(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 <C_CkPfx.h>
#include <C_CkAuthGoogle.h>
#include <C_CkSocket.h>

void ChilkatSample(void)
    {
    HCkPfx pfx;
    BOOL success;
    HCkAuthGoogle gAuth;
    const char *iss;
    const char *scope;
    const char *oauth_sub;
    int numSec;
    HCkSocket tlsSock;

    // 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.
    pfx = CkPfx_Create();
    success = CkPfx_LoadPfxFile(pfx,"qa_data/pfx/chilkat25-cbd7b42afbd8.p12","notasecret");
    if (success != TRUE) {
        printf("%s\n",CkPfx_lastErrorText(pfx));
        CkPfx_Dispose(pfx);
        return;
    }

    gAuth = CkAuthGoogle_Create();
    success = CkAuthGoogle_SetP12(gAuth,pfx);

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

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

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

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

    CkAuthGoogle_putEmailAddress(gAuth,iss);
    CkAuthGoogle_putScope(gAuth,scope);
    CkAuthGoogle_putExpireNumSeconds(gAuth,numSec);
    CkAuthGoogle_putSubEmailAddress(gAuth,oauth_sub);

    // Connect to www.googleapis.com
    tlsSock = CkSocket_Create();
    success = CkSocket_Connect(tlsSock,"www.googleapis.com",443,TRUE,5000);
    if (success != TRUE) {
        printf("%s\n",CkSocket_lastErrorText(tlsSock));
        CkPfx_Dispose(pfx);
        CkAuthGoogle_Dispose(gAuth);
        CkSocket_Dispose(tlsSock);
        return;
    }

    // Send the request to obtain the access token.
    success = CkAuthGoogle_ObtainAccessToken(gAuth,tlsSock);
    if (success != TRUE) {
        printf("%s\n",CkAuthGoogle_lastErrorText(gAuth));
        CkPfx_Dispose(pfx);
        CkAuthGoogle_Dispose(gAuth);
        CkSocket_Dispose(tlsSock);
        return;
    }

    // Examine the access token:
    printf("Access Token: %s\n",CkAuthGoogle_accessToken(gAuth));


    CkPfx_Dispose(pfx);
    CkAuthGoogle_Dispose(gAuth);
    CkSocket_Dispose(tlsSock);

    }