WordPress – cURL not sending file attachments on Azure

I know this has been covered a lot on stackoverflow but I can’t seem to find a solution to my particular issue.

We have a WP based site hosted in Azure so have needed to write our own plugin to handle email from the site using Azure Communication Services via cURL to post to the REST API.

The original script for this was written by a colleague but i’m now trying to get this to allow users to upload file attachments.

I’ve got so far but now i’m stuck. The emails are sending but nothing is attached.

Can anyone help?

This is our code

<?php
class ACSMailer{

    public static function SendMail($atts){

        $to = $atts['to'];
        $subject = $atts['subject'];
        $message = $atts['message'];
        $headers = $atts['headers'];

        $attachments = [];

        $atch = $atts['attachments'];

        foreach($atch as $atchkey => $atchval) {

            $attachments[] = [
                'name' => basename($atchval),
                'contentType' => mime_content_type($atchval),
                'contentInBase64' => base64_encode(file_get_contents($atchval)),
            ];
        }

        //error_log('HEADERS: '. print_r($atts, true));
        // TODO: Check for HTML and send as plain text

        $settings = get_option('acs_settings_option_name');
        $endpoint = $settings["endpoint"];
        $key = base64_decode($settings["key"]);

        $bodyArray = array(
            'sender' => '[email protected]',
            'content' => array('subject' => $subject, 'html' => $message),
            'importance' => 'normal',
            'recipients' => array('to' => array(array('email' => $to))),
            'attachment' => $attachments,
            'disableUserEngagementTracking' => true
            );
        $bodyStr = json_encode($bodyArray);
        $hashedBodyStr = base64_encode(hash('sha256', $bodyStr, true));

        $dateStr = gmdate('D, d M Y H:i:s T');

        $fullEndpoint = $endpoint . '/emails:send?api-version=2021-10-01-preview';
        $hostStr = str_replace('https://', '', $endpoint);
        $url = str_replace($endpoint, '', $fullEndpoint);
        
        $stringToSign = 'POST' . "n" . $url . "n" . $dateStr . ';' . $hostStr . ';' . $hashedBodyStr;
        $signature = base64_encode(hash_hmac('sha256', $stringToSign, $key, true));
        $uuid = vsprintf( '%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex(random_bytes(16)), 4) );


        $curl = curl_init();

        curl_setopt_array($curl, array(
            CURLOPT_URL => $fullEndpoint,
            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 => $bodyStr,
            CURLOPT_HTTPHEADER => array(
                'Content-Type: application/json',
                'Date: ' . $dateStr,
                'Authorization: HMAC-SHA256 SignedHeaders=date;host;x-ms-content-sha256&Signature=' . $signature,
                'x-ms-content-sha256: ' . $hashedBodyStr,
                'repeatability-request-id: ' . $uuid,
                'repeatability-first-sent: ' . $dateStr
            ),
        ));

        $response = curl_exec($curl);

        curl_close($curl);

        
        error_log('DATE: '. $dateStr);
        error_log('$endpoint: ' . $endpoint);
        error_log('$fullEndpoint: ' . $fullEndpoint);
        error_log('$key: ' . $key);
        error_log('$bodyStr: ' . $bodyStr);
        error_log('$dateStr: ' . $dateStr);
        error_log('$url: ' . $url);
        error_log('$stringToSign : ' . $stringToSign );
        error_log('$signature: ' . $signature);
        error_log('$uuid: ' . $uuid);
        error_log('$hashedBodyStr: ' . $hashedBodyStr);
        error_log('$bodyArray: ' . print_r($bodyArray, true));
        error_log('API RESPONSE: ' . $response);
        
    }
}