Why does Curl 7.22 header have a different response when upgrading to 7.47?

Question

PHP

Good day everyone.
I have a code to send headers:

$arr[]='User-Agent: teeeeest';
        $arr[]='Host: '.$host;
        $c = curl_init($url);
        curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($c, CURLOPT_HTTPHEADER, $arr);
        curl_setopt($c, CURLOPT_SSL_VERIFYPEER, 0);
        curl_setopt($c, CURLOPT_SSL_VERIFYHOST, 0);
        $check = curl_exec($c);

And I get answers in the order I need:
LibCurl 7.22:

(
[Accept] => */*
[User-Agent] => teeeeest
[Host] => answer.site.com
)

But when I update libcurl to 7.47 I get the answer in a different order:

(
[Host] => answer.site.com
[Accept] => */*
[User-Agent] => teeeeest
)

What I need to fix in the \curl code is that the answer would go in the old order. Because it is critical for the application.

Answer 1

According to rfc7230, the Host header should always come first. So in 7.22 it was a bug that was fixed and in 7.47 Host comes first, which is correct.