Incomplete Base64 when sending to server - php

Question

I am trying to send an image to server, but the image should be in Base64 format. I am using this function to send it:
func upload_signature_staff(ticket: NSString){
let defaults = NSUserDefaults.standardUserDefaults()
let stringOne = defaults.stringForKey(defaultsKeys.staff_id)
let stringtwo = defaults.stringForKey(defaultsKeys.mst_customer)
let sig = defaults.stringForKey("staff_signature")
let request = NSMutableURLRequest(URL: NSURL(string: "http://xxxxxxxxxxxxx/upload.php")!)
request.HTTPMethod = "POST"
let postString = "action=add_signature&mst_customer=\((stringtwo!))&ticket=\((ticket))&signature=\((sig!))&current_user=\((stringOne!))&item_type=10"
print(postString)
request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
guard error == nil && data != nil else { // check for fundamental networking error
print("error=\(error)")
return
}
if let httpStatus = response as? NSHTTPURLResponse where httpStatus.statusCode != 200 { // check for http errors
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("response = \(response)")
}
let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
print("responseString = \(responseString)")
}
task.resume()
//self.performSegueWithIdentifier("goto_main2", sender: self)
}
The sig variable holds the Base64 string, it is being printed in my console so I can verify that the string is correct. I am also printing the postString and upon inspection it is also correct that the signature is matching the Base64 String. But when I open phpmyadmin, I see the field of my image with incomplete Base64 string, maybe 1/4 is just there.
Here's my php code, in case you want to see it:
<?php
require_once("../c.php");
$action = trim($_POST['action']);
if($action == "add_signature"){
$mst_customer = trim($_POST['mst_customer']);
$ticket = trim($_POST['ticket']);
$signature = trim($_POST['signature']);
$current_user = trim($_POST['current_user']);
$item_type = trim($_POST['item_type']);
$inputtime = time();
$sql = "INSERT INTO ticket_items SET mst_customer = '$mst_customer', ticket = '$ticket', ticket_item_type = '$item_type', details = '$signature', addedby = '$current_user', lastupdate = '$inputtime' ";
mysql_query($sql) or die(mysql_error());
}
?>

Answer 1

I think this was solved in the comments but here's a recap:
Inserting base64 strings that were too long (variable length?) in a varchar(255) field resulted in missing data. As far as I can tell, increasing the size of the field solved the immediate problem. I use the term "immediate" because, as #YvesLeBorg pointed out in the comments, this is bound to fail at some point without input size restrictions on the backend.
Additionally, I couldn't ignore the fact that the PHP/SQL code was wide open to injections.
Passing $mst_customer = trim($_POST['mst_customer']); on to "INSERT INTO ticket_items SET mst_customer = '$mst_customer' and then executing via mysql_query($sql) or die(mysql_error()); is dangerous!
Anybody could write anything in the $_POST parameter and SQL would happily accept it. Prepared statements, PDO, input sanitization etc. are there for a reason.
Finally, there was an issue concerning vanishing + signs in the base64 data. This was the result of missing url encoding of the post data.
I think that sums it up.