<?php

header('Content-type:text');
define("TOKEN", "20171201");
$wechatObj = new wechatCallbackapiTest();
if (isset($_GET['echostr'])) {
$wechatObj->valid();
}else{
$wechatObj->responseMsg();
}

class wechatCallbackapiTest
{
public function valid()
{
$echoStr = $_GET["echostr"];
if($this->checkSignature()){
header('content-type:text');
echo $echoStr;
exit;
}
}

private function checkSignature()
{
    $signature = $_GET["signature"];
    $timestamp = $_GET["timestamp"];
    $nonce = $_GET["nonce"];

    $token = TOKEN;
    $tmpArr = array($token, $timestamp, $nonce);
    sort($tmpArr, SORT_STRING);
    $tmpStr = implode( $tmpArr );
    $tmpStr = sha1( $tmpStr );

    if( $tmpStr == $signature ){
        return true;
    }else{
        return false;
    }
}

public function responseMsg()
{
    $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];

    if (!empty($postStr)){
        $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
        $fromUsername = $postObj->FromUserName;
        $toUsername = $postObj->ToUserName;
        $keyword = trim($postObj->Content);
        $time = time();
        $textTpl = "<xml>
                    <ToUserName><![CDATA[%s]]></ToUserName>
                    <FromUserName><![CDATA[%s]]></FromUserName>
                    <CreateTime>%s</CreateTime>
                    <MsgType><![CDATA[%s]]></MsgType>
                    <Content><![CDATA[%s]]></Content>
                    <FuncFlag>0</FuncFlag>
                    </xml>";
        if($keyword == "?" || $keyword == "？")
        {
            $msgType = "text";
            $contentStr = date("Y-m-d H:i:s",time());
            $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
            echo $resultStr;
        }
    }else{
        echo "5555";
        exit;
    }
}

}
?>