net/http: support BaseContext & ConnContext for http2 Server

This is the net/http half of #32476. This supplies the method needed
by the other half in x/net/http2 in the already-submitted CL 181259,
which this CL also bundles in h2_bundle.go.

Thanks to Tom Thorogood (@tmthrgd) for the bug report and test.

Fixes #32476
Updates #30694

Change-Id: I79d2a280e486fbf75d116f6695fd3abb61278765
Reviewed-on: https://go-review.googlesource.com/c/go/+/181260
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/go.mod

@@ -4,7 +4,7 @@ go 1.12
 
 require (
 	golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f
-	golang.org/x/net v0.0.0-20190514140710-3ec191127204
+	golang.org/x/net v0.0.0-20190607172144-d5cec3884524
 	golang.org/x/sys v0.0.0-20190529130038-5219a1e1c5f8 // indirect
 	golang.org/x/text v0.3.2 // indirect
 )

src/go.sum

@@ -4,6 +4,8 @@ golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190514140710-3ec191127204 h1:4yG6GqBtw9C+UrLp6s2wtSniayy/Vd/3F7ffLE427XI=
 golang.org/x/net v0.0.0-20190514140710-3ec191127204/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190607172144-d5cec3884524 h1:A4fHjHFi2zGH4/ziDBluIhhGzT/kAuTD1lKHLAztlG8=
+golang.org/x/net v0.0.0-20190607172144-d5cec3884524/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190528183647-3626398d7749 h1:oG2HS+e2B9VqK95y67B5MgJIJhOPY27/m5uJKJhHzus=

src/net/http/h2_bundle.go

@@ -3832,7 +3832,20 @@ func http2ConfigureServer(s *Server, conf *http2Server) error {
 		if http2testHookOnConn != nil {
 			http2testHookOnConn()
 		}
+		// The TLSNextProto interface predates contexts, so
+		// the net/http package passes down its per-connection
+		// base context via an exported but unadvertised
+		// method on the Handler. This is for internal
+		// net/http<=>http2 use only.
+		var ctx context.Context
+		type baseContexter interface {
+			BaseContext() context.Context
+		}
+		if bc, ok := h.(baseContexter); ok {
+			ctx = bc.BaseContext()
+		}
 		conf.ServeConn(c, &http2ServeConnOpts{
+			Context:    ctx,
 			Handler:    h,
 			BaseConfig: hs,
 		})
@@ -3843,6 +3856,10 @@ func http2ConfigureServer(s *Server, conf *http2Server) error {
 
 // ServeConnOpts are options for the Server.ServeConn method.
 type http2ServeConnOpts struct {
+	// Context is the base context to use.
+	// If nil, context.Background is used.
+	Context context.Context
+
 	// BaseConfig optionally sets the base configuration
 	// for values. If nil, defaults are used.
 	BaseConfig *Server
@@ -3853,6 +3870,13 @@ type http2ServeConnOpts struct {
 	Handler Handler
 }
 
+func (o *http2ServeConnOpts) context() context.Context {
+	if o.Context != nil {
+		return o.Context
+	}
+	return context.Background()
+}
+
 func (o *http2ServeConnOpts) baseConfig() *Server {
 	if o != nil && o.BaseConfig != nil {
 		return o.BaseConfig
@@ -3998,7 +4022,7 @@ func (s *http2Server) ServeConn(c net.Conn, opts *http2ServeConnOpts) {
 }
 
 func http2serverConnBaseContext(c net.Conn, opts *http2ServeConnOpts) (ctx context.Context, cancel func()) {
-	ctx, cancel = context.WithCancel(context.Background())
+	ctx, cancel = context.WithCancel(opts.context())
 	ctx = context.WithValue(ctx, LocalAddrContextKey, c.LocalAddr())
 	if hs := opts.baseConfig(); hs != nil {
 		ctx = context.WithValue(ctx, ServerContextKey, hs)

