(C++) Get Google API Access Token using P12 Service Account Key

Demonstrates how to get a Google API access token using a P12 service account key.

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#include <CkPfx.h>
#include <CkAuthGoogle.h>
#include <CkSocket.h>

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

    // --------------------------------------------------------------------------------
    // For a step-by-step guide for setting up your Google Workspace service account,
    // see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
    // --------------------------------------------------------------------------------

    // First load the PKCS12 (.p12 / .pfx) into a PFX object.
    CkPfx pfx;
    bool success = pfx.LoadPfxFile("qa_data/pfx/chilkat25-cbd7b42afbd8.p12","notasecret");
    if (success != true) {
        std::cout << pfx.lastErrorText() << "\r\n";
        return;
    }

    CkAuthGoogle gAuth;
    success = gAuth.SetP12(pfx);

    // The ISS is your service account email address ending in gserviceaccount.com.
    const char *iss = "chilkatsvc@chilkat25.iam.gserviceaccount.com";

    // The scope is always the following string:
    const char *scope = "https://mail.google.com/";

    // The sub is your company email address
    const char *oauth_sub = "info@chilkat.xyz";

    // The access token is valid for this number of seconds.
    int numSec = 3600;

    gAuth.put_EmailAddress(iss);
    gAuth.put_Scope(scope);
    gAuth.put_ExpireNumSeconds(numSec);
    gAuth.put_SubEmailAddress(oauth_sub);

    // Connect to www.googleapis.com
    CkSocket tlsSock;
    success = tlsSock.Connect("www.googleapis.com",443,true,5000);
    if (success != true) {
        std::cout << tlsSock.lastErrorText() << "\r\n";
        return;
    }

    // Send the request to obtain the access token.
    success = gAuth.ObtainAccessToken(tlsSock);
    if (success != true) {
        std::cout << gAuth.lastErrorText() << "\r\n";
        return;
    }

    // Examine the access token:
    std::cout << "Access Token: " << gAuth.accessToken() << "\r\n";
    }