HTTP2_Plain in node-http2 module is not working? - http2

Question

I want to create a http2 server using node-http2 module without TLS. My code is as follows:
http2 = require('http2');
const bunyan = require('bunyan');
var log = bunyan.createLogger({name: "HTTP2 server without TLS!"});
var options = {
log: log
}
var server = http2.raw.createServer(options, function(request, response) {
console.log("Receiving HTTP2 request!");
// response.writeHead(200);
response.end('Hello world from HTTP2!');
});
server.listen(8000);
However, it does not work. When connecting to this server from chrome, it shows downloading something. When I closed the server, the downloading is finished with blank file (26 bytes).
Does anyone know what is wrong here? Do I need to configure the browser? Thanks in advance!

Answer 1

Chrome and all other browsers only support HTTP/2 over TLS (h2) and not plain HTTP/2 (h2c). So your browser does not understand what is returned from the server and apparently node-http2 does not send a proper error response when it receives a non-http2 request.

Answer 2

The problem seems not just from the browser. Using [curl] curllink that supports http2 over an http:// URL does not working either. Following is the output from the curl:
$ curl -I --http2 http://54.208.83.136:8000/ -v -k
* Trying 54.208.83.136...
* Connected to 54.208.83.136 (54.208.83.136) port 8000 (#0)
> HEAD / HTTP/1.1
> Host: 54.208.83.136:8000
> User-Agent: curl/7.47.1
> Accept: */*
> Connection: Upgrade, HTTP2-Settings
> Upgrade: h2c
> HTTP2-Settings: AAMAAABkAAQAAP__
>
As we see from the curl output. It sends http/1.1 Upgrade request with proper headers set as it supposed to do according to the [http2 rfc] rfclink.
On the server side, the logs were very long, so I present here only the content of msg in the relevant three logs.
New incoming HTTP/2 connection
Client connection header prelude does not match
PROTOCOL ERROR, Fatal error, closing connection
So basically the server closed the connection because the client connection header prelude does not match. By checking the code, I figured out the error was originated from the readPrelude function of [endpoint.js] endpointlink. It is a function to read the client header, but I don't know what is wrong in the client header :(.
Thus maybe I can say the node-http2 module does not support http2 over plaintext.
Update: it turns out that I was wrong. The node-http2 module do support http2 over plaintext with direct connecting, it does not support HTTP/2 server with Upgrade from HTTP/1.1. The problem resulted from the client side using Upgrade mechanism to connect to the server not supporting Upgrade. Using nghttp client to connect sever with prior knowledge works as follows.
$ nghttp http://127.0.0.1:8000/
Hello world from HTTP2!
nghttpd server also supports HTTP2 without TLS, even though it does not support HTTP Upgrade.
$ nghttpd -d /Documents/Proxy 8080 --no-tls -v
So I highly suggest to use nghttp when you want to test HTTP2 without TLS.