Line data    Source code

       1             : // Copyright (C) 2009 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : //
      15             : // This code is based heavily on Robert Harder's <rob@iharder.net>
      16             : // public domain Base64 class, version 2.1.
      17             : //
      18             : 
      19             : package com.google.gerrit.httpd;
      20             : 
      21             : /** Base64 encoder which uses a language safe within HTTP cookies. */
      22             : class CookieBase64 {
      23             :   private static final char[] enc;
      24             : 
      25             :   static {
      26           1 :     enc = new char[64];
      27           1 :     int o = 0;
      28           1 :     o = fill(enc, o, 'a', 'z');
      29           1 :     o = fill(enc, o, 'A', 'Z');
      30           1 :     o = fill(enc, o, '0', '9');
      31           1 :     enc[o++] = '-';
      32           1 :     enc[o] = '.';
      33           1 :   }
      34             : 
      35             :   private static int fill(char[] out, int o, char f, int l) {
      36           1 :     for (char c = f; c <= l; c++) {
      37           1 :       out[o++] = c;
      38             :     }
      39           1 :     return o;
      40             :   }
      41             : 
      42             :   static String encode(byte[] in) {
      43           1 :     final StringBuilder out = new StringBuilder(in.length * 4 / 3);
      44           1 :     final int len2 = in.length - 2;
      45           1 :     int d = 0;
      46           1 :     for (; d < len2; d += 3) {
      47           1 :       encode3to4(out, in, d, 3);
      48             :     }
      49           1 :     if (d < in.length) {
      50           1 :       encode3to4(out, in, d, in.length - d);
      51             :     }
      52           1 :     return out.toString();
      53             :   }
      54             : 
      55             :   private static void encode3to4(StringBuilder out, byte[] in, int inOffset, int numSigBytes) {
      56             :     //           1         2         3
      57             :     // 01234567890123456789012345678901 Bit position
      58             :     // --------000000001111111122222222 Array position from threeBytes
      59             :     // --------|    ||    ||    ||    | Six bit groups to index ALPHABET
      60             :     //          >>18  >>12  >> 6  >> 0  Right shift necessary
      61             :     //                0x3f  0x3f  0x3f  Additional AND
      62             : 
      63             :     // Create buffer with zero-padding if there are only one or two
      64             :     // significant bytes passed in the array.
      65             :     // We have to shift left 24 in order to flush out the 1's that appear
      66             :     // when Java treats a value as negative that is cast from a byte to an int.
      67             :     //
      68             :     int inBuff =
      69           1 :         (numSigBytes > 0 ? ((in[inOffset] << 24) >>> 8) : 0)
      70           1 :             | (numSigBytes > 1 ? ((in[inOffset + 1] << 24) >>> 16) : 0)
      71           1 :             | (numSigBytes > 2 ? ((in[inOffset + 2] << 24) >>> 24) : 0);
      72             : 
      73           1 :     switch (numSigBytes) {
      74             :       case 3:
      75           1 :         out.append(enc[(inBuff >>> 18)]);
      76           1 :         out.append(enc[(inBuff >>> 12) & 0x3f]);
      77           1 :         out.append(enc[(inBuff >>> 6) & 0x3f]);
      78           1 :         out.append(enc[inBuff & 0x3f]);
      79           1 :         break;
      80             : 
      81             :       case 2:
      82           0 :         out.append(enc[(inBuff >>> 18)]);
      83           0 :         out.append(enc[(inBuff >>> 12) & 0x3f]);
      84           0 :         out.append(enc[(inBuff >>> 6) & 0x3f]);
      85           0 :         break;
      86             : 
      87             :       case 1:
      88           1 :         out.append(enc[(inBuff >>> 18)]);
      89           1 :         out.append(enc[(inBuff >>> 12) & 0x3f]);
      90           1 :         break;
      91             : 
      92             :       default:
      93             :         break;
      94             :     }
      95           1 :   }
      96             : 
      97             :   private CookieBase64() {}
      98             : }