Enable h2c traffic for http servers.

config/confighttp/confighttp.go

@@ -24,6 +24,8 @@ import (
 	"github.com/rs/cors"
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 	"go.opentelemetry.io/otel"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config"
@@ -198,6 +200,24 @@ func (hss *HTTPServerSettings) ToServer(handler http.Handler, settings component
 		o(serverOpts)
 	}
 
+	// Declare an HTTP/1 server which:
+	// Handles only HTTP/1 traffic over TLS or non-TLS
+	h1Server := &http.Server{
+		Addr: hss.Endpoint,
+	}
+
+	// Declare an HTTP/2 server which will handle any H2 protocol traffic
+	// The PriorityWriteScheduler setting is used to match
+	// the default scheduler used by the HTTP/1 server for ALPN h2 traffic.
+	// https://github.com/golang/go/blob/5da2010840a3b4d99fcdccb7cdef0ffbd6e9a29f/src/net/http/server.go#L3269
+	h2Server := &http2.Server{
+		NewWriteScheduler: func() http2.WriteScheduler { return http2.NewPriorityWriteScheduler(nil) },
+	}
+
+	// Configure the HTTP/1 server to serve TLS ALPN=h2 traffic onto the H2 server
+	// The handler specified on the HTTP/1 server will be via H2 transport
+	http2.ConfigureServer(h1Server, h2Server)
+
 	handler = middleware.HTTPContentDecompressor(
 		handler,
 		middleware.WithErrorHandler(serverOpts.errorHandler),
@@ -226,7 +246,17 @@ func (hss *HTTPServerSettings) ToServer(handler http.Handler, settings component
 		}),
 	)
 
-	return &http.Server{
-		Handler: handler,
+	// Enable the H2C handler if and only if there are no TLS settings in
+	// accordance with rfc7540 section-3.4
+	if hss.TLSSetting == nil {
+		// Configure the H1 server to intercept HTTP/2 with prior
+		// knowledge and handle that with the H2 server.
+		// This allows H2 upgrade via the HTTP/1 server path
+		handler = h2c.NewHandler(handler, h2Server)
 	}
+
+	// Set the handler on the HTTP1 server
+	h1Server.Handler = handler
+
+	return h1Server
 }

config/confighttp/confighttp_test.go

@@ -15,9 +15,11 @@
 package confighttp
 
 import (
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -27,6 +29,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/net/http2"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/component/componenttest"
@@ -378,35 +381,41 @@ func TestHttpReception(t *testing.T) {
 			hasError: true,
 		},
 	}
+
 	// prepare
+	runServer := func(t *testing.T, hss *HTTPServerSettings) (s *http.Server, addr string) {
+		ln, err := hss.ToListener()
+		assert.NoError(t, err)
+		s = hss.ToServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			_, errWrite := fmt.Fprint(w, "test")
+			assert.NoError(t, errWrite)
+		}), componenttest.NewNopTelemetrySettings())
+
+		go func() {
+			_ = s.Serve(ln)
+		}()
+
+		// Wait for the servers to start
+		<-time.After(10 * time.Millisecond)
+		return s, ln.Addr().String()
+	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			hss := &HTTPServerSettings{
 				Endpoint:   "localhost:0",
 				TLSSetting: tt.tlsServerCreds,
 			}
-			ln, err := hss.ToListener()
-			assert.NoError(t, err)
-			s := hss.ToServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				_, errWrite := fmt.Fprint(w, "test")
-				assert.NoError(t, errWrite)
-			}), componenttest.NewNopTelemetrySettings())
-
-			go func() {
-				_ = s.Serve(ln)
-			}()
 
-			// Wait for the servers to start
-			<-time.After(10 * time.Millisecond)
+			s, addr := runServer(t, hss)
 
 			prefix := "https://"
 			if tt.tlsClientCreds.Insecure {
 				prefix = "http://"
 			}
 
