Fix handling of missing Accept header

Workaround for tokio-rs/axum#1781.

src/axum.rs

@@ -3,29 +3,43 @@ use crate::params::OpaqueParams;
 use crate::response::OpaqueResponse;
 use crate::transaction::server_handler;
 use crate::Devices;
-use axum::extract::Path;
+use async_trait::async_trait;
+use axum::extract::{FromRequest, Path};
+use axum::headers::{Header, HeaderName, HeaderValue};
 use axum::http::Method;
 use axum::routing::{on, MethodFilter};
-use axum::{Form, Router, TypedHeader};
+use axum::{Form, Router};
 use futures::StreamExt;
 use mediatype::MediaTypeList;
 use std::sync::Arc;
 
 // A hack until TypedHeader supports Accept natively.
+#[derive(Default)]
 struct AcceptsImageBytes {
     accepts: bool,
 }
 
-impl axum::headers::Header for AcceptsImageBytes {
-    fn name() -> &'static axum::headers::HeaderName {
-        static ACCEPT: axum::headers::HeaderName = axum::headers::HeaderName::from_static("accept");
+#[async_trait]
+impl<B: Send> FromRequest<B> for AcceptsImageBytes {
+    type Rejection = std::convert::Infallible;
+
+    async fn from_request(
+        req: &mut axum::extract::RequestParts<B>,
+    ) -> Result<Self, Self::Rejection> {
+        Ok(Self::decode(&mut req.headers().get_all("accept").into_iter()).unwrap_or_default())
+    }
+}
+
+impl Header for AcceptsImageBytes {
+    fn name() -> &'static HeaderName {
+        static ACCEPT: HeaderName = HeaderName::from_static("accept");
         &ACCEPT
     }
 
     fn decode<'value, I>(values: &mut I) -> Result<Self, axum::headers::Error>
     where
         Self: Sized,
-        I: Iterator<Item = &'value axum::http::HeaderValue>,
+        I: Iterator<Item = &'value HeaderValue>,
     {
         let mut accepts = false;
         for value in values {
@@ -47,14 +61,12 @@ impl axum::headers::Header for AcceptsImageBytes {
         Ok(Self { accepts })
     }
 
-    fn encode<E: Extend<axum::http::HeaderValue>>(&self, values: &mut E) {
-        values.extend(std::iter::once(axum::http::HeaderValue::from_static(
-            if self.accepts {
-                "application/imagebytes"
-            } else {
-                "*/*"
-            },
-        )));
+    fn encode<E: Extend<HeaderValue>>(&self, values: &mut E) {
+        values.extend(std::iter::once(HeaderValue::from_static(if self.accepts {
+            "application/imagebytes"
+        } else {
+            "*/*"
+        })));
     }
 }
 
@@ -99,7 +111,7 @@ impl Devices {
                         usize,
                         String,
                     )>,
-                          TypedHeader(accepts_image_bytes): TypedHeader<AcceptsImageBytes>,
+                          accepts_image_bytes: AcceptsImageBytes,
                           Form(params): Form<OpaqueParams>| {
                         let is_mut = method == Method::PUT;