C# SSLStream 读取函数抛出 IOException

Question

我正在尝试创建自己的 HTTPS 代理服务器。 出于某种原因，当我尝试从 sslstream 对象读取时出现异常。 这是它：

System.dll 中发生类型为“System.IO.IOException”的未处理异常

附加信息：无法从传输连接中读取数据：连接尝试失败，因为连接方在一段时间后没有正确响应，或者由于连接的主机未能响应而建立的连接失败。

这是我的代码：

    public Server()
    {
        m_portnumber = 4434;
        m_tcplistener = new TcpListener(IPAddress.Any, m_portnumber);
        m_cert = createCertificate();
    }
    public void start()
    {
        m_tcplistener.Start();
        while (true)
        {
            TcpClient client = m_tcplistener.AcceptTcpClient();
            ClientHandler(client);
        }
    }

    private void ClientHandler(TcpClient client)
    {
        // A client has connected. Create the 
        // SslStream using the client's network stream.
        SslStream sslStream = new SslStream(
            client.GetStream(), false);
        // Authenticate the server but don't require the client to authenticate.
        try
        {
            sslStream.AuthenticateAsServer(m_cert,
                false, SslProtocols.Tls, true);
            // Display the properties and settings for the authenticated stream.
            DisplaySecurityLevel(sslStream);
            DisplaySecurityServices(sslStream);
            DisplayCertificateInformation(sslStream);
            DisplayStreamProperties(sslStream);

            // Set timeouts for the read and write to 5 seconds.
            sslStream.ReadTimeout = 5000;
            sslStream.WriteTimeout = 5000;
            // Read a message from the client.   
            Console.WriteLine("Waiting for client message...");
            string messageData = ReadMessage(sslStream);
            Console.WriteLine("Received: {0}", messageData);
        }
        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.");
            sslStream.Close();
            client.Close();
            return;
        }
        finally
        {
            // The client stream will be closed with the sslStream
            // because we specified this behavior when creating
            // the sslStream.
            sslStream.Close();
            client.Close();
        }
    }
    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();
    }
    static void DisplaySecurityLevel(SslStream stream)
    {
        Console.WriteLine("Cipher: {0} strength {1}", stream.CipherAlgorithm, stream.CipherStrength);
        Console.WriteLine("Hash: {0} strength {1}", stream.HashAlgorithm, stream.HashStrength);
        Console.WriteLine("Key exchange: {0} strength {1}", stream.KeyExchangeAlgorithm, stream.KeyExchangeStrength);
        Console.WriteLine("Protocol: {0}", stream.SslProtocol);
    }
    static void DisplaySecurityServices(SslStream stream)
    {
        Console.WriteLine("Is authenticated: {0} as server? {1}", stream.IsAuthenticated, stream.IsServer);
        Console.WriteLine("IsSigned: {0}", stream.IsSigned);
        Console.WriteLine("Is Encrypted: {0}", stream.IsEncrypted);
    }
    static void DisplayStreamProperties(SslStream stream)
    {
        Console.WriteLine("Can read: {0}, write {1}", stream.CanRead, stream.CanWrite);
        Console.WriteLine("Can timeout: {0}", stream.CanTimeout);
    }
    static void DisplayCertificateInformation(SslStream stream)
    {
        Console.WriteLine("Certificate revocation list checked: {0}", stream.CheckCertRevocationStatus);

        X509Certificate localCertificate = stream.LocalCertificate;
        if (stream.LocalCertificate != null)
        {
            Console.WriteLine("Local cert was issued to {0} and is valid from {1} until {2}.",
                localCertificate.Subject,
                localCertificate.GetEffectiveDateString(),
                localCertificate.GetExpirationDateString());
        }
        else
        {
            Console.WriteLine("Local certificate is null.");
        }
        // Display the properties of the client's certificate.
        X509Certificate remoteCertificate = stream.RemoteCertificate;
        if (stream.RemoteCertificate != null)
        {
            Console.WriteLine("Remote cert was issued to {0} and is valid from {1} until {2}.",
                remoteCertificate.Subject,
                remoteCertificate.GetEffectiveDateString(),
                remoteCertificate.GetExpirationDateString());
        }
        else
        {
            Console.WriteLine("Remote certificate is null.");
        }
    }
    private static void DisplayUsage()
    {
        Console.WriteLine("To start the server specify:");
        Console.WriteLine("serverSync certificateFile.cer");
        Environment.Exit(1);
    }

    private X509Certificate createCertificate()
    {
        byte[] c = Certificate.CreateSelfSignCertificatePfx(
                   "CN=localhost", //host name
                    DateTime.Parse("2015-01-01"), //not valid before
                    DateTime.Parse("2020-01-01"), //not valid after
                    "sslpass"); //password to encrypt key file
        using (BinaryWriter binWriter = new BinaryWriter(File.Open(@"cert.pfx", FileMode.Create)))
        {
            binWriter.Write(c);
        }
        return new X509Certificate2(@"cert.pfx", "sslpass");
    }
}

Answer 1

这不是 SSL 错误，而是 TCP 错误。 您正在连接到未侦听的 ip/端口对。 是一个主动拒绝，所以它不像你到达 IP 并告诉你没有端口。 是超时，这可能意味着无效的 IP 或目标的防火墙（故意）忽略您。

我的第一个怀疑是行m_portnumber = 4434; . 这是一个不寻常的端口号。 您确定不是打字错误，并且您想要 HTTPS 常用端口 (443) 吗？ 如果你真的是 4434，你需要检查网络连接。 确保 IP 正确解析、可访问、目标正在侦听并且防火墙允许您进入。

Answer 2

我猜上面的代码取自https://docs.microsoft.com/en-us/dotnet/api/system.net.security.sslstream?view=net-5.0

在其中一台 Windows 机器（Win10 1809）上遇到类似的 ReadMessage(SslStream sslStream) 问题。

这里有两点需要注意：

1. sslStream.Read 将读取经过身份验证的网络流中的所有内容，包括 Header 和 Body。 所以你有责任解析两者并循环出来。

2. 在我的情况下，机器从流中读取需要很长时间（超过 5 秒）。 所以我不得不删除时间读取超时。 在这里

   sslStream.ReadTimeout = 5000; \\\\ 默认情况下它是无限的