How do I troubleshoot Curl in PHP? - php

Question

I have never used Curl but I am trying to complete a self api project at my job just to gain some experience.
And I am stuck on the first step... I want to authenticate with an api.
So I am running this code and I expect to see a Success 200 response with my access token, etc but I get nothing.
No error, no feedback, the page just opens up blank
I have tired to use CURLINFO_HEADER_OUT from this page What Steps do you Take to Troubleshoot Problems with PHP cURL? but still I got a blank page
Anyway thank you to anyone in advantage for some tips
<?php
const TOKEN_ENDPOINT = 'xxxxxx';
const GRANT_TYPE = 'xxxxx';
const CLIENTID = 'xxxxxxxxxxx';
const CLIENTSECRET = 'xxxxxxxxxxxxxx';
const USERNAME = 'xxxxxxxxxxxxxxxxx';
const PASSWORD = 'xxxxxxxxxxxxxxx';
$clientCredentials = base64_encode(CLIENTID . ':' . CLIENTSECRET);
$curl = curl_init();
curl_setopt_array($curl, array(
CURLOPT_URL => TOKEN_ENDPOINT,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => '',
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 0,
CURLOPT_FOLLOWLOCATION => true,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_POSTFIELDS =>'grant_type=' . GRANT_TYPE . '&username=' . USERNAME . '&password=' . PASSWORD ,
CURLOPT_HTTPHEADER => array(
'Content-Type: application/x-www-form-urlencoded',
'Accept: application/json',
'Authorization: Basic ' . $clientCredentials
),
));
$response = curl_exec($curl);
curl_close($curl);
echo $response ;
?>

Answer 1

To check curl error, the best way is to use curl_error function
$response = curl_exec($curl);
if (curl_errno($curl)) {
$error_msg = curl_error($curl);
}
curl_close($curl);
echo $response ;
See the description of libcurl error codes here
See the description of PHP curl_errno() function here
See the description of PHP curl_error() function here

Answer 2

When all else fails, i do this (code snippet from my ApiHelper curl wrapper). Use your own logger or evidence printing mechanism. Most every time the answer to the puzzle is in the printed stuff :
// we simply stream curlopt debug info to a temporary
// file, so we can log it out later (when helper is set
// to verbose)
$st = microtime(true);
$verbiage = null;
if ($this->verbose) {
// write out the curl debug stuff
curl_setopt($ch , CURLINFO_HEADER_OUT , false);
curl_setopt($ch , CURLOPT_VERBOSE , true);
$verbiage = fopen('php://temp' , 'w+');
curl_setopt($ch , CURLOPT_STDERR , $verbiage);
}
$resp = curl_exec($ch);
$end = microtime(true); // get as float
$delta = 1000.0 * ($end - $st); // treat as float
$this->roundTripInMs = sprintf("%.2f" , $delta);
$this->getInstanceLogger()->debug("WS call : round trip took " . sprintf("%.2f" , $delta) . " ms.");
if ($this->verbose) {
// rewind and log the verbose output
rewind($verbiage);
$verboseLog = stream_get_contents($verbiage);
$this->getInstanceLogger()->info("Verbose cURL : \n$verboseLog");
fclose($verbiage);
}
$this->curlinfo = curl_getinfo($ch);
$this->verbose && $this->getInstanceLogger()->info("cURL info : \n" . json_encode($this->curlinfo , PEHR_PRETTY_JSON));
$this->httpStatus = curl_getinfo($ch , CURLINFO_RESPONSE_CODE);
if (!$resp) {
if ($this->verbose) $this->getInstanceLogger()->error("CURL request to [$url] failed\n" . json_encode($this->curlinfo , PEHR_PRETTY_JSON));
return 0;
}
curl_close($ch);
if ($resp && $this->verbose) $this->getInstanceLogger()->debug("Received json \n" . $resp);