Curl and FedEx API responding with gibberish in PHP - php

Question

I've been trying to implement the FedEx rates and transit times API in a PHP script.
I successfully connected with it to get the bearer token.
But when I try to get rates for a simple shipment, it responds with random gibberish.
I don't even get any errors. That's what frustrating.
Here is my code:
ini_set('display_errors', 1);
error_reporting(-1);
$access_url = 'https://apis-sandbox.fedex.com/oauth/token';
$access_headers = ['Content-Type' => 'application/x-www-form-urlencoded'];
$access_fields = "grant_type=client_credentials&client_id=...&client_secret=...";
$resp = curl_me($access_url, $access_headers, $access_fields);
$access_token = json_decode($resp)->access_token;
$rate_url = 'https://apis-sandbox.fedex.com/rate/v1/rates/quotes';
$rate_hdrs = [
'Authorization' => 'Bearer '.$access_token,
'X-locale' => 'en_US',
'Content-Type' => 'application/json'
];
$rate_flds = '{
"accountNumber": {
"value": "..."
},
"requestedShipment": {
"shipper": {
"address": {
"streetLines": [
"..."
],
"city": "...",
"stateOrProvinceCode": "...",
"postalCode": "...",
"countryCode": "US",
"residential": false
}
},
"recipient": {
"address": {
"postalCode": "...",
"countryCode": "US"
}
},
"shipDateStamp": "2022-12-06",
"pickupType": "DROPOFF_AT_FEDEX_LOCATION",
"requestedPackageLineItems": [{
"declaredValue": {
"amount": 123,
"currency": "USD"
},
"weight": {
"units": "LB",
"value": 12
},
"dimensions": {
"length": 12,
"width": 12,
"height": 12,
"units": "IN"
}
}],
"documentShipment": false,
"packagingType": "YOUR_PACKAGING",
"groupShipment": true
},
"carrierCodes": [
"FDXE"
]
}';
$field = build_post_fields($rate_flds);
$resp = curl_me($rate_url, $rate_hdrs, $field);
var_dump($resp);
Here are the two functions I'm using:
function curl_me($url, $headers, $postfields){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postfields);
$response = curl_exec($ch);
echo curl_error($ch);
curl_close($ch);
return $response;
}
function build_post_fields( $data,$existingKeys='',&$returnArray=[]){
if(($data instanceof CURLFile) or !(is_array($data) or is_object($data))){
$returnArray[$existingKeys]=$data;
return $returnArray;
}
else{
foreach ($data as $key => $item) {
build_post_fields($item,$existingKeys?$existingKeys."[$key]":$key,$returnArray);
}
return $returnArray;
}
}
The second function is from Yisrael Dov's answer to this question.
When I used the first function to get the access token, it worked flawlessly. But I can't figure out why the second time I used it responded with: string(176) "��� �#��W朢%jނ��d�]���(R������I���oFgHY�ת��r҆IH/"�Eq�zi����MJ{��6� �..."
I tried all kinds of different was of encoding and decoding the JSON string. But I get gibberish every time.
I've tried running that gibberish through various decoders, but of course they all returned NULL.
I was expecting at least some kind of error or warning.
Any ideas would be appreciated.

Answer 1

$rate_hdrs = [
'Authorization: Bearer '.$access_token,
'X-locale: en_US',
'Content-Type: application/json',
];
look this: PHP cURL custom headers

Answer 2

Thanks to everyone for the awesome input!
I'm new to CURL, so pardon my not recognizing these mistakes.
I combined Sammitch's comments with Walter KT's answer.
Sammitch was right: the response was gzip encoded. I added curl_setopt($ch, CURLOPT_ENCODING, "gzip"); to my function, and finally got the response (with some handy errors to work through).
I also got rid of the build_post_fields() function.