How to ping faster when I reach unreachable IP?

How to ping faster when I reach unreachable IP? - c#

I have an app which pings IP or IP range. The problem is that when hosts are closed it takes longer to ping than they are open. When host is closed the time to ping is about 1-2 seconds.
How could I make it faster when hosts are closed?
This is my code:
using System;
using System.Text;
using System.Windows.Forms;
using System.Net.NetworkInformation;
namespace Range_Pinger
{
public partial class PingIPRange : Form
{
uint startIP, endIP, currentIP;
int count = 0;
int open = 0;
int closed = 0;
public PingIPRange()
{
InitializeComponent();
tmrPingInterval.Tick += new EventHandler(tmrPingInterval_Tick);
}
void tmrPingInterval_Tick(object sender, EventArgs e)
{
if (txtTo.Text == string.Empty) Ping(ip2str(startIP));
else
{
if (currentIP >= endIP) tmrPingInterval.Stop();
Ping(ip2str(currentIP));
currentIP++;
}
count++;
tsslPingCount.Text = "Total number of pings: " + count.ToString() +
" Open IPs: " + open.ToString() + " Closed IPs: " + closed.ToString();
}
static uint str2ip(string ip)
{
string[] numbers = ip.Split('.');
uint x1 = (uint)(Convert.ToByte(numbers[0]) << 24);
uint x2 = (uint)(Convert.ToByte(numbers[1]) << 16);
uint x3 = (uint)(Convert.ToByte(numbers[2]) << 8);
uint x4 = (uint)(Convert.ToByte(numbers[3]));
return x1 + x2 + x3 + x4;
}
static string ip2str(uint ip)
{
string s1 = ((ip & 0xff000000) >> 24).ToString() + ".";
string s2 = ((ip & 0x00ff0000) >> 16).ToString() + ".";
string s3 = ((ip & 0x0000ff00) >> 8).ToString() + ".";
string s4 = (ip & 0x000000ff).ToString();
return s1 + s2 + s3 + s4;
}
private void btnPing_Click(object sender, EventArgs e)
{
txtDisplay.Text = string.Empty;
tsslPingCount.Text = string.Empty;
count = 0;
open = 0;
closed = 0;
tmrPingInterval.Interval = int.Parse(nudInterval.Value.ToString());
try
{
startIP = str2ip(txtFrom.Text);
if (txtTo.Text != string.Empty) endIP = str2ip(txtTo.Text);
currentIP = startIP;
tmrPingInterval.Start();
}
catch
{
MessageBox.Show("Invalid input. It must be something like: 255.255.255.255");
}
}
private void btnStop_Click(object sender, EventArgs e)
{
tmrPingInterval.Stop();
}
private void Ping(string address)
{
Ping pingSender = new Ping();
PingOptions options = new PingOptions();
options.DontFragment = true;
string data = "01234567890123456789012345678901";
byte[] buffer = Encoding.ASCII.GetBytes(data);
int timeout = 120;
try
{
PingReply reply = pingSender.Send(address, timeout, buffer, options) ;
if (reply.Status == IPStatus.Success)
{
open++;
txtDisplay.AppendText("Host " + address + " is open." + Environment.NewLine);
}
else
{
closed++;
txtDisplay.AppendText("Host " + address + " is closed." + Environment.NewLine);
}
}
catch (Exception ex)
{
txtDisplay.SelectedText += Environment.NewLine + ex.Message;
}
}
private void tsmiExit_Click(object sender, EventArgs e)
{
this.Close();
}
}
}
This is what I have now:
[DllImport("iphlpapi.dll", ExactSpelling = true)]
public static extern int SendARP(IPAddress DestIP, int SrcIP, byte[] pMacAddr, ref uint PhyAddrLen);
private void Ping(IPAddress address)
{
byte[] macAddr = new byte[6];
uint macAddrLen = (uint)macAddr.Length;
if (SendARP(address, 0, macAddr, ref macAddrLen) == 0)
{
txtDisplay.AppendText("Host " + address + " is open." + Environment.NewLine);
}
else txtDisplay.AppendText("Host " + address + " is closed." + Environment.NewLine);
}

You shouldn't reduce the timeout. Try to send multiple pings at once async.
var ping = new Ping();
ping.PingCompleted += (sender, eventArgs) =>
{
// eventArgs.Reply.Address
// eventArgs.Reply.Status
};
ping.SendAsync(ip, etc.);

Your address is a string. Thus it will go via DNS first to see if this is possibly a hostname (even if it is an IP address).
I suggest you use the overload taking an IPAddress instead.

