(Unicode C) Refresh a Dynamics CRM OAuth2 Access Token

Demonstrates how to refresh an expiring Dynamics CRM access token using the refresh token. endpoint.

(If a REST API call fails with a 401 unauthorized error, an application can auto-recover by refreshing the access token, and then re-send the request using the new token.)

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

void ChilkatSample(void)
    {
    HCkJsonObjectW json;
    BOOL success;
    HCkDateTimeW dtExpire;
    HCkHttpRequestW req;
    HCkHttpW http;
    HCkHttpResponseW resp;
    HCkFileAccessW fac;

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

    //  We previously obtained an access token and saved the JSON to a file using this example:
    //  Get Dynamics CRM OAuth2 Access Token

    //  This example will examine the JSON and expiration date, and if near expiration will
    //  refresh the access token.

    json = CkJsonObjectW_Create();
    success = CkJsonObjectW_LoadFile(json,L"qa_data/tokens/dynamicsCrm.json");
    if (success != TRUE) {
        CkJsonObjectW_Dispose(json);
        return;
    }

    //  The contents of the JSON look like this:
    //  {
    //    "token_type": "Bearer",
    //    "scope": "user_impersonation",
    //    "expires_in": "3599",
    //    "ext_expires_in": "0",
    //    "expires_on": "1524783438",
    //    "not_before": "1524779538",
    //    "resource": "https://mydomain.api.crm.dynamics.com",
    //    "access_token": "...",
    //    "refresh_token": "...",
    //    "id_token": "..."
    //  }

    //  The "expires_on" value is a Unix time.
    dtExpire = CkDateTimeW_Create();
    CkDateTimeW_SetFromUnixTime(dtExpire,FALSE,CkJsonObjectW_IntOf(json,L"expires_on"));

    //  If this date/time expires within 10 minutes of the current system time, refresh the token.

    //  OK, we need to refresh the access token by sending a POST...
    // 

    req = CkHttpRequestW_Create();
    CkHttpRequestW_AddParam(req,L"grant_type",L"refresh_token");
    CkHttpRequestW_AddParam(req,L"redirect_uri",L"http://localhost:3017/");
    CkHttpRequestW_AddParam(req,L"client_id",L"DYNAMICS-CRM-CLIENT-ID");
    CkHttpRequestW_AddParam(req,L"client_secret",L"DYNAMICS-CRM-SECRET-KEY");
    CkHttpRequestW_AddParam(req,L"refresh_token",CkJsonObjectW_stringOf(json,L"refresh_token"));
    CkHttpRequestW_AddParam(req,L"resource",L"https://mydynamicsdomain.api.crm.dynamics.com");

    http = CkHttpW_Create();

    resp = CkHttpW_PostUrlEncoded(http,L"https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",req);
    if (CkHttpW_getLastMethodSuccess(http) != TRUE) {
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkJsonObjectW_Dispose(json);
        CkDateTimeW_Dispose(dtExpire);
        CkHttpRequestW_Dispose(req);
        CkHttpW_Dispose(http);
        return;
    }

    //  Load the JSON response.
    CkJsonObjectW_Load(json,CkHttpResponseW_bodyStr(resp));
    CkJsonObjectW_putEmitCompact(json,FALSE);

    //  Show the JSON response.
    wprintf(L"%s\n",CkJsonObjectW_emit(json));

    wprintf(L"Response status code: %d\n",CkHttpResponseW_getStatusCode(resp));

    //  If the response status code is not 200, then it's an error.
    if (CkHttpResponseW_getStatusCode(resp) != 200) {
        CkJsonObjectW_Dispose(json);
        CkDateTimeW_Dispose(dtExpire);
        CkHttpRequestW_Dispose(req);
        CkHttpW_Dispose(http);
        return;
    }

    CkHttpResponseW_Dispose(resp);

    //  If an "expires_on" member does not exist, then add the JSON member by
    //  getting the current system date/time and adding the "expires_in" seconds.
    //  This way we'll know when the token expires.
    if (CkJsonObjectW_HasMember(json,L"expires_on") != TRUE) {
        CkDateTimeW_SetFromCurrentSystemTime(dtExpire);
        CkDateTimeW_AddSeconds(dtExpire,CkJsonObjectW_IntOf(json,L"expires_in"));
        CkJsonObjectW_AppendString(json,L"expires_on",CkDateTimeW_getAsUnixTimeStr(dtExpire,FALSE));
    }

    //  Save the refreshed access token JSON to a file for future requests.
    fac = CkFileAccessW_Create();
    CkFileAccessW_WriteEntireTextFile(fac,L"qa_data/tokens/dynamicsCrm.json",CkJsonObjectW_emit(json),L"utf-8",FALSE);


    CkJsonObjectW_Dispose(json);
    CkDateTimeW_Dispose(dtExpire);
    CkHttpRequestW_Dispose(req);
    CkHttpW_Dispose(http);
    CkFileAccessW_Dispose(fac);

    }