illegal HTTP sent back

[weissi]

With my echo server

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()

Even when driving it correctly, vapor responds with illegal HTTP.

Repro:

• Start the above program
• echo -ne 'POST /echo HTTP/1.1\r\ntransfer-encoding: chunked\r\n\r\n1\r\nx\r\n0\r\n\r\n' | nc localhost 8080

Expected:

HTTP/1.1 200 OK
transfer-encoding: chunked
connection: keep-alive
date: Wed, 10 Jun 2020 22:26:51 GMT

1\r\n
x\r\n
0\r\n
\r\n

Actual:

HTTP/1.1 200 OK
content-length: 0
connection: keep-alive
date: Wed, 10 Jun 2020 22:26:51 GMT

x

Note that this is illegal HTTP. content-length is set to 0 and then we're still emitting characters. That should not be possible. For a user-facing API, there should be two options:

1. user supplies the content length in which case Vapor should validate and crash with good message if there's more or fewer bytes
2. user does not supply the content length in which case Vapor should automatically set transfer-encoding: chunked (or not add content-length: 0 which will make NIO add transfer-encoding: chunked).