http2: close connections when receiving too many headers (#32)

* http2: close connections when receiving too many headers

* fix annotation: struture -> structure

* fix format

frame.go

@@ -1528,6 +1528,7 @@ func (fr *Framer) readMetaFrame(hf *HeadersFrame) (*MetaHeadersFrame, error) {
 		if size > remainSize {
 			hdec.SetEmitEnabled(false)
 			mh.Truncated = true
+			remainSize = 0
 			return
 		}
 		remainSize -= size
@@ -1540,6 +1541,36 @@ func (fr *Framer) readMetaFrame(hf *HeadersFrame) (*MetaHeadersFrame, error) {
 	var hc headersOrContinuation = hf
 	for {
 		frag := hc.HeaderBlockFragment()
+
+		// Avoid parsing large amounts of headers that we will then discard.
+		// If the sender exceeds the max header list size by too much,
+		// skip parsing the fragment and close the connection.
+		//
+		// "Too much" is either any CONTINUATION frame after we've already
+		// exceeded the max header list size (in which case remainSize is 0),
+		// or a frame whose encoded size is more than twice the remaining
+		// header list bytes we're willing to accept.
+		if int64(len(frag)) > int64(2*remainSize) {
+			if VerboseLogs {
+				hlog.SystemLogger().Infof("http2: header list too large")
+			}
+			// It would be nice to send a RST_STREAM before sending the GOAWAY,
+			// but the structure of the server's frame writer makes this difficult.
+			return nil, ConnectionError(ErrCodeProtocol)
+		}
+
+		// Also close the connection after any CONTINUATION frame following an
+		// invalid header, since we stop tracking the size of the headers after
+		// an invalid one.
+		if invalid != nil {
+			if VerboseLogs {
+				hlog.SystemLogger().Infof("http2: invalid header: %v", invalid)
+			}
+			// It would be nice to send a RST_STREAM before sending the GOAWAY,
+			// but the structure of the server's frame writer makes this difficult.
+			return nil, ConnectionError(ErrCodeProtocol)
+		}
+
 		if _, err := hdec.Write(frag); err != nil {
 			return nil, ConnectionError(ErrCodeCompression)
 		}

server_test.go

@@ -3785,3 +3785,88 @@ func TestServer_Request_Te_Header_Check(t *testing.T) {
 		}
 	})
 }
+
+func TestServerContinuationFlood(t *testing.T) {
+	st := newHertzServerTester(t, func(c context.Context, ctx *app.RequestContext) {
+	})
+
+	defer st.Close()
+	st.writePreface()
+	st.writeInitialSettings()
+	st.writeSettingsAck()
+	framer := NewFramer(st.cc, newMockTLSConn(st.cc))
+	framer.MaxHeaderListSize = uint32(2368)
+	st.fr = framer
+	// st.fr.MaxHeaderListSize = uint32(2368)
+
+	st.writeHeaders(HeadersFrameParam{
+		StreamID:      1,
+		BlockFragment: st.encodeHeader(),
+		EndStream:     true,
+	})
+	for i := 0; i < 22000; i++ {
+		st.fr.WriteContinuation(1, false, st.encodeHeaderRaw(
+			fmt.Sprintf("x-%v", i), "1234567890",
+		))
+	}
+	st.fr.WriteContinuation(1, true, st.encodeHeaderRaw(
+		"x-last-header", "1",
+	))
+
+	var sawGoAway bool
+	for {
+		f, err := st.readFrame()
+		if err != nil {
+			break
+		}
+		switch f.(type) {
+		case *GoAwayFrame:
+			sawGoAway = true
+		case *HeadersFrame:
+			t.Fatalf("received HEADERS frame; want GOAWAY")
+		}
+	}
+	if !sawGoAway {
+		t.Errorf("connection closed with no GOAWAY frame; want one")
+	}
+}
+
+func TestServerContinuationAfterInvalidHeader(t *testing.T) {
+	st := newHertzServerTester(t, func(c context.Context, ctx *app.RequestContext) {
+	})
+
+	defer st.Close()
+
+	st.writePreface()
+	st.writeInitialSettings()
+	st.writeSettingsAck()
+
+	st.writeHeaders(HeadersFrameParam{
+		StreamID:      1,
+		BlockFragment: st.encodeHeader(),
+		EndStream:     true,
+	})
+	st.fr.WriteContinuation(1, false, st.encodeHeaderRaw(
+		"x-invalid-header", "\x00",
+	))
+	st.fr.WriteContinuation(1, true, st.encodeHeaderRaw(
+		"x-valid-header", "1",
+	))
+
+	var sawGoAway bool
+	for {
+		f, err := st.readFrame()
+		if err != nil {
+			break
+		}
+		switch f.(type) {
+		case *GoAwayFrame:
+			sawGoAway = true
+		case *HeadersFrame:
+			t.Fatalf("received HEADERS frame; want GOAWAY")
+		}
+	}
+	if !sawGoAway {
+		t.Errorf("connection closed with no GOAWAY frame; want one")
+	}
+}