ping time too long?

[haha20001]

i use sendto and receivefrom functions to ping a host
ex:
sendto(host)
timestart = datetime.now
receivefrom(buf,edp)
timestop = datetime.now - timestart

but the time was too long ,when i ping localhost the time is 56ms
how can reduce the time?

[checksal]

Does this happen when you ping from the app, or also when you ping from the cmd prompt? Are you inside of a DMZ? If you are behind a router and are being rerouted to your internal IP it can take time, but that would not be a C# issue.

[darwen]

We need more information here. I presume you're calling these methods inside of a class derived from UdpClient or some other .NET socket-based class.

I think that your 'host' variable is wrong personally.

Can you post the whole code for this ? Make sure you put it in code blocks though and format it please ! If you're not sure hit the 'code' button, enter "hello" or something and see what tags it inserts.

And no, it's not a problem with the .NET framework. It's a problem with your code. Which we need to get to the bottom of.

Darwen.

[haha20001]

the code:

namespace mPing
{
using System;
using System.Net;
using System.Net.Sockets;
/// <summary>
/// The Main Ping Class
/// </summary>
class Ping
{
//Declare some Constant Variables
const int SOCKET_ERROR = -1;
const int ICMP_ECHO = 8;
/// <summary>
/// The Starting Point of the Class
/// It Takes the Hostname parameter
/// </summary>
public static void Main(string[] argv)
{
if(argv.Length==0)
{
//If user did not enter any Parameter inform him
Console.WriteLine("Usage:Ping <hostname> /r") ;
Console.WriteLine("<hostname> The name of the Host who you want to ping");
Console.WriteLine("/r Optional Switch to Ping the host continuously") ;
}
else if(argv.Length==1)
{
//Just the hostname provided by the user
//call the method "PingHost" and pass the HostName as a parameter
PingHost(argv[0]) ;
}
else if(argv.Length==2)
{
//the user provided the hostname and the switch
if(argv[1]=="/r")
{
//loop the ping program
while(true)
{
//call the method "PingHost" and pass the HostName as a parameter
PingHost(argv[0]) ;
}
}
else
{
//if the user provided some other switch
PingHost(argv[0]) ;
}

}
else
{
//Some error occured
Console.WriteLine("Error in Arguments") ;
}
}

/// <summary>
/// This method takes the "hostname" of the server
/// and then it ping's it and shows the response time
/// </summary>
public static void PingHost(string host)
{
//Declare the IPHostEntry
IPHostEntry serverHE, fromHE;
int nBytes = 0;
int dwStart = 0, dwStop = 0;
//Initilize a Socket of the Type ICMP
Socket socket = new Socket(AddressFamily.AfINet, SocketType.SockRaw, ProtocolType.ProtICMP);

// Get the server endpoint
try
{
serverHE = DNS.GetHostByName(host);
}
catch(Exception)
{
Console.WriteLine("Host not found"); // fail
return ;
}

// Convert the server IP_EndPoint to an EndPoint
IPEndPoint ipepServer = new IPEndPoint(serverHE.AddressList[0], 0);
EndPoint epServer = (ipepServer);

// Set the receiving endpoint to the client machine
fromHE = DNS.GetHostByName(DNS.GetHostName());
IPEndPoint ipEndPointFrom = new IPEndPoint(fromHE.AddressList[0], 0);
EndPoint EndPointFrom = (ipEndPointFrom);

int PacketSize = 0;
IcmpPacket packet = new IcmpPacket();
// Construct the packet to send
packet.Type = ICMP_ECHO; //8
packet.SubCode = 0;
packet.CheckSum = UInt16.Parse("0");
packet.Identifier = UInt16.Parse("45");
packet.SequenceNumber = UInt16.Parse("0");
int PingData = 32; // sizeof(IcmpPacket) - 8;
packet.Data = new Byte[PingData];
//Initilize the Packet.Data
for (int i = 0; i < PingData; i++)
{
packet.Data[i] = (byte)'#';
}

//Variable to hold the total Packet size
PacketSize = PingData + 8;
Byte [] icmp_pkt_buffer = new Byte[ PacketSize ];
Int32 Index = 0;
//Call a Methos Serialize which counts
//The total number of Bytes in the Packet
Index = Serialize(
packet,
icmp_pkt_buffer,
PacketSize,
PingData );
//Error in Packet Size
if( Index == -1 )
{
Console.WriteLine("Error in Making Packet");
return ;
}

