--- /dev/null
+(*
+ * Copyright (C) 2008-2009 Citrix Ltd.
+ * Author Dave Scott <dave.scott@eu.citrix.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *)
+
+open Stringext
+
+let code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+let padding = '='
+
+let of_char x = if x = padding then 0 else String.index code x
+
+let to_char x = code.[x]
+
+let strip_whitespace s =
+ String.implode (List.filter (fun x->not (List.mem x [' ';'\t';'\n';'\r'])) (String.explode s))
+
+let decode x =
+ let x = strip_whitespace x in
+ let words = String.length x / 4 in
+ let padding =
+ if String.length x = 0 then 0 else (
+ if x.[String.length x - 2] = padding
+ then 2 else (if x.[String.length x - 1] = padding then 1 else 0)) in
+ let output = String.make (words * 3 - padding) '\000' in
+ for i = 0 to words - 1 do
+ let a = of_char x.[4 * i + 0]
+ and b = of_char x.[4 * i + 1]
+ and c = of_char x.[4 * i + 2]
+ and d = of_char x.[4 * i + 3] in
+ let n = (a lsl 18) lor (b lsl 12) lor (c lsl 6) lor d in
+ let x = (n lsr 16) land 255
+ and y = (n lsr 8) land 255
+ and z = n land 255 in
+ output.[3 * i + 0] <- char_of_int x;
+ if i <> words - 1 || padding < 2 then output.[3 * i + 1] <- char_of_int y;
+ if i <> words - 1 || padding < 1 then output.[3 * i + 2] <- char_of_int z;
+ done;
+ output
+
+let encode x =
+ let length = String.length x in
+ let words = (length + 2) / 3 in (* rounded up *)
+ let padding = if length mod 3 = 0 then 0 else 3 - (length mod 3) in
+ let output = String.make (words * 4) '\000' in
+ let get i = if i >= length then 0 else int_of_char x.[i] in
+ for i = 0 to words - 1 do
+ let x = get (3 * i + 0)
+ and y = get (3 * i + 1)
+ and z = get (3 * i + 2) in
+ let n = (x lsl 16) lor (y lsl 8) lor z in
+ let a = (n lsr 18) land 63
+ and b = (n lsr 12) land 63
+ and c = (n lsr 6) land 63
+ and d = n land 63 in
+ output.[4 * i + 0] <- to_char a;
+ output.[4 * i + 1] <- to_char b;
+ output.[4 * i + 2] <- to_char c;
+ output.[4 * i + 3] <- to_char d;
+ done;
+ for i = 1 to padding do
+ output.[String.length output - i] <- '=';
+ done;
+ output