add www-authenticate

Author: yoshuawuyts

src/auth/www_authenticate.rs

@@ -0,0 +1,169 @@
+use crate::auth::AuthenticationScheme;
+use crate::bail2 as bail;
+use crate::headers::{HeaderName, HeaderValue, Headers, WWW_AUTHENTICATE};
+
+/// Define the authentication method that should be used to gain access to a
+/// resource.
+///
+/// # Specifications
+///
+/// - [RFC 7235, section 4.1: WWW-Authenticate](https://tools.ietf.org/html/rfc7235#section-4.1)
+///
+/// # Implementation Notes
+///
+/// This implementation only encodes and parses a single authentication method,
+/// further authorization methods are ignored. It also always passes the utf-8 encoding flag.
+///
+/// # Examples
+///
+/// ```
+/// # fn main() -> http_types::Result<()> {
+/// #
+/// use http_types::Response;
+/// use http_types::auth::{AuthenticationScheme, WwwAuthenticate};
+///
+/// let scheme = AuthenticationScheme::Basic;
+/// let realm = "Access to the staging site";
+/// let authz = WwwAuthenticate::new(scheme, realm.into());
+///
+/// let mut res = Response::new(200);
+/// authz.apply(&mut res);
+///
+/// let authz = WwwAuthenticate::from_headers(res)?.unwrap();
+///
+/// assert_eq!(authz.scheme(), AuthenticationScheme::Basic);
+/// assert_eq!(authz.realm(), realm);
+/// #
+/// # Ok(()) }
+/// ```
+#[derive(Debug)]
+pub struct WwwAuthenticate {
+    scheme: AuthenticationScheme,
+    realm: String,
+}
+
+impl WwwAuthenticate {
+    /// Create a new instance of `WwwAuthenticate`.
+    pub fn new(scheme: AuthenticationScheme, realm: String) -> Self {
+        Self { scheme, realm }
+    }
+
+    /// Create a new instance from headers.
+    pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
+        let headers = match headers.as_ref().get(WWW_AUTHENTICATE) {
+            Some(headers) => headers,
+            None => return Ok(None),
+        };
+
+        // If we successfully parsed the header then there's always at least one
+        // entry. We want the last entry.
+        let value = headers.iter().last().unwrap();
+
+        let mut iter = value.as_str().splitn(2, ' ');
+        let scheme = iter.next();
+        let credential = iter.next();
+        let (scheme, realm) = match (scheme, credential) {
+            (None, _) => bail!(400, "Could not find scheme"),
+            (Some(_), None) => bail!(400, "Could not find realm"),
+            (Some(scheme), Some(realm)) => (scheme.parse()?, realm.to_owned()),
+        };
+
+        let realm = realm.trim_start();
+        let realm = match realm.strip_prefix(r#"realm=""#) {
+            Some(realm) => realm,
+            None => bail!(400, "realm not found"),
+        };
+
+        let mut chars = realm.chars();
+        let mut closing_quote = false;
+        let realm = (&mut chars)
+            .take_while(|c| {
+                if c == &'"' {
+                    closing_quote = true;
+                    false
+                } else {
+                    true
+                }
+            })
+            .collect();
+        if !closing_quote {
+            bail!(400, r"Expected a closing quote");
+        }
+
+        Ok(Some(Self { scheme, realm }))
+    }
+
+    /// Sets the header.
+    pub fn apply(&self, mut headers: impl AsMut<Headers>) {
+        headers.as_mut().insert(self.name(), self.value());
+    }
+
+    /// Get the `HeaderName`.
+    pub fn name(&self) -> HeaderName {
+        WWW_AUTHENTICATE
+    }
+
+    /// Get the `HeaderValue`.
+    pub fn value(&self) -> HeaderValue {
+        let output = format!(r#"{} realm="{}", charset="UTF-8""#, self.scheme, self.realm);
+
+        // SAFETY: the internal string is validated to be ASCII.
+        unsafe { HeaderValue::from_bytes_unchecked(output.into()) }
+    }
+
+    /// Get the authorization scheme.
+    pub fn scheme(&self) -> AuthenticationScheme {
+        self.scheme
+    }
+
+    /// Set the authorization scheme.
+    pub fn set_scheme(&mut self, scheme: AuthenticationScheme) {
+        self.scheme = scheme;
+    }
+
+    /// Get the authorization realm.
+    pub fn realm(&self) -> &str {
+        self.realm.as_str()
+    }
+
+    /// Set the authorization realm.
+    pub fn set_realm(&mut self, realm: String) {
+        self.realm = realm;
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::headers::Headers;
+
+    #[test]
+    fn smoke() -> crate::Result<()> {
+        let scheme = AuthenticationScheme::Basic;
+        let realm = "Access to the staging site";
+        let authz = WwwAuthenticate::new(scheme, realm.into());
+
+        let mut headers = Headers::new();
+        authz.apply(&mut headers);
+
+        assert_eq!(
+            headers["WWW-Authenticate"],
+            r#"Basic realm="Access to the staging site", charset="UTF-8""#
+        );
+
+        let authz = WwwAuthenticate::from_headers(headers)?.unwrap();
+
+        assert_eq!(authz.scheme(), AuthenticationScheme::Basic);
+        assert_eq!(authz.realm(), realm);
+        Ok(())
+    }
+
+    #[test]
+    fn bad_request_on_parse_error() -> crate::Result<()> {
+        let mut headers = Headers::new();
+        headers.insert(WWW_AUTHENTICATE, "<nori ate the tag. yum.>");
+        let err = WwwAuthenticate::from_headers(headers).unwrap_err();
+        assert_eq!(err.status(), 400);
+        Ok(())
+    }
+}