Move bencode-related methods to the bencode pkg.

This will allow a separation of the dht package.

addresses.go

@@ -0,0 +1,23 @@
+package bencode
+
+import "fmt"
+
+// These are not strictly bencode features, but often needed by both DHT and
+// Torrent clients.
+
+func BinaryToDottedPort(port string) string {
+	return fmt.Sprintf("%d.%d.%d.%d:%d", port[0], port[1], port[2], port[3],
+		(uint16(port[4])<<8)|uint16(port[5]))
+}
+
+// 97.98.99.100:25958 becames "abcdef".
+func DottedPortToBinary(b string) string {
+	a := make([]byte, 6, 6)
+	var c uint16
+
+	fmt.Sscanf(b, "%d.%d.%d.%d:%d", &a[0], &a[1], &a[2], &a[3], &c)
+	a[4] = uint8(c >> 8)
+	a[5] = uint8(c)
+
+	return string(a)
+}