139 lines
4.3 KiB
PHP
139 lines
4.3 KiB
PHP
<?php
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// +----------------------------------------------------------------------
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// | YwxApp [ WE CAN DO IT JUST THINK ]
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// +----------------------------------------------------------------------
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// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
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// +----------------------------------------------------------------------
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// | Author: ywxapp<admin@ywxapp.cn>
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// +----------------------------------------------------------------------
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declare(strict_types=1);
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namespace ywxapp\service;
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use think\facade\Cache;
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/**
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* 图形验证码服务（API 友好，基于 GD + Cache，无需 session）
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*
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* 设计要点：
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* - 生成时返回 {token, image(base64), expire}，前端把 image 直接塞进 <img src>，
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* 提交时回传 token + 用户输入的 captcha；服务端比对 Cache 中的 token 值。
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* - 与 think-captcha 的 session 方案不同，本服务完全无状态，适配小程序 / APP / SPA 等场景。
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* - 验证码一次性（校验成功后立即失效），有效期 120s。
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*
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* @package ywxapp\service
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*/
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class CaptchaService
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{
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const PREFIX = 'captcha_';
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const EXPIRE = 120;
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public static function instance(): self
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{
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return new self();
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}
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/**
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* 生成图形验证码
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*
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* @param int $length 字符数
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* @return array ['token'=>string, 'image'=>string(base64 data uri), 'expire'=>int]
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* @throws \Exception
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*/
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public function generate(int $length = 4): array
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{
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if (!extension_loaded('gd')) {
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throw new \Exception('服务器未启用 GD 扩展，无法生成图形验证码');
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}
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$code = $this->randomCode($length);
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$token = bin2hex(random_bytes(16));
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Cache::set(self::PREFIX . $token, strtolower($code), self::EXPIRE);
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return [
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'token' => $token,
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'image' => $this->renderImage($code),
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'expire' => self::EXPIRE,
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];
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}
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/**
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* 校验图形验证码（一次性）
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*
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* @param string $token 生成时返回的 token
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* @param string $code 用户输入
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* @return bool
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*/
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public function verify(string $token, string $code): bool
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{
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if ($token === '' || $code === '') {
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return false;
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}
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$key = self::PREFIX . $token;
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$stored = Cache::get($key);
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if ($stored === null) {
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return false;
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}
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$ok = strtolower(trim($code)) === strtolower((string) $stored);
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if ($ok) {
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Cache::delete($key);
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}
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return $ok;
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}
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/**
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* 生成随机可读字符（去除易混淆的 0/O/1/I/L）
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*/
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protected function randomCode(int $length): string
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{
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$chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
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$max = strlen($chars) - 1;
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$code = '';
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for ($i = 0; $i < $length; $i++) {
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$code .= $chars[mt_rand(0, $max)];
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}
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return $code;
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}
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/**
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* 用 GD 绘制验证码 PNG，返回 data URI
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*/
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protected function renderImage(string $code): string
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{
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$w = 120;
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$h = 44;
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$img = imagecreatetruecolor($w, $h);
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// 背景
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$bg = imagecolorallocate($img, 240, 242, 245);
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imagefill($img, 0, 0, $bg);
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// 干扰点
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for ($i = 0; $i < 80; $i++) {
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$c = imagecolorallocate($img, mt_rand(170, 230), mt_rand(170, 230), mt_rand(170, 230));
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imagesetpixel($img, mt_rand(0, $w - 1), mt_rand(0, $h - 1), $c);
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}
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// 干扰线
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for ($i = 0; $i < 3; $i++) {
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$c = imagecolorallocate($img, mt_rand(150, 210), mt_rand(150, 210), mt_rand(150, 210));
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imageline($img, mt_rand(0, $w), mt_rand(0, $h), mt_rand(0, $w), mt_rand(0, $h), $c);
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}
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// 字符
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$len = strlen($code);
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for ($i = 0; $i < $len; $i++) {
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$color = imagecolorallocate($img, mt_rand(30, 130), mt_rand(30, 130), mt_rand(30, 130));
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$size = mt_rand(5, 5); // imagechar 内置字体大小(1-5)
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$x = (int) (10 + $i * ($w / $len));
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$y = mt_rand(8, 16);
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imagechar($img, $size, $x, $y, $code[$i], $color);
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}
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ob_start();
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imagepng($img);
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$raw = ob_get_clean();
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imagedestroy($img);
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return 'data:image/png;base64,' . base64_encode($raw);
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}
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}
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