func iNewLspServer(port int, params *LspParams) (*LspServer, error) {
srv := new(LspServer)
srv.nextId = 1
if params == nil {
// Insert default parameters
params = &LspParams{5, 2000}
}
srv.params = params
hostport := fmt.Sprintf(":%v", port)
addr, err := lspnet.ResolveUDPAddr("udp", hostport)
if lsplog.CheckReport(1, err) {
return nil, err
}
srv.udpConn, err = lspnet.ListenUDP("udp", addr)
if lsplog.CheckReport(1, err) {
return nil, err
}
srv.readBuf = NewBuf()
// Need enough room to recycle close messages
srv.appReadChan = make(LspMessageChan, 1)
srv.appWriteChan = make(LspMessageChan)
srv.netInChan = make(networkChan)
srv.epochChan = make(chan int)
srv.connById = make(map[uint16]*lspConn)
srv.connByAddr = make(map[string]*lspConn)
srv.closeReplyChan = make(chan error, 1)
srv.closeAllReplyChan = make(chan error, 1)
srv.writeReplyChan = make(chan error, 1)
go srv.serverLoop()
go srv.udpReader()
go epochTrigger(srv.params.EpochMilliseconds, srv.epochChan, &srv.stopGlobalNetworkFlag)
return srv, nil
}
// Shut down all network activity
func (srv *LspServer) stopGlobalNetwork() {
srv.stopGlobalNetworkFlag = true
err := srv.udpConn.Close()
if lsplog.CheckReport(4, err) {
lsplog.Vlogf(6, "Server Continuing\n")
}
}
// Write message to UDP connection. Address specified by con
func (srv *LspServer) udpWrite(con *lspConn, msg *LspMessage) {
b := msg.genPacket()
_, err := srv.udpConn.WriteToUDP(b, con.addr)
if lsplog.CheckReport(6, err) {
srv.Vlogf(6, "Write failed\n")
}
}
// Shutting down network communications
func (cli *LspClient) stopNetwork() {
cli.lspConn.stopNetworkFlag = true
err := cli.udpConn.Close()
if lsplog.CheckReport(4, err) {
lsplog.Vlogf(6, "Client Continuing\n")
}
}
// Write message to UDP connection. Address already registered with connection
func (cli *LspClient) udpWrite(msg *LspMessage) {
b := msg.genPacket()
_, err := cli.udpConn.Write(b)
if lsplog.CheckReport(6, err) {
cli.Vlogf(6, "Write failed\n")
}
}
// Goroutine that reads messages from UDP connection and writes to message channel
func (cli *LspClient) udpReader() {
udpConn := cli.udpConn
mc := cli.netInChan
var buffer [1500]byte
for !cli.lspConn.stopNetworkFlag {
n, _, err := udpConn.ReadFromUDP(buffer[0:])
if lsplog.CheckReport(1, err) {
cli.Vlogf(6, "Client continuing\n")
continue
}
m, merr := extractMessage(buffer[0:n])
if lsplog.CheckReport(1, merr) {
cli.Vlogf(6, "Client continuing\n")
continue
}
mc <- m
}
}
// Goroutine that reads messages from UDP connection and writes to message channel
func (srv *LspServer) udpReader() {
udpConn := srv.udpConn
netc := srv.netInChan
var buffer [1500]byte
for !srv.stopGlobalNetworkFlag {
n, addr, err := udpConn.ReadFromUDP(buffer[0:])
if lsplog.CheckReport(1, err) {
srv.Vlogf(5, "Server continuing\n")
continue
}
m, merr := extractMessage(buffer[0:n])
if lsplog.CheckReport(1, merr) {
srv.Vlogf(6, "Server continuing\n")
continue
}
srv.Vlogf(5, "Received message %s\n", m)
d := &networkData{m, addr}
netc <- d
}
}
func iNewLspClient(hostport string, params *LspParams) (*LspClient, error) {
cli := new(LspClient)
if params == nil {
// Insert default parameters
params = &LspParams{5, 2000}
}
cli.params = params
addr, err := lspnet.ResolveUDPAddr("udp", hostport)
if lsplog.CheckReport(1, err) {
return nil, err
}
cli.lspConn = newConn(addr, 0, 0)
// Client's first received message will be data message.
