poloniex futures api php - php

Question

I am unable to POST data to Poloniex Futures API. While the GET works fine.
The POST returns 400005 [msg] => Invalid PF-API-SIGN
Here is the Code for config.php
global $baseurl;
$baseurl = "https://futures-api.poloniex.com";
global $api_key;
$api_key = "XXXXX";
global $api_secret;
$api_secret = "XXXXX";
global $api_passphrase;
$api_passphrase = "XXXXXX";
function signature($request_path = '', $body = '', $timestamp = false, $method = 'POST') {
$body = is_array($body) ? json_encode($body) : $body; // Body must be in json format
$timestamp = $timestamp ? $timestamp : time() * 1000;
$what = $timestamp . $method . $request_path . $body;
return base64_encode(hash_hmac("sha256", $what, $api_secret, true));
}
Working code to get Ticket Data
Code for ticker.php
include_once "config.php";
$endpoint = "/api/v1/position?symbol=BTCUSDTPERP";
$url = "https://futures-api.poloniex.com".$endpoint;
$sigs = signature($endpoint,'',true,"GET");
$now = time() * 1000;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$headers = [
"PF-API-SIGN: $sigs",
"PF-API-TIMESTAMP: $now",
"PF-API-KEY: $api_key",
"PF-API-PASSPHRASE: $api_passphrase"
];
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
$server_output = curl_exec ($ch);
curl_close ($ch);
$return_data = json_decode($server_output ,true);
print_r($return_data );
Here is what I have tried for Add Margin Manually
POST /api/v1/position/margin/deposit-margin
Code for post_data.php
include_once "config.php";
$endpoint = "/api/v1/position/margin/deposit-margin";
$url = "https://futures-api.poloniex.com".$endpoint;
$now = time() * 1000;
$vars_margin = ["symbol"=>"BTCUSDTPERP","margin"=>1,"bizNo"=>"1112222"];
$vars_margin = json_encode($vars_margin);
$vars_margin_post_fields = "symbol=BTCUSDTPERP&margin=1&bizNo=1112222";
$sigs = signature($endpoint,$vars_margin,true,"POST");
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,$vars_margin_post_fields); //Post Fields
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$headers = [
"PF-API-SIGN: $sigs",
"PF-API-TIMESTAMP: $now",
"PF-API-KEY: $api_key",
"PF-API-PASSPHRASE: $api_passphrase"
];
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
$server_output = curl_exec ($ch);
curl_close ($ch);
$return_data = json_decode($server_output ,true);
print_r($return_data );
Really not sure why the post method always says
Array ( [code] => 400005 [msg] => Invalid PF-API-SIGN )
Any help will be appreciated.
Thanks

Answer 1

The Post fields should match what was signed, the json_encoded value.
So try this:
curl_setopt($ch, CURLOPT_POSTFIELDS, $vars_margin);
and be sure to add a header to indicate that the POST data is json encoded:
...
"PF-API-PASSPHRASE: $api_passphrase",
"content-type: application/json"
];