func sendFullWrite(filename string, content string) {
//sends inital WRQ
//waits for ack block 0,0 or times out
//loop
// sends data
// waits for ack, or handles error, or resends
// if data sent and acknowledged was last data, end
ServerAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:10001")
checkError(err)
LocalAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
checkError(err)
Conn, err := net.DialUDP("udp", LocalAddr, ServerAddr)
checkError(err)
defer Conn.Close()
/* initialize variables for tracking acknowledgements and location in content*/
index := 0
f := []byte(content)
max := min(512, len(f))
data := f[index:max]
block := []byte{0, 0}
/*send inital WRQ*/
/*send inital WRQ*/
tftp.SendWRQ(filename, Conn)
packet := make(chan []byte)
defer close(packet)
go getPacket(Conn, packet)
select {
case <-time.After(15 * time.Second):
fmt.Println("WRQ from ", LocalAddr, " never acknowledged")
return
case r := <-packet:
switch r[1] {
case 4:
//ACK packet recieved
ackBlock, err := tftp.GetAckBlock(r)
if err != nil {
errCode := []byte{0, 0}
errMsg := "badly formed ACK packet"
tftp.SendERROR(errCode, errMsg, Conn)
return
}
if ackBlock[1] == block[1] {
break
}
case 5:
//ERROR packet recieved
_, errMsg, err := tftp.GetError(r)
if err != nil {
return
}
fmt.Println(string(errMsg), " recieved by ", LocalAddr)
return
}
}
SendLoop:
for {
//send Data
block[1]++
tftp.SendDATA(block, data, Conn)
//wait for ack
LoopAck:
for {
select {
case <-time.After(time.Second * 3):
tftp.SendDATA(block, data, Conn)
case <-time.After(time.Second * 15):
fmt.Println("DATA packet ", string(block), " from ", LocalAddr, " never acknowledged")
return
case r := <-packet:
switch r[1] {
case 4:
//ACK packet recieved
ackBlock, err := tftp.GetAckBlock(r)
if err != nil {
errCode := []byte{0, 0}
errMsg := "badly formed ACK packet"
tftp.SendERROR(errCode, errMsg, Conn)
return
}
if ackBlock[1] == block[1] {
break LoopAck
}
case 5:
//ERROR packet recieved
_, errMsg, err := tftp.GetError(r)
if err != nil {
return
}
fmt.Println(string(errMsg), " recieved by ", LocalAddr)
return
}
}
}
if max == len(content) {
break SendLoop
}
//update data
index += 512
max = min(index+512, len(f))
data = f[index:max]
}
}
func sendFullRead(filename string) (string, error) {
//sends RRQ
//loop:
// listens for DATA with block ahead of prev ACK packet
// send ACK packet for current DATA
// if len(current DATA) < 512, send final ACK and close
ServerAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:10001")
checkError(err)
LocalAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
checkError(err)
Conn, err := net.DialUDP("udp", LocalAddr, ServerAddr)
checkError(err)
defer Conn.Close()
temp := []byte{}
tftp.SendRRQ(filename, Conn)
prev_block := []byte{0, 0}
packet := make(chan []byte)
defer close(packet)
go getPacket(Conn, packet)
Read:
for {
select {
case r := <-packet:
switch r[1] {
case 3:
//DATA packet recieved
block, data, err := tftp.GetData(r)
if err != nil {
return "", err
}
if block[1] == prev_block[1]+1 {
tftp.SendACK(block, Conn)
prev_block[1] = block[1]
temp = append(temp, data...)
if len(data) < 512 {
break Read
}
} else if block[1] != 0 {
tftp.SendACK(prev_block, Conn)
} // else the RRQ itself failed somehow
case 5:
//ERROR packet recieved
_, errMsg, err := tftp.GetError(r)
if err != nil {
return "", err
}
fmt.Println(string(errMsg), " recieved by ", LocalAddr)
return "", errors.New(string(errMsg))
}
case <-time.After(1 * time.Second):
tftp.SendACK(prev_block, Conn)
case <-time.After(15 * time.Second):
fmt.Println("A read request by ", LocalAddr, " timed out")
return "", errors.New("rrq timed out")
}
}
return string(temp), nil
}