From 35242394e10abc559a904accf2b66cae7541a88b Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 6 Feb 2017 15:42:37 +0700
Subject: [PATCH] generate new connection ID after version negotiation

fixes #404
---
 client.go      | 7 ++++++-
 client_test.go | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/client.go b/client.go
index e5e6abe1c..c3772b632 100644
--- a/client.go
+++ b/client.go
@@ -175,9 +175,14 @@ func (c *Client) handlePacket(packet []byte) error {
 			return qerr.VersionNegotiationMismatch
 		}
 
-		utils.Infof("Switching to QUIC version %d", highestSupportedVersion)
+		// switch to negotiated version
 		c.version = highestSupportedVersion
 		c.versionNegotiated = true
+		c.connectionID, err = utils.GenerateConnectionID()
+		if err != nil {
+			return err
+		}
+		utils.Infof("Switching to QUIC version %d. New connection ID: %x", highestSupportedVersion, c.connectionID)
 
 		c.session.Close(errCloseSessionForNewVersion)
 		err = c.createNewSession(hdr.SupportedVersions)
diff --git a/client_test.go b/client_test.go
index 4a38f187c..f21b6e928 100644
--- a/client_test.go
+++ b/client_test.go
@@ -211,12 +211,14 @@ var _ = Describe("Client", func() {
 			newVersion := protocol.Version35
 			Expect(newVersion).ToNot(Equal(client.version))
 			Expect(session.packetCount).To(BeZero())
+			client.connectionID = 0x1337
 			err := client.handlePacket(getVersionNegotiation([]protocol.VersionNumber{newVersion}))
 			Expect(client.version).To(Equal(newVersion))
 			Expect(client.versionNegotiated).To(BeTrue())
 			Expect(versionNegotiateCallbackCalled).To(BeTrue())
 			// it swapped the sessions
 			Expect(client.session).ToNot(Equal(session))
+			Expect(client.connectionID).ToNot(Equal(0x1337)) // it generated a new connection ID
 			Expect(err).ToNot(HaveOccurred())
 			// it didn't pass the version negoation packet to the session (since it has no payload)
 			Expect(session.packetCount).To(BeZero())