C#在Linux+Mono环境中使用微信支付证书

最近特殊的需求，要把微信平台一个功能页面部署到Linux（CentOS6.5）下，其中涉及到微信支付退款。

鉴于之前实践过mono+jexus+asp.net mvc的部署，于是问题重点在于解决对商户证书的调用问题。

查看微信支付官方文档关于证书的使用说明

• ◆ apiclient_cert.p12是商户证书文件，除PHP外的开发均使用此证书文件。
• ◆ 商户如果使用.NET环境开发，请确认Framework版本大于2.0，必须在操作系统上双击安装证书apiclient_cert.p12后才能被正常调用。
• ◆ 商户证书调用或安装都需要使用到密码，该密码的值为微信商户号（mch_id）
• ◆ PHP开发环境请使用商户证书文件apiclient_cert.pem和apiclient_key.pem ，rootca.pem是CA证书。

1.使用mono自带工具certmgr导入.p12证书

certmgr -add -c -m -p 密码 My ApiClient_cert.p12

2.编写测试程序

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

public class TlsTest
{
    public static void Main(string[] args)
    {

        HttpWebResponse webreponse;
        string strHtml = "NO";
        try
        {
            //系统必须已经导入cert指向的证书
            string url = "https://api.mch.weixin.qq.com/secapi/pay/refund";
            //My即对应”个人“存储区，固定不可改变
            X509Store store = new X509Store("My", StoreLocation.LocalMachine);
            store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
            X509Certificate cer = store.Certificates.Find(X509FindType.FindByThumbprint, "546FCAA50DB599C5439AC8139C69393D5DB243D0", false)[0];
            //遍历证书查看Hash；windows下可直接双击安装，查看属性
            //Console.WriteLine(store.Certificates.Count);
            //foreach(var c in store.Certificates){
            //    //Console.WriteLine("{0},{1},{2},{3},{4},{5}", c.GetCertHashString(), c.FriendlyName, c.GetFormat(), c.IssuerName, c.SubjectName, c.Thumbprint);
            //    if (c.GetCertHashString() == "546FCAA50DB599C5439AC8139C69393D5DB243D0")
            //    {
            //        Console.WriteLine("found");
            //        cer = c;
            //        break;
            //    }
            //}
            HttpWebRequest webrequest = (HttpWebRequest)HttpWebRequest.Create(url);
            webrequest.ClientCertificates.Add(cer);
            webrequest.Method = "post";
            webrequest.KeepAlive = true;
            webreponse = (HttpWebResponse)webrequest.GetResponse();

            Stream stream = webreponse.GetResponseStream();
            string resp = string.Empty;
            using (StreamReader reader = new StreamReader(stream))
            {
                resp = reader.ReadToEnd();
            }
            strHtml = resp;
        }
        catch (Exception exp)
        {
            strHtml = exp.ToString();

        }

        Console.WriteLine(strHtml);
    }
}

3.运行测试程序

mono SSLtest.exe

结果运行报错

System.Net.WebException: Error: TrustFailure (The authentication or decryption has failed.) ---> System.IO.IOException: The authentication or decryption has failed. ---> System.IO.IOException: The authentication or decryption has failed. ---> Mono.Security.Protocol.Tls.TlsException: Invalid certificate received from server. Error code: 0xffffffff800b0109
  at Mono.Security.Protocol.Tls.RecordProtocol.EndReceiveRecord (IAsyncResult asyncResult) <0x40713980 + 0x0013e> in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslClientStream.SafeEndReceiveRecord (IAsyncResult ar, Boolean ignoreEmpty) <0x407138b0 + 0x00031> in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslClientStream.NegotiateAsyncWorker (IAsyncResult result) <0x4070d2d0 + 0x0023a> in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at Mono.Security.Protocol.Tls.SslClientStream.EndNegotiateHandshake (IAsyncResult result) <0x40726300 + 0x000f3> in <filename unknown>:0 
  at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult) <0x40726050 + 0x00086> in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at Mono.Security.Protocol.Tls.SslStreamBase.EndRead (IAsyncResult asyncResult) <0x4070a990 + 0x00199> in <filename unknown>:0 
  at Mono.Net.Security.Private.LegacySslStream.EndAuthenticateAsClient (IAsyncResult asyncResult) <0x4070a8f0 + 0x00042> in <filename unknown>:0 
  at Mono.Net.Security.Private.LegacySslStream.AuthenticateAsClient (System.String targetHost, System.Security.Cryptography.X509Certificates.X509CertificateCollection clientCertificates, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation) <0x40704650 + 0x00055> in <filename unknown>:0 
  at Mono.Net.Security.MonoTlsStream.CreateStream (System.Byte[] buffer) <0x40703e00 + 0x00145> in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult) <0x406fcf50 + 0x001ed> in <filename unknown>:0 
  at System.Net.HttpWebRequest.GetResponse () <0x406f5210 + 0x00053> in <filename unknown>:0 
  at TlsTest.Main (System.String[] args) <0x406a7d80 + 0x002c6> in <filename unknown>:0

4.发现错误原因是"Invalid certificate received from server"，这个问题在Mono文档中已有说明：

That’s probably because you do not trust the site you are connecting to. Note that a default installation of Mono doesn’t trust anyone!

默认情况下，任何站点都不被Mono信任！

同时也给出了4个解决方案：

• 使用cert-sync工具同步Mono和系统的证书存储区
• 程序实现ICertificatePolicy自行决定信任规则
• 使用certmgr.exe导入受信证书
• 使用mozroots.exe自动导入常用的可信根证书

5.尝试解决方案2

ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

private static bool CheckValidationResult(object sender, X509Certificate c, X509Chain chain, SslPolicyErrors errors)
{
      return true;
}

报错问题虽然可以解决，但对所有情况均信任不是一个好的解决方法，根据X509Certificate c进行判断理应可行，没有再进一步探索

6.尝试解决方案4

使用mozroots自动下载安装常用的根证书

mozroots --import --sync

显示成功导入100+根证书，重新执行测试程序仍然报错。

这个结果一度使我认为此方法无效，但偶然在本地测试却通过了。

对比发现生效的下载路径是：

https://hg.mozilla.org/releases/mozilla-release/raw-file/default/security/nss/lib/ckfw/builtins/certdata.txt

而无效的下载路径是：

http://mxr.mozilla.org/seamonkey/source/security/nss/lib/ckfw/builtins/certdata.txt?raw=1

于是手动下载文件并指定mozroots安装指定的文件

wget https://hg.mozilla.org/releases/mozilla-release/raw-file/default/security/nss/lib/ckfw/builtins/certdata.txt
mozroots --import --sync --file certdata.txt

这时，执行测试程序运行正常

<xml><return_code><![CDATA[FAIL]]></return_code>
<return_msg><![CDATA[post数据为空]]></return_msg>
</xml>

7.总结

使用mozroots是解决问题的简单方法，但由于mono版本问题会导致默认的下载文件并不有效

本地有效版本：mono 4.6.0.0，使用中已提示建议使用cert-sync [WARNING: mozroots is deprecated, please move to cert-sync instead.]

服务器版本：mono 4.4.1.0，默认下载文件无效，这不得不说是个坑。