Client request stalls if streaming body request is not drained

[klaas]

I'm not sure if this is a bug or meant to be like this. I ran into this and it took me some time to figure out what I was doing wrong.

I'm using

base.on(.POST, "myupload", body: .stream) { req -> EventLoopFuture<HTTPResponseStatus> in
    let requestPromise = req.eventLoop.makePromise(of: HTTPResponseStatus.self)

    // [ ... handle body stream and complete requestPromise at the end ... ]

    return requestPromise.futureResult
}

to handle a streaming request with a reasonably large image file (e.g. 1 MB). This works fine.

BUT: When I change my code to validate some headers beforehand, it will stall and the client request will not get a response when the header is missing.

base.on(.POST, "myupload", body: .stream) { req -> EventLoopFuture<HTTPResponseStatus> in
    guard nil != req.headers["MyHeader"].first else {
        return req.eventLoop.makeSucceededFuture(.badRequest)
    }

    let requestPromise = req.eventLoop.makePromise(of: HTTPResponseStatus.self)

    // [ ... handle body stream and complete requestPromise at the end ... ]

    return requestPromise.futureResult
}

When I add some simple code to collect the body stream, it works again:

base.on(.POST, "myupload", body: .stream) { req -> EventLoopFuture<HTTPResponseStatus> in
    guard nil != req.headers["MyHeader"].first else {
        _ = req.body.collect(max: 10)
        return req.eventLoop.makeSucceededFuture(.badRequest)
    }

    let requestPromise = req.eventLoop.makePromise(of: HTTPResponseStatus.self)

    // [ ... handle body stream and complete requestPromise at the end ... ]

    return requestPromise.futureResult
}

Steps to reproduce

Setup a POST route with a streaming body and invoke it with httpie (http://httpie.org) from the command line to upload an image to this route:

http POST "http://localhost:8080/myupload" MyHeader:123 <yourImage.jpeg

This works.

http POST "http://localhost:8080/myupload" NotMyHeader:123 <yourImage.jpeg

This stalls in 4 out of 5 times and will eventually time out.

Expected behavior

Will not time event when the body stream is not collected / drained.

Actual behavior

It stalls in 4 out of 5 times.

Environment

• Vapor Framework version: 4.5.0
• Vapor Toolbox version: 3.1.0
• OS version: macOS 10.15.4

[tanner0101]

This has been fixed in https://github.com/vapor/vapor/releases/tag/4.7.0, thanks for reporting!