Rust

Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time. Rust

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

// First, let's get the current date/time from time-c.nist.gov
let socket = chilkat::Socket::new();

// Connect to an NIST time server and read the current date/time
let mut max_wait_ms = 8000;
let use_tls = false;
if socket.connect("time-c.nist.gov", 37, use_tls, max_wait_ms).is_err() {
    println!("{}", socket.last_error_text());
    return;
}

// The time server will send a big-endian 32-bit integer representing
// the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
// The ReceiveInt32 method will receive a 4-byte integer, but returns
// true or false to indicate success.  If successful, the integer
// is obtained via the ReceivedInt property.
let big_endian = true;
if socket.receive_int32(big_endian).is_err() {
    println!("{}", socket.last_error_text());
    return;
}

let dt = chilkat::DateTime::new();
let _ = dt.set_from_ntp_time(socket.received_int());

// Show the current local date/time
let b_local_time = true;
println!("Current local date/time: {}", dt.get_as_rfc822(b_local_time).unwrap_or_default());

max_wait_ms = 10;
let _ = socket.close(max_wait_ms);

// ------------------------------------------------------------------------
// OK, we have the current date/time.  We'll use it to set the IAT property
// in the code below.

// First load the JSON key into a string.
let fac = chilkat::FileAccess::new();
let Ok(json_key) = fac.read_entire_text_file("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8") else {
    println!("{}", fac.last_error_text());
    return;
};

// A JSON private key should look 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"
// 	}

let g_auth = chilkat::AuthGoogle::new();
g_auth.set_json_key(&json_key);

// Choose a scope.
g_auth.set_scope("https://www.googleapis.com/auth/cloud-platform");

// Request an access token that is valid for this many seconds.
g_auth.set_expire_num_seconds(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.)
g_auth.set_sub_email_address("");

// ------------------------------------------------------------------------
// Set the IAT using the date/time from the NIST time server.
let unix_time = dt.get_as_unix_time(false) as i32;
println!("unixTime = {}", unix_time);
g_auth.set_iat(unix_time);

// 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.
let tls_sock = chilkat::Socket::new();
if tls_sock.connect("www.googleapis.com", 443, true, 5000).is_err() {
    println!("{}", tls_sock.last_error_text());
    return;
}

// Send the request to obtain the access token.
if g_auth.obtain_access_token(&tls_sock).is_err() {
    println!("{}", g_auth.last_error_text());
    return;
}

// Examine the access token:
println!("Access Token: {}", g_auth.access_token());