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Named Pipes IPC: Python server, C# Client

Title sums it up. There are plenty of examples around with a c# server and python client communicating back and forth.
I'd like to understand how I can instead create a python server and c# client for some interprocess communication.

I managed to find a solution. To begin, I'd first like to clarify some confusing terminology and obscure naming conventions used in dotnet core.
It appears that the NamedPipeServerStream and NamedPipeClientStream don't actually operate on named pipes but instead on unix domain sockets. This means that we must use sockets to communicate between processes rather than FIFO files.
Another frustration I find with dotnet core is that when creating a socket or connecting to one, the NamedPipeServerStream and NamedPipeClientStream classes will add "CoreFxPipe_" to the beginning of the socket name. See related question.
Python Server
#!/usr/bin/python3
import socket
import os
import struct
SOCK_PATH = "/tmp/CoreFxPipe_mySocket"
with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as sock:
try:
os.remove(SOCK_PATH)
except OSError:
pass
sock.bind(SOCK_PATH)
sock.listen()
conn, addr = sock.accept()
with conn:
try:
while True:
amount_expected = struct.unpack('I', conn.recv(4))[0]
print("amount_expected :", amount_expected)
message = conn.recv(amount_expected)
print("Received message : ", message.decode())
# Send data
message_rev = message[::-1].decode()
print("Sent message (reversed) : ", message_rev)
conn.sendall(
struct.pack(
'I',
len(message_rev)
)
+ message_rev.encode('utf-8')
)
except (struct.error, KeyboardInterrupt) as e:
print(e)
finally:
print('closing socket')
C# Client
using System;
using System.IO;
using System.IO.Pipes;
using System.Text;
class PipeClient
{
static void Main(string[] args)
{
using (NamedPipeClientStream pipeClient =
new NamedPipeClientStream(".", "mySocket", PipeDirection.InOut))
{
// Connect to the pipe or wait until the pipe is available.
Console.WriteLine("Attempting to connect to pipe...");
pipeClient.Connect();
try
{
// Read user input and send that to the client process.
using (BinaryWriter _bw = new BinaryWriter(pipeClient))
using (BinaryReader _br = new BinaryReader(pipeClient))
{
while (true)
{
//sw.AutoFlush = true;
Console.Write("Enter text: ");
var str = Console.ReadLine();
var buf = Encoding.ASCII.GetBytes(str); // Get ASCII byte array
_bw.Write((uint)buf.Length); // Write string length
_bw.Write(buf); // Write string
Console.WriteLine("Wrote: \"{0}\"", str);
Console.WriteLine("Let's hear from the server now..");
var len = _br.ReadUInt32();
var temp = new string(_br.ReadChars((int)len));
Console.WriteLine("Received from client: {0}", temp);
}
}
}
// Catch the IOException that is raised if the pipe is broken
// or disconnected.
catch (IOException e)
{
Console.WriteLine("ERROR: {0}", e.Message);
}
}
Console.Write("Press Enter to continue...");
}
}
Sources:
https://abgoswam.wordpress.com/2017/07/13/named-pipes-c-python-net-core/
https://realpython.com/python-sockets/
https://unix.stackexchange.com/questions/75904/are-fifo-pipe-unix-domain-socket-the-same-thing-in-linux-kernel

C# socket hangs when receive in loop - python as socket server

I'm familiar with C#, and know some python. Recent days I'm learning the book Programming Python, 4th Edition and have run the very basic socket samples: echo-server.py and echo-client.py
They work well on my Windows, python 3.x.
python server:
from socket import *
myHost = 'localhost'
myPort = 50007
sockobj = socket(AF_INET, SOCK_STREAM)
sockobj.bind((myHost, myPort))
sockobj.listen(5)
while True:
connection, address = sockobj.accept()
print('Server connected by', address)
while True:
data = connection.recv(1024)
if not data: break
connection.send(b'Echo=>' + data)
connection.close()
Now I want to learn socket in C# too, so I wrote a C# .net framework 4.5 socket client, expecting to receive and show what echo-client.py does.
I got the C# demo from msdn and made some refactor to reduce code size.
public static void Main(string[] args)
{
string server = "localhost";
int port = 50007;
string request = "GET / HTTP/1.1\r\nHost: " + server +
"\r\nConnection: Close\r\n\r\n";
Byte[] sent = Encoding.ASCII.GetBytes(request);
Byte[] recv = new Byte[256];
IPHostEntry hostEntry = Dns.GetHostEntry(server);
IPEndPoint ipe = new IPEndPoint(hostEntry.AddressList[1], port);
Socket s =
new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
s.Connect(ipe);
s.Send(sent, sent.Length, 0);
int bytes = 0;
string page = "recived:\r\n";
//do
{
bytes = s.Receive(recv, recv.Length, 0);
page = page + Encoding.ASCII.GetString(recv, 0, bytes);
}
//while (bytes > 0);
Console.WriteLine(page);
Console.WriteLine("result");
Console.ReadKey();
}
My test steps:
If I set up a web site using local IIS, such as
http://localhost:801, then above code can show the homepage html
contents, this means my C# code is working.
Run echo-server.py, and change C# code's port to 50007, then run,
nothing output in console, and application does not exit, if I place a break point within the loop, I can see the loop has only run once. The python server did output some log saying C# is connecting.
Comment do while loop(as commented in code), this time the output is exactly same as echo-client.py(expected).
So I'm wondering what's wrong when I'm using do while loop?

