Authenticate with a Minecraft account

mc-authenticate.php

<?php

/**
 * Authenticate with a Minecraft account
 * 
 * After a few fails, Mojang server will deny all requests, so use a proxy to bypass that limit
 *
 * @example $account = authenticate('user@gmail.com', '123456', '107.170.58.132:3128');
 *
 * @param  string $id       Minecraft username or Mojang email
 * @param  string $password Account's password
 * @param  string $proxy    Proxy address like: "ip:port"
 * @return array|bool       Array with id and name, false if authentication failed
 */
function authenticate($id, $password, $proxy = null) {
    if (!function_exists('curl_init') or !extension_loaded('curl')) {
        return false;
    }

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, 'https://authserver.mojang.com/authenticate');
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));

    if ($proxy) curl_setopt($ch, CURLOPT_PROXY, $proxy);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_MAXREDIRS, 10);

    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode(array(
        'agent' => array(
            'name' => 'Minecraft',
            'version' => 1,
        ),
        'username' => $id,
        'password' => $password
    )));

    $output = curl_exec($ch);
    curl_close($ch);
    $json = json_decode($output, true);    
    
    if (!empty($json) and is_array($json) and array_key_exists('selectedProfile', $json) and is_array($json['selectedProfile'])
            and array_key_exists('id', $json['selectedProfile']) and array_key_exists('name', $json['selectedProfile'])) {
        return array(
            'id' => $json['selectedProfile']['id'],
            'name' => $json['selectedProfile']['name']
        );
    }
    
    return false;
}