I created a live host scanner not too long ago. It uses ARP to check if a computer is online.
An ARP request is much faster than if you'd ping a host.
Here's the code I used to check if a Host is available:
//You'll need this pinvoke signature as it is not part of the .Net framework
[DllImport("iphlpapi.dll", ExactSpelling = true)]
public static extern int SendARP(int DestIP, int SrcIP,
byte[] pMacAddr, ref uint PhyAddrLen);
//These vars are needed, if the the request was a success
//the MAC address of the host is returned in macAddr
private byte[] macAddr = new byte[6];
private uint macAddrLen;
//Here you can put the IP that should be checked
private IPAddress Destination = IPAddress.Parse("127.0.0.1");
//Send Request and check if the host is there
if (SendARP((int)Destination.Address, 0, macAddr, ref macAddrLen) == 0)
{
//SUCCESS! Igor it's alive!
}
If you're interested Nmap also uses this technique to scan for available hosts.
ARP scan puts Nmap and its optimized algorithms in charge of ARP requests. And if it gets a response back, Nmap doesn't even need to worry about the IP-based ping packets since it already knows the host is up. This makes ARP scan much faster and more reliable than IP-based scans. So it is done by default when scanning ethernet hosts that Nmap detects are on a local ethernet network. Even if different ping types (such as -PE or -PS) are specified, Nmap uses ARP instead for any of the targets which are on the same LAN.
EDIT:
This only works within the current subnet! As long as there is no router between the requesting machine and the target it should work fine.
ARP is a non-routable protocol, and can therefore only be used between systems on the same Ethernet network. [...]
arp-scan can be used to discover IP hosts on the local network. It can discover all hosts, including those that block all IP traffic such as firewalls and systems with ingress filters. - Excerpt from NTA-Monitor wiki
For more information on the SendARP function you can check the pinvoke.net documentation.

You need to redesign your application to use multithreading -> tasks. Issue a task for each ping, and when you receive a response from a given host fire an event and update the UI. Changing socket timeout will only help you to reduce the timeout from outrageous to insufferable.

Not sure if this is any help (see final post on the thread), it seems an almost identical problem. What you're butting up against there is the protocol stack's timeout. You can get around it if you use socket to connect as you'll have more control.

Related

How to send audio data on rtsp backchannel?

