// listen to incoming UDP data using the given hostport, used on server side
func (h *networkUtility) listen(hostport string) error {
serverAddr, err := lspnet.ResolveUDPAddr("udp", hostport)
if err != nil {
return nil
}
conn, err := lspnet.ListenUDP("udp", serverAddr)
if err != nil {
return err
}
h.conn = conn
return nil
}
func (now *Connect) listen(hostport string) error {
serverAddr, err := lspnet.ResolveUDPAddr("udp", hostport)
if err != nil {
return nil
}
conn, err := lspnet.ListenUDP("udp", serverAddr)
if err != nil {
return err
}
now.conn = conn
now.addr = serverAddr
return nil
}
func (s *server) StartListen(port string) error {
uAddr, err := lspnet.ResolveUDPAddr("udp", ":"+port)
if err != nil {
fmt.Println("Unable to resolve UDP addr ", port)
return err
}
s.sConn, err = lspnet.ListenUDP("udp", uAddr)
if err != nil {
fmt.Println("Unable to listen on port ", port)
return err
}
go s.handleMessages()
go s.ticking()
for {
select {
case <-s.quitAllChan:
fmt.Println("server quit listener")
return nil
default:
// read a msg from UDP and check its type
buf := make([]byte, 2000)
n, addr, err := s.sConn.ReadFromUDP(buf)
if err != nil {
return err
}
msg := Message{}
json.Unmarshal(buf[0:n], &msg)
switch msg.Type {
case MsgConnect:
// receive a conn msg from client
s.addChan <- addr
case MsgData:
// add to data channel if hash match, drop otherwise
if hex.EncodeToString(calMD5Hash(msg)) == hex.EncodeToString(msg.Hash) {
s.dataChan <- &msg
} else {
fmt.Println("Hash does not match")
}
case MsgAck:
s.ackChan <- &msg
}
}
}
return err
}
func NewFixedSizeUDPServer(maxMsgSize int, port int) (UDPServer, error) {
addr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf(":%v", port))
if err != nil {
return nil, err
}
conn, err := net.ListenUDP("udp", addr) // non-blocking. no need to wait for any client to establish a connection like TCP does
if err != nil {
return nil, err
}
return &FixedSizeUDPServer{
maxMsgSize: maxMsgSize,
addr: addr,
conn: conn,
closed: false,
}, nil
}
// NewServer creates, initiates, and returns a new server. This function should
// NOT block. Instead, it should spawn one or more goroutines (to handle things
// like accepting incoming client connections, triggering epoch events at
// fixed intervals, synchronizing events using a for-select loop like you saw in
// project 0, etc.) and immediately return. It should return a non-nil error if
// there was an error resolving or listening on the specified port number.
func NewServer(port int, params *Params) (Server, error) {
s := &server{
nextConnectId: 1,
clients: make(map[int]*abstractClient),
readFromClientChan: make(chan *msgPackage),
writeToClientChan: make(chan *Message),
readRequest: &requestRead{
ask: make(chan int),
response: make(chan *Message),
},
writeRequest: &requestWrite{
ask: make(chan []byte),
connId: make(chan int),
response: make(chan error),
},
readList: list.New(),
writeList: list.New(),
flag: false,
// variables for window size
windowSize: params.WindowSize,
mapNeedSend: list.New(),
// variables for epoch
epochChan: make(chan int),
epochMillis: params.EpochMillis,
epochLimit: params.EpochLimit,
// close
deleteClient: make(chan int),
closeConnRequest: &requestCloseConn{
ask: make(chan int),
getError: make(chan error),
},
waitToWriteFinish: false,
writeFinished: make(chan int),
waitToAckFinish: false,
ackFinished: make(chan int),
closeRead: make(chan int, 1),
closeEpoch: make(chan int, 1),
closeEvent: make(chan int, 1),
// close conn
closeConn: make(chan int, 1),
}
// start server
addr, err := lspnet.ResolveUDPAddr("udp", "localhost:"+strconv.Itoa(port))
if err != nil {
return nil, err
}
conn, err := lspnet.ListenUDP("udp", addr)
if err != nil {
return nil, err
}
s.conn = conn
go s.readMessage()
go s.handleMessage()
go s.epochFire()
fmt.Println("new server")
return s, nil
}