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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
use actix_http::{header, uri::Uri, RequestHead};

use super::{Guard, GuardContext};

/// Creates a guard that matches requests targeting a specific host.
///
/// # Matching Host
/// This guard will:
/// - match against the `Host` header, if present;
/// - fall-back to matching against the request target's host, if present;
/// - return false if host cannot be determined;
///
/// # Matching Scheme
/// Optionally, this guard can match against the host's scheme. Set the scheme for matching using
/// `Host(host).scheme(protocol)`. If the request's scheme cannot be determined, it will not prevent
/// the guard from matching successfully.
///
/// # Examples
/// The `Host` guard can be used to set up a form of [virtual hosting] within a single app.
/// Overlapping scope prefixes are usually discouraged, but when combined with non-overlapping guard
/// definitions they become safe to use in this way. Without these host guards, only routes under
/// the first-to-be-defined scope would be accessible. You can test this locally using `127.0.0.1`
/// and `localhost` as the `Host` guards.
/// ```
/// use actix_web::{web, http::Method, guard, App, HttpResponse};
///
/// App::new()
///     .service(
///         web::scope("")
///             .guard(guard::Host("www.rust-lang.org"))
///             .default_service(web::to(|| async {
///                 HttpResponse::Ok().body("marketing site")
///             })),
///     )
///     .service(
///         web::scope("")
///             .guard(guard::Host("play.rust-lang.org"))
///             .default_service(web::to(|| async {
///                 HttpResponse::Ok().body("playground frontend")
///             })),
///     );
/// ```
///
/// The example below additionally guards on the host URI's scheme. This could allow routing to
/// different handlers for `http:` vs `https:` visitors; to redirect, for example.
/// ```
/// use actix_web::{web, guard::Host, HttpResponse};
///
/// web::scope("/admin")
///     .guard(Host("admin.rust-lang.org").scheme("https"))
///     .default_service(web::to(|| async {
///         HttpResponse::Ok().body("admin connection is secure")
///     }));
/// ```
///
/// [virtual hosting]: https://en.wikipedia.org/wiki/Virtual_hosting
#[allow(non_snake_case)]
pub fn Host(host: impl AsRef<str>) -> HostGuard {
    HostGuard {
        host: host.as_ref().to_string(),
        scheme: None,
    }
}

fn get_host_uri(req: &RequestHead) -> Option<Uri> {
    req.headers
        .get(header::HOST)
        .and_then(|host_value| host_value.to_str().ok())
        .or_else(|| req.uri.host())
        .and_then(|host| host.parse().ok())
}

#[doc(hidden)]
pub struct HostGuard {
    host: String,
    scheme: Option<String>,
}

impl HostGuard {
    /// Set request scheme to match
    pub fn scheme<H: AsRef<str>>(mut self, scheme: H) -> HostGuard {
        self.scheme = Some(scheme.as_ref().to_string());
        self
    }
}

impl Guard for HostGuard {
    fn check(&self, ctx: &GuardContext<'_>) -> bool {
        // parse host URI from header or request target
        let req_host_uri = match get_host_uri(ctx.head()) {
            Some(uri) => uri,

            // no match if host cannot be determined
            None => return false,
        };

        match req_host_uri.host() {
            // fall through to scheme checks
            Some(uri_host) if self.host == uri_host => {}

            // Either:
            // - request's host does not match guard's host;
            // - It was possible that the parsed URI from request target did not contain a host.
            _ => return false,
        }

        if let Some(ref scheme) = self.scheme {
            if let Some(ref req_host_uri_scheme) = req_host_uri.scheme_str() {
                return scheme == req_host_uri_scheme;
            }

            // TODO: is this the correct behavior?
            // falls through if scheme cannot be determined
        }

        // all conditions passed
        true
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test::TestRequest;

    #[test]
    fn host_from_header() {
        let req = TestRequest::default()
            .insert_header((
                header::HOST,
                header::HeaderValue::from_static("www.rust-lang.org"),
            ))
            .to_srv_request();

        let host = Host("www.rust-lang.org");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("www.rust-lang.org").scheme("https");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org").scheme("https");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("crates.io");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("localhost");
        assert!(!host.check(&req.guard_ctx()));
    }

    #[test]
    fn host_without_header() {
        let req = TestRequest::default()
            .uri("www.rust-lang.org")
            .to_srv_request();

        let host = Host("www.rust-lang.org");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("www.rust-lang.org").scheme("https");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org").scheme("https");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("crates.io");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("localhost");
        assert!(!host.check(&req.guard_ctx()));
    }

    #[test]
    fn host_scheme() {
        let req = TestRequest::default()
            .insert_header((
                header::HOST,
                header::HeaderValue::from_static("https://www.rust-lang.org"),
            ))
            .to_srv_request();

        let host = Host("www.rust-lang.org").scheme("https");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("www.rust-lang.org");
        assert!(host.check(&req.guard_ctx()));

        let host = Host("www.rust-lang.org").scheme("http");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("blog.rust-lang.org").scheme("https");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("crates.io").scheme("https");
        assert!(!host.check(&req.guard_ctx()));

        let host = Host("localhost");
        assert!(!host.check(&req.guard_ctx()));
    }
}