// now get this critter into a UInt16 array

//Get the Half size of the Packet
Double double_length = Convert.ToDouble(Index);
Double dtemp = Math.Ceil( double_length / 2);
int cksum_buffer_length = Convert.ToInt32(dtemp);
//Create a Byte Array
UInt16 [] cksum_buffer = new UInt16[cksum_buffer_length];
//Code to initilize the Uint16 array
int icmp_header_buffer_index = 0;
for( int i = 0; i < cksum_buffer_length; i++ ) {
cksum_buffer[i] =
BitConverter.ToUInt16(icmp_pkt_buffer,icmp_header_buffer_index);
icmp_header_buffer_index += 2;
}
//Call a method which will return a checksum
UInt16 u_cksum = checksum(cksum_buffer, cksum_buffer_length);
//Save the checksum to the Packet
packet.CheckSum = u_cksum;

// Now that we have the checksum, serialize the packet again
Byte [] sendbuf = new Byte[ PacketSize ];
//again check the packet size
Index = Serialize(
packet,
sendbuf,
PacketSize,
PingData );
//if there is a error report it
if( Index == -1 )
{
Console.WriteLine("Error in Making Packet");
return ;
}


dwStart = System.Environment.TickCount; // Start timing
//send the Pack over the socket
if ((nBytes = socket.SendTo(sendbuf, PacketSize, 0, epServer)) == SOCKET_ERROR)
{
Console.WriteLine("Socket Error cannot Send Packet");
}
// Initialize the buffers. The receive buffer is the size of the
// ICMP header plus the IP header (20 bytes)
Byte [] ReceiveBuffer = new Byte[256];
nBytes = 0;
//Receive the bytes
bool recd =false ;
int timeout=0 ;

//loop for checking the time of the server responding
while(!recd)
{
nBytes = socket.ReceiveFrom(ReceiveBuffer, 256, 0, ref EndPointFrom);
if (nBytes == SOCKET_ERROR)
{
Console.WriteLine("Host not Responding") ;
recd=true ;
break;
}
else if(nBytes>0)
{
dwStop = System.Environment.TickCount - dwStart; // stop timing
Console.WriteLine("Reply from "+epServer.ToString()+" in "+dwStop+"MS :Bytes Received"+nBytes);
recd=true;
break;
}
timeout=System.Environment.TickCount - dwStart;
if(timeout>1000)
{
Console.WriteLine("Time Out") ;
recd=true;
}

}

//close the socket
socket.Close();
}
/// <summary>
/// This method get the Packet and calculates the total size
/// of the Pack by converting it to byte array
/// </summary>
public static Int32 Serialize( IcmpPacket packet, Byte [] Buffer, Int32 PacketSize, Int32 PingData )
{
Int32 cbReturn = 0;
// serialize the struct into the array
int Index=0;

Byte [] b_type = new Byte[1];
b_type[0] = (packet.Type);

Byte [] b_code = new Byte[1];
b_code[0] = (packet.SubCode);

Byte [] b_cksum = BitConverter.GetBytes(packet.CheckSum);
Byte [] b_id = BitConverter.GetBytes(packet.Identifier);
Byte [] b_seq = BitConverter.GetBytes(packet.SequenceNumber);

// Console.WriteLine("Serialize type ");
Array.Copy( b_type, 0, Buffer, Index, b_type.Length );
Index += b_type.Length;

// Console.WriteLine("Serialize code ");
Array.Copy( b_code, 0, Buffer, Index, b_code.Length );
Index += b_code.Length;

// Console.WriteLine("Serialize cksum ");
Array.Copy( b_cksum, 0, Buffer, Index, b_cksum.Length );
Index += b_cksum.Length;

// Console.WriteLine("Serialize id ");
Array.Copy( b_id, 0, Buffer, Index, b_id.Length );
Index += b_id.Length;

Array.Copy( b_seq, 0, Buffer, Index, b_seq.Length );
Index += b_seq.Length;

// copy the data
Array.Copy( packet.Data, 0, Buffer, Index, PingData );
Index += PingData;
if( Index != PacketSize/* sizeof(IcmpPacket) */) {
cbReturn = -1;
return cbReturn;
}

cbReturn = Index;
return cbReturn;
}
/// <summary>
/// This Method has the algorithm to make a checksum
/// </summary>
public static UInt16 checksum( UInt16[] buffer, int size )
{
Int32 cksum = 0;
int counter;

counter = 0;

while ( size > 0 ) {

UInt16 val = buffer[counter];

cksum += Convert.ToInt32( buffer[counter] );
counter += 1;
size -= 1;
}

cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >> 16);
return (UInt16)(~cksum);
}
} // class ping
/// <summary>
/// Class that holds the Pack information
/// </summary>
public class IcmpPacket
{
public Byte Type; // type of message
public Byte SubCode; // type of sub code
public UInt16 CheckSum; // ones complement checksum of struct
public UInt16 Identifier; // identifier
public UInt16 SequenceNumber; // sequence number
public Byte [] Data;

} // class IcmpPacket
}

[haha20001]

the end i use two threads to ping more hosts.
one thread calls sendto function,the other calls receivefrom.
if i ping one host twice in one cycle,and the first time it costs 56ms,and the second time costs 1ms,why?