From fd28921bdd81ae5f98aa46d44e62d16dbaf2534b Mon Sep 17 00:00:00 2001
From: Lucas Clemente <lucas@clemente.io>
Date: Thu, 21 Apr 2016 09:21:21 +0200
Subject: [PATCH] test version negotiation packet

---
 server.go      | 23 ++++++++++++-----------
 server_test.go | 17 +++++++++++++++++
 2 files changed, 29 insertions(+), 11 deletions(-)
 create mode 100644 server_test.go

diff --git a/server.go b/server.go
index 3eb816c9..bc296632 100644
--- a/server.go
+++ b/server.go
@@ -68,11 +68,13 @@ func (s *Server) ListenAndServe(address string) error {
 			continue
 		}
 
-		fmt.Printf("<- Got packet %d (%d bytes) from %v\n", publicHeader.PacketNumber, n, remoteAddr)
+		// fmt.Printf("<- Got packet %d (%d bytes) from %v\n", publicHeader.PacketNumber, n, remoteAddr)
 
 		// Send Version Negotiation Packet if the client is speaking a different protocol version
 		if publicHeader.VersionFlag && !protocol.IsSupportedVersion(publicHeader.VersionNumber) {
-			if err := sendVersionNegotiation(conn, remoteAddr, publicHeader); err != nil {
+			fmt.Println("Sending VersionNegotiationPacket")
+			_, err = conn.WriteToUDP(composeVersionNegotiation(publicHeader.ConnectionID), remoteAddr)
+			if err != nil {
 				fmt.Printf("Error sending version negotiation: %s", err.Error())
 			}
 			continue
@@ -91,18 +93,17 @@ func (s *Server) ListenAndServe(address string) error {
 	}
 }
 
-func sendVersionNegotiation(conn *net.UDPConn, remoteAddr *net.UDPAddr, publicHeader *PublicHeader) error {
-	fmt.Println("Sending VersionNegotiationPacket")
+func composeVersionNegotiation(connectionID protocol.ConnectionID) []byte {
 	fullReply := &bytes.Buffer{}
-	responsePublicHeader := PublicHeader{ConnectionID: publicHeader.ConnectionID, PacketNumber: 1, VersionFlag: true}
+	responsePublicHeader := PublicHeader{
+		ConnectionID: connectionID,
+		PacketNumber: 1,
+		VersionFlag:  true,
+	}
 	err := responsePublicHeader.WritePublicHeader(fullReply)
 	if err != nil {
-		return err
+		panic(err) // Should not happen ;)
 	}
 	fullReply.Write(protocol.SupportedVersionsAsTags)
-	_, err = conn.WriteToUDP(fullReply.Bytes(), remoteAddr)
-	if err != nil {
-		return err
-	}
-	return nil
+	return fullReply.Bytes()
 }
diff --git a/server_test.go b/server_test.go
new file mode 100644
index 00000000..c65a5f06
--- /dev/null
+++ b/server_test.go
@@ -0,0 +1,17 @@
+package quic
+
+import (
+	"github.com/lucas-clemente/quic-go/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Server", func() {
+	It("composes version negotiation packets", func() {
+		expected := append(
+			[]byte{0x2d, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0},
+			protocol.SupportedVersionsAsTags...,
+		)
+		Expect(composeVersionNegotiation(1)).To(Equal(expected))
+	})
+})