Expose the default headers used by clients

This is convenient in debug and testing scenario for code using
reqwest. In particular for introspecting to know what will be sent
without introducing a MITM.

Author: er-vin

src/async_impl/client.rs

@@ -83,7 +83,7 @@ pub struct Client {
 /// A `ClientBuilder` can be used to create a `Client` with custom configuration.
 #[must_use]
 pub struct ClientBuilder {
-    config: Config,
+    pub(crate) config: Config,
 }
 
 enum HttpVersionPref {
@@ -150,10 +150,10 @@ impl Service<hyper::Request<crate::async_impl::body::Body>> for HyperService {
     }
 }
 
-struct Config {
+pub(crate) struct Config {
     // NOTE: When adding a new field, update `fmt::Debug for ClientBuilder`
     accepts: Accepts,
-    headers: HeaderMap,
+    pub(crate) headers: HeaderMap,
     #[cfg(feature = "__tls")]
     hostname_verification: bool,
     #[cfg(feature = "__tls")]
@@ -2357,6 +2357,11 @@ impl Client {
         ClientBuilder::new()
     }
 
+    /// Get the headers this `Client` will add to all its `Request`s.
+    pub fn headers(&self) -> &crate::header::HeaderMap {
+        &self.inner.as_ref().headers
+    }
+
     /// Convenience method to make a `GET` request to a URL.
     ///
     /// # Errors

src/blocking/client.rs

@@ -1199,6 +1199,11 @@ impl Client {
         ClientBuilder::new()
     }
 
+    /// Get the headers this `Client` will add to all its `Request`s.
+    pub fn headers(&self) -> &crate::header::HeaderMap {
+        &self.inner.headers
+    }
+
     /// Convenience method to make a `GET` request to a URL.
     ///
     /// # Errors
@@ -1302,6 +1307,7 @@ impl fmt::Debug for ClientBuilder {
 #[derive(Clone)]
 struct ClientHandle {
     timeout: Timeout,
+    headers: crate::header::HeaderMap,
     inner: Arc<InnerClientHandle>,
 }
 
@@ -1332,6 +1338,7 @@ impl Drop for InnerClientHandle {
 impl ClientHandle {
     fn new(builder: ClientBuilder) -> crate::Result<ClientHandle> {
         let timeout = builder.timeout;
+        let headers = builder.inner.config.headers.clone();
         let builder = builder.inner;
         let (tx, rx) = mpsc::unbounded_channel::<(async_impl::Request, OneshotResponse)>();
         let (spawn_tx, spawn_rx) = oneshot::channel::<crate::Result<()>>();
@@ -1400,6 +1407,7 @@ impl ClientHandle {
 
         Ok(ClientHandle {
             timeout,
+            headers,
             inner: inner_handle,
         })
     }

tests/blocking.rs

@@ -216,6 +216,8 @@ fn test_default_headers() {
     let url = format!("http://{}/1", server.addr());
     let res = client.get(&url).send().unwrap();
 
+    assert_eq!(client.headers()["reqwest-test"], "orly");
+
     assert_eq!(res.url().as_str(), &url);
     assert_eq!(res.status(), reqwest::StatusCode::OK);
 }
@@ -250,6 +252,8 @@ fn test_override_default_headers() {
         .send()
         .unwrap();
 
+    assert_eq!(client.headers()[&http::header::AUTHORIZATION], "iamatoken");
+
     assert_eq!(res.url().as_str(), &url);
     assert_eq!(res.status(), reqwest::StatusCode::OK);
 }
@@ -275,6 +279,10 @@ fn test_appended_headers_not_overwritten() {
         .send()
         .unwrap();
 
+    let mut accepts = client.headers().get_all("accept").into_iter();
+    assert_eq!(accepts.next().unwrap(), "*/*");
+    assert_eq!(accepts.next(), None);
+
     assert_eq!(res.url().as_str(), &url);
     assert_eq!(res.status(), reqwest::StatusCode::OK);
 
@@ -298,6 +306,10 @@ fn test_appended_headers_not_overwritten() {
         .send()
         .unwrap();
 
+    let mut accepts = client.headers().get_all("accept").into_iter();
+    assert_eq!(accepts.next().unwrap(), "text/html");
+    assert_eq!(accepts.next(), None);
+
     assert_eq!(res.url().as_str(), &url);
     assert_eq!(res.status(), reqwest::StatusCode::OK);
 }

tests/client.rs

@@ -47,15 +47,18 @@ async fn auto_headers() {
     });
 
     let url = format!("http://{}/1", server.addr());
-    let res = reqwest::Client::builder()
+    let client = reqwest::Client::builder()
         .no_proxy()
         .build()
-        .unwrap()
-        .get(&url)
+        .unwrap();
+    let res = client.get(&url)
         .send()
         .await
         .unwrap();
 
+    assert_eq!(client.headers()["accept"], "*/*");
+    assert_eq!(client.headers().get("user-agent"), None);
+
     assert_eq!(res.url().as_str(), &url);
     assert_eq!(res.status(), reqwest::StatusCode::OK);
     assert_eq!(res.remote_addr(), Some(server.addr()));
@@ -93,15 +96,17 @@ async fn user_agent() {
     });
 
     let url = format!("http://{}/ua", server.addr());
-    let res = reqwest::Client::builder()
+    let client = reqwest::Client::builder()
         .user_agent("reqwest-test-agent")
         .build()
-        .expect("client builder")
-        .get(&url)
+        .expect("client builder");
+    let res = client.get(&url)
         .send()
         .await
         .expect("request");
 
+    assert_eq!(client.headers()["user-agent"], "reqwest-test-agent");
+
     assert_eq!(res.status(), reqwest::StatusCode::OK);
 }