The Connect Method in Socket (System.Net) Make an Exception (After Wi-Fi Connection Successfully)!

[AlirezaP]

Library/API/IoT binding

System.Net

Visual Studio version

VS2022

.NET nanoFramework extension version

No response

Target name(s)

ESP32_REV0

Firmware version

1.12.1.102

Device capabilities

Target capabilities:
Has nanoBooter: NO
IFU capable: NO
Has proprietary bootloader: YES

Description

When You try to Make a Connection (Socket) To a Specific endpoint It Will Make an Exception!

How to reproduce

1. Prepare Two Esp32-Wroom32 Devices (One Is Server and Another Is Client)
2. Make Wi-Fi Configuration for Server (To be Access point). Prepare SSID And Password
3. Configure the Wi-Fi for the client to connect to the server. (Client Must be Connect To server With SSID And Password That Set in Step2)
4. Connect Client to Server by Wi-Fi
5. Make Socket Connection from Client to Server (TCP Send/Receive Data)
6. When the Client Try to make a socket connection to The Server (On Connect Method), bang!! An Exception was thrown!

Note: The server works well. After the Server be Start You Can See the Server SSID in Your Laptop Wi-Fi Scan
For More Test I Replace the Client, I Used My Laptop as Client (instead esp32): I create a console Application in visual studio and I copy the Client Code to the Console Application then I Connect to the Server by Laptop Wi-fi (With Server SSID AND PASS) then I run Console Application and It Worked!

Summary: If we use esp32 as client we get exception. if we use console Application as client it worked. with same code.

Expected behaviour

Connecting to server 192.168.4.1:80...
++++ Exception System.Net.Sockets.SocketException - CLR_E_FAIL (1) ++++
++++ Message:
++++ System.Net.Sockets.NativeSocket::poll [IP: 0000] ++++
++++ System.Net.Sockets.Socket::Poll [IP: 0017] ++++
++++ System.Net.Sockets.Socket::Connect [IP: 0053] ++++
++++ APSecurityHome.Program::Main [IP: 0079] ++++
Exception thrown: 'System.Net.Sockets.SocketException' in System.Net.dll
Error: Exception was thrown: System.Net.Sockets.SocketException code:10035

Screenshots

No response

Sample project or code

Server Code:

Wireless80211Configuration wconf = GetConfiguration();
wconf.Options = Wireless80211Configuration.ConfigurationOptions.None | Wireless80211Configuration.ConfigurationOptions.SmartConfig;
wconf.SaveConfiguration();
if (Setup() == false)
{
    Power.RebootDevice();
}
var dhcpserver = new DhcpServer
{
    CaptivePortalUrl = $"http://{SoftApIP}"
};
var dhcpInitResult = dhcpserver.Start(IPAddress.Parse(SoftApIP), new IPAddress(new byte[] { 255, 255, 255, 0 }));
if (!dhcpInitResult)
{
    Power.RebootDevice();
}
    
using (Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
{
       try
       {
           serverSocket.Bind(new IPEndPoint(IPAddress.Parse(SoftApIP), ServerPort));
           serverSocket.Listen(5); 

           Console.WriteLine($"Server listening on {SoftApIP}:{ServerPort}");

           while (true)
           {
               // Accept incoming client connection
               using (Socket clientSocket = serverSocket.Accept())
               {
                   Console.WriteLine("Client connected!");

                   byte[] buffer = new byte[256];
                   int bytesReceived = clientSocket.Receive(buffer);
                   if (bytesReceived > 0)
                   {
                       string receivedData = new string(Encoding.UTF8.GetChars(buffer, 0, bytesReceived));
                       Console.WriteLine($"Received data: {receivedData}");

                       string response = "Hello from server!";
                       byte[] responseData = Encoding.UTF8.GetBytes(response);
                       clientSocket.Send(responseData);
                       Console.WriteLine("Response sent to client.");
                   }
               }

               Console.WriteLine("Client disconnected.");
           }
       }
       catch (Exception ex)
       {
           Console.WriteLine($"Error: {ex.Message}");
       }
}

Client Code:

bool success;
CancellationTokenSource cs = new(120000);
success = WifiNetworkHelper.ConnectDhcp(SSID, Password, requiresDateTime: true, token: cs.Token);
var ip = Wireless80211.GetCurrentIPAddress();
Debug.WriteLine(ip);

 while (true)
 {
     try
     {
         using (Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
         {

             Console.WriteLine($"Connecting to server {ServerIP}:{ServerPort}...");
             clientSocket.Connect(new IPEndPoint(IPAddress.Parse(ServerIP), ServerPort)); //Here We Have Exception

            // if (clientSocket.Available == )
             {
                 Console.WriteLine("Connected to server!");

                 //Data to send
                 string dataToSend = "Hello from ESP32 Client!";
                 byte[] buffer = Encoding.UTF8.GetBytes(dataToSend);

                 //Send data to server
                 Console.WriteLine("Sending data...");
                 clientSocket.Send(buffer);
                 Console.WriteLine("Data sent!");

                 //Optionally receive a response
                 byte[] responseBuffer = new byte[256];
                 int bytesReceived = clientSocket.Receive(responseBuffer);
                 if (bytesReceived > 0)
                 {
                     string response = new string(Encoding.UTF8.GetChars(responseBuffer, 0, bytesReceived));
                     Console.WriteLine($"Received response from server: {response}");
                 }
             }
         }
     }
     catch (SocketException ex)
     {
         Console.WriteLine($"Error: {ex.Message} code:{ex.ErrorCode}");
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Error: {ex.Message}");
     }

     Thread.Sleep(2000);
 }

Aditional information

No response

[alberk8]

try replace this in the client code success = WifiNetworkHelper.ConnectDhcp(SSID, Password, requiresDateTime: false, token: cs.Token);
because there is no time server (NTP) on your server (no access to internet).

[AlirezaP]

I did that. It did not work! It seems the problem came from the Net library or firmware

[0use-TE]

try replace this in the client code success = WifiNetworkHelper.ConnectDhcp(SSID, Password, requiresDateTime: false, token: cs.Token);尝试在客户端代码中替换这个 success = WifiNetworkHelper.ConnectDhcp(SSID, Password, requiresDateTime: false, token: cs.Token); because there is no time server (NTP) on your server (no access to internet).因为您的服务器上没有时间服务器（NTP），无法访问互联网。

It is useful for me,thank you very much!❤