cli.lspConn.nextRecvSeqNum = NextSeqNum(0)
cli.udpConn, err = lspnet.DialUDP("udp", nil, addr)
if lsplog.CheckReport(1, err) {
return nil, err
}
// Need enough room to recycle close messages at end
cli.appReadChan = make(LspMessageChan, 2)
cli.readBuf = NewBuf()
cli.appWriteChan = make(LspMessageChan, 1)
cli.netInChan = make(LspMessageChan, 1)
cli.epochChan = make(chan int)
cli.closeReplyChan = make(chan error, 2)
cli.writeReplyChan = make(chan error, 2)
go cli.clientLoop()
go cli.udpReader()
go epochTrigger(cli.params.EpochMilliseconds, cli.epochChan, &cli.lspConn.stopNetworkFlag)
// Send connection request to server
nm := GenConnectMessage()
cli.udpWrite(nm)
cli.lspConn.pendingMsg = nm
cli.lspConn.nextSendSeqNum = NextSeqNum(0)
cm := <-cli.appReadChan
if cm.Type == MsgCONNECT {
return cli, nil
}
return nil, lsplog.MakeErr("Connection failed")
}
func (srv *LspServer) networkHandler() {
lsplog.Vlogf(3, "[Server] Started the network handler")
for { // Should loop only if the connection is still on.
lsplog.Vlogf(6, "[Server] Going to read a packet")
m, addr, err := srv.readPacket()
if err != nil {
lsplog.CheckReport(3, err)
lsplog.Vlogf(6, "[Server] Ignoring this packet")
continue
}
go srv.packetHandler(m, addr)
}
}
func main() {
var ihelp *bool = flag.Bool("h", false, "Show help information")
var iport *int = flag.Int("p", 6666, "Port number")
var ihost *string = flag.String("H", "localhost", "Host address")
var iverb *int = flag.Int("v", 1, "Verbosity (0-6)")
var irdrop *int = flag.Int("r", 0, "Network read packet drop percentage")
var iwdrop *int = flag.Int("w", 0, "Network write packet drop percentage")
var elim *int = flag.Int("k", 5, "Epoch limit")
var ems *int = flag.Int("d", 2000, "Epoch duration (millisecconds)")
flag.Parse()
if *ihelp {
flag.Usage()
os.Exit(0)
}
if flag.NArg() > 0 {
// Look for host:port on command line
ok := true
fields := strings.Split(flag.Arg(0), ":")
ok = ok && len(fields) == 2
if ok {
*ihost = fields[0]
n, err := fmt.Sscanf(fields[1], "%d", iport)
ok = ok && n == 1 && err == nil
}
if !ok {
flag.Usage()
os.Exit(0)
}
}
params := &lsp12.LspParams{*elim, *ems}
lsplog.SetVerbose(*iverb)
lspnet.SetReadDropPercent(*irdrop)
lspnet.SetWriteDropPercent(*iwdrop)
hostport := fmt.Sprintf("%s:%v", *ihost, *iport)
fmt.Printf("Connecting to server at %s\n", hostport)
cli, err := lsp12.NewLspClient(hostport, params)
if err != nil {
fmt.Printf("... failed. Error message %s\n", err.Error())
}
if lsplog.CheckReport(1, err) {
return
}
runclient(cli)
}
func (cli *LspClient) readPacket() (m *LspMessage, addr *lspnet.UDPAddr, e error) {
b := make([]byte, 1000)
n, addr, err := cli.udpConn.ReadFromUDP(b)
if addr == nil || n == 0 {
lsplog.Vlogf(3, "[Client] Recieved a terminating packet.")
