file_get_contents() returns FALSE while simple GET request via Chrome returns JSON data

Question

I'm not sure why am I getting this behavior? I'm trying to implement the Blockchain.com web APIs in my PHP script. Their documentation states that I should use file_get_contents PHP function to query it, which I do as such:

$xpub = "xpub123455";
$callback_url = "https://example.com";
$APIKey = "12345";
$url = "https://api.blockchain.info/v2/receive?xpub=".urlencode($xpub).'&callback='.urlencode($callback_url).'&key='.urlencode($APIKey);
//echo("URL: ".htmlentities($url)."<br><br>");
$res = @file_get_contents($url);
if($res)
{
    echo("RES: ".htmlentities(var_export($res, true)));
}
else
{
    $err = error_get_last();
    echo("err: ".($err && isset($err['message']) ? $err['message'] : "-"));
}

In that case file_get_contents returns false and if I then call error_get_last, I get the following error:

err: file_get_contents(-url-): failed to open stream: HTTP request failed! HTTP/1.1 401 Unauthorized

But if I just copy the URL that is being passed to file_get_contents and paste it into the address bar for Chrome:

https://api.blockchain.info/v2/receive?xpub=xpub123455&callback=https%3A%2F%2Fexample.com&key=12345

it returns a valid JSON data:

Why are these two outputs different? And how can I get a JSON response from file_get_contents?

Answer 1

The allow_url_fopen function is probably restricted.

It is better to use cURL instead of file_get_contents:

function url_get_contents ($Url) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $Url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $output = curl_exec($ch);
    curl_close($ch);
    return $output;
}

then you can use this function:

$res = @url_get_contents($url);

Answer 2

To answer this question:

And how can I get a JSON response from file_get_contents?

You can obtain a json response from file_get_contents with (I added a http.ignore_errors flag here, this will prevent PHP from throwing an error):

$xpub = "xpub123455";
$callback_url = "https://example.com";
$APIKey = "12345";
$url = "https://api.blockchain.info/v2/receive?xpub=".urlencode($xpub).'&callback='.urlencode($callback_url).'&key='.urlencode($APIKey);

//add http.ignore_errors flag here 
$res = file_get_contents($url, false, stream_context_create([
    "http" => [
      'ignore_errors' => true
    ]
]));

/*
 * string(40) "{message" : "API Key is not valid"}"
 */
var_dump($res);

Could you share the api key since helping is a bit difficult since you must go through a review process before you get an api key. And therefor it is not possible to reproduce the error.