使用HSE_REQ_GET_CERT_INFO_EX调用ServerSupportFunction后，pCertInfo为null

  我试图从ISAPI扩展中获取主题备用名称（电子邮件地址）。但是，pCertInfo始终为null。

   I am trying to get the subject alternative name (email address) from within an ISAPI Extension. However, pCertInfo is always null.

     CERT_CONTEXT_EX certContextEx;
        memset(&certContextEx,0,sizeof(CERT_CONTEXT_EX));
        char certbuf[64*1024];
        certContextEx.cbAllocated =sizeof(certbuf);
        certContextEx.CertContext.pbCertEncoded =(BYTE *)&certbuf;
        BOOL gotCert = pECB->ServerSupportFunction(pECB->ConnID, HSE_REQ_GET_CERT_INFO_EX,&certContextEx,0,0);

        logFile << "got cert context ex successfully? " << (gotCert==1?"true":"false") << std::endl;
        logFile.flush();

        char certTemp[BUFFER_SIZE];
        wsprintf(certTemp,"cert encoded size %d\n",certContextEx.CertContext.cbCertEncoded);
        logFile << certTemp;
        logFile.flush();

        logFile << "pbCertEncoded " << certContextEx.CertContext.pbCertEncoded << std::endl;
        logFile.flush();

        logFile << "pCert Info " << certContextEx.CertContext.pCertInfo << std::endl;
        logFile.flush();

输出

**********

**********

成功获得证书上下文？ true

got cert context ex successfully? true

证书编码大小1290

cert encoded size 1290

pbCertEncoded 0,0， î [1] [1] [1]
2ÒÌ0

pbCertEncoded 0‚0‚ î [1][1][1] 2ÒÌ0

     *†H†÷

pCert Info 00000000

pCert Info 00000000

**************** ****

********************

我认为我需要做以下的事情来获得正确的扩展。 当然'j'需要是正确的索引，但pCertInfo始终为null。 

I believe I need to do something like the following to get the right extension.  Of course 'j' would need to be the right index but pCertInfo is always null. 

certContextEx.CertContext.pCertInfo->->rgExtension[j]

那么我该如何得到pCertInfo值？

So how do I get the pCertInfo to be value?