src/net/http/serve_test.go

@@ -6066,6 +6066,50 @@ func TestServerContexts(t *testing.T) {
 	}
 }
 
+func TestServerContextsHTTP2(t *testing.T) {
+	setParallel(t)
+	defer afterTest(t)
+	type baseKey struct{}
+	type connKey struct{}
+	ch := make(chan context.Context, 1)
+	ts := httptest.NewUnstartedServer(HandlerFunc(func(rw ResponseWriter, r *Request) {
+		if r.ProtoMajor != 2 {
+			t.Errorf("unexpected HTTP/1.x request")
+		}
+		ch <- r.Context()
+	}))
+	ts.Config.BaseContext = func(ln net.Listener) context.Context {
+		if strings.Contains(reflect.TypeOf(ln).String(), "onceClose") {
+			t.Errorf("unexpected onceClose listener type %T", ln)
+		}
+		return context.WithValue(context.Background(), baseKey{}, "base")
+	}
+	ts.Config.ConnContext = func(ctx context.Context, c net.Conn) context.Context {
+		if got, want := ctx.Value(baseKey{}), "base"; got != want {
+			t.Errorf("in ConnContext, base context key = %#v; want %q", got, want)
+		}
+		return context.WithValue(ctx, connKey{}, "conn")
+	}
+	ts.TLS = &tls.Config{
+		NextProtos: []string{"h2", "http/1.1"},
+	}
+	ts.StartTLS()
+	defer ts.Close()
+	ts.Client().Transport.(*Transport).ForceAttemptHTTP2 = true
+	res, err := ts.Client().Get(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+	ctx := <-ch
+	if got, want := ctx.Value(baseKey{}), "base"; got != want {
+		t.Errorf("base context key = %#v; want %q", got, want)
+	}
+	if got, want := ctx.Value(connKey{}), "conn"; got != want {
+		t.Errorf("conn context key = %#v; want %q", got, want)
+	}
+}
+
 // Issue 30710: ensure that as per the spec, a server responds
 // with 501 Not Implemented for unsupported transfer-encodings.
 func TestUnsupportedTransferEncodingsReturn501(t *testing.T) {

src/net/http/server.go

@@ -1796,7 +1796,7 @@ func (c *conn) serve(ctx context.Context) {
 		*c.tlsState = tlsConn.ConnectionState()
 		if proto := c.tlsState.NegotiatedProtocol; validNPN(proto) {
 			if fn := c.server.TLSNextProto[proto]; fn != nil {
-				h := initNPNRequest{tlsConn, serverHandler{c.server}}
+				h := initNPNRequest{ctx, tlsConn, serverHandler{c.server}}
 				fn(c.server, tlsConn, h)
 			}
 			return
@@ -3347,10 +3347,17 @@ func (globalOptionsHandler) ServeHTTP(w ResponseWriter, r *Request) {
 // uninitialized fields in its *Request. Such partially-initialized
 // Requests come from NPN protocol handlers.
 type initNPNRequest struct {
-	c *tls.Conn
-	h serverHandler
+	ctx context.Context
+	c   *tls.Conn
+	h   serverHandler
 }
 
+// BaseContext is an exported but unadvertised http.Handler method
+// recognized by x/net/http2 to pass down a context; the TLSNextProto
+// API predates context support so we shoehorn through the only
+// interface we have available.
+func (h initNPNRequest) BaseContext() context.Context { return h.ctx }
+
 func (h initNPNRequest) ServeHTTP(rw ResponseWriter, req *Request) {
 	if req.TLS == nil {
 		req.TLS = &tls.ConnectionState{}

src/vendor/modules.txt

@@ -7,7 +7,7 @@ golang.org/x/crypto/hkdf
 golang.org/x/crypto/internal/chacha20
 golang.org/x/crypto/internal/subtle
 golang.org/x/crypto/poly1305
-# golang.org/x/net v0.0.0-20190514140710-3ec191127204
+# golang.org/x/net v0.0.0-20190607172144-d5cec3884524
 golang.org/x/net/dns/dnsmessage
 golang.org/x/net/http/httpguts
 golang.org/x/net/http/httpproxy