(Unicode C) 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

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#include <C_CkHttpW.h>
#include <C_CkHttpRequestW.h>
#include <C_CkHttpResponseW.h>
#include <C_CkJsonObjectW.h>

void ChilkatSample(void)
    {
    HCkHttpW http;
    HCkHttpRequestW req;
    HCkHttpResponseW resp;
    int respStatusCode;
    HCkJsonObjectW json;
    const wchar_t *token_type;
    const wchar_t *expires_in;
    const wchar_t *ext_expires_in;
    const wchar_t *expires_on;
    const wchar_t *not_before;
    const wchar_t *resource;
    const wchar_t *access_token;

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

    http = CkHttpW_Create();

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

    req = CkHttpRequestW_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.

    CkHttpRequestW_AddParam(req,L"grant_type",L"client_credentials");
    CkHttpRequestW_AddParam(req,L"client_id",L"MY_CLIENT_ID");
    CkHttpRequestW_AddParam(req,L"client_secret",L"MY_CLIENT_SECRET");
    CkHttpRequestW_AddParam(req,L"resource",L"https://service.contoso.com/");

    // The URL passed to PostUrlEncoded has this form:   https://login.microsoftonline.com/<tenant_id>/oauth2/token
    resp = CkHttpW_PostUrlEncoded(http,L"https://login.microsoftonline.com/<tenant_id>/oauth2/token",req);
    if (CkHttpW_getLastMethodSuccess(http) == FALSE) {
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkHttpW_Dispose(http);
        CkHttpRequestW_Dispose(req);
        return;
    }

    respStatusCode = CkHttpResponseW_getStatusCode(resp);
    wprintf(L"Response Status Code = %d\n",respStatusCode);

    json = CkJsonObjectW_Create();
    CkJsonObjectW_putEmitCompact(json,FALSE);
    CkJsonObjectW_Load(json,CkHttpResponseW_bodyStr(resp));
    wprintf(L"Response JSON:\n");
    wprintf(L"%s\n",CkJsonObjectW_emit(json));

    if (respStatusCode >= 400) {
        wprintf(L"Response Header:\n");
        wprintf(L"%s\n",CkHttpResponseW_header(resp));
        wprintf(L"Failed.\n");
        CkHttpResponseW_Dispose(resp);
        CkHttpW_Dispose(http);
        CkHttpRequestW_Dispose(req);
        CkJsonObjectW_Dispose(json);
        return;
    }

    // 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 = CkJsonObjectW_stringOf(json,L"token_type");
    expires_in = CkJsonObjectW_stringOf(json,L"expires_in");
    ext_expires_in = CkJsonObjectW_stringOf(json,L"ext_expires_in");
    expires_on = CkJsonObjectW_stringOf(json,L"expires_on");
    not_before = CkJsonObjectW_stringOf(json,L"not_before");
    resource = CkJsonObjectW_stringOf(json,L"resource");
    access_token = CkJsonObjectW_stringOf(json,L"access_token");

    CkHttpResponseW_Dispose(resp);


    CkHttpW_Dispose(http);
    CkHttpRequestW_Dispose(req);
    CkJsonObjectW_Dispose(json);

    }