crux_http/middleware/
redirect.rs

1//! HTTP Redirect middleware.
2//!
3//! # Examples
4//!
5//! ```no_run
6//! # enum Event { ReceiveResponse(crux_http::Result<crux_http::Response<Vec<u8>>>) }
7//! # struct Capabilities { http: crux_http::Http<Event> }
8//! # fn update(caps: &Capabilities) {
9//!
10//! caps.http
11//!     .get("https://httpbin.org/redirect/2")
12//!     .middleware(crux_http::middleware::Redirect::default())
13//!     .send(Event::ReceiveResponse)
14//! # }
15//! ```
16
17use crate::middleware::{Middleware, Next, Request};
18use crate::{Client, ResponseAsync, Result};
19use http_types::{headers, StatusCode, Url};
20
21// List of acceptable 300-series redirect codes.
22const REDIRECT_CODES: &[StatusCode] = &[
23    StatusCode::MovedPermanently,
24    StatusCode::Found,
25    StatusCode::SeeOther,
26    StatusCode::TemporaryRedirect,
27    StatusCode::PermanentRedirect,
28];
29
30/// A middleware which attempts to follow HTTP redirects.
31#[derive(Debug)]
32pub struct Redirect {
33    attempts: u8,
34}
35
36impl Redirect {
37    /// Create a new instance of the Redirect middleware, which attempts to follow redirects
38    /// up to as many times as specified.
39    ///
40    /// Consider using `Redirect::default()` for the default number of redirect attempts.
41    ///
42    /// This middleware will follow redirects from the `Location` header if the server returns
43    /// any of the following http response codes:
44    /// - 301 Moved Permanently
45    /// - 302 Found
46    /// - 303 See other
47    /// - 307 Temporary Redirect
48    /// - 308 Permanent Redirect
49    ///
50    /// # Errors
51    ///
52    /// An error will be passed through the middleware stack if the value of the `Location`
53    /// header is not a validly parsing url.
54    ///
55    /// # Caveats
56    ///
57    /// This will presently make at least one additional HTTP request before the actual request to
58    /// determine if there is a redirect that should be followed, so as to preserve any request body.
59    ///
60    /// # Examples
61    ///
62    /// ```no_run
63    /// # enum Event { ReceiveResponse(crux_http::Result<crux_http::Response<Vec<u8>>>) }
64    /// # struct Capabilities { http: crux_http::Http<Event> }
65    /// # fn update(caps: &Capabilities) {
66    ///
67    /// caps.http
68    ///     .get("https://httpbin.org/redirect/2")
69    ///     .middleware(crux_http::middleware::Redirect::default())
70    ///     .send(Event::ReceiveResponse)
71    /// # }
72    /// ```
73    pub fn new(attempts: u8) -> Self {
74        Redirect { attempts }
75    }
76}
77
78#[async_trait::async_trait]
79impl Middleware for Redirect {
80    async fn handle(
81        &self,
82        mut req: Request,
83        client: Client,
84        next: Next<'_>,
85    ) -> Result<ResponseAsync> {
86        let mut redirect_count: u8 = 0;
87
88        // Note(Jeremiah): This is not ideal.
89        //
90        // HttpClient is currently too limiting for efficient redirects.
91        // We do not want to make unnecessary full requests, but it is
92        // presently required due to how Body streams work.
93        //
94        // Ideally we'd have methods to send a partial request stream,
95        // without sending the body, that would potnetially be able to
96        // get a server status before we attempt to send the body.
97        //
98        // As a work around we clone the request first (without the body),
99        // and try sending it until we get some status back that is not a
100        // redirect.
101
102        let mut base_url = req.url().clone();
103
104        while redirect_count < self.attempts {
105            redirect_count += 1;
106            let r: Request = req.clone();
107            let res: ResponseAsync = client.send(r).await?;
108            if REDIRECT_CODES.contains(&res.status()) {
109                if let Some(location) = res.header(headers::LOCATION) {
110                    let http_req: &mut http_types::Request = req.as_mut();
111                    *http_req.url_mut() = match Url::parse(location.last().as_str()) {
112                        Ok(valid_url) => {
113                            base_url = valid_url;
114                            base_url.clone()
115                        }
116                        Err(e) => match e {
117                            http_types::url::ParseError::RelativeUrlWithoutBase => {
118                                base_url.join(location.last().as_str())?
119                            }
120                            e => return Err(e.into()),
121                        },
122                    };
123                }
124            } else {
125                break;
126            }
127        }
128
129        Ok(next.run(req, client).await?)
130    }
131}
132
133impl Default for Redirect {
134    /// Create a new instance of the Redirect middleware, which attempts to follow up to
135    /// 3 redirects (not including the actual request).
136    fn default() -> Self {
137        Self { attempts: 3 }
138    }
139}
crux_http/middleware/redirect.rs

crux_http/middleware/
redirect.rs
