(MFC) SharePoint -- Get Server Form Digest Value

Demonstrates how to get a server form digest value to be placed in the X-RequestDigest HTTP request header for POST, PUT, MERGE, and DELETE requests. A form digest value is typically valid for 1800 seconds (i.e. 30 minutes). This example persists the value to a file, and only requests a new form digest value if the existing one is near expiration.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkFileAccess.h>
#include <CkXml.h>
#include <CkDateTime.h>
#include <CkHttp.h>
#include <CkHttpResponse.h>

void ChilkatSample(void)
    {
    CkString strOut;

    //  This requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  First, let's see if we already have a persisted form digest value
    //  that hasn't yet expired.
    CkFileAccess fac;
    CkXml xml;
    bool success;

    //  My example code (below) persists the form digest XML in this format:
    // 
    //  	<savedFormDigestValue>
    //  	<d:ExpireDateTime>2017-04-12T20:46:39Z</d:ExpireDateTime>
    //  	<d:FormDigestValue>0x3059FFB920651834540F3E6792EA73F5746B302E953FF4E808E485DB1E6C2836C7CF924644995F092453B02A94DE14A7962674B7B16780AF16EAFB8C246BCDC7,12 Apr 2017 17:08:22 -0000</d:FormDigestValue>
    //  	</savedFormDigestValue>
    // 

    CkDateTime dtExpire;
    CkDateTime dtNow;

    const char *formDigestXmlFile = "qa_data/sharepoint/savedFormDigestValue.xml";
    if (fac.FileExists(formDigestXmlFile) == true) {

        xml.LoadXmlFile(formDigestXmlFile);

        //  Get the expire date/time
        dtExpire.SetFromTimestamp(xml.getChildContent("d:ExpireDateTime"));

        //  Get the current date/time
        dtNow.SetFromCurrentSystemTime();

        //  Get both times as Unix time values
        int tNow = dtNow.GetAsUnixTime(false);
        int tExpire = dtExpire.GetAsUnixTime(false);

        //  If tNow >= tExpire, then fall through.
        //  Otherwise, just use the cached digest value.
        if (tNow < tExpire) {
            strOut.append("Cached digest value is not yet expired.");
            strOut.append("\r\n");
            strOut.append("X-RequestDigest: ");
            strOut.append(xml.getChildContent("d:FormDigestValue"));
            strOut.append("\r\n");
            SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
            return;
        }

    }

    //  If we got to this point, the cached digest value either does not exist, or expired.

    CkHttp http;

    //  If SharePoint Windows classic authentication is used, then set the
    //  Login, Password, LoginDomain, and NtlmAuth properties.
    http.put_Login("SHAREPOINT_USERNAME");
    http.put_Password("SHAREPOINT_PASSWORD");
    http.put_LoginDomain("SHAREPOINT_NTLM_DOMAIN");
    http.put_NtlmAuth(true);

    //  The more common case is to use SharePoint Online authentication (via the SPOIDCRL cookie).
    //  If so, do not set Login, Password, LoginDomain, and NtlmAuth, and instead
    //  establish the cookie as shown at SharePoint Online Authentication

    //  When creating, updating, and deleting SharePoint entities, we'll need
    //  to first get the server's form digest value to send in the X-RequestDigest header.
    //  This can be retrieved by making a POST request with an empty body to
    //  http://<site url>/_api/contextinfo and extracting the value of the
    //  d:FormDigestValue node in the XML that the contextinfo endpoint returns.

    //  Note: The last argument ("utf-8") is meaningless here because the body is empty.
    CkHttpResponse *resp = http.PostXml("https://SHAREPOINT_HTTPS_DOMAIN/_api/contextinfo","","utf-8");
    if (http.get_LastMethodSuccess() != true) {
        strOut.append(http.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    if (resp->get_StatusCode() != 200) {
        //  A response status code not equal to 200 indicates failure.
        strOut.append("Response status code = ");
        strOut.appendInt(resp->get_StatusCode());
        strOut.append("\r\n");
        strOut.append("Response body:");
        strOut.append("\r\n");
        strOut.append(resp->bodyStr());
        strOut.append("\r\n");
        delete resp;
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    xml.LoadXml(resp->bodyStr());
    delete resp;

    //  The response XML looks like this:

    //  <?xml version="1.0" encoding="utf-8" ?>
    //  <d:GetContextWebInformation xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:georss="http://www.georss.org/georss" xmlns:gml="http://www.opengis.net/gml" m:type="SP.ContextWebInformation">
    //      <d:FormDigestTimeoutSeconds m:type="Edm.Int32">1800</d:FormDigestTimeoutSeconds>
    //      <d:FormDigestValue>0x3059FFB920651834540F3E6792EA73F5746B302E953FF4E808E485DB1E6C2836C7CF924644995F092453B02A94DE14A7962674B7B16780AF16EAFB8C246BCDC7,12 Apr 2017 17:08:22 -0000</d:FormDigestValue>
    //      <d:LibraryVersion>15.0.4569.1000</d:LibraryVersion>
    //      <d:SiteFullUrl>https://SHAREPOINT_HTTPS_DOMAIN</d:SiteFullUrl>
    //      <d:SupportedSchemaVersions m:type="Collection(Edm.String)">
    //          <d:element>14.0.0.0</d:element>
    //          <d:element>15.0.0.0</d:element>
    //      </d:SupportedSchemaVersions>
    //      <d:WebFullUrl>https://SHAREPOINT_HTTPS_DOMAIN</d:WebFullUrl>
    //  </d:GetContextWebInformation>
    // 

    //  Cache the digest value, and also an expiration time.  If this code is run again
    //  before the digest expires, we'll just get it from the file.
    CkXml xml2;

    xml2.put_Tag("savedFormDigestValue");
    xml2.NewChild2("d:FormDigestValue",xml.getChildContent("d:FormDigestValue"));

    int timeoutInSec = xml.GetChildIntValue("d:FormDigestTimeoutSeconds");
    strOut.append("Timeout in seconds = ");
    strOut.appendInt(timeoutInSec);
    strOut.append("\r\n");

    //  Convert this to an expire timestamp.
    //  Let's make it expire 30 seconds prior to the actual timeout, just to be safe.
    if (timeoutInSec > 30) {
        timeoutInSec = timeoutInSec - 30;
    }

    dtExpire.SetFromCurrentSystemTime();
    dtExpire.AddSeconds(timeoutInSec);
    xml2.NewChild2("d:ExpireDateTime",dtExpire.getAsTimestamp(false));

    //  Persist the digest and expire time to a file.
    xml2.SaveXml(formDigestXmlFile);

    strOut.append("Here is the new form digest value:");
    strOut.append("\r\n");
    strOut.append("X-RequestDigest: ");
    strOut.append(xml.getChildContent("d:FormDigestValue"));
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }