implement receiving of stateless resets

internal/protocol/params.go

@@ -8,6 +8,9 @@ const MaxPacketSizeIPv4 = 1252
 // MaxPacketSizeIPv6 is the maximum packet size that we use for sending IPv6 packets.
 const MaxPacketSizeIPv6 = 1232
 
+// MinStatelessResetSize is the minimum size of a stateless reset packet
+const MinStatelessResetSize = 1 + 20 + 16
+
 // NonForwardSecurePacketSizeReduction is the number of bytes a non forward-secure packet has to be smaller than a forward-secure packet
 // This makes sure that those packets can always be retransmitted without splitting the contained StreamFrames
 const NonForwardSecurePacketSizeReduction = 50

packet_handler_map.go

@@ -2,6 +2,7 @@ package quic
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"net"
 	"sync"
@@ -12,6 +13,11 @@ import (
 	"github.com/lucas-clemente/quic-go/internal/wire"
 )
 
+type packetHandlerEntry struct {
+	handler    packetHandler
+	resetToken *[16]byte
+}
+
 // The packetHandlerMap stores packetHandlers, identified by connection ID.
 // It is used:
 // * by the server to store sessions
@@ -22,9 +28,10 @@ type packetHandlerMap struct {
 	conn      net.PacketConn
 	connIDLen int
 
-	handlers map[string] /* string(ConnectionID)*/ packetHandler
-	server   unknownPacketHandler
-	closed   bool
+	handlers    map[string] /* string(ConnectionID)*/ packetHandlerEntry
+	resetTokens map[[16]byte] /* stateless reset token */ packetHandler
+	server      unknownPacketHandler
+	closed      bool
 
 	deleteRetiredSessionsAfter time.Duration
 
@@ -37,7 +44,8 @@ func newPacketHandlerMap(conn net.PacketConn, connIDLen int, logger utils.Logger
 	m := &packetHandlerMap{
 		conn:                       conn,
 		connIDLen:                  connIDLen,
-		handlers:                   make(map[string]packetHandler),
+		handlers:                   make(map[string]packetHandlerEntry),
+		resetTokens:                make(map[[16]byte]packetHandler),
 		deleteRetiredSessionsAfter: protocol.RetiredConnectionIDDeleteTimeout,
 		logger:                     logger,
 	}
@@ -47,13 +55,29 @@ func newPacketHandlerMap(conn net.PacketConn, connIDLen int, logger utils.Logger
 
 func (h *packetHandlerMap) Add(id protocol.ConnectionID, handler packetHandler) {
 	h.mutex.Lock()
-	h.handlers[string(id)] = handler
+	h.handlers[string(id)] = packetHandlerEntry{handler: handler}
+	h.mutex.Unlock()
+}
+
+func (h *packetHandlerMap) AddWithResetToken(id protocol.ConnectionID, handler packetHandler, token [16]byte) {
+	h.mutex.Lock()
+	h.handlers[string(id)] = packetHandlerEntry{handler: handler, resetToken: &token}
+	h.resetTokens[token] = handler
 	h.mutex.Unlock()
 }
 
 func (h *packetHandlerMap) Remove(id protocol.ConnectionID) {
+	h.removeByConnectionIDAsString(string(id))
+}
+
+func (h *packetHandlerMap) removeByConnectionIDAsString(id string) {
 	h.mutex.Lock()
-	delete(h.handlers, string(id))
+	if handlerEntry, ok := h.handlers[id]; ok {
+		if token := handlerEntry.resetToken; token != nil {
+			delete(h.resetTokens, *token)
+		}
+		delete(h.handlers, id)
+	}
 	h.mutex.Unlock()
 }
 
@@ -63,9 +87,7 @@ func (h *packetHandlerMap) Retire(id protocol.ConnectionID) {
 
 func (h *packetHandlerMap) retireByConnectionIDAsString(id string) {
 	time.AfterFunc(h.deleteRetiredSessionsAfter, func() {
-		h.mutex.Lock()
-		delete(h.handlers, id)
-		h.mutex.Unlock()
+		h.removeByConnectionIDAsString(id)
 	})
 }
 
@@ -79,7 +101,8 @@ func (h *packetHandlerMap) CloseServer() {
 	h.mutex.Lock()
 	h.server = nil
 	var wg sync.WaitGroup
-	for id, handler := range h.handlers {
+	for id, handlerEntry := range h.handlers {
+		handler := handlerEntry.handler
 		if handler.GetPerspective() == protocol.PerspectiveServer {
 			wg.Add(1)
 			go func(id string, handler packetHandler) {
@@ -103,12 +126,12 @@ func (h *packetHandlerMap) close(e error) error {
 	h.closed = true
 
