(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_CkJsonObject.h>
#include <C_CkDateTime.h>
#include <C_CkHttpRequest.h>
#include <C_CkHttp.h>
#include <C_CkHttpResponse.h>
#include <C_CkFileAccess.h>

void ChilkatSample(void)
    {
    HCkJsonObject json;
    BOOL success;
    HCkDateTime dtExpire;
    HCkHttpRequest req;
    HCkHttp http;
    HCkHttpResponse resp;
    HCkFileAccess 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 = CkJsonObject_Create();
    success = CkJsonObject_LoadFile(json,"qa_data/tokens/dynamicsCrm.json");
    if (success != TRUE) {
        CkJsonObject_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 = CkDateTime_Create();
    CkDateTime_SetFromUnixTime(dtExpire,FALSE,CkJsonObject_IntOf(json,"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 = CkHttpRequest_Create();
    CkHttpRequest_AddParam(req,"grant_type","refresh_token");
    CkHttpRequest_AddParam(req,"redirect_uri","http://localhost:3017/");
    CkHttpRequest_AddParam(req,"client_id","DYNAMICS-CRM-CLIENT-ID");
    CkHttpRequest_AddParam(req,"client_secret","DYNAMICS-CRM-SECRET-KEY");
    CkHttpRequest_AddParam(req,"refresh_token",CkJsonObject_stringOf(json,"refresh_token"));
    CkHttpRequest_AddParam(req,"resource","https://mydynamicsdomain.api.crm.dynamics.com");

    http = CkHttp_Create();

    resp = CkHttp_PostUrlEncoded(http,"https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",req);
    if (CkHttp_getLastMethodSuccess(http) != TRUE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkJsonObject_Dispose(json);
        CkDateTime_Dispose(dtExpire);
        CkHttpRequest_Dispose(req);
        CkHttp_Dispose(http);
        return;
    }

    //  Load the JSON response.
    CkJsonObject_Load(json,CkHttpResponse_bodyStr(resp));
    CkJsonObject_putEmitCompact(json,FALSE);

    //  Show the JSON response.
    printf("%s\n",CkJsonObject_emit(json));

    printf("Response status code: %d\n",CkHttpResponse_getStatusCode(resp));

    //  If the response status code is not 200, then it's an error.
    if (CkHttpResponse_getStatusCode(resp) != 200) {
        CkJsonObject_Dispose(json);
        CkDateTime_Dispose(dtExpire);
        CkHttpRequest_Dispose(req);
        CkHttp_Dispose(http);
        return;
    }

    CkHttpResponse_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 (CkJsonObject_HasMember(json,"expires_on") != TRUE) {
        CkDateTime_SetFromCurrentSystemTime(dtExpire);
        CkDateTime_AddSeconds(dtExpire,CkJsonObject_IntOf(json,"expires_in"));
        CkJsonObject_AppendString(json,"expires_on",CkDateTime_getAsUnixTimeStr(dtExpire,FALSE));
    }

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


    CkJsonObject_Dispose(json);
    CkDateTime_Dispose(dtExpire);
    CkHttpRequest_Dispose(req);
    CkHttp_Dispose(http);
    CkFileAccess_Dispose(fac);

    }