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March 25, 2021 08:05
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using System; | |
using System.Collections; | |
using System.Net; | |
using System.Net.Security; | |
using System.Net.Sockets; | |
using System.Security.Authentication; | |
using System.Security.Cryptography; | |
using System.Text; | |
using System.Security.Cryptography.X509Certificates; | |
using System.IO; | |
namespace Examples.System.Net | |
{ | |
public class SslTcpClient | |
{ | |
private static Hashtable certificateErrors = new Hashtable(); | |
// The following method is invoked by the RemoteCertificateValidationDelegate. | |
public static bool ValidateServerCertificate( | |
object sender, | |
X509Certificate certificate, | |
X509Chain chain, | |
SslPolicyErrors sslPolicyErrors) | |
{ | |
if (sslPolicyErrors == SslPolicyErrors.None) | |
return true; | |
Console.WriteLine("Certificate error: {0}", sslPolicyErrors); | |
var cert = certificate.Export(X509ContentType.Cert); | |
var pem = new String(PemEncoding.Write("CERTIFICATE", cert)); | |
File.WriteAllText("certificate.pem", pem); | |
// Do not allow this client to communicate with unauthenticated servers. | |
return false; | |
} | |
public static void RunClient(string machineName, string serverName) | |
{ | |
// Create a TCP/IP client socket. | |
// machineName is the host running the server application. | |
TcpClient client = new TcpClient(machineName,443); | |
Console.WriteLine("Client connected."); | |
// Create an SSL stream that will close the client's stream. | |
SslStream sslStream = new SslStream( | |
client.GetStream(), | |
false, | |
new RemoteCertificateValidationCallback (ValidateServerCertificate), | |
null | |
); | |
// The server name must match the name on the server certificate. | |
try | |
{ | |
sslStream.AuthenticateAsClient(serverName); | |
} | |
catch (AuthenticationException e) | |
{ | |
Console.WriteLine("Exception: {0}", e.Message); | |
if (e.InnerException != null) | |
{ | |
Console.WriteLine("Inner exception: {0}", e.InnerException.Message); | |
} | |
Console.WriteLine ("Authentication failed - closing the connection."); | |
client.Close(); | |
return; | |
} | |
// Encode a test message into a byte array. | |
// Signal the end of the message using the "<EOF>". | |
byte[] messsage = Encoding.UTF8.GetBytes("Hello from the client.<EOF>"); | |
// Send hello message to the server. | |
sslStream.Write(messsage); | |
sslStream.Flush(); | |
// Read message from the server. | |
string serverMessage = ReadMessage(sslStream); | |
Console.WriteLine("Server says: {0}", serverMessage); | |
// Close the client connection. | |
client.Close(); | |
Console.WriteLine("Client closed."); | |
} | |
static string ReadMessage(SslStream sslStream) | |
{ | |
// Read the message sent by the server. | |
// The end of the message is signaled using the | |
// "<EOF>" marker. | |
byte [] buffer = new byte[2048]; | |
StringBuilder messageData = new StringBuilder(); | |
int bytes = -1; | |
do | |
{ | |
bytes = sslStream.Read(buffer, 0, buffer.Length); | |
// Use Decoder class to convert from bytes to UTF8 | |
// in case a character spans two buffers. | |
Decoder decoder = Encoding.UTF8.GetDecoder(); | |
char[] chars = new char[decoder.GetCharCount(buffer,0,bytes)]; | |
decoder.GetChars(buffer, 0, bytes, chars,0); | |
messageData.Append (chars); | |
// Check for EOF. | |
if (messageData.ToString().IndexOf("<EOF>") != -1) | |
{ | |
break; | |
} | |
} while (bytes != 0); | |
return messageData.ToString(); | |
} | |
private static void DisplayUsage() | |
{ | |
Console.WriteLine("To start the client specify:"); | |
Console.WriteLine("clientSync machineName [serverName]"); | |
Environment.Exit(1); | |
} | |
public static int Main(string[] args) | |
{ | |
string serverCertificateName = null; | |
string machineName = null; | |
if (args == null ||args.Length <1 ) | |
{ | |
DisplayUsage(); | |
} | |
// User can specify the machine name and server name. | |
// Server name must match the name on the server's certificate. | |
machineName = args[0]; | |
if (args.Length <2 ) | |
{ | |
serverCertificateName = machineName; | |
} | |
else | |
{ | |
serverCertificateName = args[1]; | |
} | |
SslTcpClient.RunClient (machineName, serverCertificateName); | |
return 0; | |
} | |
} | |
} |
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