C++

HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to get an HMRC OAuth2 access token from a desktop (installed) application or script. This example gets an HMRC MTD VAT read/write access token. C++

#include <CkOAuth2.h>
#include <CkJsonObject.h>
#include <CkDateTime.h>
#include <CkFileAccess.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  To further clarify, see OAuth 2.0 Authorization Flow

    CkOAuth2 oauth2;

    //  This should be the port in the localhost callback URL for your app.
    //  Important: Make sure the callback URI in your HMRC developer app 
    //  is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
    //  The callback URL would look like "http://localhost:3017/" if the port number is 3017.

    //  IMPORTANT: Don't forget to setup your HMRC application to use the Redirect URI "http://localhost:3017/" as shown
    //  here: Configure Redirect URI for HMRC application
    oauth2.put_ListenPort(3017);

    oauth2.put_AuthorizationEndpoint("https://test-api.service.hmrc.gov.uk/oauth/authorize");
    oauth2.put_TokenEndpoint("https://test-api.service.hmrc.gov.uk/oauth/token");

    //  Replace with your actual client ID
    oauth2.put_ClientId("HMRC-CLIENT-ID");

    //  The scopes are documented in the HMRC reference documentation for each API.
    //  This example gets a read/write access token for the HMRC MTD VAT API.
    oauth2.put_Scope("read:vat write:vat");

    //  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    const char *url = oauth2.startAuth();
    if (oauth2.get_LastMethodSuccess() != true) {
        std::cout << oauth2.lastErrorText() << "\r\n";
        return;
    }

    //  Launch the default browser on the system and navigate to the url.
    //  The LaunchBrowser method was added in Chilkat v10.1.2.
    success = oauth2.LaunchBrowser(url);
    if (success == false) {
        std::cout << oauth2.lastErrorText() << "\r\n";
        return;
    }

    //  Wait for the user to approve or deny authorization in the browser.
    int numMsWaited = 0;
    while ((numMsWaited < 90000) && (oauth2.get_AuthFlowState() < 3)) {
        oauth2.SleepMs(100);
        numMsWaited = numMsWaited + 100;
    }

    //  If the browser does not respond within the specified time, AuthFlowState will be:
    //  
    //  1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
    //  2: Waiting for Final Response – The thread is awaiting the final access token response.
    //  In either case, cancel the background task initiated by StartAuth.

    if (oauth2.get_AuthFlowState() < 3) {
        oauth2.Cancel();
        std::cout << "No response from the browser!" << "\r\n";
        return;
    }

    //  Check AuthFlowState to determine if authorization was granted, denied, or failed:
    //  
    //  3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
    //  4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
    //  5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

    if (oauth2.get_AuthFlowState() == 5) {
        std::cout << "OAuth2 failed to complete." << "\r\n";
        std::cout << oauth2.failureInfo() << "\r\n";
        return;
    }

    if (oauth2.get_AuthFlowState() == 4) {
        std::cout << "OAuth2 authorization was denied." << "\r\n";
        std::cout << oauth2.accessTokenResponse() << "\r\n";
        return;
    }

    if (oauth2.get_AuthFlowState() != 3) {
        std::cout << "Unexpected AuthFlowState:" << oauth2.get_AuthFlowState() << "\r\n";
        return;
    }

    std::cout << "OAuth2 authorization granted!" << "\r\n";
    std::cout << "Access Token = " << oauth2.accessToken() << "\r\n";

    //  Get the full JSON response:
    CkJsonObject json;
    json.Load(oauth2.accessTokenResponse());
    json.put_EmitCompact(false);
    std::cout << json.emit() << "\r\n";

    //  The JSON response looks 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": "..."
    //  }

    //  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 (json.HasMember("expires_on") != true) {
        CkDateTime dtExpire;
        dtExpire.SetFromCurrentSystemTime();
        dtExpire.AddSeconds(json.IntOf("expires_in"));
        json.AppendString("expires_on",dtExpire.getAsUnixTimeStr(false));
    }

    std::cout << json.emit() << "\r\n";

    //  Save the JSON to a file for future requests.
    CkFileAccess fac;
    fac.WriteEntireTextFile("qa_data/tokens/hmrc.json",json.emit(),"utf-8",false);
    }