http2/h2c: propagate HTTP/1 server configuration to HTTP/2

Fixes golang/go#37089

Change-Id: I793bf8b420fd7b5a47b45ad1521c5b5f9e0321b2
GitHub-Last-Rev: 805b90e
GitHub-Pull-Request: #139
Reviewed-on: https://go-review.googlesource.com/c/net/+/419181
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Damien Neil <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Damien Neil <[email protected]>

http2/h2c/h2c.go

@@ -70,6 +70,15 @@ func NewHandler(h http.Handler, s *http2.Server) http.Handler {
 	}
 }
 
+// extractServer extracts existing http.Server instance from http.Request or create an empty http.Server
+func extractServer(r *http.Request) *http.Server {
+	server, ok := r.Context().Value(http.ServerContextKey).(*http.Server)
+	if ok {
+		return server
+	}
+	return new(http.Server)
+}
+
 // ServeHTTP implement the h2c support that is enabled by h2c.GetH2CHandler.
 func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Handle h2c with prior knowledge (RFC 7540 Section 3.4)
@@ -87,6 +96,7 @@ func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		defer conn.Close()
 		s.s.ServeConn(conn, &http2.ServeConnOpts{
 			Context:          r.Context(),
+			BaseConfig:       extractServer(r),
 			Handler:          s.Handler,
 			SawClientPreface: true,
 		})
@@ -104,6 +114,7 @@ func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		defer conn.Close()
 		s.s.ServeConn(conn, &http2.ServeConnOpts{
 			Context:        r.Context(),
+			BaseConfig:     extractServer(r),
 			Handler:        s.Handler,
 			UpgradeRequest: r,
 			Settings:       settings,

http2/h2c/h2c_test.go

@@ -13,6 +13,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"golang.org/x/net/http2"
@@ -74,3 +75,62 @@ func TestContext(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestPropagation(t *testing.T) {
+	var (
+		server *http.Server
+		// double the limit because http2 will compress header
+		headerSize  = 1 << 11
+		headerLimit = 1 << 10
+	)
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.ProtoMajor != 2 {
+			t.Errorf("Request wasn't handled by h2c.  Got ProtoMajor=%v", r.ProtoMajor)
+		}
+		if r.Context().Value(http.ServerContextKey).(*http.Server) != server {
+			t.Errorf("Request doesn't have expected http server: %v", r.Context())
+		}
+		if len(r.Header.Get("Long-Header")) != headerSize {
+			t.Errorf("Request doesn't have expected http header length: %v", len(r.Header.Get("Long-Header")))
+		}
+		fmt.Fprint(w, "Hello world")
+	})
+
+	h2s := &http2.Server{}
+	h1s := httptest.NewUnstartedServer(NewHandler(handler, h2s))
+
+	server = h1s.Config
+	server.MaxHeaderBytes = headerLimit
+	server.ConnState = func(conn net.Conn, state http.ConnState) {
+		t.Logf("server conn state: conn %s -> %s, status changed to %s", conn.RemoteAddr(), conn.LocalAddr(), state)
+	}
+
+	h1s.Start()
+	defer h1s.Close()
+
+	client := &http.Client{
+		Transport: &http2.Transport{
+			AllowHTTP: true,
+			DialTLS: func(network, addr string, _ *tls.Config) (net.Conn, error) {
+				conn, err := net.Dial(network, addr)
+				if conn != nil {
+					t.Logf("client dial tls: %s -> %s", conn.RemoteAddr(), conn.LocalAddr())
+				}
+				return conn, err
+			},
+		},
+	}
+
+	req, err := http.NewRequest("GET", h1s.URL, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	req.Header.Set("Long-Header", strings.Repeat("A", headerSize))
+
+	_, err = client.Do(req)
+	if err == nil {
+		t.Fatal("expected server err, got nil")
+	}
+}