From 171e1527df2a11bf1ba457780e65c9c32ed4bc02 Mon Sep 17 00:00:00 2001
From: Fabricio Seger Kolling <dulldusk@gmail.com>
Date: Sun, 14 May 2017 04:11:27 -0300
Subject: [PATCH] HTTPD default 8Kb header limit check, to avoid 500 Internal
 Server Error

The HTTP spec does not define a limit, however many servers do by
default:
Apache 2.0, 2.2: 8K
nginx: 4K - 8K
IIS: varies by version, 8K - 16K
Tomcat: varies by version, 8K - 48K(?!)

Ans it is not just with ChormePHP.
Some user agents and some requests just get too big for web server
defaults.
It seems like a silly problem to run into, but it keeps happening.
---
 ChromePhp.php | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/ChromePhp.php b/ChromePhp.php
index 577b1ce..8757bb9 100755
--- a/ChromePhp.php
+++ b/ChromePhp.php
@@ -78,6 +78,11 @@ class ChromePhp
      */
     const TABLE = 'table';
 
+    /**
+     * @var int
+     */
+    const HTTPD_HEADER_LIMIT = 8192; // 8Kb - Default for most HTTPD Servers
+
     /**
      * @var string
      */
@@ -391,7 +396,25 @@ protected function _addRow(array $logs, $backtrace, $type)
 
     protected function _writeHeader($data)
     {
-        header(self::HEADER_NAME . ': ' . $this->_encode($data));
+        $header = self::HEADER_NAME . ': ' . $this->_encode($data);
+        // Most HTTPD servers have a default header line length limit of 8kb, must test to avoid 500 Internal Server Error.
+        if (strlen($header) > self::HTTPD_HEADER_LIMIT) {
+            $data['rows'] = array();
+            $data['rows'][] = array(array('ChromePHP Error: The HTML header will surpass the limit of '.$this->_formatSize(self::HTTPD_HEADER_LIMIT).' ('.$this->_formatSize(strlen($header)).') - You can increase the HTTPD_HEADER_LIMIT on ChromePHP class, according to your Apache LimitRequestFieldsize directive'), '', self::ERROR);
+            $header = self::HEADER_NAME . ': ' . $this->_encode($data);
+        }
+        header($header);
+    }
+
+    protected function _formatSize($arg) {
+        if ($arg>0){
+            $j = 0;
+            $ext = array("bytes","Kb","Mb","Gb","Tb");
+            while ($arg >= pow(1024,$j)) ++$j; {
+                $arg = (round($arg/pow(1024,$j-1)*100)/100).($ext[$j-1]);
+            }
+            return $arg;
+        } else return "0Kb";
     }
 
     /**