php SRP6 Login

<?php
session_start();
error_reporting(E_ALL);
$conn = mysqli_connect("127.0.0.1", "root", "ascent", "auth");

function calculateSRP6Verifier($username, $password, $salt) {
  $g = gmp_init(7);
  $N = gmp_init('894B645E89E1535BBDAD5B8B290650530801B18EBFBF5E8FAB3C82872A3E9BB7', 16);
  $h1 = sha1(strtoupper($username . ':' . $password), TRUE);
  $h2 = sha1($salt.$h1, TRUE);
  $h2 = gmp_import($h2, 1, GMP_LSW_FIRST);
  $verifier = gmp_powm($g, $h2, $N);
  $verifier = gmp_export($verifier, 1, GMP_LSW_FIRST);
  $verifier = str_pad($verifier, 32, chr(0), STR_PAD_RIGHT);
  return $verifier;
}

function getsalt($username, $password) {
  $conn = mysqli_connect("127.0.0.1", "root", "ascent", "auth");
  $stmt = $conn->prepare("SELECT * FROM account WHERE username = ?");
  $stmt->bind_param("s", $username);
  $stmt->execute();
  $result = $stmt->get_result();
  if($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
      return calculateSRP6Verifier($row['username'], $password, $row['salt']);
    }
  }
}

$verifier = getsalt($_POST['username'], $_POST['password']);

$stmt = $conn->prepare("SELECT * FROM account WHERE username = ? AND verifier = ?");
$stmt->bind_param("ss", $_POST['username'], $verifier);
$stmt->execute();
$result = $stmt->get_result();
if($result->num_rows > 0) {
  while($row = $result->fetch_assoc()) {
    $_SESSION['username'] = $row['username'];
    $_SESSION['uid'] = $row['id'];
    header("location: ../?p=home");
  }
}else{
  echo "Wrong username or password";
  header("refresh:3; ../?p=home");
}
?>