Sending voice to Telegram through PHP app - php-telegram-bot

Question

Here is the situation.
I have an Android app, which can send voice file with HTTP POST anywhere I specify. Also I would like to download these voice files to Telegram bot automatically. I wrote a PHP bot and I can accept and translate to Telegram any fields that come in said POST. One thing I miss is the file itself.
I don't know how to "say" to telegram API I download a file.
So what do I have: present file in $_FILE stream (I can read the name of it), I throw it in sendVoice function as $voice, also I do know I have to use simple multipart/form-data POST method to send file.
My question is: is it possible to use something but CURL to POST right from PHP? If not, what am I missing then? Other methods I use are messages and photo sending via file_get_contents(), I wonder if it's still suitable for voice file?
Here is the code I have now, which I found somewhere (I have 0 cURL knowledge):
function sendVoice($chat_id, $voice, $caption) {
$boundary = uniqid();
$delimiter = '-------------' . $boundary;
$fields = array(
"chat_id" => $chat_id,
"caption" => $caption
);
$post_data = build_data_files($boundary, $fields, $voice);
$ch = curl_init($GLOBALS['api'].'/sendVoice');
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
//"Authorization: Bearer $TOKEN",
"Content-Type: multipart/form-data; boundary=" . $delimiter,
"Content-Length: " . strlen($post_data))
);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_exec($ch);
curl_close($ch);
}
function build_data_files($boundary, $fields, $files){
$data = '';
$eol = "\r\n";
$delimiter = '-------------' . $boundary;
foreach ($fields as $name => $content) {
$data .= "--" . $delimiter . $eol
. 'Content-Disposition: form-data; name="' . $name . "\"".$eol.$eol
. $content . $eol;
}
foreach ($files as $name => $content) {
$data .= "--" . $delimiter . $eol
. 'Content-Disposition: form-data; name="' . $name . '"; filename="' . $name . '"' . $eol
//. 'Content-Type: image/png'.$eol
. 'Content-Transfer-Encoding: binary'.$eol
;
$data .= $eol;
$data .= $content . $eol;
}
$data .= "--" . $delimiter . "--".$eol;
return $data;
}

Answer 1

This was actally much easier. Since we have file present in $_FILES, we can do all of the cURL in just sendVoice() function without any hassle of rebinding boundaries or specifying content types.
Here is the final code which worked for me:
function sendVoice($chat_id, $voice, $caption) {
$filepath = realpath($_FILES['file']['tmp_name']);
$post_data = array(
'chat_id' => $chat_id,
'voice' => new CURLFile($filepath),
'caption' => $caption
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $GLOBALS['api'].'/sendVoice');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_exec($ch);
curl_close($ch);
}
That will download an .OGG file as voice message (because I do not want any files to appear in my music player). Later it is possible to just add more fields such as duration in $post_data array and Telegram would eat them accordingly.