Fix oauth 0.5 breakage

Updates `divviup-api` to adapt to the breaking changes in `oauth 0.5`.
Much of this follows from advice in the [upgrade guide][1].

- move entire crate to `http 1.1.0`
    - use `http-compat-1` feature on `trillium-http`
- adopt builder pattern for constructing `oauth2::BasicClient`
    - add type alias `ConfiguredOauthClient` as a shorthand for
      `oauth2::BasicClient<...>`
- add wrapper around `trillium_client::Client` so we can implement
  `oauth2::AsyncHttpClient` on it
    - translate `oauth2::HttpRequest/Response` to/from Trillium
      equivalents

[1]: https://github.com/ramosbugs/oauth2-rs/blob/main/UPGRADE.md

Cargo.toml

@@ -74,7 +74,7 @@ trillium-compression = "0.1.3"
 trillium-conn-id = "0.2.3"
 trillium-cookies = "0.4.2"
 trillium-forwarding = "0.2.4"
-trillium-http = { version = "0.3.14", features = ["http-compat", "serde"] }
+trillium-http = { version = "0.3.14", features = ["http-compat-1", "serde"] }
 trillium-logger = "0.4.5"
 trillium-macros = "0.0.6"
 trillium-prometheus = "0.2.0"

src/handler/oauth2.rs

@@ -1,19 +1,30 @@
 use crate::{User, USER_SESSION_KEY};
 use oauth2::{
     basic::{BasicClient, BasicErrorResponseType},
-    AuthUrl, AuthorizationCode, ClientId, ClientSecret, CsrfToken, HttpResponse, PkceCodeChallenge,
-    PkceCodeVerifier, RedirectUrl, RequestTokenError, Scope, StandardErrorResponse, TokenResponse,
-    TokenUrl,
+    AsyncHttpClient, AuthUrl, AuthorizationCode, ClientId, ClientSecret, CsrfToken, EndpointNotSet,
+    EndpointSet, HttpRequest, HttpResponse, PkceCodeChallenge, PkceCodeVerifier, RedirectUrl,
+    RequestTokenError, Scope, StandardErrorResponse, TokenResponse, TokenUrl,
 };
 use querystrong::QueryStrong;
-use std::sync::Arc;
+use std::{future::Future, pin::Pin, sync::Arc};
 use trillium::{conn_try, conn_unwrap, Conn, KnownHeaderName::Authorization, Status};
 use trillium_client::{Client, ClientSerdeError};
 use trillium_http::Headers;
 use trillium_redirect::RedirectConnExt;
 use trillium_sessions::SessionConnExt;
 use url::Url;
 
+/// Type alias for an oauth2::Client once we've finished configuring it in `OauthClient::new`.
+/// Crate oauth's guide to upgrading to 0.5 recommends defining this kind of alias:
+/// https://github.com/ramosbugs/oauth2-rs/blob/main/UPGRADE.md#add-typestate-generic-types-to-client
+pub type ConfiguredOauthClient = BasicClient<
+    EndpointSet,    // HasAuthURL
+    EndpointNotSet, // HasDeviceAuthURL
+    EndpointNotSet, // HasIntrospectionURL
+    EndpointNotSet, // HasRevocationURL
+    EndpointSet,    // HasTokenURL
+>;
+
 #[derive(Clone, Debug)]
 pub struct Oauth2Config {
     pub authorize_url: Url,
@@ -93,7 +104,7 @@ enum OauthError {
     #[error(transparent)]
     InvalidStatusCode(#[from] oauth2::http::status::InvalidStatusCode),
     #[error(transparent)]
-    HeaderConversionError(#[from] trillium_http::http_compat::HeaderConversionError),
+    HeaderConversionError(#[from] trillium_http::http_compat1::HeaderConversionError),
     #[error(transparent)]
     UrlError(#[from] url::ParseError),
     #[error("error response: {0}")]
@@ -104,6 +115,8 @@ enum OauthError {
     Other(String),
     #[error("expected a successful status, but found {0:?}")]
     UnexpectedStatus(Option<Status>),
+    #[error(transparent)]
+    HttpCrateError(#[from] oauth2::http::Error),
 }
 
