From d7b7abc7ebd2efd04b9fcf835f97dbb45683e296 Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flo@geekplace.eu>
Date: Mon, 5 Aug 2019 22:20:36 +0200
Subject: [PATCH] Delete XML whitespace before feeding the Base64 decoder

---
 .../java/org/jivesoftware/smack/util/StringUtils.java  | 10 ++++++++--
 .../jivesoftware/smack/util/stringencoder/Base64.java  |  4 ++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java b/smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java
index 26b7d4bee..261f8570d 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/util/StringUtils.java
@@ -543,9 +543,15 @@ public class StringUtils {
         return cs.toString();
     }
 
-    private static final Pattern XMLWHITESPACE = Pattern.compile("[\t\n\r ]");
+    /**
+     * Defined by XML 1.0 § 2.3 as:
+     *  S      ::=      (#x20 | #x9 | #xD | #xA)+
+     *
+     * @see <a href="https://www.w3.org/TR/xml/#sec-white-space">XML 1.0 § 2.3</a>
+     */
+    private static final Pattern XML_WHITESPACE = Pattern.compile("[\t\n\r ]");
 
     public static String deleteXmlWhitespace(String string) {
-        return XMLWHITESPACE.matcher(string).replaceAll("");
+        return XML_WHITESPACE.matcher(string).replaceAll("");
     }
 }
diff --git a/smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java b/smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java
index eb71b5f7f..050321bcb 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java
@@ -19,6 +19,7 @@ package org.jivesoftware.smack.util.stringencoder;
 import java.nio.charset.StandardCharsets;
 
 import org.jivesoftware.smack.util.Objects;
+import org.jivesoftware.smack.util.StringUtils;
 
 public class Base64 {
 
@@ -57,6 +58,9 @@ public class Base64 {
     // TODO: We really should not mask the IllegalArgumentException. But some unit test depend on this behavior, like
     // ibb.packet.DataPacketExtension.shouldReturnNullIfDataIsInvalid().
     public static final byte[] decode(String string) {
+        // xs:base64Binary may include XML whitespace which we need to delete before feeding the string into the Base64
+        // decoder. See also XML Schema Part 2: Datatypes Second Edition § 3.2.16.
+        string = StringUtils.deleteXmlWhitespace(string);
         try {
             return base64encoder.decode(string);
         } catch (IllegalArgumentException e) {