Fix broken codePoint check (OF-391)

char in java is 16-bit. Therefore checking for anything greater then
0xFFFF makes no sense. We want to know here if the character is maybe
part of a surrogate pair, that's why 'is(High|Low)Surrogate(char)' is
now used.

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@13995 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/openfire/net/MXParser.java

@@ -362,25 +362,45 @@ public class MXParser extends org.xmlpull.mxp1.MXParser {
         inputEncoding = oldEncoding;
     }
 
+	private boolean highSurrogateSeen = false;
+
 	/**
 	 * Makes sure that each individual character is a valid XML character.
 	 * 
 	 * Note that when MXParser is being modified to handle multibyte chars correctly, this method needs to change (as
 	 * then, there are more codepoints to check).
+	 * 
+	 * Also note that the current implementations allows high surrogates followed by non low surrogates.
 	 */
     @Override
     protected char more() throws IOException, XmlPullParserException {
     	final char codePoint  = super.more(); // note - this does NOT return a codepoint now, but simply a (single byte) character!
+		boolean validCodepoint = false;
 		if ((codePoint == 0x0) ||  // 0x0 is not allowed, but flash clients insist on sending this as the very first character of a stream. We should stop allowing this codepoint after the first byte has been parsed.
-				(codePoint == 0x9) ||          				     
+				(codePoint == 0x9) ||
 				(codePoint == 0xA) ||
 				(codePoint == 0xD) ||
 				((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
-				((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) ||
-				((codePoint >= 0x10000) && (codePoint <= 0x10FFFF))) {
+				((codePoint >= 0xE000) && (codePoint <= 0xFFFD))) {
+			validCodepoint = true;
+		}
+		else if (Character.isLowSurrogate(codePoint)) {
+			if (highSurrogateSeen) {
+				validCodepoint = true;
+			} else {
+				throw new XmlPullParserException("Low surrogate '0x " + String.format("%x", (int) codePoint) + " without preceeding high surrogate");
+			}
+		}
+		else if (Character.isHighSurrogate(codePoint)) {
+			highSurrogateSeen = true;
+			// Return here so that highSurrogateSeen is not reset
 			return codePoint;
 		}
-		
-		throw new XmlPullParserException("Illegal XML character: " + Integer.parseInt(codePoint+"", 16));
+		// Always reset high surrogate seen
+		highSurrogateSeen = false;
+		if (validCodepoint)
+			return codePoint;
+
+		throw new XmlPullParserException("Illegal XML character '0x" + String.format("%x", (int) codePoint) + "'");
     }
 }