I am working with an IP camera that supports Audio output(Audio Back-channel). What I want to do is The live stream my PC microphone audio data over provided RTSP URL so that what ever said at PC microphone will be audible at camera speaker end. I have read about onvif streaming specification that tells me that once I got RTSP url of camera media I have to send my audio data over provided rtsp url for audio output at camera end. Also my camera supports Onvif profile T.
What I have tried so far is -
public static RtspClient rtspClient;
public static IWaveIn sourceStream;
private static void CallAudio()
{
string CameraIp = "192.168.1.69";
string UserName = "admin";
string Password = "admin123";
var ClientMessageInspector = new ClientMessageInspector(UserName, Password);
//Call Device Url and get Services.
string DeviceServiceUrl = "http://" + CameraIp + "/onvif/device_service";
var deviceClient = new DeviceClient("DeviceBinding", new EndpointAddress(DeviceServiceUrl));
deviceClient.Endpoint.Behaviors.Add(ClientMessageInspector);
var getServices = deviceClient.GetServices(false);
//Call media2 getStreamingUri.
string url = "http://" + CameraIp + "/onvif/media2_service";
var Media2Client = new Media2Client("Media2Binding", new EndpointAddress(url));
Media2Client.Endpoint.Behaviors.Add(ClientMessageInspector);
var media2GetProfiles = Media2Client.GetProfiles(null, null);
var resp = Media2Client.GetAudioDecoderConfigurationOptions(null, null);
var responseGetAudioStreamUri = Media2Client.GetStreamUri("tcp", profiles[0].token); //This gets rtsp url of media from camera.
rtspClient = new RtspClient(responseGetAudioStreamUri, UserName, Password);
sourceStream = new WaveInEvent();
sourceStream.WaveFormat = new WaveFormat(64, 8, 1); //8000 16
sourceStream.DataAvailable += new EventHandler<WaveInEventArgs>(SourceStream_DataAvailable);
sourceStream.StartRecording();
Console.ReadKey();
}
//This method gets data from PC microphone and enocodes it into Mu-Law G711 and send to rtsp url.
private static void SourceStream_DataAvailable(object sender, WaveInEventArgs e)
{
byte[] encoded = TwoWayAudio_Encode_MuLaw(e.Buffer, 0, e.BytesRecorded);
rtspClient.SendData(encoded, encoded.Length, 3);
}
private static byte[] TwoWayAudio_Encode_MuLaw(byte[] data, int offset, int length)
{
byte[] encoded = new byte[length / 2];
int outIndex = 0;
for (int n = 0; n < length; n += 2)
{
encoded[outIndex++] = MuLawEncoder.LinearToMuLawSample(BitConverter.ToInt16(data, offset + n));
}
return encoded;
}
The rtsp client that I am using in my project for Describe, Setup and Play of rtsp URL is taken from this github repo https://github.com/BogdanovKirill/RtspClientSharp.
Rtspclient.cs
using Rtsp;
using Rtsp.Messages;
using Rtsp.Sdp;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
namespace Rtsp
{
public class RtspClient
{
private RtspListener rtsp_client;
private RtspTcpTransport tcp_socket;
public string url;
public bool canPlay = false;
public string username;
public string password;
public ushort seqNo = 0;
public event EventHandler<string> RtspError;
public event EventHandler<byte[]> RtpDataReceived;
public Stopwatch stopwatch { get; private set; }
public RtspClient(string _url, string _username, string _password)
{
url = _url;
username = _username;
password = _password;
var uri = new Uri(_url);
tcp_socket = new RtspTcpTransport(uri.Host, 554); // 554);
if (tcp_socket.Connected == false)
{
Console.WriteLine("Error - did not connect");
return;
}
// Connect a RTSP Listener to the TCP Socket to send messages and listen for replies
rtsp_client = new RtspListener(tcp_socket);
rtsp_client.MessageReceived += Rtsp_client_MessageReceived;
rtsp_client.DataReceived += DataReceived;
rtsp_client.Start(); // start reading messages from the server
rtsp_client.AutoReconnect = true;
RtspRequest describe_message = new RtspRequestDescribe();
describe_message.RtspUri = uri;
describe_message.AddHeader("Accept: application/sdp");
describe_message.AddHeader("Require: www.onvif.org/ver20/backchannel");
rtsp_client.SendMessage(describe_message);
stopwatch = new Stopwatch();
stopwatch.Start();
}
private void DataReceived(object sender, RtspChunkEventArgs e)
{
int rtp_version = (e.Message.Data[0] >> 6);
int rtp_padding = (e.Message.Data[0] >> 5) & 0x01;
int rtp_extension = (e.Message.Data[0] >> 4) & 0x01;
int rtp_csrc_count = (e.Message.Data[0] >> 0) & 0x0F;
int rtp_marker = (e.Message.Data[1] >> 7) & 0x01;
int rtp_payload_type = (e.Message.Data[1] >> 0) & 0x7F;