 impl From<RequestTokenError<OauthError, StandardErrorResponse<BasicErrorResponseType>>>
@@ -138,7 +151,7 @@ pub struct OauthClient(Arc<OauthClientInner>);
 #[derive(Debug)]
 struct OauthClientInner {
     oauth_config: Oauth2Config,
-    oauth2_client: BasicClient,
+    oauth2_client: ConfiguredOauthClient,
 }
 
 impl OauthClient {
@@ -153,20 +166,7 @@ impl OauthClient {
             .exchange_code(auth_code)
             .set_pkce_verifier(pkce_verifier)
             .add_extra_param("audience", &self.0.oauth_config.audience)
-            .request_async(|req| async move {
-                let mut conn = http_client
-                    .build_conn(req.method, req.url)
-                    .with_body(req.body)
-                    .with_request_headers(Headers::from(req.headers))
-                    .await?;
-                let status_code = conn.status().unwrap().try_into()?;
-                let body = conn.response_body().read_bytes().await?;
-                Ok::<_, OauthError>(HttpResponse {
-                    status_code,
-                    headers: conn.response_headers().clone().try_into()?,
-                    body,
-                })
-            })
+            .request_async(&ClientWrapper(http_client))
             .await?;
 
         let mut client_conn = self
@@ -190,25 +190,58 @@ impl OauthClient {
     }
 
     pub fn new(config: &Oauth2Config) -> Self {
-        let oauth2_client = BasicClient::new(
-            ClientId::new(config.client_id.clone()),
-            Some(ClientSecret::new(config.client_secret.clone())),
-            AuthUrl::from_url(config.authorize_url.clone()),
-            Some(TokenUrl::from_url(config.token_url.clone())),
-        )
-        .set_redirect_uri(RedirectUrl::from_url(config.redirect_url.clone()));
+        let oauth2_client = BasicClient::new(ClientId::new(config.client_id.clone()))
+            .set_client_secret(ClientSecret::new(config.client_secret.clone()))
+            .set_auth_uri(AuthUrl::from_url(config.authorize_url.clone()))
+            .set_token_uri(TokenUrl::from_url(config.token_url.clone()))
+            .set_redirect_uri(RedirectUrl::from_url(config.redirect_url.clone()));
 
         Self(Arc::new(OauthClientInner {
             oauth_config: config.clone(),
             oauth2_client,
         }))
     }
 
-    pub fn oauth2_client(&self) -> &BasicClient {
+    pub fn oauth2_client(&self) -> &ConfiguredOauthClient {
         &self.0.oauth2_client
     }
 
     pub fn http_client(&self) -> &Client {
         &self.0.oauth_config.http_client
     }
 }
+
+// Wraps a [`trillium_client::Client`] so we can implement [`oauth2::AsyncHttpClient`] on it, as
+// otherwise the orphan rule would forbid this.
+struct ClientWrapper(Client);
+
+// Inspired by the impls `oauth2` provides for `reqwest::Client`
+// https://github.com/ramosbugs/oauth2-rs/blob/23b952b23e6069525bc7e4c4f2c4924b8d28ce3a/src/reqwest.rs
+impl<'c> AsyncHttpClient<'c> for ClientWrapper {
+    type Error = OauthError;
+    type Future = Pin<Box<dyn Future<Output = Result<HttpResponse, Self::Error>> + Send + 'c>>;
+
+    fn call(&'c self, req: HttpRequest) -> Self::Future {
+        Box::pin(async move {
+            // Translate the oauth2::http::Request into a Trillium request
+            let mut conn = self
+                .0
+                .build_conn(req.method(), req.uri().to_string().parse::<Url>()?)
+                .with_body(req.body().clone())
+                .with_request_headers(Headers::from(req.headers().clone()))
+                .await?;
+            let status_code: oauth2::http::StatusCode = conn.status().unwrap().try_into()?;
+            let body = conn.response_body().read_bytes().await?;
+
+            // Now transform the Trillium response back into an http::Response
+            let mut builder = oauth2::http::Response::builder().status(status_code);
+            let http_headers: oauth2::http::HeaderMap =
+                conn.response_headers().clone().try_into()?;
+            builder
+                .headers_mut()
+                .ok_or_else(|| OauthError::Other("no headers in builder?".into()))?
+                .extend(http_headers);
+            Ok::<_, OauthError>(builder.body(body)?)
+        })
+    }
+}