(Unicode C) Get Google Cloud Storage Access Token using Service Account JSON Private Key

Demonstrates how to get a Google Cloud Storage access token using a JSON service account private key. Obtaining an access token for a service account requires no user interaction (it does not require a browser, nor callback URI's, etc.).

When an access token expires, an application can be (and should be) designed to automatically fetch a new access token.

Chilkat C/C++ Library Downloads
MS Visual C/C++ Linux/CentOS C/C++ Alpine Linux C/C++ MAC OS X C/C++	armhf/aarch64 C/C++ C++ Builder iOS C/C++ Android C/C++	Solaris C/C++ MinGW C/C++

#include <C_CkFileAccessW.h>
#include <C_CkAuthGoogleW.h>
#include <C_CkSocketW.h>
#include <C_CkStringBuilderW.h>

void ChilkatSample(void)
    {
    HCkFileAccessW fac;
    const wchar_t *jsonKey;
    HCkAuthGoogleW gAuth;
    HCkSocketW tlsSock;
    BOOL success;
    HCkStringBuilderW sbToken;

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

    // First load the JSON key into a string.
    fac = CkFileAccessW_Create();
    jsonKey = CkFileAccessW_readEntireTextFile(fac,L"qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json",L"utf-8");
    if (CkFileAccessW_getLastMethodSuccess(fac) != TRUE) {
        wprintf(L"%s\n",CkFileAccessW_lastErrorText(fac));
        CkFileAccessW_Dispose(fac);
        return;
    }

    // A JSON private key should look something like this:

    // 	{
    // 	  "type": "service_account",
    // 	  "project_id": "chilkattest-1350",
    // 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
    // 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
    // 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
    // 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
    // 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    // 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
    // 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    // 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
    // 	}

    gAuth = CkAuthGoogleW_Create();
    CkAuthGoogleW_putJsonKey(gAuth,jsonKey);

    // Choose a scope.
    CkAuthGoogleW_putScope(gAuth,L"https://www.googleapis.com/auth/cloud-platform");

    // Request an access token that is valid for this many seconds.
    CkAuthGoogleW_putExpireNumSeconds(gAuth,3600);

    // If the application is requesting delegated access:
    // The email address of the user for which the application is requesting delegated access,
    // then set the email address here. (Otherwise leave it empty.)
    CkAuthGoogleW_putSubEmailAddress(gAuth,L"");

    // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
    // The Chilkat socket object is used so that the connection can be established
    // through proxies or an SSH tunnel if desired.
    tlsSock = CkSocketW_Create();
    success = CkSocketW_Connect(tlsSock,L"www.googleapis.com",443,TRUE,5000);
    if (success != TRUE) {
        wprintf(L"%s\n",CkSocketW_lastErrorText(tlsSock));
        CkFileAccessW_Dispose(fac);
        CkAuthGoogleW_Dispose(gAuth);
        CkSocketW_Dispose(tlsSock);
        return;
    }

    // Send the request to obtain the access token.
    success = CkAuthGoogleW_ObtainAccessToken(gAuth,tlsSock);
    if (success != TRUE) {
        wprintf(L"%s\n",CkAuthGoogleW_lastErrorText(gAuth));
        CkFileAccessW_Dispose(fac);
        CkAuthGoogleW_Dispose(gAuth);
        CkSocketW_Dispose(tlsSock);
        return;
    }

    // Examine the access token:
    wprintf(L"Access Token: %s\n",CkAuthGoogleW_accessToken(gAuth));

    // We're going to save this access token to a file to be used
    // by other examples.
    sbToken = CkStringBuilderW_Create();
    CkStringBuilderW_Append(sbToken,CkAuthGoogleW_accessToken(gAuth));
    CkStringBuilderW_WriteFile(sbToken,L"qa_data/tokens/googleCloudStorageAccessToken.txt",L"utf-8",FALSE);


    CkFileAccessW_Dispose(fac);
    CkAuthGoogleW_Dispose(gAuth);
    CkSocketW_Dispose(tlsSock);
    CkStringBuilderW_Dispose(sbToken);

    }