- Reduced global variables to 2 variables, all others are scoped local

variables.
- initConns function takes client and server control channel address as
input (along with pathAlgo and interactive for choosing the paths while
setting up the addresses), and returns the connections, the data
channel addresses, and an error.
- find max bandwidth option can be used with the 'cs' and/or the 'sc'
flags to set the duration, packet sizes, and starting bandwidth for the
 test. If the flags are not set, default values are used

bwtester/bwtestclient/bwtestclient.go

@@ -37,44 +37,6 @@ const (
 var (
 	InferedPktSize int64
 	overlayType    string
-
-	sciondPath      string
-	sciondFromIA    bool
-	dispatcherPath  string
-	clientCCAddrStr string
-	serverCCAddrStr string
-	clientPort      uint
-	serverPort      uint16
-	// Address of client control channel (CC)
-	clientCCAddr *snet.Addr
-	// Address of server control channel (CC)
-	serverCCAddr *snet.Addr
-	// Control channel connection
-	CCConn snet.Conn
-
-	// Address of client data channel (DC)
-	clientDCAddr *snet.Addr
-	// Address of server data channel (DC)
-	serverDCAddr *snet.Addr
-	// Data channel connection
-	DCConn snet.Conn
-
-	clientBwpStr string
-	clientBwp    BwtestParameters
-	serverBwpStr string
-	serverBwp    BwtestParameters
-	interactive  bool
-	pathAlgo     string
-	useIPv6      bool
-
-	err   error
-	tzero time.Time // initialized to "zero" time
-
-	receiveDone chan struct{} // used to signal when the HandleDCConnReceive goroutine has completed
-
-	maxBandwidth bool
-
-	pathEntry *sciond.PathReplyEntry
 )
 
 func prepareAESKey() []byte {
@@ -279,6 +241,40 @@ func getPacketCount(count string) int64 {
 }
 
 func main() {
+	var (
+		sciondPath      string
+		sciondFromIA    bool
+		dispatcherPath  string
+		clientCCAddrStr string
+		serverCCAddrStr string
+		clientPort      uint
+
+		// Control channel connection
+		CCConn snet.Conn
+		// Address of client control channel (CC)
+		clientCCAddr *snet.Addr
+		// Address of server control channel (CC)
+		serverCCAddr *snet.Addr
+
+		// Address of client data channel (DC)
+		clientDCAddr *snet.Addr
+		// Address of server data channel (DC)
+		serverDCAddr *snet.Addr
+		// Data channel connection
+		DCConn snet.Conn
+
+		clientBwpStr string
+		clientBwp    BwtestParameters
+		serverBwpStr string
+		serverBwp    BwtestParameters
+		interactive  bool
+		pathAlgo     string
+		useIPv6      bool
+
+		maxBandwidth bool
+
+		err error
+	)
 	flag.StringVar(&sciondPath, "sciond", "", "Path to sciond socket")
 	flag.BoolVar(&sciondFromIA, "sciondFromIA", false, "SCIOND socket path from IA address:ISD-AS")
 	flag.StringVar(&dispatcherPath, "dispatcher", "/run/shm/dispatcher/default.sock",
@@ -291,7 +287,11 @@ func main() {
 	flag.BoolVar(&interactive, "i", false, "Interactive mode")
 	flag.StringVar(&pathAlgo, "pathAlgo", "", "Path selection algorithm / metric (\"shortest\", \"mtu\")")
 	flag.BoolVar(&useIPv6, "6", false, "Use IPv6")
-	flag.BoolVar(&maxBandwidth, "findMax", false, "Find the maximum bandwidth achievable")
+	flag.BoolVar(&maxBandwidth, "findMax", false, "Find the maximum bandwidth achievable.\nYou can"+
+		"use the flags \"cs\" and \"sc\" to set the parameters along with initial bandwidth to test on the link.\n"+
+		"The other parameters will be fixed except for the packet count which will change in every run.\nThe higher"+
+		" the duration of the test, the more accurate the results, but it will take longer to find the "+
+		"maximum bandwidth.")
 
 	flag.Parse()
 	flagset := make(map[string]bool)
@@ -304,8 +304,6 @@ func main() {
 		os.Exit(0)
 	}
 
-	receiveDone = make(chan struct{})
-
 	if useIPv6 {
 		overlayType = "udp6"
 	} else {
@@ -338,82 +336,76 @@ func main() {
 		sciondPath = sciond.GetDefaultSCIONDPath(nil)
 	}
 
-	initConns()
+	CCConn, DCConn, serverDCAddr, clientDCAddr, err = initConns(serverCCAddr, clientCCAddr, pathAlgo, interactive)
+	if err != nil {
+		Check(err)
+	}
 
