How to configure Vert.x for HTTP/2 without TLS

[Tim Fox]

Hi folks,

I am trying to get a vert.x WebClient to talk to a Vert.x HTTP server using HTTP/2 but without using TLS (It works fine using TLS).

I start the server with SSL disabled, and I connect using a WebClient after setting ProtocolVersion to HttpVersion.HTTP_2, but it fails with the error:

"HTTP/2 client preface string missing or corrupt".

Is there some other property I need to set here?

[Julien Viet]

Hi,

à priori it should work out of the box.

e.g here is an example showing a basic HTTP/2 server and client https://github.com/vert-x3/vertx-examples/tree/master/core-examples/src/main/java/io/vertx/example/core/http2/h2c

if you provide a reproducer we can investigate

Julien

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[Tim Fox]

Hey Julien,

The issue only seems to occur when I send the request body as a stream, if I send it as a buffer or string it works ok.

I'm probably doing something dumb with the stream, but can't figure it out.

Here's a gist with a reproducer https://gist.github.com/purplefox/45fe9ad9135d1d92052a016ad6662dc3

The server basically just echoes back the request body to the response.

The client attempts to submit a POST using a stream to provide the body.

You should see an exception logged out when you run it.

Thanks!

On Monday, 17 February 2020 10:31:09 UTC, Julien Viet wrote:

Hi,

à priori it should work out of the box.

e.g here is an example showing a basic HTTP/2 server and client https://github.com/vert-x3/vertx-examples/tree/master/core-examples/src/main/java/io/vertx/example/core/http2/h2c

if you provide a reproducer we can investigate

Julien

On 17 Feb 2020, at 09:45, Tim Fox <timv...@gmail.com> wrote:

Hi folks,

I am trying to get a vert.x WebClient to talk to a Vert.x HTTP server using HTTP/2 but without using TLS (It works fine using TLS).

I start the server with SSL disabled, and I connect using a WebClient after setting ProtocolVersion to HttpVersion.HTTP_2, but it fails with the error:

"HTTP/2 client preface string missing or corrupt".

Is there some other property I need to set here?

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[Julien Viet]

Hi Tim,

thanks for the reproducer, it seems due to the HTTP request being chunked.

When using HTTP over clear text (h2c) the default choice is to use an HTTP upgrade mechanism to establish an HTTP/2 channel. However the first HTTP request is always used as the first request, i.e if you do an HTTP post and send a body then the first request will be done using HTTP/1 and a real chunked encoded request (while the server will respond with an HTTP/2 response)

It seems that setting the request as chunked messes up with the HTTP/2 upgrade, this is a bug and will be fixed.

As work-around if you do control the HTTP2 server and it supports it I would recommend using H2C with prior knowledge which is still clear text but without HTTP upgrades (both client and server directly uses HTTP/2 encoding in clear text). Vertx HTTP server supports it out of the box and Vertx HTTP client supports it by using the calling setHttp2ClearTestUpgrade(false) on the options to enable it.

Julien

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[Tim Fox]

Thank you sir, all working now (with the workaround) :)

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[Julien Viet]

great! I'm glad it work for you.

This is actually more than a work around as it is spec compliant.

In practice it is more efficient to use because the upgrade mechanism of the first request will block other concurrent requests your client might be doing (so if you send a large body, other requests will have to wait until the first request is fully sent).

With prior knowledge connection fully multiplexes all requests.

So if you can afford using it, then you should go for it.

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[Julien Viet]

Hi,

the issue has been filed https://github.com/eclipse-vertx/vert.x/issues/3286

The patch should be released in 3.9 and next 4.0 milestone.

Julien