func csum(b []byte) uint16 {
// Make checksum
csumcv := len(b) - 1 // checksum coverage
s := uint32(0)
for i := 0; i < csumcv; i += 2 {
s += uint32(b[i+1])<<8 | uint32(b[i])
}
if csumcv&1 == 0 {
s += uint32(b[csumcv])
}
s = s>>16 + s&0xffff
s = s + s>>16
return netu.Htons(^uint16(s))
}
func main() {
// Get app params from console args
var err error
Params, err = NewAppParams(os.Args[1:])
if err != nil {
fmt.Fprintln(os.Stderr, err.Error())
return
}
// seed pseudo random generator; We'll need it later
rand.Seed(time.Now().UnixNano())
// Overwrite local only because my network is a bitch
if localAddr := os.Getenv("GRNVS_TRACE6_LADDR"); localAddr != "" {
fmt.Fprintf(os.Stderr, "Using %s as local ip address\n", localAddr)
Params.LocalAddress, err = net.ResolveIPAddr("ip6", localAddr)
if err != nil {
panic(err)
}
}
// Init raw socket for writing (IPPROTO_RAW is only for writing -> man 7 raw)
connWrite = createConn(syscall.AF_INET6, syscall.IPPROTO_RAW)
defer connWrite.Close()
// Socket for reading
sockRead, err = syscall.Socket(syscall.AF_PACKET, syscall.SOCK_DGRAM, int(netu.Htons(syscall.ETH_P_IPV6)))
if err != nil {
panic(err)
}
fileRead = os.NewFile(uintptr(sockRead), fmt.Sprintf("fd-sock-read-%d", sockRead))
defer syscall.Close(sockRead)
defer fileRead.Close()
// Create the base package, IPv6-Header + ICMP6 Echo Request
// Generate id for icmp package
id := uint16(rand.Uint32())
pck, l := icmp6.NewEchoRequest(id, 0)
// craft request package
req := &request{
Header: ipv6.NewHeader(&Params.LocalAddress.IP, &Params.RemoteAddress.IP),
Body: pck,
}
// set some ipv6 header values
req.Header.NextHeader = 0x3a
req.Header.PayloadLen = l
chanReply = make(chan *response, 1)
// Start traceing
//done := false
seq := uint16(0)
var resp *response
for i := 1; i <= Params.MaxHops; i++ {
// print current hop
fmt.Printf("%d", i)
// Send a package for each hop
for j := 0; j < Params.Attempts; j++ {
// get request data
p := req.Marshal(i, seq)
// Send icmp package
connWrite.WriteTo(p, Params.RemoteAddress)
// Wait for response
resp, err = recvResponse(req, &Params.RemoteAddress.IP)
if err != nil {
fmt.Printf(err.Error())
return
}
if resp.Timeout {
fmt.Printf(" *")
} else if resp.EchoReply || resp.TimeExceeded {
fmt.Printf(" %s", resp.Sender.String())
} else if resp.DestinationUnreachable {
fmt.Printf(" %s!X", resp.Sender.String())
}
// increment sequence
seq++
}
fmt.Print("\n")
// stop if we are done
if resp.EchoReply || resp.DestinationUnreachable {
os.Exit(1) // Termination
}
}
}