HTTP header specifies the referrer
+/// policy that the user agent applies when determining what
+/// referrer information should be included with requests made,
+/// and with browsing contexts created from the context of the
+/// protected resource.
+///
+/// # ABNF
+/// ```plain
+/// Referrer-Policy: 1#policy-token
+/// policy-token   = "no-referrer" / "no-referrer-when-downgrade"
+///                  / "same-origin" / "origin"
+///                  / "origin-when-cross-origin" / "unsafe-url"
+/// ```
+///
+/// # Example values
+/// * `no-referrer`
+///
+/// # Example
+/// ```
+/// use hyper::header::{Headers, ReferrerPolicy};
+///
+/// let mut headers = Headers::new();
+/// headers.set(ReferrerPolicy::NoReferrer);
+/// ```
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum ReferrerPolicy {
+    /// `no-referrer`
+    NoReferrer,
+    /// `no-referrer-when-downgrade`
+    NoReferrerWhenDowngrade,
+    /// `same-origin`
+    SameOrigin,
+    /// `origin`
+    Origin,
+    /// `origin-when-cross-origin`
+    OriginWhenCrossOrigin,
+    /// `unsafe-url`
+    UnsafeUrl,
+}
+
+impl Header for ReferrerPolicy {
+    fn header_name() -> &'static str {
+        static NAME: &'static str = "Referrer-Policy";
+        NAME
+    }
+
+    fn parse_header(raw: &[Vec<u8>]) -> ::Result<ReferrerPolicy> {
+        use self::ReferrerPolicy::*;
+        parsing::from_one_raw_str(raw).and_then(|s: String| {
+            let slice = &s.to_ascii_lowercase()[..];
+            // See https://www.w3.org/TR/referrer-policy/#determine-policy-for-token
+            match slice {
+                "no-referrer" | "never" => Ok(NoReferrer),
+                "no-referrer-when-downgrade" | "default" => Ok(NoReferrerWhenDowngrade),
+                "same-origin" => Ok(SameOrigin),
+                "origin" => Ok(Origin),
+                "origin-when-cross-origin" => Ok(OriginWhenCrossOrigin),
+                "unsafe-url" | "always" => Ok(UnsafeUrl),
+                _ => Err(::Error::Header),
+            }
+        })
+    }
+}
+
+impl HeaderFormat for ReferrerPolicy {
+    fn fmt_header(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::ReferrerPolicy::*;
+        f.write_str(match *self {
+            NoReferrer => "no-referrer",
+            NoReferrerWhenDowngrade => "no-referrer-when-downgrade",
+            SameOrigin => "same-origin",
+            Origin => "origin",
+            OriginWhenCrossOrigin => "origin-when-cross-origin",
+            UnsafeUrl => "unsafe-url",
+        })
+    }
+}
+
+#[test]
+fn test_parse_header() {
+    let a: ReferrerPolicy = Header::parse_header([b"origin".to_vec()].as_ref()).unwrap();
+    let b = ReferrerPolicy::Origin;
+    assert_eq!(a, b);
+    let e: ::Result<ReferrerPolicy> = Header::parse_header([b"foobar".to_vec()].as_ref());
+    assert!(e.is_err());
+}