[php] RAW POST using cURL in PHP

How can I do a RAW POST in PHP using cURL?

Raw post as in without any encoding, and my data is stored in a string. The data should be formatted like this:

... usual HTTP header ...
Content-Length: 1039
Content-Type: text/plain

89c5fdataasdhf kajshfd akjshfksa hfdkjsa falkjshfsa
ajshd fkjsahfd lkjsahflksahfdlkashfhsadkjfsalhfd
ajshdfhsafiahfiuwhflsf this is just data from a string
more data kjahfdhsakjfhsalkjfdhalksfd

One option is to manually write the entire HTTP header being sent, but that seems less optimal.

Anyway, can I just pass options to curl_setopt() that say use POST, use text/plain, and send the raw data from a $variable?

Implementation with Guzzle library:

use GuzzleHttp\Client;
use GuzzleHttp\RequestOptions;

$httpClient = new Client();

$response = $httpClient->post(
    'https://postman-echo.com/post',
    [
        RequestOptions::BODY => 'POST raw request content',
        RequestOptions::HEADERS => [
            'Content-Type' => 'application/x-www-form-urlencoded',
        ],
    ]
);

echo(
    $response->getBody()->getContents()
);

PHP CURL extension:

$curlHandler = curl_init();

curl_setopt_array($curlHandler, [
    CURLOPT_URL => 'https://postman-echo.com/post',
    CURLOPT_RETURNTRANSFER => true,

    /**
     * Specify POST method
     */
    CURLOPT_POST => true,

    /**
     * Specify request content
     */
    CURLOPT_POSTFIELDS => 'POST raw request content',
]);

$response = curl_exec($curlHandler);

curl_close($curlHandler);

echo($response);

Source code