 	var wg sync.WaitGroup
-	for _, handler := range h.handlers {
+	for _, handlerEntry := range h.handlers {
 		wg.Add(1)
-		go func(handler packetHandler) {
-			handler.destroy(e)
+		go func(handlerEntry packetHandlerEntry) {
+			handlerEntry.handler.destroy(e)
 			wg.Done()
-		}(handler)
+		}(handlerEntry)
 	}
 
 	if h.server != nil {
@@ -149,25 +172,37 @@ func (h *packetHandlerMap) handlePacket(addr net.Addr, data []byte) error {
 	}
 
 	h.mutex.RLock()
-	handler, ok := h.handlers[string(iHdr.DestConnectionID)]
+	handlerEntry, handlerFound := h.handlers[string(iHdr.DestConnectionID)]
 	server := h.server
-	h.mutex.RUnlock()
 
 	var sentBy protocol.Perspective
 	var version protocol.VersionNumber
 	var handlePacket func(*receivedPacket)
-	if ok { // existing session
+	if handlerFound { // existing session
+		handler := handlerEntry.handler
 		sentBy = handler.GetPerspective().Opposite()
 		version = handler.GetVersion()
 		handlePacket = handler.handlePacket
 	} else { // no session found
+		// this might be a stateless reset
+		if !iHdr.IsLongHeader && len(data) >= protocol.MinStatelessResetSize {
+			var token [16]byte
+			copy(token[:], data[len(data)-16:])
+			if sess, ok := h.resetTokens[token]; ok {
+				h.mutex.RUnlock()
+				sess.destroy(errors.New("received a stateless reset"))
+				return nil
+			}
+		}
 		if server == nil { // no server set
+			h.mutex.RUnlock()
 			return fmt.Errorf("received a packet with an unexpected connection ID %s", iHdr.DestConnectionID)
 		}
 		handlePacket = server.handlePacket
 		sentBy = protocol.PerspectiveClient
 		version = iHdr.Version
 	}
+	h.mutex.RUnlock()
 
 	hdr, err := iHdr.Parse(r, sentBy, version)
 	if err != nil {

packet_handler_map_test.go

@@ -184,6 +184,54 @@ var _ = Describe("Packet Handler Map", func() {
 		})
 	})
 
+	Context("stateless reset handling", func() {
+		It("handles packets for connections added with a reset token", func() {
+			packetHandler := NewMockPacketHandler(mockCtrl)
+			connID := protocol.ConnectionID{0xde, 0xca, 0xfb, 0xad}
+			token := [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
+			handler.AddWithResetToken(connID, packetHandler, token)
+			// first send a normal packet
+			handledPacket := make(chan struct{})
+			packetHandler.EXPECT().GetPerspective()
+			packetHandler.EXPECT().GetVersion()
+			packetHandler.EXPECT().handlePacket(gomock.Any()).Do(func(p *receivedPacket) {
+				Expect(p.header.DestConnectionID).To(Equal(connID))
+				close(handledPacket)
+			})
+			conn.dataToRead <- getPacket(connID)
+			Eventually(handledPacket).Should(BeClosed())
+		})
+
+		It("handles stateless resets", func() {
+			packetHandler := NewMockPacketHandler(mockCtrl)
+			connID := protocol.ConnectionID{0xde, 0xca, 0xfb, 0xad}
+			token := [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
+			handler.AddWithResetToken(connID, packetHandler, token)
+			packet := append([]byte{0x40} /* short header packet */, make([]byte, 50)...)
+			packet = append(packet, token[:]...)
+			destroyed := make(chan struct{})
+			packetHandler.EXPECT().destroy(errors.New("received a stateless reset")).Do(func(error) {
+				close(destroyed)
+			})
+			conn.dataToRead <- packet
+			Eventually(destroyed).Should(BeClosed())
+		})
+
+		It("deletes reset tokens when the session is retired", func() {
+			handler.deleteRetiredSessionsAfter = scaleDuration(10 * time.Millisecond)
+			connID := protocol.ConnectionID{0xde, 0xad, 0xbe, 0xef, 0x42}
+			token := [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
+			handler.AddWithResetToken(connID, NewMockPacketHandler(mockCtrl), token)
+			handler.Retire(connID)
+			time.Sleep(scaleDuration(30 * time.Millisecond))
+			Expect(handler.handlePacket(nil, getPacket(connID))).To(MatchError("received a packet with an unexpected connection ID 0xdeadbeef42"))
+			packet := append([]byte{0x40, 0xde, 0xca, 0xfb, 0xad, 0x99} /* short header packet */, make([]byte, 50)...)
+			packet = append(packet, token[:]...)
+			Expect(handler.handlePacket(nil, packet)).To(MatchError("received a packet with an unexpected connection ID 0xdecafbad99"))
+			Expect(handler.resetTokens).To(BeEmpty())
+		})
+	})
+
 	Context("running a server", func() {
 		It("adds a server", func() {
 			connID := protocol.ConnectionID{0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88}