A POC showing how to serve a HTTP2 server over an outgoing connection (PTTH style)

http2_test.go

// Run with
//
//     $ GODEBUG=http2debug=2 go test . -v
//
// for debug output
package main

import (
	"crypto/tls"
	"fmt"
	"io"
	"net"
	"net/http"
	"strings"
	"sync"
	"testing"

	"github.com/stretchr/testify/require"
	"golang.org/x/net/http2"
)

const handlerPayload = "Hello World"

func TestHTTP2Stuff(t *testing.T) {
	cert, err := tls.X509KeyPair(LocalhostCert, LocalhostKey)
	require.NoError(t, err)

	l, err := net.Listen("tcp", "127.0.0.1:0")
	require.NoError(t, err)
	t.Cleanup(func() { l.Close() })

	cfg := tls.Config{
		Certificates:       []tls.Certificate{cert},
		InsecureSkipVerify: true,
	}
	tlsListener := tls.NewListener(l, &cfg)

	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		defer wg.Done()
		dialServer(t, cert, l.Addr().String())
	}()
	go func() {
		defer wg.Done()
		cc, err := tlsListener.Accept()
		require.NoError(t, err)

		defer func() { cc.Close() }()

		handleConn(t, cc)
	}()
	wg.Wait()
}

func handleConn(t *testing.T, c net.Conn) {
	t.Logf("server: Accepted connection from %s", c.RemoteAddr().String())

	err := c.(*tls.Conn).Handshake()
	require.NoError(t, err)

	tr := http2.Transport{}
	cc, err := tr.NewClientConn(c)
	require.NoError(t, err)

	req, err := http.NewRequest(http.MethodPost, "https://"+c.RemoteAddr().String(), nil)
	require.NoError(t, err)

	resp1, err := cc.RoundTrip(req)
	require.NoError(t, err)
	defer resp1.Body.Close()
	t.Logf("server: Received first response: %s", resp1.Status)

	// Do a second request while the first is still in progress
	resp2, err := cc.RoundTrip(req)
	require.NoError(t, err)
	t.Logf("server: Received second response: %s", resp2.Status)

	data, err := io.ReadAll(resp1.Body)
	require.NoError(t, err)

	require.Equal(t, "HTTP/2.0", resp1.Proto)
	require.Equal(t, handlerPayload, string(data))

	data, err = io.ReadAll(resp2.Body)
	require.NoError(t, err)

	require.Equal(t, "HTTP/2.0", resp2.Proto)
	require.Equal(t, handlerPayload, string(data))
}

func dialServer(t *testing.T, cert tls.Certificate, addr string) {
	t.Logf("client: Dialing %s", addr)
	cfg := tls.Config{
		Certificates:       []tls.Certificate{cert},
		InsecureSkipVerify: true,
	}
	con, err := tls.Dial("tcp", addr, &cfg)
	require.NoError(t, err)

	t.Log("client: Serving requests on connection now")
	var server http2.Server
	server.ServeConn(con, &http2.ServeConnOpts{
		Handler: http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
			t.Logf("client: Serving request: url=%s proto=%s", req.URL.String(), req.Proto)
			fmt.Fprint(w, handlerPayload)
		}),
	})
}

// Copied from stdlib net/http/internal/testcert.go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// LocalhostCert is a PEM-encoded TLS cert with SAN IPs
// "127.0.0.1" and "[::1]", expiring at Jan 29 16:00:00 2084 GMT.
// generated from src/crypto/tls:
// go run generate_cert.go  --rsa-bits 1024 --host 127.0.0.1,::1,example.com --ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
var LocalhostCert = []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)

// LocalhostKey is the private key for localhostCert.
var LocalhostKey = []byte(testingKey(`-----BEGIN RSA TESTING KEY-----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-----END RSA TESTING KEY-----`))

func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "PRIVATE KEY") }