uint rtp_sequence_number = ((uint)e.Message.Data[2] << 8) + (uint)(e.Message.Data[3]);
uint rtp_timestamp = ((uint)e.Message.Data[4] << 24) + (uint)(e.Message.Data[5] << 16) + (uint)(e.Message.Data[6] << 8) + (uint)(e.Message.Data[7]);
uint rtp_ssrc = ((uint)e.Message.Data[8] << 24) + (uint)(e.Message.Data[9] << 16) + (uint)(e.Message.Data[10] << 8) + (uint)(e.Message.Data[11]);
int rtp_payload_start = 4 // V,P,M,SEQ
+ 4 // time stamp
+ 4 // ssrc
+ (4 * rtp_csrc_count); // zero or more csrcs
uint rtp_extension_id = 0;
uint rtp_extension_size = 0;
if (rtp_extension == 1)
{
rtp_extension_id = ((uint)e.Message.Data[rtp_payload_start + 0] << 8) + (uint)(e.Message.Data[rtp_payload_start + 1] << 0);
rtp_extension_size = ((uint)e.Message.Data[rtp_payload_start + 2] << 8) + (uint)(e.Message.Data[rtp_payload_start + 3] << 0);
rtp_payload_start += 4 + (int)rtp_extension_size; // extension header and extension payload
}
Console.WriteLine("RTP Data"
+ " V=" + rtp_version
+ " P=" + rtp_padding
+ " X=" + rtp_extension
+ " CC=" + rtp_csrc_count
+ " M=" + rtp_marker
+ " PT=" + rtp_payload_type
+ " Seq=" + rtp_sequence_number
+ " Time=" + rtp_timestamp
+ " SSRC=" + rtp_ssrc
+ " Size=" + e.Message.Data.Length);
// If rtp_marker is '1' then this is the final transmission for this packet.
// If rtp_marker is '0' we need to accumulate data with the same timestamp
// ToDo - Check Timestamp matches
// Add to the tempoary_rtp List
if (rtp_payload_type == 98 || rtp_payload_type == 0)
{
byte[] rtp_payload = new byte[e.Message.Data.Length - rtp_payload_start]; // payload with RTP header removed
System.Array.Copy(e.Message.Data, rtp_payload_start, rtp_payload, 0, rtp_payload.Length); // copy payload
RtpDataReceived?.Invoke(null, rtp_payload);
}
}
public bool SendData(byte[] data, int count, int channel)
{
byte[] rtp_packet = new byte[12 + data.Length];
int rtp_version = 2;
int rtp_padding = 0;
int rtp_extension = 0;
int rtp_csrc_count = 0;
int rtp_marker = 1; // set to 1 if the last NAL in the array
//int rtp_payload_type = 98;
int rtp_payload_type = 0;
RTPPacketUtil.WriteHeader(rtp_packet, rtp_version, rtp_padding, rtp_extension, rtp_csrc_count, rtp_marker, rtp_payload_type);
RTPPacketUtil.WriteSequenceNumber(rtp_packet, seqNo);
seqNo++;
RTPPacketUtil.WriteTS(rtp_packet, (uint)stopwatch.ElapsedMilliseconds);
UInt32 empty_ssrc = 1293847657;
RTPPacketUtil.WriteSSRC(rtp_packet, empty_ssrc);
// Now append the raw NAL
System.Array.Copy(data, 0, rtp_packet, 12, data.Length);
if (canPlay)
{
rtsp_client.SendData(channel, rtp_packet);
return true;
}
else return false;
}
private void Rtsp_client_MessageReceived(object sender, RtspChunkEventArgs e)
{
RtspResponse message = e.Message as RtspResponse;
if (message.ReturnCode == 500)
{
RtspError?.Invoke(this, "Internal Server Error");
}
if (message.ReturnCode == 401)
{
Rtsp.Messages.RtspRequest msg = null;
switch (message.OriginalRequest.Method)
{
case "DESCRIBE":
msg = new RtspRequestDescribe();
break;
case "SETUP":
msg = new RtspRequestSetup();
break;
default:
break;
}
msg.RtspUri = new Uri(url);
var header = message.Headers["WWW-Authenticate"];
var _realm = GrabHeaderVar("realm", header);
var _nonce = GrabHeaderVar("nonce", header);
var ha1 = CalculateMd5Hash(string.Format("{0}:{1}:{2}", username, _realm, password));
var ha2 = CalculateMd5Hash(string.Format("{0}:{1}", message.OriginalRequest.Method, url));
var digestResponse = CalculateMd5Hash(string.Format("{0}:{1}:{2}", ha1, _nonce, ha2));
var digest = string.Format("Digest username=\"{0}\", realm=\"{1}\", nonce=\"{2}\", uri=\"{3}\", response=\"{4}\" ",
username, _realm, _nonce, url, digestResponse);
msg.AddHeader("Authorization: " + digest);
msg.AddHeader("Accept: application/sdp");
rtsp_client.SendMessage(msg);
return;
}
Console.WriteLine("Received " + message.OriginalRequest.ToString());
if (message.OriginalRequest != null && message.OriginalRequest is RtspRequestDescribe)
{
// Got a reply for DESCRIBE
// Examine the SDP
Console.Write(Encoding.UTF8.GetString(message.Data));
SdpFile sdp_data;
using (StreamReader sdp_stream = new StreamReader(new MemoryStream(message.Data)))
{
sdp_data = SdpFile.Read(sdp_stream);
}
// Process each 'Media' Attribute in the SDP.
// If the attribute is for Video, then send a SETUP
for (int x = 0; x < sdp_data.Medias.Count; x++)
{
if (sdp_data.Medias[x].MediaType == Rtsp.Sdp.Media.MediaTypes.audio || sdp_data.Medias[x].MediaType == Rtsp.Sdp.Media.MediaTypes.video)
{
// seach the atributes for control, fmtp and rtpmap
