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(*
* Copyright (c) 2006-2009 Citrix Systems Inc.
* Copyright (c) 2010 Thomas Gazagnaire <thomas@gazagnaire.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*)
let default_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
let uri_safe_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
let padding = '='
let of_char ?(alphabet = default_alphabet) x =
if x = padding then 0 else String.index alphabet x
let to_char ?(alphabet = default_alphabet) x = alphabet.[x]
let decode ?alphabet input =
let length = String.length input in
let input =
if length mod 4 = 0 then input else input ^ String.make (4 - (length mod 4)) padding
in
let length = String.length input in
let words = length / 4 in
let padding =
match length with
| 0 -> 0
| _ when input.[length - 2] = padding -> 2
| _ when input.[length - 1] = padding -> 1
| _ -> 0
in
let output = Bytes.make ((words * 3) - padding) '\000' in
for i = 0 to words - 1 do
let a = of_char ?alphabet input.[(4 * i) + 0]
and b = of_char ?alphabet input.[(4 * i) + 1]
and c = of_char ?alphabet input.[(4 * i) + 2]
and d = of_char ?alphabet input.[(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
Bytes.set output ((3 * i) + 0) (char_of_int x);
if i <> words - 1 || padding < 2 then Bytes.set output ((3 * i) + 1) (char_of_int y);
if i <> words - 1 || padding < 1 then Bytes.set output ((3 * i) + 2) (char_of_int z)
done;
Bytes.unsafe_to_string output
let encode ?(pad = true) ?alphabet input =
let length = String.length input in
let words = (length + 2) / 3 in
(* rounded up *)
let padding_len = if length mod 3 = 0 then 0 else 3 - (length mod 3) in
let output = Bytes.make (words * 4) '\000' in
let get i = if i >= length then 0 else int_of_char input.[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
Bytes.set output ((4 * i) + 0) (to_char ?alphabet a);
Bytes.set output ((4 * i) + 1) (to_char ?alphabet b);
Bytes.set output ((4 * i) + 2) (to_char ?alphabet c);
Bytes.set output ((4 * i) + 3) (to_char ?alphabet d)
done;
for i = 1 to padding_len do
Bytes.set output (Bytes.length output - i) padding
done;
if pad
then Bytes.unsafe_to_string output
else Bytes.sub_string output 0 (Bytes.length output - padding_len)
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