How to Send File to SignalR hub From websocket-sharp Client?

We are using the websocket-sharp in one of our applications which establishes a websocket connection with our SignalR Hub on the server, we are able to send the text messages and receive the response for the same but unable to post a byte[].
Code for sending text to server is this:
public void TestGroupData(string groupname)
{
DataCarrier dataCarrier = new DataCarrier()
{
H = "BILHub",
M = "GetAllGroupsFor",
A = new string[] { groupname }
};
string wsPacket = JsonConvert.SerializeObject(payLoad);
this._ws.Send(wsPacket);
//this.MakeServerCall(dataCarrier);
}
When we try to send byte[] using the below code, its not going through:
public void TestFileData()
{
try
{
// Read the file data
Console.WriteLine("Started reading file");
string fileName = #"C:\Saurabh\Data\Song.mp3";
byte[] file = File.ReadAllBytes(fileName);
DataCarrier dataCarrier = new DataCarrier()
{
H = "BILHub",
M = "SendFile",
A = new object[] { file }
};
string wsPacket = JsonConvert.SerializeObject(dataCarrier);
this._ws.SendAsync(file , OnSendComplete);
}
catch (Exception ex)
{
Console.WriteLine(ex);
//throw;
}
}
Any help with this? How can I set my hub name in _ws.sendAsync()?

Sending big files is not really what SignalR is meant for.
SignalR is good for real-time messaging purposes between server & clients, for a rather small sized messages (as messahe size has a real impact on performance).
For such a need I would look into ASP.NET Web API, especially by using chunked upload (splitting file in multiple pieces to avoid connection interruptions)

System.IO.IOException:Sharing violation on path - multiple clients

I have two applications. The server send files to my clients. The clients are implemented in Unity3d with C#. Each client has one thread to receive files from server. If I send the files over the network, I write the bytes to the file with this code:
private Thread clientThread;
private object writeLock = new object();
public void StartConnection()
{
// Start connection to server.
clientThread = new Thread(GetFiles);
}
public void GetFiles()
{
string fullPath;
// Receive bytes from server
fullPath = Path.Combine(clientDirPath, fileNameFromServer);
lock(writeLock)
{
using (BinaryWriter bWrite = new BinaryWriter(File.Open(fullPath, FileMode.Create)))
{
bWrite.Write(binaryFileContent);
bWrite.Flush();
}
}
Now, if I start multple clients and send files to receive them synchronously on the client-side, I get this error message: System.IO.IOException:Sharing violation on path. Whether I use the lock-statement it is not working. Do anyone know the way to get it working?
EDIT: I added more code.

Raw FTP SSL with C#

I'm trying to understand how SSL works. In my wish to make a small FTP client which supports SSL I've run into some problems:
TcpClient FtpConnection = new TcpClient(FtpServer, FtpPort);
NetworkStream FtpStream = FtpConnection.GetStream();
StreamReader FtpReader = new StreamReader(FtpStream);
FtpWriter = new StreamWriter(IrcStream);
send_cmd("AUTH SSL");
send_cmd is just a FtpWriter.WriteLine(text); FtpWriter.Flush(); function.
My "problem" is this: First I need to make a (non-ssl) connection to the FTP, then tell it to do a ssl connection (AUTH SSL), and I would guess I then need to make a new connection - something like:
TcpClient client = new TcpClient(FtpServer, FtpPort);
SslStream sslStream = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);
try
{
sslStream.AuthenticateAsClient("foobar");
}
catch (AuthenticationException e)
{
MessageBox.Show("Authentication failed - closing the connection.");
client.Close();
return;
}
Taken from msdn.
I keep dying on handshake failed due to unexpected packet format (which I've tried googling, but all say it's because the author has connected to a wrong port), which I take as: The connection is not ssl until AUTH SSL is send to it. So my question is, how would i go about making this a "hybrid" connection so I can make an SSL connection to the server?
Any help is greatly appreciated!

Using a library like that is the opposite of what I wanted. Since I found so few hits when searching the web, I'll post what I figured out:
Building a C# ftp client is basically like so:
TcpClient blabla = new TcpClient("some.host", 21);
NetworkStream blabla_stream = blabla.GetStream();
StreamReader unsecure_reader = new StreamReader(blabla_stream);
StreamWriter blabla_writer = new StreamWriter(blabla_stream);
blabla_writer.WriteLine("AUTH SSL");
string response = "";
while ((response = unsecure_reader.ReadLine()) != null)
{
if (response.Substring(0,3) == "234")
{
SslStream ssl_connection = new SslStream(blabla.GetStream(), false, new RemoteCertificateValidationCallback(validate_certificate), null);
ssl_connection.AuthenticateAsClient("");
StreamReader ssl_stream = new StreamReader(ssl_connection);
ftp_writer = new StreamWriter(ssl_connection);
}
}
where validate_certificate is a function based on msdn's (you can google it and mod it easily yourself).
For more info see RFC 4217 and 2228.

http://ftps.codeplex.com/
This project contains every pieces you need.