return nil, addr, lsplog.ConnectionClosed()
} else {
lsplog.Vlogf(5, "[Client] Recieved a packet from %s:%d", addr.IP.String(), addr.Port)
}
if err != nil {
lsplog.CheckFatal(err)
return nil, nil, err
}
recieved := CreateEmptyPacket()
err = json.Unmarshal(b[0:n], recieved)
if err != nil {
lsplog.CheckReport(3, err)
return nil, addr, err
}
lsplog.Vlogf(6, "[Client] Recieved packet %+v", recieved)
return recieved, addr, err
}
func (srv *LspServer) readPacket() (m *LspMessage, addr *lspnet.UDPAddr, e error) {
b := make([]byte, 1000)
n, addr, err := srv.udpConn.ReadFromUDP(b)
if addr == nil {
lsplog.Vlogf(3, "[Server] Recieved a terminating packet.")
return nil, addr, lsplog.ConnectionClosed()
} else {
lsplog.Vlogf(4, "[Server] Recieved a packet from %s:%d with length %d", addr.IP.String(), addr.Port, n)
}
if err != nil {
lsplog.Vlogf(3, "[Server] Error occured while reading from UDP.")
lsplog.CheckFatal(err)
return nil, nil, err
}
recieved := CreateEmptyPacket()
err = json.Unmarshal(b[0:n], recieved)
if err != nil {
lsplog.Vlogf(6, "[Server] Error while unmarshalling %X", b)
lsplog.CheckReport(4, err)
return nil, addr, err
}
lsplog.Vlogf(5, "[Server] Recieved packet %+v", recieved)
return recieved, addr, err
}
func (cli *LspClient) networkHandler() {
lsplog.Vlogf(3, "[Client] Started the network handler")
for { // Should loop only if the connection is still on.
lsplog.Vlogf(6, "[Client] Going to read a packet")
m, addr, err := cli.readPacket()
if err != nil && addr == nil { // Found out that whenever a connection is closed, the address becomes nil.
lsplog.CheckReport(3, err)
lsplog.Vlogf(3, "[Client] Terminating network handler.")
break
}
if err != nil {
lsplog.CheckReport(3, err)
continue
}
if !bytes.Equal(addr.IP, cli.udpAddr.IP) {
lsplog.Vlogf(5, "[Client] Address of packet is unknown. Ignoring packet.")
continue
}
lsplog.Vlogf(5, "[Client] Packet recieved is valid.")
if IsConnectionAck(m) && !cli.connectionAlive {
lsplog.Vlogf(5, "[Client] Connection acknowledged.")
cli.connId = m.ConnId
cli.makeConnectionAlive()
} else if IsDataPacket(m) {
lsplog.Vlogf(4, "[Client] Recieved a data packet from server.")
if m.ConnId == cli.connId {
lsplog.Vlogf(6, "[Client] Data packet belongs to this client.")
if m.SeqNum == cli.serverSeqNum {
lsplog.Vlogf(5, "[Client] Data packet has an expected sequence.")
cli.read.Insert(m.Payload)
cli.serverSeqNum = (cli.serverSeqNum + 1) % math.MaxInt8
lsplog.Vlogf(5, "[Client] Server sequence number became (%d).", cli.serverSeqNum)
dataAck := CreateDataAck(cli.connId, m.SeqNum)
cli.lastAck = dataAck
cli.lspSend(dataAck)
} else {
lsplog.Vlogf(5, "[Client] Message sequence number (%d) in packet is not expected (%d).", m.SeqNum, cli.serverSeqNum)
}
} else {
lsplog.Vlogf(4, "[Client] connId (%d) in packet is not the same as the client connId (%d).", m.ConnId, cli.connId)
}
} else {
lsplog.Vlogf(4, "[Client] Recieved an acknowledgment packet from server.")
<-cli.sentLocker
deletedElements := list.New()
for e := cli.sent.Front(); e != nil; e = e.Next() {
sentMessage := e.Value.(*LspMessage)
if sentMessage.SeqNum <= m.SeqNum {
deletedElements.PushBack(e)
}
}
for e := deletedElements.Front(); e != nil; e = e.Next() {
cli.sent.Remove(e.Value.(*list.Element))
}
cli.sentLocker <- 1
}
cli.resetEpochCounter()
}
lsplog.Vlogf(3, "[Client] Terminated network handler")
}