From 37495d967abdc789f8ec5c009b647c997313f0cd Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Tue, 27 Nov 2018 13:00:10 +0700
Subject: [PATCH] keep the connection IDs when receiving a version negotiation
 packet

---
 client.go | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/client.go b/client.go
index 493da4b9e..8d13c0484 100644
--- a/client.go
+++ b/client.go
@@ -164,7 +164,18 @@ func newClient(
 			}
 		}
 	}
+
+	srcConnID, err := generateConnectionID(config.ConnectionIDLength)
+	if err != nil {
+		return nil, err
+	}
+	destConnID, err := generateConnectionIDForInitial()
+	if err != nil {
+		return nil, err
+	}
 	c := &client{
+		srcConnID:         srcConnID,
+		destConnID:        destConnID,
 		conn:              &conn{pconn: pconn, currentAddr: remoteAddr},
 		createdPacketConn: createdPacketConn,
 		tlsConf:           tlsConf,
@@ -173,7 +184,7 @@ func newClient(
 		handshakeChan:     make(chan struct{}),
 		logger:            utils.DefaultLogger.WithPrefix("client"),
 	}
-	return c, c.generateConnectionIDs()
+	return c, nil
 }
 
 // populateClientConfig populates fields in the quic.Config with their default values, if none are set
@@ -234,20 +245,6 @@ func populateClientConfig(config *Config, createdPacketConn bool) *Config {
 	}
 }
 
-func (c *client) generateConnectionIDs() error {
-	srcConnID, err := generateConnectionID(c.config.ConnectionIDLength)
-	if err != nil {
-		return err
-	}
-	destConnID, err := generateConnectionIDForInitial()
-	if err != nil {
-		return err
-	}
-	c.srcConnID = srcConnID
-	c.destConnID = destConnID
-	return nil
-}
-
 func (c *client) dial(ctx context.Context) error {
 	c.logger.Infof("Starting new connection to %s (%s -> %s), source connection ID %s, destination connection ID %s, version %s", c.tlsConf.ServerName, c.conn.LocalAddr(), c.conn.RemoteAddr(), c.srcConnID, c.destConnID, c.version)
 
@@ -358,9 +355,6 @@ func (c *client) handleVersionNegotiationPacket(hdr *wire.Header) error {
 	// switch to negotiated version
 	c.initialVersion = c.version
 	c.version = newVersion
-	if err := c.generateConnectionIDs(); err != nil {
-		return err
-	}
 
 	c.logger.Infof("Switching to QUIC version %s. New connection ID: %s", newVersion, c.destConnID)
 	c.session.destroy(errCloseSessionForNewVersion)