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frame_get_routers.go
81 lines (71 loc) · 1.51 KB
/
frame_get_routers.go
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package temp
import (
"encoding/binary"
"errors"
"net"
"strconv"
"time"
)
func XcGetRouters(ipAddress string, timeout time.Duration, address string) (result []*net.UDPAddr, err error) {
result = make([]*net.UDPAddr, 0)
addressBS := []byte(address)
conn, err := net.ListenPacket("udp", ":")
if err != nil {
return
}
ipStr, portStr, err := net.SplitHostPort(ipAddress)
if err != nil {
return
}
var addr net.UDPAddr
addr.IP = net.ParseIP(ipStr)
if addr.IP == nil {
err = errors.New("wrong IP address")
return
}
portInt, err := strconv.ParseInt(portStr, 10, 32)
if err != nil {
return
}
addr.Port = int(portInt)
request := make([]byte, 8+len(addressBS))
request[0] = 0x04
copy(request[8:], addressBS)
var n int
n, err = conn.WriteTo(request, &addr)
if err != nil {
return
}
if n != len(request) {
err = errors.New("data sent partially")
return
}
buffer := make([]byte, 1024)
err = conn.SetReadDeadline(time.Now().Add(timeout))
if err != nil {
return
}
n, _, err = conn.ReadFrom(buffer)
if err != nil {
return
}
if n < 8 {
err = errors.New("wrong response - size of frame")
return
}
if buffer[1] != 0 {
err = errors.New("error code:" + strconv.FormatInt(int64(buffer[1]), 10))
return
}
if ((n - 8) % 32) != 0 {
err = errors.New("wrong frame len")
return
}
for i := 8; i < n; i += 32 {
var udpAddr net.UDPAddr
udpAddr.IP = buffer[i+2 : i+2+16]
udpAddr.Port = int(binary.LittleEndian.Uint16(buffer[i+2+16:]))
result = append(result, &udpAddr)
}
return
}