func WriteFile(in <-chan *tftp.File, m map[string][]byte, verbose *bool) {
for r := range in {
if *verbose {
fmt.Println(r.Name, " to be written ")
}
_, present := m[r.Name]
if !present {
m[r.Name] = r.Data
} else {
errCode := []byte{0, 6}
errMsg := "No overwriting allowed"
if *verbose {
fmt.Println(errMsg)
}
tftp.SendERRORTo(errCode, errMsg, r.Conn, r.Raddr)
}
}
}
func main() {
/* flag for turning on verbose output */
verbose := flag.Bool("verbose", false, "a bool")
flag.Parse()
/* handler for map of channels to communicate with routines handling read/write requests */
add := make(chan *net.UDPAddr)
send := make(chan sendPair)
done := make(chan *net.UDPAddr)
getChannel := make(chan *net.UDPAddr)
gottenChannel := make(chan chan []byte)
sendConfirmation := make(chan bool)
defer close(gottenChannel)
defer close(sendConfirmation)
go ChannelHandler(add, send, sendConfirmation, done, getChannel, gottenChannel, verbose)
/* local memory for storing files */
m := map[string][]byte{}
/* channel for the file writer go routine */
newFile := make(chan *tftp.File)
defer close(newFile)
go WriteFile(newFile, m, verbose)
/* Lets prepare a address at any address at port 10001*/
ServerAddr, err := net.ResolveUDPAddr("udp", ":10001")
CheckError(err)
/* Now listen at selected port */
ServerConn, err := net.ListenUDP("udp", ServerAddr)
CheckError(err)
defer ServerConn.Close()
buf := make([]byte, 1024)
for {
n, addr, err := ServerConn.ReadFromUDP(buf)
CheckError(err)
if n < 2 || buf[0] != 0 || buf[1] == 0 || buf[1] > 5 {
tftp.SendERRORTo([]byte{0, 0}, "bad opcode", ServerConn, addr)
continue
}
switch buf[1] {
case 1:
//handle RRQ
if *verbose {
fmt.Println("Recived ", string(buf[0:n]), " from ", addr, " as RRQ")
}
filename, err := tftp.GetRRQname(buf[0:n])
if err != nil {
errCode := []byte{0, 0}
errMsg := "Badly formed RRQ packet"
if *verbose {
fmt.Println(errMsg, " from ", addr)
}
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
} else {
_, present := m[filename]
if present {
add <- addr
getChannel <- addr
temp := <-gottenChannel
if temp != nil {
go tftp.HandleRRQ(filename, temp, done, ServerConn, addr, m[filename], verbose)
}
} else {
errCode := []byte{0, 1}
errMsg := filename + " not found"
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
}
}
case 2:
//handle WRQ
if *verbose {
fmt.Println("Recieved ", string(buf[0:n]), " from ", addr, " as WRQ")
}
filename, err := tftp.GetWRQname(buf[0:n])
if err != nil {
errCode := []byte{0, 0}
errMsg := "Badly formed WRQ packet"
if *verbose {
fmt.Println(errMsg, " from ", addr)
}
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
} else {
_, present := m[filename]
if present {
errCode := []byte{0, 6}
errMsg := "No overwriting allowed"
if *verbose {
fmt.Println(errMsg)
}
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
} else {
add <- addr
getChannel <- addr
temp := <-gottenChannel
if temp != nil {
go tftp.HandleWRQ(filename, temp, done, ServerConn, addr, newFile, verbose)
}
}
}
case 3:
//handle DATA
if *verbose {
fmt.Println(" Recieved ", string(buf[0:n]), " from ", addr, " as DATA")
}
send <- sendPair{addr, buf[0:n]}
sent := <-sendConfirmation
if !sent {
errCode := []byte{0, 5}
errMsg := "No write request associated with this return address"
if *verbose {
fmt.Println(" ", errMsg, " ", addr)
}
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
}
case 4:
//handle ACK
if *verbose {
fmt.Println(" Recieved ", string(buf[0:n]), " from ", addr, " as ACK")
}
send <- sendPair{addr, buf[0:n]}
sent := <-sendConfirmation
if !sent {
errCode := []byte{0, 5}
errMsg := "No read request associated with this return address"
if *verbose {
fmt.Println(" ", errMsg, " ", addr)
}
tftp.SendERRORTo(errCode, errMsg, ServerConn, addr)
}
case 5:
//handle ERROR
/*
all errors should term connection, EXCEPT if the error is because
"the source port of a recieved tftp is incorrect. in this case
an errr tftp is sent to the originating host"
*/
if *verbose {
fmt.Println(" Recieved ", string(buf[0:n]), " from ", addr, " as ERROR")
}
done <- addr
}
}
}