(C) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

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#include <C_CkPrivateKey.h>
#include <C_CkJwt.h>
#include <C_CkJsonObject.h>
#include <C_CkHttp.h>
#include <C_CkHttpRequest.h>
#include <C_CkHttpResponse.h>

void ChilkatSample(void)
    {
    HCkPrivateKey privkey;
    BOOL success;
    HCkJwt jwt;
    HCkJsonObject jsonHeader;
    HCkJsonObject jsonPayload;
    int curDateTime;
    const char *jwtStr;
    HCkHttp http;
    HCkHttpRequest req;
    HCkHttpResponse resp;
    HCkJsonObject json;

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

    // We're going to duplicate this CURL statement:
    // curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
    // -H "Content-Type: application/x-www-form-urlencoded" \
    // -H "API-Key: xxxxxx" \
    // -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

    // Load our pre-creaed private key PEM file.
    // Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
    // Token generation will not work unless public key is associated with your app.
    privkey = CkPrivateKey_Create();

    success = CkPrivateKey_LoadPemFile(privkey,"qa_data/pem/abnAmroPrivateKey.pem");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privkey));
        CkPrivateKey_Dispose(privkey);
        return;
    }

    // Create the JWT.
    jwt = CkJwt_Create();

    // Create the header:
    // {
    //     "typ": "JWT",
    //     "alg": "RS256"
    // }
    jsonHeader = CkJsonObject_Create();
    CkJsonObject_UpdateString(jsonHeader,"typ","JWT");
    CkJsonObject_UpdateString(jsonHeader,"alg","RS256");

    // Create the payload:
    // {
    //     "nbf": 1499947668,
    //     "exp": 1499948668,
    //     "iss": "me",
    //     "sub": "anApiKey",
    //     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
    // }
    jsonPayload = CkJsonObject_Create();

    curDateTime = CkJwt_GenNumericDate(jwt,0);

    // Set the "not process before" timestamp to now.
    success = CkJsonObject_AddIntAt(jsonPayload,-1,"nbf",curDateTime);

    // Set the timestamp defining an expiration time (end time) for the token
    // to be now + 1 hour (3600 seconds)
    success = CkJsonObject_AddIntAt(jsonPayload,-1,"exp",curDateTime + 3600);

    CkJsonObject_UpdateString(jsonPayload,"iss","me");
    CkJsonObject_UpdateString(jsonPayload,"sub","anApiKey");
    CkJsonObject_UpdateString(jsonPayload,"aud","https://auth-sandbox.abnamro.com/oauth/token");

    // Produce the smallest possible JWT:
    CkJwt_putAutoCompact(jwt,TRUE);

    jwtStr = CkJwt_createJwtPk(jwt,CkJsonObject_emit(jsonHeader),CkJsonObject_emit(jsonPayload),privkey);
    if (CkJwt_getLastMethodSuccess(jwt) != TRUE) {
        printf("%s\n",CkJwt_lastErrorText(jwt));
        CkPrivateKey_Dispose(privkey);
        CkJwt_Dispose(jwt);
        CkJsonObject_Dispose(jsonHeader);
        CkJsonObject_Dispose(jsonPayload);
        return;
    }

    http = CkHttp_Create();

    req = CkHttpRequest_Create();
    CkHttpRequest_AddParam(req,"client_assertion_type","urn:ietf:params:oauth:client-assertion-type:jwt-bearer");
    CkHttpRequest_AddParam(req,"grant_type","client_credentials");
    CkHttpRequest_AddParam(req,"client_assertion",jwtStr);
    CkHttpRequest_AddParam(req,"scope","tikkie");

    resp = CkHttp_PostUrlEncoded(http,"https://api-sandbox.abnamro.com/v1/oauth/token",req);
    if (CkHttp_getLastMethodSuccess(http) == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkPrivateKey_Dispose(privkey);
        CkJwt_Dispose(jwt);
        CkJsonObject_Dispose(jsonHeader);
        CkJsonObject_Dispose(jsonPayload);
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        return;
    }

    if (CkHttpResponse_getStatusCode(resp) != 200) {
        printf("%s\n",CkHttpResponse_bodyStr(resp));
        CkHttpResponse_Dispose(resp);
        CkPrivateKey_Dispose(privkey);
        CkJwt_Dispose(jwt);
        CkJsonObject_Dispose(jsonHeader);
        CkJsonObject_Dispose(jsonPayload);
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        return;
    }

    // Get the JSON result:
    // {
    //     "access_token": "{your access token}",
    //     "expires_in": "{duration of validity in seconds}",
    //     "scope": "{scope(s) for which the access token is valid}",
    //     "token_type": "{it is always Bearer}"
    // }
    json = CkJsonObject_Create();
    CkJsonObject_Load(json,CkHttpResponse_bodyStr(resp));
    printf("access_token: %s\n",CkJsonObject_stringOf(json,"access_token"));
    printf("token_type: %s\n",CkJsonObject_stringOf(json,"token_type"));
    printf("expires_in: %s\n",CkJsonObject_stringOf(json,"expires_in"));
    printf("scope: %s\n",CkJsonObject_stringOf(json,"scope"));

    CkHttpResponse_Dispose(resp);


    CkPrivateKey_Dispose(privkey);
    CkJwt_Dispose(jwt);
    CkJsonObject_Dispose(jsonHeader);
    CkJsonObject_Dispose(jsonPayload);
    CkHttp_Dispose(http);
    CkHttpRequest_Dispose(req);
    CkJsonObject_Dispose(json);

    }