How can i send multi url using Curl in PHP - php

Question

I have a multi url to send to other server using CURL
I want each link to send using GET method get me some value in response header
So i'm trying this solution with curl-multi-init.php
but only the first curl is executed when I put it after first URL and other appropriate.
But when I deleted the result is
Warning: Undefined array key 11 in //path on line 41
Deprecated: explode(): Passing null to parameter #2 ($string) of type
string is deprecated in //path on line 41
Warning: Undefined array key 1 in //path on line 44
Warning: Undefined array key 1 in //path on line 46
0
Warning: Undefined array
key 1 in //path on line 55
<?php
$ch1 = curl_init();
$header1 = [
'Content-Type: application/json',
'Accept: application/json,version=2',
'Accept-Language: en-US,en-SA;q=0.9'
];
$response_headers = [];
$header_callback = function($ch1,$header1) use (&$response_headers){
$len = strlen($header1);
$response_headers[] = $header1;
return $len;
};
// set first URL and other appropriate
curl_setopt($ch1, CURLOPT_URL, "http://127.0.0.1/v1/rest/auth");
curl_setopt($ch1, CURLOPT_HEADER, true);
curl_setopt($ch1, CURLOPT_RETURNTRANSFER, 0);
curl_setopt($ch1, CURLOPT_HTTPHEADER, $header1);
curl_setopt($ch1, CURLOPT_HEADERFUNCTION, $header_callback);
curl_setopt($ch1, CURLOPT_CUSTOMREQUEST, 'GET');
$response1 = curl_exec($ch1);
$part = explode(":",$response_headers[11]);
echo $part[1];
$auth = ( (doubleval(doubleval ($part[1]) / 13) % 99999) * 17 );
echo number_format($auth, 0, '.', '');
curl_close($ch1);
echo $response1;
$ch2 = curl_init();
$header2 = [
'Content-Type: application/json',
'Accept: application/json,version=2',
'Auth:'.$part[1],
'Aut:'.$auth,
'Accept-Language: en-US,en-SA;q=0.9'
];
$response_headers2 = [];
$header_callback2 = function($ch2,$header2) use (&$response_headers2){
$len2 = strlen($header2);
$response_headers2[] = $header2;
return $len2;
};
curl_setopt($ch2, CURLOPT_URL, "http://127.0.0.1/v1/rest/auth?usr=root&pwd=root");
curl_setopt($ch2, CURLOPT_HEADER, true);
curl_setopt($ch2, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch2, CURLOPT_HTTPHEADER, $header2);
curl_setopt($ch2, CURLOPT_CUSTOMREQUEST, 'GET');
curl_setopt($ch2, CURLOPT_HEADERFUNCTION, $header_callback2);
$response2 = curl_exec($ch2);
$session = explode(":",$response_headers2[1]);
echo $session[1];
curl_close($ch2);
echo $response2;
var_dump($ch2); //result of var_dump($ch2) //object(CurlHandle)#3 (0) { }
$ch3 = curl_init();
$header3 = [
'Content-Type: application/json',
'Accept: application/json,version=2',
'Session:'.$session[1],
'Accept-Language: en-US,en-SA;q=0.9'
];
$response_headers3 = [];
$header_callback3 = function($ch3,$header3) use (&$response_headers3){
$len3 = strlen($header3);
$response_headers3[] = $header3;
return $len3;
};
curl_setopt($ch3, CURLOPT_URL, "http://127.0.0.1/api/example1");
curl_setopt($ch3, CURLOPT_HEADER, 0);
curl_setopt($ch3, CURLOPT_HEADER, true);
curl_setopt($ch3, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch3, CURLOPT_HTTPHEADER, $header3);
curl_setopt($ch3, CURLOPT_CUSTOMREQUEST, 'GET');
curl_setopt($ch3, CURLOPT_HEADERFUNCTION, $header_callback2);
$response3 = curl_exec($ch3);
curl_close($ch3);
echo $response3;
$ch4 = curl_init();
curl_setopt($ch4, CURLOPT_URL, "http://127.0.0.1/api/example2");
curl_setopt($ch4, CURLOPT_HEADER, true);
curl_setopt($ch4, CURLOPT_CUSTOMREQUEST, 'GET');
$response4 = curl_exec($ch4);
curl_close($ch4);
echo $response4;
?>
So how can i use multi curl to get value from each response header ?