-	if maxBandwidth {
-		findMaxBandwidth()
+	if !flagset["cs"] && flagset["sc"] { // Only one direction set, used same for reverse
+		clientBwpStr = serverBwpStr
+		fmt.Println("Only sc parameter set, using same values for cs")
+	}
+	clientBwp = parseBwtestParameters(clientBwpStr)
+	clientBwp.Port = clientDCAddr.Host.L4.Port()
+	if !flagset["sc"] && flagset["cs"] { // Only one direction set, used same for reverse
+		serverBwpStr = clientBwpStr
+		fmt.Println("Only cs parameter set, using same values for sc")
+	}
+	serverBwp = parseBwtestParameters(serverBwpStr)
+	serverBwp.Port = serverDCAddr.Host.L4.Port()
 
+	fmt.Println("\nTest parameters:")
+	fmt.Println("clientDCAddr -> serverDCAddr", clientDCAddr, "->", serverDCAddr)
+	fmt.Printf("client->server: %d seconds, %d bytes, %d packets\n",
+		int(clientBwp.BwtestDuration/time.Second), clientBwp.PacketSize, clientBwp.NumPackets)
+	fmt.Printf("server->client: %d seconds, %d bytes, %d packets\n",
+		int(serverBwp.BwtestDuration/time.Second), serverBwp.PacketSize, serverBwp.NumPackets)
+
+	if maxBandwidth {
+		findMaxBandwidth(CCConn, DCConn, serverCCAddr, serverDCAddr, clientCCAddr, clientDCAddr, serverBwp, clientBwp)
 	} else {
-		if !flagset["cs"] && flagset["sc"] { // Only one direction set, used same for reverse
-			clientBwpStr = serverBwpStr
-			fmt.Println("Only sc parameter set, using same values for cs")
-		}
-		clientBwp = parseBwtestParameters(clientBwpStr)
-		clientBwp.Port = uint16(clientPort + 1)
-		if !flagset["sc"] && flagset["cs"] { // Only one direction set, used same for reverse
-			serverBwpStr = clientBwpStr
-			fmt.Println("Only cs parameter set, using same values for sc")
-		}
-		serverBwp = parseBwtestParameters(serverBwpStr)
-		serverBwp.Port = serverPort + 1
-
-		fmt.Println("\nTest parameters:")
-		fmt.Println("clientDCAddr -> serverDCAddr", clientDCAddr, "->", serverDCAddr)
-		fmt.Printf("client->server: %d seconds, %d bytes, %d packets\n",
-			int(clientBwp.BwtestDuration/time.Second), clientBwp.PacketSize, clientBwp.NumPackets)
-		fmt.Printf("server->client: %d seconds, %d bytes, %d packets\n",
-			int(serverBwp.BwtestDuration/time.Second), serverBwp.PacketSize, serverBwp.NumPackets)
-
-		singleRun(func() {
-			Check(fmt.Errorf("Error, could not receive a server response, MaxTries attempted without success."))
-		},
+
+		singleRun(CCConn, DCConn, serverBwp, clientBwp,
+			func() {
+				Check(fmt.Errorf("Error, could not receive a server response, MaxTries attempted without success."))
+			},
 			func() {
 				Check(fmt.Errorf("Error, could not fetch server results, MaxTries attempted without success."))
 			})
 	}
 }
 
-func findMaxBandwidth() {
+func findMaxBandwidth(CCConn, DCConn snet.Conn, serverCCAddr, serverDCAddr, clientCCAddr, clientDCAddr *snet.Addr,
+	serverBwp, clientBwp BwtestParameters) {
 	var (
-		clientOldBw, serverOldBw, clientThreshold, serverThreshold int64
-		serverMax, clientMax                                       bool
-		finished                                                   bool
+		clientOldBw, serverOldBw         int64
+		clientThreshold, serverThreshold int64
+		serverMax, clientMax             bool
+		finished                         bool
 		// run is used to hold the number of the current run.
 		run uint16
 	)
 
-	// set the server and client bandwidth in the beginning to 512kbps
-	serverBw, clientBw := int64(512e3), int64(512e3)
+	// Calculate from bandwidth parameters from the user
+	serverBw := (serverBwp.NumPackets * serverBwp.PacketSize * 8) / int64(serverBwp.BwtestDuration/time.Second)
+	clientBw := (clientBwp.NumPackets * clientBwp.PacketSize * 8) / int64(clientBwp.BwtestDuration/time.Second)
 
 	for !finished {
-
 		run++
 		fmt.Println(strings.Repeat("#", 50))
 		fmt.Println("Run: ", run)
 
 		DCConn = resetConn(DCConn, clientDCAddr, serverDCAddr)
 
