Make Attachment File Format only .txt .doc .docx - php

Question

I create a PHP contact form with file attachment with helping a online tutorial. But i want to function it like user only upload .txt .doc .docx file format, no other format will be accepted.
<?php
$from = "name#example.com";
$to = $_POST['email'];
$subject =$_POST['subject'];
$message = $_POST['body'];
// Temporary paths of selected files
$file1 = $_FILES['file1']['tmp_name'];
$file2 = $_FILES['file2']['tmp_name'];
$file3 = $_FILES['file3']['tmp_name'];
// File names of selected files
$filename1 = $_FILES['file1']['name'];
$filename2 = $_FILES['file2']['name'];
$filename3 = $_FILES['file3']['name'];
// array of filenames to be as attachments
$files = array($file1, $file2, $file3);
$filenames = array($filename1, $filename2, $filename3);
// include the from email in the headers
$headers = "From: $from";
// boundary
$time = md5(time());
$boundary = "==Multipart_Boundary_x{$time}x";
// headers used for send attachment with email
$headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$boundary}\"";
// multipart boundary
$message = "--{$boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n";
$message .= "--{$boundary}\n";
// attach the attachments to the message
for($x=0; $x<count($files); $x++){
$file = fopen($files[$x],"r");
$content = fread($file,filesize($files[$x]));
fclose($file);
$content = chunk_split(base64_encode($content));
$message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$files[$x]\"\n" .
"Content-Disposition: attachment;\n" . " filename=\"$filenames[$x]\"\n" .
"Content-Transfer-Encoding: base64\n\n" . $content . "\n\n";
$message .= "--{$boundary}\n";
}
// sending mail
$sendmail = mail($to, $subject, $message, $headers);
// verify if mail is sent or not
if ($sendmail) {
echo "Sent successfully!";
} else {
echo "Error occurred. Try again!";
}
?>

Answer 1

the use of $_FILE["filename"]["type"] is not recomended for file type checking as the type parameter is browser specific i.e different browser can have different type So we will try to extract the format from the string function
$filename=$_FILES["file1"]["name"];//get the name of the file
$extension=strrchr($filename, ".");//extracting the extension
if($extension=".txt" || $extension=".doc" || $extension=".docx")
{
//send mail;
}
else
{
//error;
}

Answer 2

Simply,
$filename_array = explode(".",$filename);
$ext = ".".$filename_array[count($filename_array)-1];
if($ext!==".txt" && $ext!==".doc" && $ext!==".docx"):
//Do bad extension code
endif;
//Do code that passed extension validation
Hope this helps!

Answer 3

$allowed = array('.txt', '.doc', '.docx')
$fileNames = array();
$filename1= $_FILES['file1']['name'];
$ext1 = pathinfo($path, PATHINFO_EXTENSION);
if(in_array($ext1, $allowed)){
array_push($fileNames, $filename1); //repeat for 2, 3, etc...
}

Answer 4

function allowed_file(){
//Add the allowed mime-type files to an 'allowed' array
$allowed = array('application/doc', 'application/txt', 'another/type');
//Check uploaded file type is in the above array (therefore valid)
if(in_array($_FILES['file']['name'], $allowed))
{
// Your code
}
}
Reference : php file upload, how to restrict file upload type