rok-auth-basic 0.1.0

HTTP Basic authentication guard for the rok ecosystem
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

use std::{
    future::Future,
    pin::Pin,
    sync::Arc,
    task::{Context, Poll},
};

use axum::{
    body::Body,
    http::{header, Request, Response, StatusCode},
};
use base64::{engine::general_purpose::STANDARD, Engine};
use tower::{Layer, Service};

use rok_auth::Claims;

// ── VerifyFn type alias ───────────────────────────────────────────────────────

/// A boxed async function that maps `(username, password)` to `Option<Claims>`.
///
/// Return `Some(claims)` to allow the request through; `None` to reject with
/// `401 Unauthorized`.
pub type VerifyFn = Arc<
    dyn Fn(String, String) -> Pin<Box<dyn Future<Output = Option<Claims>> + Send>> + Send + Sync,
>;

// ── BasicAuthLayer ────────────────────────────────────────────────────────────

/// Tower [`Layer`] that enforces HTTP Basic authentication on every request.
///
/// On success, the verified [`Claims`] are injected into request extensions so
/// the `Ctx` extractor in `rok-auth` can see the authenticated user without
/// re-verifying the credentials.
///
/// On failure the layer short-circuits and returns `401 Unauthorized` with a
/// `WWW-Authenticate: Basic realm="…"` challenge header.
///
/// # Example
///
/// ```rust,ignore
/// use rok_auth::Claims;
/// use rok_auth_basic::BasicAuthLayer;
///
/// let layer = BasicAuthLayer::new("My API", |user: String, pass: String| async move {
///     if user == "admin" && pass == std::env::var("API_PASS").unwrap_or_default() {
///         Some(Claims::new(user, vec!["admin"]))
///     } else {
///         None
///     }
/// });
///
/// let app = Router::new()
///     .route("/metrics", get(metrics_handler))
///     .layer(layer);
/// ```
#[derive(Clone)]
pub struct BasicAuthLayer {
    verifier: VerifyFn,
    realm: String,
}

impl BasicAuthLayer {
    /// Build a layer with a custom `realm` and async `verifier` closure.
    ///
    /// `verifier` receives `(username, password)` and should return
    /// `Some(Claims)` on success or `None` to reject the request.
    pub fn new<F, Fut>(realm: impl Into<String>, verifier: F) -> Self
    where
        F: Fn(String, String) -> Fut + Send + Sync + 'static,
        Fut: Future<Output = Option<Claims>> + Send + 'static,
    {
        Self {
            realm: realm.into(),
            verifier: Arc::new(move |u, p| Box::pin(verifier(u, p))),
        }
    }
}

impl<Svc> Layer<Svc> for BasicAuthLayer {
    type Service = BasicAuthService<Svc>;

    fn layer(&self, inner: Svc) -> Self::Service {
        BasicAuthService {
            inner,
            verifier: Arc::clone(&self.verifier),
            realm: self.realm.clone(),
        }
    }
}

// ── BasicAuthService ──────────────────────────────────────────────────────────

#[derive(Clone)]
pub struct BasicAuthService<Svc> {
    inner: Svc,
    verifier: VerifyFn,
    realm: String,
}

type BoxFut<T, E> = Pin<Box<dyn Future<Output = Result<T, E>> + Send>>;

impl<Svc, ReqBody> Service<Request<ReqBody>> for BasicAuthService<Svc>
where
    Svc: Service<Request<ReqBody>, Response = Response<Body>> + Clone + Send + 'static,
    Svc::Error: Send,
    Svc::Future: Send,
    ReqBody: Send + 'static,
{
    type Response = Response<Body>;
    type Error = Svc::Error;
    type Future = BoxFut<Self::Response, Self::Error>;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.inner.poll_ready(cx)
    }

    fn call(&mut self, mut req: Request<ReqBody>) -> Self::Future {
        let verifier = Arc::clone(&self.verifier);
        let realm = self.realm.clone();
        let clone = self.inner.clone();
        let mut inner = std::mem::replace(&mut self.inner, clone);

        Box::pin(async move {
            // ── 1. Parse Authorization: Basic <base64> ─────────────────────────
            let Some((username, password)) = parse_basic_header(req.headers()) else {
                return Ok(deny(&realm));
            };

            // ── 2. Verify credentials ──────────────────────────────────────────
            let Some(claims) = verifier(username, password).await else {
                return Ok(deny(&realm));
            };

            // ── 3. Inject Claims into extensions for Ctx extractor ─────────────
            req.extensions_mut().insert(claims);

            // ── 4. Proceed to inner service ────────────────────────────────────
            inner.call(req).await
        })
    }
}

// ── Helpers ───────────────────────────────────────────────────────────────────

/// Parse `Authorization: Basic <base64(user:pass)>` → `(username, password)`.
pub fn parse_basic_header(headers: &axum::http::HeaderMap) -> Option<(String, String)> {
    let value = headers.get(header::AUTHORIZATION)?.to_str().ok()?;
    let encoded = value.strip_prefix("Basic ")?;
    let decoded = STANDARD.decode(encoded.trim()).ok()?;
    let s = String::from_utf8(decoded).ok()?;
    let mut parts = s.splitn(2, ':');
    let username = parts.next()?.to_string();
    let password = parts.next()?.to_string();
    Some((username, password))
}

fn deny(realm: &str) -> Response<Body> {
    Response::builder()
        .status(StatusCode::UNAUTHORIZED)
        .header(header::WWW_AUTHENTICATE, format!("Basic realm=\"{realm}\""))
        .header(header::CONTENT_TYPE, "application/json")
        .body(Body::from(
            r#"{"error":"Unauthorized","message":"Basic authentication required"}"#,
        ))
        .unwrap()
}