ConnectInfo extractor no longer accepted in middleware::from_fn_with_state

[leonardoarcari]

• I have looked for existing issues (including closed) about this

Bug Report

Version

├── axum v0.7.1
│   ├── axum-core v0.4.0
│   ├── axum-macros v0.4.0 (proc-macro)
├── axum-extra v0.9.0
│   ├── axum v0.7.1 (*)
│   ├── axum-core v0.4.0 (*)

Platform

Windows 11 x64

Description

Starting from Axum v0.7, I can no longer extract ConnectInfo in a middleware::from_fn_with_state middleware. The following piece of code does not compile:

let app = Router::new()
            .route("/", get(|| async { "Hello World!" }))
            .route_layer(
                ServiceBuilder::new()
                    .layer(TraceLayer::new_for_http())
                    .layer(middleware::from_fn_with_state(
                        ctx.clone(),
                        requests_stats,
                    ))
            )
            .with_state(ctx.clone())
            .into_make_service_with_connect_info();

pub async fn requests_stats(
    State(state): State<AppContext>,
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    req: Request,
    next: Next,
) -> Result<Response> {
    /* middlware body */
}

Fails with the following error:

error[E0277]: the trait bound `axum::middleware::FromFn<fn(axum::extract::State<Arc<AppContextInner>>, ConnectInfo<SocketAddr>, hyper::Request<axum::body::Body>, axum::middleware::Next) -> impl futures::Future<Output = std::result::Result<hyper::Response<axum::body::Body>, DcaError>> {requests_stats}, Arc<AppContextInner>, Route, _>: tower::Service<hyper::Request<axum::body::Body>>` is not satisfied
   --> dcapal-backend\src\lib.rs:158:14
    |
158 |             .route_layer(
    |              ^^^^^^^^^^^ the trait `tower::Service<hyper::Request<axum::body::Body>>` is not implemented for `axum::middleware::FromFn<fn(axum::extract::State<Arc<AppContextInner>>, ConnectInfo<SocketAddr>, hyper::Request<axum::body::Body>, axum::middleware::Next) -> impl futures::Future<Output = std::result::Result<hyper::Response<axum::body::Body>, DcaError>> {requests_stats}, Arc<AppContextInner>, Route, _>`
    |
    = help: the following other types implement trait `tower::Service<Request>`:
              axum::middleware::FromFn<F, S, I, (T1,)>
              axum::middleware::FromFn<F, S, I, (T1, T2)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6, T7)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6, T7, T8)>
            and 8 others
    = note: required for `Trace<FromFn<fn(State<Arc<...>>, ..., ..., ...) -> ... {requests_stats}, ..., ..., ...>, ...>` to implement `tower::Service<hyper::Request<axum::body::Body>>`

Removing ConnectInfo<> extractors fixes it. This used to compile just fine on Axum v0.6.*.

Let me know if you need additional information.

Cheers! 🙇

[davidpdrsn]

Works fine for me

use std::net::SocketAddr;

use axum::{
    extract::{ConnectInfo, Request, State},
    middleware::{from_fn_with_state, Next},
    response::Response,
    routing::get,
    Router,
};

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/", get(|| async { "Hello World!" }))
        .route_layer(from_fn_with_state("state", requests_stats))
        .into_make_service_with_connect_info::<SocketAddr>();

    // run it
    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();
    println!("listening on {}", listener.local_addr().unwrap());
    axum::serve(listener, app).await.unwrap();
}

pub async fn requests_stats(
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    State(state): State<&'static str>,
    req: Request,
    next: Next,
) -> Response {
    dbg!(addr);
    dbg!(state);
    next.run(req).await
}

I see this in the console when sending a request

[examples/hello-world/src/main.rs:38] addr = 127.0.0.1:53708
[examples/hello-world/src/main.rs:39] state = "state"

[leonardoarcari]

Thanks for taking a look! That's interesting, I digged a bit more and it looks like my code breaks due to &Request being passed to another async function in requests_stats body.

This breaks

pub async fn requests_stats(
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    State(state): State<AppContext>,
    req: Request,
    next: Next,
) -> Result<Response> {
    // Visitors stats
    record_visitors_stats(&req, addr).await?;

    Ok(next.run(req).await)
}

async fn record_visitors_stats(
    req: &Request,
    addr: SocketAddr,
) -> Result<()> {
    static IP_HEADERS: [&str; 2] = ["CF-Connecting-IP", "X-Real-IP"];
    let ip = IP_HEADERS
        .iter()
        .find_map(|header| {
            req.headers().get("X-Real-IP").map(|h| {
                /* Do stuff with header */
            })
        })
        .unwrap_or(addr.ip());

    Ok(())
}

Funny enough, directly passing a &HeaderMap fixes it

pub async fn requests_stats(
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    State(state): State<AppContext>,
    req: Request,
    next: Next,
) -> Result<Response> {
    // Visitors stats
    let headers = req.headers();
    record_visitors_stats(headers, addr).await?;

    Ok(next.run(req).await)
}

async fn record_visitors_stats(
    headers: &HeaderMap,
    addr: SocketAddr,
) -> Result<()> {
    static IP_HEADERS: [&str; 2] = ["CF-Connecting-IP", "X-Real-IP"];
    let ip = IP_HEADERS
        .iter()
        .find_map(|header| {
            req.headers().get("X-Real-IP").map(|h| {
                /* Do stuff with header */
            })
        })
        .unwrap_or(addr.ip());

    Ok(())
}

Is it possible that the new axum_core::Body implementation breaks it due to the wrapped BoxBody which is !Sync?

[davidpdrsn]

Ah yes that makes sense. Request<Body> is not !Sync (because as you say Body is !Sync). That means &Request<Body> is !Send meaning the future returned by record_visitors_stats is also !Send and that makes it not compile. So you'll have to pass the headers directly.

The reason Body is !Sync is that you can't really do anything with &Body from multiple threads since streaming it requires a &mut Body (or rather a Pin<&mut Body>). So therefore streams are normally not !Sync. Another example of this is BoxStream from futures.

[leonardoarcari]

Yeah that sounds reasonable! Thanks for clarifying this, it wasn't trivial 🙂 Something like #1985 would have been so helpful but I'm glad we got to the bottom of it. Cheers man! 🙇

[an1217]

I don't know if you have a consistent script change the server script to axum::serve(add, app.into_make_service_with_connect_info::()) The extractor will be available but I have no way of knowing if it belongs to the proxy server