I was wondering how I could use StreamReader for TCP Socket Server.
// server
var server = new TcpListener(IPAddress.Any, 5125);
// server start
server.Start();
var client = server.AcceptTcpClient();
var reader = new StreamReader(client.GetStream());
string line;
while ((line = reader.ReadLine()) != null)
{
Console.WriteLine(line);
}
Console.WriteLine("Disconnected");
Currently, if the client sends something, it does not read or display anything, and on the other hand, I tried using the stream and storing it into a buffer buffer = byte[1024]; stream.Read(buffer, 0, buffer.Length) which displays incoming messages, but when the client disconnects client.Connected still thinks that there is connected and keeps looping endlessly and does not break out of the loop, even when tried with Try/Catch
Your help would be much appreciated! Thank you
PS: I'm very new to C#, so please excuse my ignorance in case this is a simple issue that I don't how to solve
Related
I'm trying to communicate with a device that has a Serial COM port that goes out (using RS232 Protocol), which I've hooked up to a converter box that converts the connection to Ethernet.
I've successfully connected to the converter box (which has its own IP) and I've successfully communicated with the device by sending it commands over telnet by using PuTTY, to which it has responded with various data that I've been able to parse.
I've established a connection by creating a new TcpClient, and I'm able to send strings to the device, but every time I get a response back, it's always "??\u0003" which I've researched and found that \uhhhh is a Unicode escape protocol. This confuses me because I have used ASCII encoding for everything.
public string TcpConnect(string cmd)
{
var client = new TcpClient();
//cmd = "ping";
Console.WriteLine("Connecting to server");
client.Connect("169.254.20.40", 23); //22 = ssh, 23 = telnet, 80 = http
Console.WriteLine("CONNECTED SUCCESSFULLY");
Stream tcpStream = client.GetStream();
ASCIIEncoding A = new ASCIIEncoding();
byte[] enable = A.GetBytes("enable" + Environment.NewLine);
byte[] connect = A.GetBytes("connect line 1" + Environment.NewLine);
byte[] ba = A.GetBytes(cmd);
Console.WriteLine("Transmitting.....");
tcpStream.Write(enable, 0, enable.Length);
tcpStream.Write(connect, 0, connect.Length);
tcpStream.Write(ba, 0, ba.Length);
byte[] responseBytes = new byte[4096];
int numBytesRead = tcpStream.Read(responseBytes, 0, responseBytes.Length);
var message = A.GetString(responseBytes, 0, numBytesRead);
Console.WriteLine("\nServer Closed.");
return message;
}
If I were to pass in "$TEAA4B9\r\n" as the message, I would expect something along the lines of "$TEA,086,040,031,000,3798" which is nowhere close to what I'm getting (which is ??\u0003)
Nevermind figured it out
Just kidding! Here's what I did: I added a "System.Threading.Thread.Sleep("1000") before the "tcpStream.Read" line at the bottom, and now it outputs the data I need. The device was outputting garbage on the first line (perhaps a handshake, not sure) and that's all that was being read before it was being stored into "message" and returned (not enough time was spent reading before it moved on to the next line of code)
I have a requirement to get the data into a string using TcpClient. The site requires authentication as well. I found a snippet to get data into stream but it is throwing
exception that the connection terminated unexpectedly
. Below is the sample code
TcpClient oClient = new TcpClient();
oClient.Connect("xxx.xxx.xxx.xxx", 80);
NetworkStream ns = oClient.GetStream();
StreamWriter sw = new StreamWriter(ns);
sw.Write(
string.Format(
"GET /{0} HTTP/1.1\r\nUser-Agent: {1}\r\nHost: iq\r\n\r\n",
"/",
"MyTCPClient")
);
sw.Flush();
StringBuilder sb = new StringBuilder();
while (true)
{
int i = ns.ReadByte(); // Inefficient but more reliable
if (i == -1) break; // Other side has closed socket
sb.Append((char)i); // Accrue 'c' to save page data
}
oClient.Close();
How can I include the authentication step as well.
P.S.: Just to summarize, I want to get the html of a page in string using TcpClient which involves authentication as well.
Edit: I am going for this approach as the URL had period at the end which was being removed by URI.
I have created a LAN chat messaging application using C# that connects all clients who run the program to a server on my computer.
I am now trying to convert this application to work with android devices via Xamarin Studio.
When testing this, the device correctly connects to the server as it can send a message ( saying the device has logged in) which is then broadcasted to the other clients.
However, once the application sends this message the program then closes immediately.
Within the desktop version of the chat client I use the code(which is ran on another thread):
NetworkStream serverStream = default(NetworkStream);
private void getMessage()
{
while (this.keepOpen)
{
Console.WriteLine("getMessage");
serverStream = clientSocket.GetStream();
int buffSize = 0;
byte[] inStream = new byte[clientSocket.ReceiveBufferSize];
buffSize = clientSocket.ReceiveBufferSize;
try
{
Console.WriteLine("Read stream");
serverStream.Read(inStream, 0, buffSize);
Console.WriteLine ("Final test");
}
catch
{
Console.WriteLine("failed to read stream");
}
string returndata = Encoding.ASCII.GetString(inStream);
readData = "" + returndata;
message();
}
}
This works the first time it is called as the line "Final test" is displayed. However, after this, when the method gets to this stage again (as it is in a never ending loop) I get an error message saying:
'[dalvikvm-heap] Grow heap (frag case) to 13.455MB for 4194308-byte allocation'
'[dalvikvm-heap] Grow heap (frag case) to 21.444MB for 8388612-byte allocation'
And the line "Final test" is not shown thus the line 'serverStream.Read(inStream, 0, buffSize);' is crashing the app. I have tried to use .Flush() and .Close() however none of these work.
