我正在使用Windows 10上的Unity Engine（2017.2.0f3）创建一个游戏，我试图从网页上获取HTML。据我所知，Unity使用“Mono”C＃编译器和运行时v2.0（根据在mono --version中运行Unity\Editor\Data\Mono\bin的结果），还使用v5.0.1（根据在mono --version中运行Unity\Editor\Data\MonoBleedingEdge\bin的结果）。我目前正在使用HTML Agility Pack进行解析。当试图访问HTTP安全网站时，例如dictionary.com，一切都按预期工作，但无论我做什么，我都无法访问HTTPS安全网站，例如urbandictionary.com（编辑：显然，问题是特定于此网站的，因为使用mozroots导入证书后，可以访问github.com），并始终收到异常：TlsException: The authentication or decryption has failed.我知道HTML Agility Pack不支持HTTPS，并根据this answer编写了我的代码。我已经尝试过here和here描述的解决方案，但无济于事。我试过运行mozroots，我位于PathTo/Unity/Editor/Data/MonoBleedingEdge/lib/mono/4.5/mozroots，使用--import，--sync和--quiet标志，但同样的异常被抛出（如果这确实有效，我对它的可移植性持怀疑态度，但也许我可以实现自己的mozroots的版本，如评论所建议的）。此外，我被告知Unity使用的Mono版本不支持TLS 1.2，这是有问题的。如果没有解决此问题的方法，是否有任何解决方法？
注意：为清晰起见删节
class MyWebClient : WebClient
{
protected override WebRequest GetWebRequest(Uri address)
{
HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
request.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
return request;
}
}
class GetHtml
{
public static void Get(string url)
{
string documentString = new MyWebClient().DownloadString(url);
...
}
}
class CallingClass
{
public void CallingMethod()
{
ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;
//With or without the above line ^, the same TlsException is thrown.
GetHtml.Get("https://www.urbandictionary.com/define.php?term=example");
//HTTP works properly, but HTTPS, as in this example, does not.
}
}
日志如下：
TlsException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.RecordProtocol.ProcessAlert (AlertLevel alertLevel, AlertDescription alertDesc)
Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult)
Rethrow as WebException: Error getting response stream (Write: The authentication or decryption has failed.): SendFailure
System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult)
System.Net.HttpWebRequest.GetResponse ()
System.Net.WebClient.GetWebResponse (System.Net.WebRequest request)
System.Net.WebClient.DownloadDataCore (System.Uri address, System.Object userToken)
编辑：我已经尝试更新运行时版本。唯一的选择是在Project Settings-> Player菜单中从.Net 3.5更改为4.6，这是实验性的。代码运行时我仍然会遇到异常，但输出日志略有不同。
TlsException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.RecordProtocol.EndReceiveRecord (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslClientStream.SafeEndReceiveRecord (System.IAsyncResult ar, System.Boolean ignoreEmpty) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslClientStream.NegotiateAsyncWorker (System.IAsyncResult result) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslClientStream.EndNegotiateHandshake (System.IAsyncResult result) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslStreamBase.EndRead (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Net.Security.Private.LegacySslStream.EndAuthenticateAsClient (System.IAsyncResult asyncResult) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Mono.Net.Security.Private.LegacySslStream.AuthenticateAsClient (System.String targetHost, System.Security.Cryptography.X509Certificates.X509CertificateCollection clientCertificates, System.Security.Authentication.SslProtocols enabledSslProtocols, System.Boolean checkCertificateRevocation) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Mono.Net.Security.MonoTlsStream.CreateStream (System.Byte[] buffer) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebConnection.CreateStream (System.Net.HttpWebRequest request) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Rethrow as WebException: Error: SecureChannelFailure (The authentication or decryption has failed.)
System.Net.WebClient.DownloadDataInternal (System.Uri address, System.Net.WebRequest& request) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebClient.DownloadString (System.Uri address) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebClient.DownloadString (System.String address) (at <344dc4d3f1ad41809df78607b6121a41>:0)
此问题计数由HTTP协议引起。如果服务器使用安全的HTTP（实际上是HTTPS），则当底层协议无法处理X509 Certificate时，可能会创建错误。
尝试更改此行：
HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
至：
HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
request.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;
或者，或者，使用以下方法将验证回调应用于全局过滤器：
ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;
在代码中创建任何HttpWebRequest对象之前。
如果您想更仔细地处理证书验证，请在此处显示回调：https://msdn.microsoft.com/en-us/library/office/dd633677
这应该可以解决您的问题。
经过一些严谨的研究后发现Unity（2017.2.0f3）目前使用的Mono版本不支持TLS 1.2，正如开发人员here所解释的那样。此外，仔细检查异常日志显示，在内部，正在使用遗留后端：Mono.Net.Security.Private.LegacySslStream而不是Mono.Net.Security.Private.SslStream。截至目前，唯一的解决方案将涉及第三方库或解决方法。
感谢@Evk指出我正确的方向。