(Delphi DLL) Azure AD Service-to-service access token request

Send an Azure AD service-to-service token request to get an access token using a shared secret.

For more information, see https://docs.microsoft.com/en-us/azure/active-directory/develop/v1-oauth2-client-creds-grant-flow#service-to-service-access-token-request

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, HttpRequest, HttpResponse, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
req: HCkHttpRequest;
resp: HCkHttpResponse;
respStatusCode: Integer;
json: HCkJsonObject;
token_type: PWideChar;
expires_in: PWideChar;
ext_expires_in: PWideChar;
expires_on: PWideChar;
not_before: PWideChar;
resource: PWideChar;
access_token: PWideChar;

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

http := CkHttp_Create();

// To see the exact HTTP request sent and the response, set the SessionLogFilename property:
CkHttp_putSessionLogFilename(http,'qa_output/chilkatHttpLog.txt');

req := CkHttpRequest_Create();

// Set the following request params:
// grant_type 	required 	Specifies the requested grant type. In a Client Credentials Grant flow, the value must be client_credentials.
// 
// client_id 	required 	Specifies the Azure AD client id of the calling web service. 
//     To find the calling application's client ID, in the Azure portal, click Azure Active Directory, click App registrations, click the application. 
//     The client_id is the Application ID
// 
// client_secret 	required 	Enter a key registered for the calling web service or daemon application in Azure AD. 
//     To create a key, in the Azure portal, click Azure Active Directory, click App registrations, click the application, click Settings, click Keys, and add a Key.
//     URL-encode this secret when providing it.
// 
// resource 	required 	Enter the App ID URI of the receiving web service. To find the App ID URI, in the Azure portal, click Azure Active Directory, 
//     click App registrations, click the service application, and then click Settings and Properties.

CkHttpRequest_AddParam(req,'grant_type','client_credentials');
CkHttpRequest_AddParam(req,'client_id','MY_CLIENT_ID');
CkHttpRequest_AddParam(req,'client_secret','MY_CLIENT_SECRET');
CkHttpRequest_AddParam(req,'resource','https://service.contoso.com/');

// The URL passed to PostUrlEncoded has this form:   https://login.microsoftonline.com/<tenant_id>/oauth2/token
resp := CkHttp_PostUrlEncoded(http,'https://login.microsoftonline.com/<tenant_id>/oauth2/token',req);
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

respStatusCode := CkHttpResponse_getStatusCode(resp);
Memo1.Lines.Add('Response Status Code = ' + IntToStr(respStatusCode));

json := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);
CkJsonObject_Load(json,CkHttpResponse__bodyStr(resp));
Memo1.Lines.Add('Response JSON:');
Memo1.Lines.Add(CkJsonObject__emit(json));

if (respStatusCode >= 400) then
  begin
    Memo1.Lines.Add('Response Header:');
    Memo1.Lines.Add(CkHttpResponse__header(resp));
    Memo1.Lines.Add('Failed.');
    CkHttpResponse_Dispose(resp);
    Exit;
  end;

// Sample response:

// {
//   "token_type": "Bearer",
//   "expires_in": "3599",
//   "ext_expires_in": "3599",
//   "expires_on": "1570059833",
//   "not_before": "1570055933",
//   "resource": "https://adminchilkatsoft.onmicrosoft.com/eb1b8ced-76b7-4845-aec5-d3e91776e345",
//   "access_token": "eyJ0eXAiO ... pmgw"
// }

// To get the items from the JSON....
token_type := CkJsonObject__stringOf(json,'token_type');
expires_in := CkJsonObject__stringOf(json,'expires_in');
ext_expires_in := CkJsonObject__stringOf(json,'ext_expires_in');
expires_on := CkJsonObject__stringOf(json,'expires_on');
not_before := CkJsonObject__stringOf(json,'not_before');
resource := CkJsonObject__stringOf(json,'resource');
access_token := CkJsonObject__stringOf(json,'access_token');

CkHttpResponse_Dispose(resp);

CkHttp_Dispose(http);
CkHttpRequest_Dispose(req);
CkJsonObject_Dispose(json);

end;