don't send certificate chains to client requests without STK

fixes #141

handshake/crypto_setup.go

@@ -174,6 +174,9 @@ func (h *CryptoSetup) isInchoateCHLO(cryptoData map[Tag][]byte) bool {
 	if !ok || !bytes.Equal(h.scfg.ID, scid) {
 		return true
 	}
+	if _, ok := cryptoData[TagPUBS]; !ok {
+		return true
+	}
 	if err := h.scfg.stkSource.VerifyToken(h.ip, cryptoData[TagSTK]); err != nil {
 		utils.Infof("STK invalid: %s", err.Error())
 		return false
@@ -186,36 +189,41 @@ func (h *CryptoSetup) handleInchoateCHLO(sni string, data []byte, cryptoData map
 		return nil, qerr.Error(qerr.CryptoInvalidValueLength, "CHLO too small")
 	}
 
-	var chloOrNil []byte
-	if h.version > protocol.Version30 {
-		chloOrNil = data
-	}
-
-	proof, err := h.scfg.Sign(sni, chloOrNil)
-	if err != nil {
-		return nil, err
-	}
-
-	commonSetHashes := cryptoData[TagCCS]
-	cachedCertsHashes := cryptoData[TagCCRT]
-
-	certCompressed, err := h.scfg.GetCertsCompressed(sni, commonSetHashes, cachedCertsHashes)
-	if err != nil {
-		return nil, err
-	}
-
 	token, err := h.scfg.stkSource.NewToken(h.ip)
 	if err != nil {
 		return nil, err
 	}
 
-	var serverReply bytes.Buffer
-	WriteHandshakeMessage(&serverReply, TagREJ, map[Tag][]byte{
+	replyMap := map[Tag][]byte{
 		TagSCFG: h.scfg.Get(),
-		TagCERT: certCompressed,
-		TagPROF: proof,
 		TagSTK:  token,
-	})
+	}
+
+	if h.scfg.stkSource.VerifyToken(h.ip, cryptoData[TagSTK]) == nil {
+		var chloOrNil []byte
+		if h.version > protocol.Version30 {
+			chloOrNil = data
+		}
+
+		proof, err := h.scfg.Sign(sni, chloOrNil)
+		if err != nil {
+			return nil, err
+		}
+
+		commonSetHashes := cryptoData[TagCCS]
+		cachedCertsHashes := cryptoData[TagCCRT]
+
+		certCompressed, err := h.scfg.GetCertsCompressed(sni, commonSetHashes, cachedCertsHashes)
+		if err != nil {
+			return nil, err
+		}
+		// Token was valid, send more details
+		replyMap[TagPROF] = proof
+		replyMap[TagCERT] = certCompressed
+	}
+
+	var serverReply bytes.Buffer
+	WriteHandshakeMessage(&serverReply, TagREJ, replyMap)
 	return serverReply.Bytes(), nil
 }
 

handshake/crypto_setup_test.go

@@ -203,8 +203,28 @@ var _ = Describe("Crypto setup", func() {
 			response, err := cs.handleInchoateCHLO("", bytes.Repeat([]byte{'a'}, protocol.ClientHelloMinimumSize), nil)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(response).To(HavePrefix("REJ"))
-			Expect(response).To(ContainSubstring("certcompressed"))
 			Expect(response).To(ContainSubstring("initial public"))
+			Expect(signer.gotCHLO).To(BeFalse())
+		})
+
+		It("REJ messages don't include cert or proof without STK", func() {
+			response, err := cs.handleInchoateCHLO("", bytes.Repeat([]byte{'a'}, protocol.ClientHelloMinimumSize), nil)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(response).To(HavePrefix("REJ"))
+			Expect(response).ToNot(ContainSubstring("certcompressed"))
+			Expect(response).ToNot(ContainSubstring("proof"))
+			Expect(signer.gotCHLO).To(BeFalse())
+		})
+
+		It("REJ messages include cert and proof with valid STK", func() {
+			response, err := cs.handleInchoateCHLO("", bytes.Repeat([]byte{'a'}, protocol.ClientHelloMinimumSize), map[Tag][]byte{
+				TagSTK: validSTK,
+				TagSNI: []byte("foo"),
+			})
+			Expect(err).ToNot(HaveOccurred())
+			Expect(response).To(HavePrefix("REJ"))
+			Expect(response).To(ContainSubstring("certcompressed"))
+			Expect(response).To(ContainSubstring("proof"))
 			Expect(signer.gotCHLO).To(BeTrue())
 		})
 
@@ -244,6 +264,7 @@ var _ = Describe("Crypto setup", func() {
 				TagSNI:  []byte("quic.clemente.io"),
 				TagNONC: nonce32,
 				TagSTK:  validSTK,
+				TagPUBS: nil,
 			})
 			err := cs.HandleCryptoStream()
 			Expect(err).NotTo(HaveOccurred())
@@ -258,6 +279,7 @@ var _ = Describe("Crypto setup", func() {
 				TagSNI:  []byte("quic.clemente.io"),
 				TagNONC: nonce32,
 				TagSTK:  validSTK,
+				TagPUBS: nil,
 			})
 			err := cs.HandleCryptoStream()
 			Expect(err).NotTo(HaveOccurred())
@@ -267,11 +289,18 @@ var _ = Describe("Crypto setup", func() {
 		})
 
 		It("recognizes inchoate CHLOs missing SCID", func() {
-			Expect(cs.isInchoateCHLO(map[Tag][]byte{})).To(BeTrue())
+			Expect(cs.isInchoateCHLO(map[Tag][]byte{TagPUBS: nil})).To(BeTrue())
+		})
+
+		It("recognizes inchoate CHLOs missing PUBS", func() {
+			Expect(cs.isInchoateCHLO(map[Tag][]byte{TagSCID: nil})).To(BeTrue())
 		})
 
 		It("recognizes proper CHLOs", func() {
-			Expect(cs.isInchoateCHLO(map[Tag][]byte{TagSCID: scfg.ID})).To(BeFalse())
+			Expect(cs.isInchoateCHLO(map[Tag][]byte{
+				TagSCID: scfg.ID,
+				TagPUBS: nil,
+			})).To(BeFalse())
 		})
 
 		It("errors on too short inchoate CHLOs", func() {