-		// Use the maximum duration to get more accurate results
-		clientBwp = BwtestParameters{
-			BwtestDuration: MaxDuration,
-			PacketSize:     InferedPktSize,
-			NumPackets:     (clientBw * 10) / (InferedPktSize * 8),
-			PrgKey:         prepareAESKey(),
-			Port:           uint16(clientPort + 1),
-		}
-		serverBwp = BwtestParameters{
-			BwtestDuration: MaxDuration,
-			PacketSize:     InferedPktSize,
-			NumPackets:     (serverBw * 10) / (InferedPktSize * 8),
-			PrgKey:         prepareAESKey(),
-			Port:           serverPort + 1,
-		}
+		// calculate the new number of packets to send based on
+		serverBwp.NumPackets = (serverBw * int64(serverBwp.BwtestDuration/time.Second)) / (serverBwp.PacketSize * 8)
+		clientBwp.NumPackets = (clientBw * int64(clientBwp.BwtestDuration/time.Second)) / (clientBwp.PacketSize * 8)
 
-		fmt.Println("\nTest parameters:")
-		fmt.Printf("client->server: 	%.3f Mbps\n", float64(clientBw)/1e6)
+		fmt.Println("\nBandwidth values:")
 		fmt.Printf("server->client: 	%.3f Mbps\n", float64(serverBw)/1e6)
+		fmt.Printf("client->server: 	%.3f Mbps\n", float64(clientBw)/1e6)
 
-		res, sres, failed := singleRun(func() {
+		res, sres, failed := singleRun(CCConn, DCConn, serverBwp, clientBwp, func() {
 			handleSCError(&serverMax, &clientMax, &serverBw, &clientBw,
 				&serverOldBw, &clientOldBw, &serverThreshold, &clientThreshold)
 		}, func() {
@@ -424,20 +416,20 @@ func findMaxBandwidth() {
 			//resetCCConn()
 			CCConn = resetConn(CCConn, clientCCAddr, serverCCAddr)
 		} else {
-			ach := 8 * clientBwp.PacketSize * sres.CorrectlyReceived / int64(clientBwp.BwtestDuration/time.Second)
-			handleBandwidth(&clientMax, &clientBw, &clientOldBw, &clientThreshold, ach, "client -> server")
-
-			ach = 8 * serverBwp.PacketSize * res.CorrectlyReceived / int64(serverBwp.BwtestDuration/time.Second)
+			ach := 8 * serverBwp.PacketSize * res.CorrectlyReceived / int64(serverBwp.BwtestDuration/time.Second)
 			handleBandwidth(&serverMax, &serverBw, &serverOldBw, &serverThreshold, ach, "server -> client")
+
+			ach = 8 * clientBwp.PacketSize * sres.CorrectlyReceived / int64(clientBwp.BwtestDuration/time.Second)
+			handleBandwidth(&clientMax, &clientBw, &clientOldBw, &clientThreshold, ach, "client -> server")
 		}
 
 		// Check if we found the maximum bandwidth for the client and the server
 		finished = clientMax && serverMax
 		time.Sleep(time.Second)
 	}
 
-	fmt.Println("Max client to server available bandwidth: ", float64(clientBw)/1e6, " Mbps")
-	fmt.Println("Max server to client available bandwidth: ", float64(serverBw)/1e6, " Mbps")
+	fmt.Println("Max server -> client available bandwidth: ", float64(serverBw)/1e6, " Mbps")
+	fmt.Println("Max client -> server available bandwidth: ", float64(clientBw)/1e6, " Mbps")
 	os.Exit(0)
 }
 
@@ -554,7 +546,10 @@ func decreaseBandwidth(currentBandwidth, threshold, achievedBandwidth, oldBandwi
 // initConns sets up the paths to the server, initializes the Control Channel
 // connection, sets up the Data connection addresses, starts the Data Channel
 // connection, then it updates packet size.
-func initConns() {
+func initConns(serverCCAddr, clientCCAddr *snet.Addr, pathAlgo string, interactive bool) (CCConn,
+	DCConn snet.Conn, serverDCAddr, clientDCAddr *snet.Addr, err error) {
+	var pathEntry *sciond.PathReplyEntry
+
 	// Setup the paths and
 	if !serverCCAddr.IA.Eq(clientCCAddr.IA) {
 		if interactive {
@@ -580,11 +575,12 @@ func initConns() {
 