String control = ""; // the "track" or "stream id"
String fmtp = ""; // holds SPS and PPS
String rtpmap = ""; // holds the Payload format, 96 is often used with H264
foreach (Rtsp.Sdp.Attribut attrib in sdp_data.Medias[x].Attributs)
{
if (attrib.Key.Equals("control")) control = attrib.Value;
if (attrib.Key.Equals("fmtp")) fmtp = attrib.Value;
if (attrib.Key.Equals("rtpmap")) rtpmap = attrib.Value;
}
// Get the Payload format number for the Video Stream
String[] split_rtpmap = rtpmap.Split(' ');
var video_payload = 0;
bool result = Int32.TryParse(split_rtpmap[0], out video_payload);
// Send SETUP for the Video Stream
// using Interleaved mode (RTP frames over the RTSP socket)
Rtsp.Messages.RtspRequest setup_message = new Rtsp.Messages.RtspRequestSetup();
setup_message.RtspUri = new Uri(url + "/" + control);
//setup_message.AddHeader("Transport: RTP/AVP/TCP;interleaved=0");
setup_message.AddHeader("Require: www.onvif.org/ver20/backchannel");
rtsp_client.SendMessage(setup_message);
}
}
}
if (message.OriginalRequest != null && message.OriginalRequest is RtspRequestSetup)
{
// Got Reply to SETUP
Console.WriteLine("Got reply from Setup. Session is " + message.Session);
String session = message.Session; // Session value used with Play, Pause, Teardown
// Send PLAY
RtspRequest play_message = new RtspRequestPlay();
play_message.RtspUri = new Uri(url);
play_message.Session = session;
play_message.AddHeader("Require: www.onvif.org/ver20/backchannel");
rtsp_client.SendMessage(play_message);
}
if (message.OriginalRequest != null && message.OriginalRequest is RtspRequestPlay)
{
// Got Reply to PLAY
Console.WriteLine("Got reply from Play " + message.Command);
canPlay = true;
}
}
private static string GrabHeaderVar(string varName, string header)
{
var regHeader = new Regex(string.Format(#"{0}=""([^""]*)""", varName));
var matchHeader = regHeader.Match(header);
if (matchHeader.Success)
return matchHeader.Groups[1].Value;
throw new ApplicationException(string.Format("Header {0} not found", varName));
}
private static string CalculateMd5Hash(string input)
{
var inputBytes = Encoding.ASCII.GetBytes(input);
var hash = MD5.Create().ComputeHash(inputBytes);
var sb = new StringBuilder();
foreach (var b in hash)
sb.Append(b.ToString("x2"));
return sb.ToString();
}
public void Dispose()
{
rtsp_client.Stop();
rtsp_client.Dispose();
}
}
}
So before calling any rtsp method a i have added Rtsp Require: www.onvif.org/ver20/backchannel which is important for checking whether camera support AudioBack channel.
The output i get after calling Describe, Setup and play is Ok.
Received Rtsp.Messages.RtspRequestDescribe
v=0
o=- 0 0 IN IP4 192.168.1.69
s=LIVE VIEW
c=IN IP4 0.0.0.0
t=0 0
a=control:rtsp://192.168.1.69/rtsp_tunnel?p=0&h26x=4&aon=1&aud=0
m=video 0 RTP/AVP 35
a=rtpmap:35 H264/90000
a=control:rtsp://192.168.1.69/rtsp_tunnel?p=0&h26x=4&aon=1&aud=0&stream=video
a=recvonly
a=fmtp:35 packetization-mode=1;profile-level-id=4d0029;sprop-parameter-
sets=Z00AKZpkA8ARPy4C1BQEFAg=,aO48gA==
m=audio 0 RTP/AVP 96
a=rtpmap:96 mpeg4-generic/16000/1
a=fmtp:96 streamtype=5; profile-level-id=5; mode=AAC-hbr; config=1408; SizeLength=13; IndexLength=3;
IndexDeltaLength=3
a=control:rtsp://192.168.1.69/rtsp_tunnel?p=0&h26x=4&aon=1&aud=0&stream=audio
a=recvonly
m=audio 0 RTP/AVP 0
a=rtpmap:0 PCMU/8000/1
a=control:rtsp://192.168.1.69/rtsp_tunnel?p=0&h26x=4&aon=1&aud=0&stream=backchannel
a=sendonly
Received Rtsp.Messages.RtspRequestSetup
Got reply from Setup. Session is 12346e9856840dc
Received Rtsp.Messages.RtspRequestSetup
Got reply from Setup. Session is 12346e9856840dc
Received Rtsp.Messages.RtspRequestSetup
Got reply from Setup. Session is 12346e9856840dc
Received Rtsp.Messages.RtspRequestPlay
Got reply from Play RTSP/1.0 200 OK
Received Rtsp.Messages.RtspRequestPlay
Got reply from Play RTSP/1.0 200 OK
Received Rtsp.Messages.RtspRequestPlay
Got reply from Play RTSP/1.0 200 OK
After Getting Response from Play method i start sending my encoded data using send method in Rtsp client.
But the audio is not audible at camera end. My question is simple-
Is it is possible to send audio data over RTSP URL.
Is there any issue with the way I called my methods which is wrong?could any one please point that out.
Is there any easy way (or example/tutorial) that shows how to do audio backchannel over rtsp please provide it to.
Please don't mind I am new to Rtsp. Thanks in advance. If any issue with the question tell me I will edit it for move clear understanding.

