Add redirect handling to AcmeClient and including relevant error reporting.

Author: mdegel

src/acme.rs

@@ -43,6 +43,9 @@ const MAX_SERVER_RETRY_INTERVAL: Duration = Duration::from_secs(60);
 
 static REPLAY_NONCE: http::HeaderName = http::HeaderName::from_static("replay-nonce");
 
+// Maximum number of redirects to follow for a single request.
+const MAX_REDIRECTS: usize = 10;
+
 pub enum NewAccountOutput<'a> {
     Created(&'a str),
     Found(&'a str),
@@ -170,12 +173,29 @@ where
     }
 
     pub async fn get(&self, url: &Uri) -> Result<http::Response<Bytes>, RequestError> {
-        let req = http::Request::builder()
-            .uri(url)
-            .method(http::Method::GET)
-            .header(http::header::CONTENT_LENGTH, 0)
-            .body(String::new())?;
-        Ok(self.http.request(req).await?)
+        let mut u = url.clone();
+
+        for _ in 0..MAX_REDIRECTS {
+            let req = http::Request::builder()
+                .uri(&u)
+                .method(http::Method::GET)
+                .header(http::header::CONTENT_LENGTH, 0)
+                .body(String::new())?;
+            let res = self.http.request(req).await?;
+
+            if res.status().is_redirection() {
+                if let Some(location) = try_get_header(res.headers(), http::header::LOCATION) {
+                    u = Uri::try_from(location).map_err(RequestError::UrlParse)?;
+                    continue;
+                } else {
+                    return Err(RequestError::RedirectNoLocation);
+                }
+            }
+
+            return Ok(res);
+        }
+
+        Err(RequestError::TooManyRedirects)
     }
 
     pub async fn post<P: AsRef<[u8]>>(

src/acme/error.rs

@@ -145,6 +145,15 @@ pub enum RequestError {
 
     #[error("cannot sign request body ({0})")]
     Sign(#[from] crate::jws::Error),
+
+    #[error("cannot parse URL ({0})")]
+    UrlParse(#[from] http::uri::InvalidUri),
+
+    #[error("redirect response missing Location header")]
+    RedirectNoLocation,
+
+    #[error("too many redirects")]
+    TooManyRedirects,
 }
 
 impl From<HttpClientError> for RequestError {