The sending portion of my code runs perfectly using 'serverSocket.Write()' as other clients can receive the messages so why would reading data from the server crash the app?
P.S This is my first android app so I wanted to use a language I was more comfortable with than attempting from scratch with java.
Thanks in advance.
Realised that this error was because I was allocating too much memory when trying to send a messag.
Simple changed
byte[] inStream = new byte[clientSocket.ReceiveBufferSize];
buffSize = clientSocket.ReceiveBufferSize;
To
byte[] inStream = new byte[4096];
buffSize = 4096;
I'm relatively new to C# but here goes:
I am developing a remote file service client/server console application in C# which is supposed to exchange messages using synchronous sockets.
One of the main problems (even thought it might seem simple) is to return a string from the server, to the client using streamreader/streamwriter.
The application user a command line interface with options (from a switch statement) to execute actions. I.e. typing 1 and enter would execute the code to send the string from the server to the client.
Below is a sample code from the client:
try
{
using (TcpClient client = (TcpClient)clientObject)
using (NetworkStream stream = client.GetStream())
using (StreamReader rd = new StreamReader(stream))
using (StreamWriter wr = new StreamWriter(stream))
{
string menuOption = rd.ReadLine();
switch (menuOption)
{
case "1":
case "one":
string passToClient = "Test Message!";
wr.WriteLine(passToClient);
break;
}
while (menuOption != "4");
}
}
I understand the code I posted is just a snippet of the program, but it would take up a fair amount of space and was hoping you can gather what I mean from this, if not I will post more.
This is just to give a general idea of what I am going for,
I appreciate any help / advice you can give. Its not so much code examples I'm looking for (although a little would help) but more some explanation on streamreader/writer as I cant seem to understand much of what is online.
Thanks.
I think you're just missing a wr.flush(); but this article should cover everything you need:
http://thuruinhttp.wordpress.com/2012/01/07/simple-clientserver-in-c/
Whenever you use StreamWriter you need to Flush() the contents of the stream. I'll quote MSDN as the reason becomes quite clear:
Clears all buffers for the current writer and causes any buffered data to be written to the underlying stream.
You can call it quite simply like:
wr.flush();
Solution can be simpler:
StreamWriter wr = new StreamWriter(stream) { AutoFlush = true }
I just ran a test using your code, and it works fine, I can step right into the "one" case statement.
I am guessing you are either not including the line-break in the string you are sending, or you just have the TcpClient or TcpListener configured wrong.
Here is the Client-Side code for my test:
TcpClient client = new TcpClient("127.0.0.1", 13579);
string message = "one" + Environment.NewLine;
Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
NetworkStream stream = client.GetStream();
stream.Write(data, 0, data.Length);
Here is the Server-Side:
IPAddress localAddr = IPAddress.Parse("127.0.0.1");
TcpListener server = new TcpListener(localAddr, 13579);
server.Start();
TcpClient client = server.AcceptTcpClient();
using (client)
using (NetworkStream stream = client.GetStream())
using (StreamReader rd = new StreamReader(stream))
using (StreamWriter wr = new StreamWriter(stream))
{
string menuOption = rd.ReadLine();
switch (menuOption)
{
case "1":
case "one":
string passToClient = "Test Message!";
wr.WriteLine(passToClient);
break;
}
while (menuOption != "4") ;
}
Just run the server-side code first, which will block while waiting for connection and then while waiting for data. Then run the client-side code. You should be able to catch a breakpoint on the switch().
With my code I can read a message on the server and write from the client. But I am not being able to write a response from the server and read in the client.
The code on the client
var cli = new TcpClient();
cli.Connect("127.0.0.1", 6800);
string data = String.Empty;
using (var ns = cli.GetStream())
{
using (var sw = new StreamWriter(ns))
{
sw.Write("Hello");
sw.Flush();
//using (var sr = new StreamReader(ns))
//{
// data = sr.ReadToEnd();
//}
}
}
cli.Close();
The code on the server
tcpListener = new TcpListener(IPAddress.Any, port);
tcpListener.Start();
while (run)
{
var client = tcpListener.AcceptTcpClient();
string data = String.Empty;
using (var ns = client.GetStream())
{
using (var sr = new StreamReader(ns))
{
data = sr.ReadToEnd();
//using (var sw = new StreamWriter(ns))
//{
// sw.WriteLine("Hi");
// sw.Flush();
//}
}
}
client.Close();
}
How can I make the server reply after reading the data and make the client read this data?
Since you are using
TcpClient client = tcpListener.AcceptTcpClient();
, you can write back to the client directly without needing it to self-identify. The code you have will actually work if you use Stream.Read() or .ReadLine() instead of .ReadToEnd(). ReadToEnd() will block forever on a network stream, until the stream is closed. See this answer to a similar question, or from MSDN,
ReadToEnd assumes that the stream
knows when it has reached an end. For
interactive protocols in which the
server sends data only when you ask
for it and does not close the
connection, ReadToEnd might block
indefinitely because it does not reach
an end, and should be avoided.
If you use ReadLine() at one side, you will need to use WriteLine() - not Write() - at the other side. The alternative is to use a loop that calls Stream.Read() until there is nothing left to read. You can see a full example of this for the server side in the AcceptTcpClient() documentation on MSDN. The corresponding client example is in the TcpClient documentation.
Cheesy, inneficient, but does the trick on a one-time throwaway program:
Client: In the stream, include the port and IP address it wishes to receive the response from.
Client: Create a listener for that
port and IP.
Server: Read in the port/IP info and
in turn connect, then send the reply
stream.
However, this is a great place to start, look into Sockets class for proper bi-directional communication.