I figured it out what I was doing wrong. Actually above mentioned steps are fine and camera returning Ok, what I was doing wrong was here in above code :
sourceStream.WaveFormat = new WaveFormat(64, 8, 1); //8000 16
Instead of 64 & 8 parameter it should be :
sourceStream.WaveFormat = new WaveFormat(8000, 16, 1); //8000 16
It was all voice smapling rate due to which voice send was not audible. Thankyou!

Access denied when sending data with UdpClient

I am trying to create a small Application which reads data from the Serial-/Com-Port and broadcasts the data to my network using port 15000.
Everything works fine on Windows and Linux (using Mono) but I get a Socket Exception on macOS with the following message: Access denied
I tried to run my Application with elevated permissions:
sudo mono ./SerialMonitor.exe
But that doesn't work too.
Is there any way to get rid of that exception? And why does it work without any issues on Windows and Linux?
Here is my code:
using System;
using System.IO.Ports;
using System.Net;
using System.Net.Sockets;
using System.Text;
namespace SerialMonitor
{
class MainClass
{
static SerialPort mSerial = new SerialPort();
static String[] mSerialPorts;
static UdpClient mNetwork;
static IPEndPoint mIP;
static String mData = "";
public static void Main(string[] args)
{
mNetwork = new UdpClient();
mIP = new IPEndPoint(IPAddress.Parse("192.168.1.255"), 15000);
mSerialPorts = SerialPort.GetPortNames();
Console.WriteLine("Select a serial port:");
if (mSerialPorts.Length == 0)
{
Console.WriteLine("No serial ports available!");
return;
}
for (int i = 0; i < mSerialPorts.Length; i++)
{
Console.WriteLine(i + 1 + ": " + mSerialPorts[i]);
}
Console.Write("Selection: ");
int selection = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Selected port: " + mSerialPorts[selection - 1]);
mSerial.PortName = mSerialPorts[selection - 1];
mSerial.BaudRate = 9600;
mSerial.NewLine = "\r\n";
mSerial.Open();
mSerial.DiscardInBuffer();
Console.WriteLine("\nData:");
while (true)
{
try
{
MainClass.mData = mSerial.ReadLine();
Console.WriteLine(MainClass.mData);
byte[] bytes = Encoding.ASCII.GetBytes(MainClass.mData);
mNetwork.Send(bytes, bytes.Length, mIP);
}
catch(SocketException ex)
{
Console.WriteLine("\nNETWORK ERROR: " + ex.Message);
Console.Read();
return;
}
catch (Exception ex)
{
Console.WriteLine("\nERROR: " + ex.Message);
Console.Read();
return;
}
}
}
}
}
I am using Visual Studio Community 2017 for Mac
Version 7.1 (build 1297)
Mono 5.2.0.215 (d15-3/da80840) (64-bit)
Project configuration:
.NET Framework 4.6.1
x86

If you want to send broadcast messages across your local subnet (or broadcasts in general) you have to enable broadcasts on your socket with:
mNetwork.EnableBroadcast = true;
Reference:
https://msdn.microsoft.com/en-us/library/system.net.sockets.udpclient(v=vs.110).aspx
http://answers.unity3d.com/questions/248494/socket-exception-access-denied.html

C# UDP listener on multiple ports fetched from text box [duplicate]

