cURL doesn't wait for a response - php

Question

I am trying to fetch data from an API with cURL for PHP.
When I execute following script, cURL doesn't seem to wait for the request.
It immediately returns the empty field, which couldn't be populated.
function request($cityName)
{
$key = "abc";
$api = "https://...?api-key=$key&format=json&city=$cityName";
$api = urldecode(trim($api));
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $api);
curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 0);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_USERAGENT, 'abc.com');
$ret = curl_exec($curl);
$response = json_decode($ret);
var_dump($response);
curl_close($curl);
}

Answer 1

Try this, don't use urldecode
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_ENCODING, '');
curl_setopt($curl, CURLOPT_USERAGENT, 'abc.com');
$server_output = curl_exec($ch);
curl_close($ch);
print_r($server_output);

Answer 2

The OAuth extension uses curl to make the request. By default CURL will generally verify the SSL certificate to see if its valid an issued by an accepted CA. To do this, curl uses a bundled set of CA certificates.
You can either disable the SSL checks ($oauth->disableSSLChecks()). Or ensure that you have a current version of curl. More information on curl certification verification.

Answer 3

There are chances that the cURL cancels the request because of low speed connetction.
This happens if the average transfer rate drops below CURLOPT_LOW_SPEED_LIMIT bytes/second for CURLOPT_LOW_SPEED_TIME seconds.
Try the following:
curl_setopt($ch, CURLOPT_LOW_SPEED_LIMIT, 1); // cancel cURL if below 1 byte/second
curl_setopt($ch, CURLOPT_LOW_SPEED_TIME, 30); // Wait for 30 seconds
Change the values of the above options according to your requirements.