Super-simple JSON-RPC 2.0 framework for PHP

jsonrpc2.php

<?php
// Super-simple JSON-RPC 2.0 framework for PHP
// MIT License
// Namhyeon Go <abuse@catswords.net>
// created: 2024-03-22
// updated: 2024-03-25

function jsonrpc2_encode($method, $params, $id = '') {
    $data = array(
        "jsonrpc" => "2.0",
        "method" => $method,
        "params" => $params,
        "id" => $id
    );
    return json_encode($data);
}

function jsonrpc2_result_encode($result, $id = '') {
    $data = array(
        "jsonrpc" => "2.0",
        "result" => $result,
        "id" => $id
    );
    return json_encode($data);
}

function jsonrpc2_error_encode($error, $id = '') {
    $data = array(
        "jsonrpc" => "2.0",
        "error" => $error,
        "id" => $id
    );
    return json_encode($data);
}

// CSRF check
function jsonrpc2_generate_token($key = '_csrf_token') {
    if (!isset($_SESSION))
        session_start();

    $token = bin2hex(random_bytes(32));
    $_SESSION[$key] = $token;
    
    return $token;
}

// CSRF check
function jsonrpc2_check_token($token, $key = '_csrf_token') {
    if (!isset($_SESSION))
        return false;

    return !empty($token) && !empty($_SESSION[$key]) && $token == $_SESSION[$key];
}

function jsonrpc2_read_input() {
    $context = json_decode(file_get_contents('php://input'), true);
    if ($context == NULL && in_array("JSONData", $_POST)) {
        $context = json_decode($_POST['JSONData']);
    }
    return $context;
}

// CSRF check
function jsonrpc2_load_scripts($csrf_key = "_csrf_token") {
    return <<<EOF
var $csrf_key = "";

function generate_csrf_token() {
    // generate CSRF token
    $.post("ajax.html", JSON.stringify({
        "jsonrpc": "2.0",
        "method": "generate_csrf_token",
        "params": {},
        "id": ""
    }), function(data) {
        $csrf_key = data.result.$csrf_key;
    }, "json");
}
generate_csrf_token();

function get_csrf_token() {
    return $csrf_key;
}

if (typeof $.fn.serializeObject === "undefined") {
    $.fn.serializeObject = function () {
        var formData = {};
        var formArray = this.serializeArray();
        for (var i = 0, n = formArray.length; i < n; ++i)
             formData[formArray[i].name] = formArray[i].value;
         return formData;
    };
}
EOF;
}