Using eBay OAuth

Question

I have my code as shown below. I am trying to authenticate users with eBay to be able to get access token. On redirecting users back to my redirection URL to exchange code with access token, I get the error:

HTTP/1.1 100 Continue HTTP/1.1 400 Bad Request Content-Length: 109 Cneonction: close Date: Thu, 02 Mar 2017 06:47:51 GMT RlogId: t6ldssk%28ciudbq%60anng%7Fu2h%3F%3Cwk%7Difvqn*2%3D%3F%3E505-15a8dc659e6-0xf3 Set-Cookie: ebay=%5Esbf%3D%23%5E;Domain=.ebay.com;Path=/ X-EBAY-C-REQUEST-ID: ri=v22kQg9yaBLq,rci=2FDiyansIYnkONQC X-EBAY-C-VERSION: 1.0.0 X-EBAY-REQUEST-ID: 15a8dc658f8.a0968eb.5f6ef.fff87b7e![] Content-Type: application/json Connection: keep-alive {"error":"invalid_request","error_description":"'Authorization' is missing the the header:","error_uri":null}

What is wrong with my POST request?

$auth_code = $_GET['code'];
$client_id = "Client ID";
$client_secret = "Client Secret";
$redirect_uri = "RuName";
$headers = array (
    'Content-Type'  => 'application/x-www-form-urlencoded',
    'Authorization' => sprintf('Basic %s',base64_encode(sprintf('%s:%s', $client_id, $client_secret)))
);
$apiURL = "https://api.sandbox.ebay.com/identity/v1/oauth2/token";
$urlParams = array (
        "grant_type" => "authorization_code",
        "code" => urlencode($auth_code),
        "redirect_uri" => $redirect_uri
);

$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
//curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // Should be removed on production
curl_setopt ( $ch, CURLOPT_POST, 1 );
curl_setopt ( $ch, CURLOPT_HEADER, true );

curl_setopt($ch, CURLOPT_URL, $apiURL);
curl_setopt ( $ch, CURLOPT_HTTPHEADER, $headers = array ('Authorization' => sprintf('Basic %s',base64_encode(sprintf('%s:%s', $client_id, $client_secret))),'Content-Type'  => 'application/x-www-form-urlencoded') );
curl_setopt ( $ch, CURLOPT_POSTFIELDS, $urlParams );

$resp = curl_exec ( $ch );
curl_close ( $ch );

print_r ( $resp );

Answer 1

There are two small issues with your code. The first is that CURLOPT_HTTPHEADER requires an array of strings and not an associative array.

$headers = array (
    'Content-Type: application/x-www-form-urlencoded',
    'Authorization: '.sprintf('Basic %s',base64_encode(sprintf('%s:%s', $client_id, $client_secret)))
);

The second is to do with how PHP handles the CURLOPT_POSTFIELDS option. As noted in the documentation.

Passing an array to CURLOPT_POSTFIELDS will encode the data as multipart/form-data, while passing a URL-encoded string will encode the data as application/x-www-form-urlencoded.

Since the eBay API requires the body to be application/x-www-form-urlencoded you will need to pass in a string instead. You can use your array to build this string by passing it to http_build_query.

$urlParams = http_build_query(array (
        "grant_type" => "authorization_code",
        "code" => $auth_code,
        "redirect_uri" => $redirect_uri
));

I also recommend Postman to test making API requests to eBay. One of it's features is that it will also create the PHP curl code for you. The code below has been adapted from the code that Postman created.

<?php

$clientID = '<YOUR EBAY APP ID>';
$clientSecret = '<YOUR EBAY CERT ID>';
$ruName = '<YOUR EBAY RUNAME>';
$authCode = '<AUTH CODE>';

$url = 'https://api.sandbox.ebay.com/identity/v1/oauth2/token';

$headers = [
    'Content-Type: application/x-www-form-urlencoded',
    'Authorization: Basic '.base64_encode($clientID.':'.$clientSecret)
];

$body = http_build_query([
    'grant_type'   => 'authorization_code',
    'code'         => $authCode,
    'redirect_uri' => $ruName
]);

$curl = curl_init();

curl_setopt_array($curl, array(
    CURLOPT_URL            => $url,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_CUSTOMREQUEST  => 'POST',
    CURLOPT_POSTFIELDS     => $body,
    CURLOPT_HTTPHEADER     => $headers
));

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
    echo "cURL Error #:" . $err;
} else {
    echo $response."\n";
}