 	// Control channel connection
 	CCConn, err = snet.DialSCION(overlayType, clientCCAddr, serverCCAddr)
-	Check(err)
-
+	if err != nil {
+		return
+	}
 	// get the port used by clientCC after it bound to the dispatcher (because it might be 0)
-	clientPort = uint((CCConn.LocalAddr()).(*snet.Addr).Host.L4.Port())
-	serverPort = serverCCAddr.Host.L4.Port()
+	clientPort := uint((CCConn.LocalAddr()).(*snet.Addr).Host.L4.Port())
+	serverPort := serverCCAddr.Host.L4.Port()
 
 	//Address of client data channel (DC)
 	clientDCAddr = &snet.Addr{IA: clientCCAddr.IA, Host: &addr.AppAddr{
@@ -604,18 +600,22 @@ func initConns() {
 
 	//Data channel connection
 	DCConn, err = snet.DialSCION(overlayType, clientDCAddr, serverDCAddr)
-	Check(err)
-
+	if err != nil {
+		return
+	}
 	// update default packet size to max MTU on the selected path
 	if pathEntry != nil {
 		InferedPktSize = int64(pathEntry.Path.Mtu)
 	} else {
 		// use default packet size when within same AS and pathEntry is not set
 		InferedPktSize = DefaultPktSize
 	}
+
+	return
 }
 
 func resetConn(conn snet.Conn, localAddress, remoteAddress *snet.Addr) snet.Conn {
+	var err error
 	_ = conn.Close()
 
 	// give it time to close the connection before trying to open it again
@@ -632,7 +632,11 @@ func resetConn(conn snet.Conn, localAddress, remoteAddress *snet.Addr) snet.Conn
 // It should be called right after setting up the flags to start the test.
 // Returns the bandwidth test results and a boolean to indicate a
 //// failure in the measurements (when max tries is reached).
-func startTest() (*BwtestResult, bool) {
+func startTest(CCConn, DCConn snet.Conn, serverBwp, clientBwp BwtestParameters,
+	receiveDone chan struct{}) (*BwtestResult, bool) {
+	var tzero time.Time
+	var err error
+
 	t := time.Now()
 	expFinishTimeSend := t.Add(serverBwp.BwtestDuration + MaxRTT + GracePeriodSend)
 	expFinishTimeReceive := t.Add(clientBwp.BwtestDuration + MaxRTT + StragglerWaitPeriod)
@@ -713,7 +717,10 @@ func startTest() (*BwtestResult, bool) {
 // (See normalRun for an example).
 // Returns the bandwidth test results and a boolean to indicate a
 // failure in the measurements (when max tries is reached).
-func fetchResults() (*BwtestResult, bool) {
+func fetchResults(CCConn snet.Conn, clientBwp BwtestParameters) (*BwtestResult, bool) {
+	var tzero time.Time
+	var err error
+
 	pktbuf := make([]byte, 2000)
 	var numtries int64 = 0
 	sres := &BwtestResult{NumPacketsReceived: -1,
@@ -796,7 +803,7 @@ func printResults(res *BwtestResult, bwp BwtestParameters) {
 	ach := 8 * bwp.PacketSize * res.CorrectlyReceived / int64(bwp.BwtestDuration/time.Second)
 	fmt.Printf("Attempted bandwidth: %d bps / %.3f Mbps\n", att, float64(att)/1e6)
 	fmt.Printf("Achieved bandwidth: %d bps / %.3f Mbps\n", ach, float64(ach)/1e6)
-	loss := float32(bwp.NumPackets-res.CorrectlyReceived) * 100 / float32(serverBwp.NumPackets)
+	loss := float32(bwp.NumPackets-res.CorrectlyReceived) * 100 / float32(bwp.NumPackets)
 	fmt.Println("Loss rate:", loss, "%")
 	variance := res.IPAvar
 	average := res.IPAavg
@@ -808,8 +815,10 @@ func printResults(res *BwtestResult, bwp BwtestParameters) {
 
 // singleRun runs a single bandwidth test based in the clientBwp and serverBwp.
 // The test parameters should be set before using this function.
-func singleRun(scError, csError func()) (res, sres *BwtestResult, failed bool) {
-	res, failed = startTest()
+func singleRun(CCConn, DCConn snet.Conn, serverBwp, clientBwp BwtestParameters, scError,
+	csError func()) (res, sres *BwtestResult, failed bool) {
+	receiveDone := make(chan struct{})
+	res, failed = startTest(CCConn, DCConn, serverBwp, clientBwp, receiveDone)
 	if failed {
 		scError()
 		return
@@ -822,7 +831,7 @@ func singleRun(scError, csError func()) (res, sres *BwtestResult, failed bool) {
 	printResults(res, serverBwp)
 
 	// Fetch results from server
-	sres, failed = fetchResults()
+	sres, failed = fetchResults(CCConn, clientBwp)
 	if failed {
 		csError()
 		return