关于ssl：使用C＃Webclient通过https请求html


Requesting html over https with c# Webclient

我正在从无法控制的站点通过c＃WebClient类尝试各种html资源。
当我尝试访问网址时，例如
" https://archive.org/details/OTRR_In_The_Name_Of_The_Law_Singles"

我得到错误：
System.Net.WebException：请求已中止：无法创建SSL / TLS安全通道。

我发现了一些解决方案，建议我使用以下代码来忽略证书要求，并使Web客户端充当浏览器，但是我仍然收到相同的错误

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 ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(
            delegate
            {
                return true;
            });
            using(WebClient webClient = new WebClient()) {
                webClient.Headers["User-Agent"] ="Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2.6) Gecko/20100625 Firefox/3.6.6 (.NET CLR 3.5.30729)";
                webClient.Headers["Accept"] ="text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
                webClient.Headers["Accept-Language"] ="en-us,en;q=0.5";
                webClient.Headers["Accept-Encoding"] ="gzip,deflate";
                webClient.Headers["Accept-Charset"] ="ISO-8859-1,utf-8;q=0.7,*;q=0.7";
                StreamReader sr = new StreamReader(webClient.OpenRead(inputString));
}

相关讨论

阅读以下内容：http://support.microsoft.com/kb/915599

您正在访问的服务器不支持TLS，因此您需要强制其使用SSL3。

将以下行添加到您的呼叫中：

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ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

这是一个完整的示例：

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using System;
using System.IO;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

class Program
{
    static void Main(string[] args)
    {
        Uri address = new Uri("https://archive.org/details/OTRR_In_The_Name_Of_The_Law_Singles");

        ServicePointManager.ServerCertificateValidationCallback += ValidateRemoteCertificate;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 ;

        using (WebClient webClient = new WebClient())
        {
            var stream = webClient.OpenRead(address);
            using (StreamReader sr =new StreamReader(stream))
            {
                var page = sr.ReadToEnd();
            }
        }
    }

    /// <summary>
    /// Certificate validation callback.
    /// </summary>
    private static bool ValidateRemoteCertificate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error)
    {
        // If the certificate is a valid, signed certificate, return true.
        if (error == System.Net.Security.SslPolicyErrors.None)
        {
            return true;
        }

        Console.WriteLine("X509Certificate [{0}] Policy Error: '{1}'",
            cert.Subject,
            error.ToString());

        return false;
    }
相关讨论

在.net Framework 4.0中添加

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ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; //TLS 1.2
相关讨论

只需在var stream = webClient.OpenRead(address);之前添加此行

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System.Net.ServicePointManager.ServerCertificateValidationCallback += (send, certificate, chain, sslPolicyErrors) => { return true; };

那应该解决SSL / TLS错误

相关讨论

我尝试了这个示例并收到了错误
"请求已中止：无法创建SSL / TLS安全通道"

enter image description here

要解决此问题，可以在我的情况下更改Tls12的SecurityProtocol，并且运行良好。

enter image description here