HTTP echo server crashes with unfulfilled promise if client uses EOF framing

[weissi]

I tried to implement a HTTP echo server and it always crashes with a promise leak

import Vapor

var env = try Environment.detect()
try LoggingSystem.bootstrap(from: &env)

let app = Application(env)
defer { app.shutdown() }

app.on(.POST, "echo")  { request -> Response in
    return Response(body: .init(stream: { writer in
        request.body.drain { body in
            switch body {
            case .buffer(let buffer):
                return writer.write(.buffer(buffer))
            case .error(let error):
                return writer.write(.error(error))
            case .end:
                return writer.write(.end)
            }
        }
    }, count: 0))
}

try app.run()

Repro:

• run the above program
• echo -ne 'POST /echo HTTP/1.1\r\n\r\n' | nc localhost 8080 (note this doesn't send a content-length or transfer-encoding header which means it's EOF framed (message ends on EOF, NIO will handle that though and send you an .end on EOF)).

Result:

Fatal error: leaking promise created at (file: ".../checkouts/vapor/Sources/Vapor/HTTP/Server/HTTPServerHandler.swift", line: 53): file .../checkouts/vapor/Sources/Vapor/HTTP/Server/HTTPServerHandler.swift, line 53