 			hcs := &HTTPClientSettings{
-				Endpoint:   prefix + ln.Addr().String(),
+				Endpoint:   prefix + addr,
 				TLSSetting: *tt.tlsClientCreds,
 			}
 			client, errClient := hcs.ToClient(map[config.ComponentID]component.Extension{})
@@ -420,9 +429,41 @@ func TestHttpReception(t *testing.T) {
 				assert.NoError(t, errRead)
 				assert.Equal(t, "test", string(body))
 			}
+
 			require.NoError(t, s.Close())
 		})
 	}
+
+	t.Run("h2c", func(t *testing.T) {
+		hss := &HTTPServerSettings{
+			Endpoint: "localhost:0",
+		}
+
+		s, addr := runServer(t, hss)
+		// Check that h2c payloads are handled when serving insecure traffic
+		client := http.Client{
+			Transport: &http2.Transport{
+				// So http2.Transport doesn't complain the URL scheme isn't 'https'
+				AllowHTTP: true,
+				// Pretend we are dialing a TLS endpoint.
+				// Note, we ignore the passed tls.Config
+				DialTLS: func(network, addr string, cfg *tls.Config) (net.Conn, error) {
+					return net.Dial(network, addr)
+				},
+			},
+		}
+
+		hcs := &HTTPClientSettings{
+			Endpoint: "http://" + addr,
+		}
+		resp, errResp := client.Get(hcs.Endpoint)
+		assert.NoError(t, errResp)
+		body, errRead := ioutil.ReadAll(resp.Body)
+		assert.NoError(t, errRead)
+		assert.Equal(t, "test", string(body))
+		require.NoError(t, s.Close())
+
+	})
 }
 
 func TestHttpCors(t *testing.T) {
@@ -598,3 +639,61 @@ func TestHttpHeaders(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkHttpRequest(b *testing.B) {
+
+	tests := []struct {
+		name           string
+		tlsServerCreds *configtls.TLSServerSetting
+		tlsClientCreds *configtls.TLSClientSetting
+		hasError       bool
+	}{
+		{
+			name:           "noTLS",
+			tlsServerCreds: nil,
+			tlsClientCreds: &configtls.TLSClientSetting{
+				Insecure: true,
+			},
+		},
+		{
+			name: "TLS",
+			tlsServerCreds: &configtls.TLSServerSetting{
+				TLSSetting: configtls.TLSSetting{
+					CAFile:   path.Join(".", "testdata", "ca.crt"),
+					CertFile: path.Join(".", "testdata", "server.crt"),
+					KeyFile:  path.Join(".", "testdata", "server.key"),
+				},
+			},
+			tlsClientCreds: &configtls.TLSClientSetting{
+				TLSSetting: configtls.TLSSetting{
+					CAFile: path.Join(".", "testdata", "ca.crt"),
+				},
+				ServerName: "localhost",
+			},
+		},
+	}
+
+	for _, bb := range tests {
+		b.Run(bb.name, func(b *testing.B) {
+			hss := &HTTPServerSettings{
+				Endpoint:   "localhost:0",
+				TLSSetting: bb.tlsServerCreds,
+			}
+			s := hss.ToServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				_, errWrite := fmt.Fprint(w, "test")
+				assert.NoError(b, errWrite)
+			}), componenttest.NewNopTelemetrySettings())
+
+			req := httptest.NewRequest("GET", "/", nil)
+
+			for i := 0; i < b.N; i++ {
+				rw := httptest.NewRecorder()
+
+				// Use the handler generated by ToServer for benchmarking
+				// to avoid network artifacts
+				s.Handler.ServeHTTP(rw, req)
+			}
+		})
+	}
+
+}

go.mod

@@ -31,6 +31,7 @@ require (
 	go.opentelemetry.io/otel/trace v1.0.0
 	go.uber.org/atomic v1.9.0
 	go.uber.org/zap v1.19.1
+	golang.org/x/net v0.0.0-20210917221730-978cfadd31cf
 	golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1
 	google.golang.org/genproto v0.0.0-20210604141403-392c879c8b08
 	google.golang.org/grpc v1.40.0
@@ -66,7 +67,6 @@ require (
 	go.opentelemetry.io/contrib v0.23.0 // indirect
 	go.opentelemetry.io/otel/internal/metric v0.23.0 // indirect
 	go.uber.org/multierr v1.6.0 // indirect
-	golang.org/x/net v0.0.0-20210614182718-04defd469f4e // indirect
 	golang.org/x/text v0.3.6 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -518,8 +518,8 @@ golang.org/x/net v0.0.0-20210316092652-d523dce5a7f4/go.mod h1:RBQZq4jEuRlivfhVLd
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210610132358-84b48f89b13b/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20210614182718-04defd469f4e h1:XpT3nA5TvE525Ne3hInMh6+GETgn27Zfm9dxsThnX2Q=
-golang.org/x/net v0.0.0-20210614182718-04defd469f4e/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20210917221730-978cfadd31cf h1:R150MpwJIv1MpS0N/pc+NhTM8ajzvlmxlY5OYsrevXQ=
+golang.org/x/net v0.0.0-20210917221730-978cfadd31cf/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=