From 3c15a2de08d88a87099ab51c5f3c8d70c746aee7 Mon Sep 17 00:00:00 2001
From: Syl20b <sylvain.beissier@gmail.com>
Date: Tue, 25 Oct 2016 16:12:36 +0200
Subject: [PATCH] Check if the scheme can be removed from the URI when it s the
 default scheme

---
 library/HTMLPurifier/URI.php   |  6 ++++--
 tests/HTMLPurifier/URITest.php | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/library/HTMLPurifier/URI.php b/library/HTMLPurifier/URI.php
index a5e7ae29..13b16d89 100644
--- a/library/HTMLPurifier/URI.php
+++ b/library/HTMLPurifier/URI.php
@@ -124,8 +124,10 @@ class HTMLPurifier_URI
         // scheme is in our registry, since a URIFilter may convert a
         // URI that we don't allow into one we do.  So instead, we just
         // check if the scheme can be dropped because there is no host
-        // and it is our default scheme.
-        if (!is_null($this->scheme) && is_null($this->host) || $this->host === '') {
+        // or the host can be omitted and it is our default scheme.
+        if (!is_null($this->scheme) &&
+            (!$this->getSchemeObj($config, $context)->may_omit_host && (is_null($this->host) || $this->host === ''))
+        ) {
             // support for relative paths is pretty abysmal when the
             // scheme is present, so axe it when possible
             $def = $config->getDefinition('URI');
diff --git a/tests/HTMLPurifier/URITest.php b/tests/HTMLPurifier/URITest.php
index 91509d69..5d97f680 100644
--- a/tests/HTMLPurifier/URITest.php
+++ b/tests/HTMLPurifier/URITest.php
@@ -225,6 +225,22 @@ class HTMLPurifier_URITest extends HTMLPurifier_URIHarness
         $this->assertValidation('http://google.com');
     }
 
+    public function test_validate_schemeIsDefaultAndTheOnlyAllowed()
+    {
+        $uri =
+            'data:'.
+            'image/png,'.
+            'iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAABGdBTUEAALGP'.
+            'C/xhBQAAAAlwSFlzAAALEwAACxMBAJqcGAAAAAd0SU1FB9YGARc5KB0XV+IA'.
+            'AAAddEVYdENvbW1lbnQAQ3JlYXRlZCB3aXRoIFRoZSBHSU1Q72QlbgAAAF1J'.
+            'REFUGNO9zL0NglAAxPEfdLTs4BZM4DIO4C7OwQg2JoQ9LE1exdlYvBBeZ7jq'.
+            'ch9//q1uH4TLzw4d6+ErXMMcXuHWxId3KOETnnXXV6MJpcq2MLaI97CER3N0'.
+            'vr4MkhoXe0rZigAAAABJRU5ErkJggg==';
+
+        $this->config->set('URI.DefaultScheme', 'data');
+        $this->config->set('URI.AllowedSchemes', array('data' => true));
+        $this->assertValidation($uri, $uri);
+    }
 }
 
 // vim: et sw=4 sts=4