83 lines
3.3 KiB
OCaml
83 lines
3.3 KiB
OCaml
(*
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* Copyright (c) 2006-2009 Citrix Systems Inc.
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* Copyright (c) 2010 Thomas Gazagnaire <thomas@gazagnaire.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*)
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let default_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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let uri_safe_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
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let padding = '='
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let of_char ?(alphabet = default_alphabet) x =
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if x = padding then 0 else String.index alphabet x
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let to_char ?(alphabet = default_alphabet) x = alphabet.[x]
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let decode ?alphabet input =
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let length = String.length input in
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let input =
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if length mod 4 = 0 then input else input ^ String.make (4 - (length mod 4)) padding
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in
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let length = String.length input in
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let words = length / 4 in
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let padding =
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match length with
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| 0 -> 0
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| _ when input.[length - 2] = padding -> 2
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| _ when input.[length - 1] = padding -> 1
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| _ -> 0
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in
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let output = Bytes.make ((words * 3) - padding) '\000' in
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for i = 0 to words - 1 do
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let a = of_char ?alphabet input.[(4 * i) + 0]
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and b = of_char ?alphabet input.[(4 * i) + 1]
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and c = of_char ?alphabet input.[(4 * i) + 2]
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and d = of_char ?alphabet input.[(4 * i) + 3] in
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let n = (a lsl 18) lor (b lsl 12) lor (c lsl 6) lor d in
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let x = (n lsr 16) land 255 and y = (n lsr 8) land 255 and z = n land 255 in
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Bytes.set output ((3 * i) + 0) (char_of_int x);
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if i <> words - 1 || padding < 2 then Bytes.set output ((3 * i) + 1) (char_of_int y);
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if i <> words - 1 || padding < 1 then Bytes.set output ((3 * i) + 2) (char_of_int z)
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done;
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Bytes.unsafe_to_string output
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let encode ?(pad = true) ?alphabet input =
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let length = String.length input in
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let words = (length + 2) / 3 in
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(* rounded up *)
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let padding_len = if length mod 3 = 0 then 0 else 3 - (length mod 3) in
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let output = Bytes.make (words * 4) '\000' in
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let get i = if i >= length then 0 else int_of_char input.[i] in
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for i = 0 to words - 1 do
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let x = get ((3 * i) + 0) and y = get ((3 * i) + 1) and z = get ((3 * i) + 2) in
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let n = (x lsl 16) lor (y lsl 8) lor z in
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let a = (n lsr 18) land 63
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and b = (n lsr 12) land 63
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and c = (n lsr 6) land 63
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and d = n land 63 in
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Bytes.set output ((4 * i) + 0) (to_char ?alphabet a);
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Bytes.set output ((4 * i) + 1) (to_char ?alphabet b);
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Bytes.set output ((4 * i) + 2) (to_char ?alphabet c);
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Bytes.set output ((4 * i) + 3) (to_char ?alphabet d)
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done;
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for i = 1 to padding_len do
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Bytes.set output (Bytes.length output - i) padding
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done;
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if pad
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then Bytes.unsafe_to_string output
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else Bytes.sub_string output 0 (Bytes.length output - padding_len)
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