C
C
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 Downloads
#include <C_CkFileAccess.h>
#include <C_CkXml.h>
#include <C_CkDateTime.h>
#include <C_CkHttp.h>
#include <C_CkHttpResponse.h>
void ChilkatSample(void)
{
BOOL success;
HCkFileAccess fac;
HCkXml xml;
HCkDateTime dtExpire;
HCkDateTime dtNow;
const char *formDigestXmlFile;
int tNow;
int tExpire;
HCkHttp http;
const char *savedAccept;
HCkHttpResponse resp;
HCkXml xml2;
int timeoutInSec;
success = FALSE;
// 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.
fac = CkFileAccess_Create();
xml = CkXml_Create();
// 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>
//
dtExpire = CkDateTime_Create();
dtNow = CkDateTime_Create();
formDigestXmlFile = "qa_data/sharepoint/savedFormDigestValue.xml";
if (CkFileAccess_FileExists(fac,formDigestXmlFile) == TRUE) {
CkXml_LoadXmlFile(xml,formDigestXmlFile);
// Get the expire date/time
CkDateTime_SetFromTimestamp(dtExpire,CkXml_getChildContent(xml,"d:ExpireDateTime"));
// Get the current date/time
CkDateTime_SetFromCurrentSystemTime(dtNow);
// Get both times as Unix time values
tNow = CkDateTime_GetAsUnixTime(dtNow,FALSE);
tExpire = CkDateTime_GetAsUnixTime(dtExpire,FALSE);
// If tNow >= tExpire, then fall through.
// Otherwise, just use the cached digest value.
if (tNow < tExpire) {
printf("Cached digest value is not yet expired.\n");
printf("X-RequestDigest: %s\n",CkXml_getChildContent(xml,"d:FormDigestValue"));
CkFileAccess_Dispose(fac);
CkXml_Dispose(xml);
CkDateTime_Dispose(dtExpire);
CkDateTime_Dispose(dtNow);
return;
}
}
// If we got to this point, the cached digest value either does not exist, or expired.
http = CkHttp_Create();
// If SharePoint Windows classic authentication is used, then set the
// Login, Password, LoginDomain, and NtlmAuth properties.
CkHttp_putLogin(http,"SHAREPOINT_USERNAME");
CkHttp_putPassword(http,"SHAREPOINT_PASSWORD");
CkHttp_putLoginDomain(http,"SHAREPOINT_NTLM_DOMAIN");
CkHttp_putNtlmAuth(http,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.
// Apparently, SharePoint needs an "Accept" request header equal to "application/xml",
// otherwise SharePoint will return an utterly incomprehensible and useless error message.
savedAccept = CkHttp_ck_accept(http);
CkHttp_putAccept(http,"application/xml");
// Note: The last argument ("utf-8") is meaningless here because the body is empty.
resp = CkHttpResponse_Create();
success = CkHttp_HttpStr(http,"POST","https://SHAREPOINT_HTTPS_DOMAIN/_api/contextinfo","","utf-8","application/xml",resp);
if (success == FALSE) {
printf("%s\n",CkHttp_lastErrorText(http));
CkFileAccess_Dispose(fac);
CkXml_Dispose(xml);
CkDateTime_Dispose(dtExpire);
CkDateTime_Dispose(dtNow);
CkHttp_Dispose(http);
CkHttpResponse_Dispose(resp);
return;
}
// Restore the default Accept header
CkHttp_putAccept(http,savedAccept);
if (CkHttpResponse_getStatusCode(resp) != 200) {
// A response status code not equal to 200 indicates failure.
printf("Response status code = %d\n",CkHttpResponse_getStatusCode(resp));
printf("Response body:\n");
printf("%s\n",CkHttpResponse_bodyStr(resp));
CkFileAccess_Dispose(fac);
CkXml_Dispose(xml);
CkDateTime_Dispose(dtExpire);
CkDateTime_Dispose(dtNow);
CkHttp_Dispose(http);
CkHttpResponse_Dispose(resp);
return;
}
CkXml_LoadXml(xml,CkHttpResponse_bodyStr(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.
xml2 = CkXml_Create();
CkXml_putTag(xml2,"savedFormDigestValue");
CkXml_NewChild2(xml2,"d:FormDigestValue",CkXml_getChildContent(xml,"d:FormDigestValue"));
timeoutInSec = CkXml_GetChildIntValue(xml,"d:FormDigestTimeoutSeconds");
printf("Timeout in seconds = %d\n",timeoutInSec);
// 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;
}
CkDateTime_SetFromCurrentSystemTime(dtExpire);
CkDateTime_AddSeconds(dtExpire,timeoutInSec);
CkXml_NewChild2(xml2,"d:ExpireDateTime",CkDateTime_getAsTimestamp(dtExpire,FALSE));
// Persist the digest and expire time to a file.
CkXml_SaveXml(xml2,formDigestXmlFile);
printf("Here is the new form digest value:\n");
printf("X-RequestDigest: %s\n",CkXml_getChildContent(xml,"d:FormDigestValue"));
CkFileAccess_Dispose(fac);
CkXml_Dispose(xml);
CkDateTime_Dispose(dtExpire);
CkDateTime_Dispose(dtNow);
CkHttp_Dispose(http);
CkHttpResponse_Dispose(resp);
CkXml_Dispose(xml2);
}