This question already has answers here:
What is a NullReferenceException, and how do I fix it?
(27 answers)
Closed 8 years ago.
I tried searching everywhere for this question with no avail.
What I am trying to accomplish is that I enter a list of ports into a text box.
then I create a udpClient array with these ports start listening to them.
static class communicator
{
// Setting Variables
static UdpClient[] UDPreceiver;
static TcpListener[] TCPreceiver;
static IPAddress ipAddress = Dns.GetHostEntry("localhost").AddressList[0];
static bool listening = false;
// Listener function
public static void UDPstartlistening(int port)
{
// Startlistening
listening = true;
while (listening)
{
try
{
UDPreceiver[port] = new UdpClient(port); // udp server
if (UDPreceiver[port].Available > 0) // Only read if we have some data queued in buffer
{
//IPEndPoint object will allow us to read datagrams sent from any tracker.
IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
// Blocks untill data is received
Byte[] receiveBytes = UDPreceiver[port].Receive(ref RemoteIpEndPoint);
string returnData = ByteArrayToString(receiveBytes);
// Uses the IPEndPoint object to determine who sent us anything
Program.form1.addlog("Received: " + returnData.ToString() + " - from " + RemoteIpEndPoint.Address.ToString() + " on port: " + RemoteIpEndPoint.Port.ToString());
// Forward this message to the website
Task.Run(() => forwardToWebsite(returnData.ToString(), RemoteIpEndPoint.Address.ToString(), RemoteIpEndPoint.Port, "udp", port));
}
Thread.Sleep(10);
}
catch (Exception e)
{
MessageBox.Show("Source : " + e.Source + "\r\n" + "Message : " + e.Message, "Error");
}
}
}
It gives me "Object reference not set to an instance of an object." on the line that says"UDPreceiver[port].Available".
Am I doing this the right way ?

Try this, it contains some bug fixes:
put your receivers in a list instead of an un-assigned array
client should be declared outside the read-loop
you are aware of the fact that this will block the calling thread?
=> use a new Thread(() => { ... }); to run the receiving part in another thread
Code below:
static class communicator
{
// Setting Variables
static List<UdpClient> UDPreceivers = new List<UdpClient>();
//static List<TcpListener> TCPreceivers = new List<TcpListener>();
static IPAddress ipAddress = Dns.GetHostEntry("localhost").AddressList[0];
static bool listening = false;
// Listener function
public static void UDPstartlistening(int port)
{
UdpClient UDPreceiver = new UdpClient(port); // udp server
UDPreceivers.Add(UDPreceiver);
// Startlistening
listening = true;
while (listening)
{
try
{
if (UDPreceiver.Available > 0) // Only read if we have some data queued in buffer
{
//IPEndPoint object will allow us to read datagrams sent from any tracker.
IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
// Blocks untill data is received
Byte[] receiveBytes = UDPreceiver.Receive(ref RemoteIpEndPoint);
string returnData = ByteArrayToString(receiveBytes);
// Uses the IPEndPoint object to determine who sent us anything
Program.form1.addlog("Received: " + returnData.ToString() + " - from " + RemoteIpEndPoint.Address.ToString() + " on port: " + RemoteIpEndPoint.Port.ToString());
// Forward this message to the website
Task.Run(() => forwardToWebsite(returnData.ToString(), RemoteIpEndPoint.Address.ToString(), RemoteIpEndPoint.Port, "udp", port));
}
Thread.Sleep(10);
}
catch (Exception e)
{
MessageBox.Show("Source : " + e.Source + "\r\n" + "Message : " + e.Message, "Error");
}
}
}
}

I Think you need to have a closer look at examples all over internet, the object you just created UDPreceiver[port] is not in the state for receiving data. According to here the object should call BeginReceive. Have no C# but this might help.

C# running server on thread using a lot of CPU

I'm trying to write a voting server and client, so you start the program and it displays the voting form and you can vote on various items. For the server part I've got the server running in a separate thread, but it's using a lot of CPU, how do I reduce the amount of CPU it's using?
this is my server:
Form1 main = new Form1();
try
{
IPAddress ipAd = IPAddress.Parse(main.ipAddress); //use local m/c IP address, and use the same in the client
/* Initializes the Listener */
TcpListener myList = new TcpListener(ipAd, 55548);
/* Start Listeneting at the specified port */
myList.Start();
while (true)
{
string message = "";
Socket s = myList.AcceptSocket();
if (main.users.Contains(s.RemoteEndPoint.ToString()) == false)
main.users.Add(s.RemoteEndPoint.ToString());
byte[] b = new byte[500];
int k = s.Receive(b);
for (int i = 0; i < k; i++)
{
message += (Convert.ToString(b[i]));
}
string[] messageArray = message.Split('/');
MessageBox.Show("help");
if (messageArray[0].CompareTo("vote") == 0)
{
if (main.votes.ContainsKey(messageArray[1]) != true) main.votes.Add(messageArray[1], 1);
else main.votes[messageArray[1]]++;
string[] temp = main.textBox1.Text.Split(' ');
int numVotes = Convert.ToInt32(temp[1]);
numVotes++;
main.textBox1.Text = temp[0] + " " + Convert.ToString(numVotes);
}
if (messageArray[0].CompareTo("start") == 0)
{
main.updateEverything();
}
if(messageArray[0].CompareTo("withdraw") == 0)
{
main.votes[messageArray[1]]--;
string[] temp = main.textBox1.Text.Split(' ');
int numVotes = Convert.ToInt32(temp[1]);
numVotes--;
main.textBox1.Text = temp[0] + " " + Convert.ToString(numVotes);
}
/* clean up */
s.Close();
myList.Stop();
}
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
}

