PHP XMLReader 400 Bad Request - php

Question

I'm trying to get started using XMLReader to process large XML files, but I am getting a strange HTTP 400 Bad Request when I try to run the following code:
<?php
$reader = new XMLReader ();
$reader->open ( "testfile.xml" );
while ( $reader->read () ) {
switch ($reader->nodeType) {
case (XMLREADER::ELEMENT) :
echo "<" . $reader->name . "> <br>";
break;
case (XMLREADER::TEXT) :
if ($reader->hasValue) {
echo $reader->value . "<br>";
}
break;
}
}
$reader->close();
?>
I have also tried it this way and get the same 400 Bad Request error:
<?php
$reader = new XMLReader ();
$reader->open ( "testfile.xml" );
while ( $reader->read() ) {
switch ($reader->nodeType) {
case (XMLREADER::ELEMENT) :
echo "<" . $reader->name . "> <br>";
$reader->read();
if (($reader->nodeType == XMLREADER::TEXT) && $reader->hasValue) {
echo $reader->value . "<br>";
}
break;
}
}
$reader->close();
?>
In both cases, the error goes away when I comment out echo reader->value ."<br>";. Apache error logs aren't showing anything. Also, in spite of the 400 error, the page is created and rendered as expected with the elements and text values (i.e., the code appears to work, it just gives an HTTP error as well).
It is also worth noting that it seems to work without error on a small, simple test XML file with only one root and one child element with text. It's only on the larger more complicated XML file that I'm actually intending to process that I'm getting the error.
Thanks in advance for any help!

Answer 1

FYI in case anyone else runs into this, I found out I needed to use htmlspecialchars() to escape the value. I changed:
echo $reader->value . "<br>";
to
echo htmlspecialchars($reader->value, ENT_XML1, 'UTF-8') . "<br>";
Guess there must be some html in the XML that the browser was trying to interpret causing the 400 error.