在curl请求中传递url给出404 Not Found

Question

在传递目标URL到curl时出现一个奇怪的问题。如果我对curl进行硬编码，则不会出现任何错误。

<?php

namespace App\Http\Middleware;

use Illuminate\Support\Facades\Redis;

use Illuminate\Http\Response;

use Closure;

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

class CurlGlobal
{

    # Headers received and read by our callback
    private $headers = array();

    private $url;

    public function header_callback($handle, $header)
    {
        $len = strlen($header);

        $this->headers[] = $header; 

        return $len;

    }

    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $this->url = trim($request->plain_url);

        //$this->url = 'https://s.ytimg.com/yts/img/favicon_96-vflW9Ec0w.png';

        var_dump($this->url); //https://s.ytimg.com/yts/img/favicon_96-vflw9ec0w.png
        var_dump('$request->plain_url '. $request->plain_url); // https://s.ytimg.com/yts/img/favicon_96-vflw9ec0w.png

        $curl_options = array(
            CURLOPT_URL => $this->url,
            CURLOPT_CONNECTTIMEOUT => 60,
            CURLOPT_TIMEOUT => 300, 
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_SSL_VERIFYHOST => false,
            CURLOPT_USERAGENT => $request->server('HTTP_USER_AGENT'), // Change useragent to both a latest chrome & safari (image formats)
            CURLOPT_FAILONERROR => true, //request failure on HTTP response >= 400
            CURLOPT_IPRESOLVE => CURL_IPRESOLVE_V4, # Always connect to ipv4
         );

        $curl_options[CURLOPT_HEADERFUNCTION] = array(
            &$this,
            'header_callback'
        );

        var_dump($curl_options);
        #######Execute the curl request(TODO move to another middleware) #########

        # Get a cURL handle
        $ch = curl_init();
        # Set the options
        curl_setopt_array($ch, $curl_options);
        # Make the request
        curl_exec($ch);
        # Close the curl handle
        if( ! $result = curl_exec($ch)) 
        { 
            dd(curl_error($ch)); 
        } 

        //dd($request->plain_url);

        dd($this->headers);

        return $next($request);
        //return response($this->return_data);
    }
}

调试信息

string(52) "https://s.ytimg.com/yts/img/favicon_96-vflW9Ec0w.png"
string(72) "$request->plain_url https://s.ytimg.com/yts/img/favicon_96-vflw9ec0w.png"
array(9) {
  [10002]=>
  string(52) "https://s.ytimg.com/yts/img/favicon_96-vflW9Ec0w.png"
  [78]=>
  int(60)
  [13]=>
  int(300)
  [64]=>
  bool(false)
  [81]=>
  bool(false)
  [10018]=>
  string(105) "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.157 Safari/537.36"
  [45]=>
  bool(true)
  [113]=>
  int(1)
  [20079]=>
  array(2) {
    [0]=>
    object(App\Http\Middleware\CurlGlobal)#222 (2) {
      ["headers":"App\Http\Middleware\CurlGlobal":private]=>
      array(0) {
      }
      ["url":"App\Http\Middleware\CurlGlobal":private]=>
      string(52) "https://s.ytimg.com/yts/img/favicon_96-vflW9Ec0w.png"
    }
    [1]=>
    string(15) "header_callback"
  }
}

如果我取消注释以下行，则不会收到任何curl错误，但我不明白为什么当前的实现无法正常工作。

//$this->url = 'https://s.ytimg.com/yts/img/favicon_96-vflW9Ec0w.png';

调试显示传递了相同的URL，但我不知道出了什么问题。