move cutting of packets at the payload length to the multiplexer

client.go

@@ -412,11 +412,6 @@ func (c *client) handleIETFQUICPacket(p *receivedPacket) error {
 		default:
 			return fmt.Errorf("Received unsupported packet type: %s", p.header.Type)
 		}
-		if protocol.ByteCount(len(p.data)) < p.header.PayloadLen {
-			return fmt.Errorf("packet payload (%d bytes) is smaller than the expected payload length (%d bytes)", len(p.data), p.header.PayloadLen)
-		}
-		p.data = p.data[:int(p.header.PayloadLen)]
-		// TODO(#1312): implement parsing of compound packets
 	}
 
 	// this is the first packet we are receiving

client_multiplexer.go

@@ -129,6 +129,14 @@ func (m *clientMultiplexer) handlePacket(addr net.Addr, data []byte, p *connMana
 	hdr.Raw = data[:len(data)-r.Len()]
 	packetData := data[len(data)-r.Len():]
 
+	if hdr.IsLongHeader {
+		if protocol.ByteCount(len(packetData)) < hdr.PayloadLen {
+			return fmt.Errorf("packet payload (%d bytes) is smaller than the expected payload length (%d bytes)", len(packetData), hdr.PayloadLen)
+		}
+		packetData = packetData[:int(hdr.PayloadLen)]
+		// TODO(#1312): implement parsing of compound packets
+	}
+
 	client.handlePacket(&receivedPacket{
 		remoteAddr: addr,
 		header:     hdr,

client_multiplexer_test.go

@@ -112,6 +112,53 @@ var _ = Describe("Client Multiplexer", func() {
 		Expect(err).To(MatchError("received a packet with an unexpected connection ID 0x0102030405060708"))
 	})
 
+	It("errors on packets that are smaller than the Payload Length in the packet header", func() {
+		connID := protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8}
+		hdr := &wire.Header{
+			IsLongHeader:     true,
+			Type:             protocol.PacketTypeHandshake,
+			PayloadLen:       1000,
+			DestConnectionID: connID,
+			PacketNumberLen:  protocol.PacketNumberLen1,
+			Version:          versionIETFFrames,
+		}
+		buf := &bytes.Buffer{}
+		Expect(hdr.Write(buf, protocol.PerspectiveServer, versionIETFFrames)).To(Succeed())
+		buf.Write(bytes.Repeat([]byte{0}, 500))
+
+		sess := NewMockQuicSession(mockCtrl)
+		sess.EXPECT().GetVersion().Return(versionIETFFrames)
+		manager := NewMockPacketHandlerManager(mockCtrl)
+		manager.EXPECT().Get(connID).Return(sess, true)
+		err := getClientMultiplexer().(*clientMultiplexer).handlePacket(nil, buf.Bytes(), &connManager{manager: manager, connIDLen: 8})
+		Expect(err).To(MatchError("packet payload (500 bytes) is smaller than the expected payload length (1000 bytes)"))
+	})
+
+	It("errors on packets that are smaller than the Payload Length in the packet header", func() {
+		connID := protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8}
+		hdr := &wire.Header{
+			IsLongHeader:     true,
+			Type:             protocol.PacketTypeHandshake,
+			PayloadLen:       456,
+			DestConnectionID: connID,
+			PacketNumberLen:  protocol.PacketNumberLen1,
+			Version:          versionIETFFrames,
+		}
+		buf := &bytes.Buffer{}
+		Expect(hdr.Write(buf, protocol.PerspectiveServer, versionIETFFrames)).To(Succeed())
+		buf.Write(bytes.Repeat([]byte{0}, 500))
+
+		sess := NewMockQuicSession(mockCtrl)
+		sess.EXPECT().GetVersion().Return(versionIETFFrames)
+		sess.EXPECT().handlePacket(gomock.Any()).Do(func(p *receivedPacket) {
+			Expect(p.data).To(HaveLen(456))
+		})
+		manager := NewMockPacketHandlerManager(mockCtrl)
+		manager.EXPECT().Get(connID).Return(sess, true)
+		err := getClientMultiplexer().(*clientMultiplexer).handlePacket(nil, buf.Bytes(), &connManager{manager: manager, connIDLen: 8})
+		Expect(err).ToNot(HaveOccurred())
+	})
+
 	It("closes the packet handlers when reading from the conn fails", func() {
 		conn := newMockPacketConn()
 		conn.readErr = errors.New("test error")

client_test.go

@@ -671,48 +671,6 @@ var _ = Describe("Client", func() {
 		Expect(cl.GetVersion()).To(Equal(cl.version))
 	})
 
-	It("errors on packets that are smaller than the Payload Length in the packet header", func() {
-		cl.session = NewMockQuicSession(mockCtrl) // don't EXPECT any handlePacket calls
-		hdr := &wire.Header{
-			IsLongHeader:     true,
-			Type:             protocol.PacketTypeHandshake,
-			PayloadLen:       1000,
-			SrcConnectionID:  protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8},
-			DestConnectionID: protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8},
-			PacketNumberLen:  protocol.PacketNumberLen1,
-			Version:          versionIETFFrames,
-		}
-		err := cl.handlePacketImpl(&receivedPacket{
-			remoteAddr: addr,
-			header:     hdr,
-			data:       make([]byte, 456),
-		})
-		Expect(err).To(MatchError("received a packet with an unexpected connection ID (0x0102030405060708, expected 0x0000000000001337)"))
-	})
-
-	It("cuts packets at the payload length", func() {
-		sess := NewMockQuicSession(mockCtrl)
-		sess.EXPECT().handlePacket(gomock.Any()).Do(func(packet *receivedPacket) {
-			Expect(packet.data).To(HaveLen(123))
-		})
-		cl.session = sess
-		hdr := &wire.Header{
-			IsLongHeader:     true,
-			Type:             protocol.PacketTypeHandshake,
-			PayloadLen:       123,
-			SrcConnectionID:  connID,
-			DestConnectionID: connID,
-			PacketNumberLen:  protocol.PacketNumberLen1,
-			Version:          versionIETFFrames,
-		}
-		err := cl.handlePacketImpl(&receivedPacket{
-			remoteAddr: addr,
-			header:     hdr,
-			data:       make([]byte, 456),
-		})
-		Expect(err).ToNot(HaveOccurred())
-	})
-
 	It("ignores packets with the wrong Long Header Type", func() {
 		hdr := &wire.Header{
 			IsLongHeader:     true,