You are using a blocking type of connection. The loop you create causes a CPU overhead because of the TcpListener.AcceptConnection(). Your solution is to accept non-blocking socket connections, which is done by receiving data from socket asynchronously.
Here's the msdn link that explains how it works.
http://msdn.microsoft.com/en-us/library/dxkwh6zw.aspx

I see you have string concatenations which basically affects performance; try using a StringBuilder - the message variable should be of type StringBuilder.

How to access 5xxxx Modbus address

I am trying to access addresses such as 50526 on a Socomec Diris A40 using nmodbus. Unlike other examples I have seen which start with 3 or 4, these addresses all start with a 5. 50544, 50550, 50556 are but a few more im intersted in.
As far as I understand it at the moment, the first number represents the Modbus function and does not actually refer to the real address, i.e. 30000 addresses use function 04, 40000 addresses function 03 (?). I have seen the first digit omitted and the rest used as the address. If I try this with my 50000 addresses I get some success, but not with all values and the results dont seem correct. MODPOLL returns the same results as my code.
I could really use some help! If anyone can advise me on how to access these 5xxxx registers, I would be extremely grateful.
Method code:
public static void ModbusSerialRtuMasterReadRegisters()
{
using (SerialPort port = new SerialPort("COM1"))
{
// configure serial port
port.BaudRate = 9600;
port.DataBits = 8;
port.Parity = Parity.None;
port.StopBits = StopBits.One;
try
{
port.Open();
Console.WriteLine("port " + port.PortName + " open: " + port.IsOpen + "\n");
}
catch(Exception ex)
{
Console.WriteLine("Unable to open port: " + ex);
}
// create modbus master
IModbusSerialMaster master = ModbusSerialMaster.CreateRtu(port);
byte slaveId = 1;
ushort startAddress = 1;
ushort numRegisters = 5;
ushort[] registers = new ushort[numRegisters];;
// read registers
try
{
registers = master.ReadHoldingRegisters(slaveId, startAddress, numRegisters);
for (int i = 0; i < numRegisters; i++)
Console.WriteLine("Register {0}={1}", startAddress + i, registers[i]);
}
catch (Modbus.SlaveException se)
{
Console.WriteLine("Could not find register... \n \n" + se);
}
try
{
port.Close();
Console.WriteLine("\nport " + port.PortName + " open: " + port.IsOpen + "\n");
}
catch (Exception ex)
{
Console.WriteLine("Unable to close port: " + ex);
}
}

Try to subtract 40001 or 40000 from 5xxxx address (addresses start with 1 or 0).

Registers with 5xxxx address are holding registers. (40001 to 5xxxx range)
So to find Modbus register address you should subtract its address from 40001.
for example 50512 - 40001=10511 (290F H)
good luck

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

How to ping faster when I reach unreachable IP? - c#

You shouldn't reduce the timeout. Try to send multiple pings at once async. var ping = new Ping(); ping.PingCompleted += (sender, eventArgs) => { // eventArgs.Reply.Address // eventArgs.Reply.Status }; ping.SendAsync(ip, etc.);

Your address is a string. Thus it will go via DNS first to see if this is possibly a hostname (even if it is an IP address). I suggest you use the overload taking an IPAddress instead.

You need to redesign your application to use multithreading -> tasks. Issue a task for each ping, and when you receive a response from a given host fire an event and update the UI. Changing socket timeout will only help you to reduce the timeout from outrageous to insufferable.

Not sure if this is any help (see final post on the thread), it seems an almost identical problem. What you're butting up against there is the protocol stack's timeout. You can get around it if you use socket to connect as you'll have more control.

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Access denied when sending data with UdpClient

C# UDP listener on multiple ports fetched from text box [duplicate]

C# running server on thread using a lot of CPU

How to access 5xxxx Modbus address

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