1 files changed, 67 insertions, 0 deletions
diff --git a/Swiften/IDN/UTF8Validator.h b/Swiften/IDN/UTF8Validator.h
new file mode 100644
index 0000000..5df8769
--- /dev/null
+++ b/Swiften/IDN/UTF8Validator.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2015 Isode Limited.
+ * All rights reserved.
+ * See the COPYING file for more information.
+ */
+
+#pragma once
+
+#include <cstddef>
+
+namespace Swift {
+
+// UTF-8 validation based on the description in https://tools.ietf.org/html/rfc3629#section-3 .
+template <typename CharType>
+bool UTF8IsValid(const CharType* data, size_t length) {
+	bool isValid = true;
+	const CharType* current = data;
+	const CharType* end = data + length;
+	while (isValid && (current < end)) {
+		// one byte sequences
+		if ((*current & 0x80) == 0x0) {
+			current++;
+			continue;
+		}
+		// longer byte sequences
+		else {
+			// two byte sequences
+			if ((*current & 0xE0) == 0xC0) {
+				current++;
+				if ( (current < end) && ((*current & 0xC0) == 0x80) ) {
+					current++;
+					continue;
+				}
+			}
+			// three byte sequences
+			else if ((*current & 0xF0) == 0xE0) {
+				current++;
+				if ( ((current + 1) < end) && ((*current & 0xC0) == 0x80) ) {
+					current++;
+					if ((*current & 0xC0) == 0x80) {
+						current++;
+						continue;
+					}
+				}
+			}
+			// four byte sequences
+			else if ((*current & 0xF8) == 0xF0) {
+				current++;
+				if ( ((current + 2) < end) && ((*current & 0xC0) == 0x80) ) {
+					current++;
+					if ((*current & 0xC0) == 0x80) {
+						current++;
+						if ((*current & 0xC0) == 0x80) {
+							current++;
+							continue;
+						}
+					}
+				}
+			}
+			// invalid sequences
+			isValid = false;
+		}
+	}
+	return isValid;
+}
+
+}