1 files changed, 18 insertions, 0 deletions
diff --git a/Swiften/StringCodecs/Hexify.cpp b/Swiften/StringCodecs/Hexify.cpp
index 367743c..668079b 100644
--- a/Swiften/StringCodecs/Hexify.cpp
+++ b/Swiften/StringCodecs/Hexify.cpp
@@ -31,4 +31,22 @@ std::string Hexify::hexify(const ByteArray& data) {
 	return std::string(result.str());
 }
 
+ByteArray Hexify::unhexify(const std::string& hexstring) {
+	if (hexstring.size() % 2) {
+		return ByteArray();
+	}
+	ByteArray result = ByteArray(hexstring.size() / 2);
+	for (size_t pos = 0; pos < hexstring.size() - 1; pos += 2) {
+		char c;
+		c = hexstring[pos];
+		int a = (c>='0'&&c<='9') ? c-'0' : (c>='A'&&c<='Z') ? c-'A' + 10 : (c>='a'&&c<='z') ? c-'a' + 10 : -1;
+		c = hexstring[pos+1];
+		int b = (c>='0'&&c<='9') ? c-'0' : (c>='A'&&c<='Z') ? c-'A' + 10 : (c>='a'&&c<='z') ? c-'a' + 10 : -1;
+		if (a == -1 || b == -1) return ByteArray(); // fail
+		result[pos/2] = (a<<4) | b;
+
+	}
+	return result;
+}
+
 }