modp_b64/modp_b64.cc

   1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
   2 /* vi: set expandtab shiftwidth=4 tabstop=4: */
   3 /**
   4  * \file
   5  * <PRE>
   6  * MODP_B64 - High performance base64 encoder/decoder
   7  * Version 1.3 -- 17-Mar-2006
   8  * http://modp.com/release/base64
   9  *
  10  * Copyright &copy; 2005, 2006  Nick Galbreath -- nickg [at] modp [dot] com
  11  * All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions are
  15  * met:
  16  *
  17  *   Redistributions of source code must retain the above copyright
  18  *   notice, this list of conditions and the following disclaimer.
  19  *
  20  *   Redistributions in binary form must reproduce the above copyright
  21  *   notice, this list of conditions and the following disclaimer in the
  22  *   documentation and/or other materials provided with the distribution.
  23  *
  24  *   Neither the name of the modp.com nor the names of its
  25  *   contributors may be used to endorse or promote products derived from
  26  *   this software without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  30  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  31  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  32  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  33  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  34  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  38  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  *
  40  * This is the standard "new" BSD license:
  41  * http://www.opensource.org/licenses/bsd-license.php
  42  * </PRE>
  43  */
  44
  45 /* public header */
  46 #include "modp_b64.h"
  47
  48 /*
  49  * If you are ripping this out of the library, comment out the next
  50  * line and uncomment the next lines as approrpiate
  51  */
  52 //#include "config.h"
  53
  54 /* if on motoral, sun, ibm; uncomment this */
  55 /* #define WORDS_BIGENDIAN 1 */
  56 /* else for Intel, Amd; uncomment this */
  57 /* #undef WORDS_BIGENDIAN */
  58
  59 #include "modp_b64_data.h"
  60
  61 #define BADCHAR 0x01FFFFFF
  62
  63 /**
  64  * you can control if we use padding by commenting out this
  65  * next line.  However, I highly recommend you use padding and not
  66  * using it should only be for compatability with a 3rd party.
  67  * Also, 'no padding' is not tested!
  68  */
  69 #define DOPAD 1
  70
  71 /*
  72  * if we aren't doing padding
  73  * set the pad character to NULL
  74  */
  75 #ifndef DOPAD
  76 #undef CHARPAD
  77 #define CHARPAD '\0'
  78 #endif
  79
  80 int modp_b64_encode(char* dest, const char* str, int len)
  81 {
  82     int i;
  83     uint8_t* p = (uint8_t*) dest;
  84
  85     /* unsigned here is important! */
  86     uint8_t t1, t2, t3;
  87
  88     for (i = 0; i < len - 2; i += 3) {
  89         t1 = str[i]; t2 = str[i+1]; t3 = str[i+2];
  90         *p++ = e0[t1];
  91         *p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
  92         *p++ = e1[((t2 & 0x0F) << 2) | ((t3 >> 6) & 0x03)];
  93         *p++ = e2[t3];
  94     }
  95
  96     switch (len - i) {
  97     case 0:
  98         break;
  99     case 1:
 100         t1 = str[i];
 101         *p++ = e0[t1];
 102         *p++ = e1[(t1 & 0x03) << 4];
 103         *p++ = CHARPAD;
 104         *p++ = CHARPAD;
 105         break;
 106     default: /* case 2 */
 107         t1 = str[i]; t2 = str[i+1];
 108         *p++ = e0[t1];
 109         *p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
 110         *p++ = e2[(t2 & 0x0F) << 2];
 111         *p++ = CHARPAD;
 112     }
 113
 114     *p = '\0';
 115     return p - (uint8_t*)dest;
 116 }
 117
 118 #ifdef WORDS_BIGENDIAN   /* BIG ENDIAN -- SUN / IBM / MOTOROLA */
 119 int modp_b64_decode(char* dest, const char* src, int len)
 120 {
 121     if (len == 0) return 0;
 122
 123 #ifdef DOPAD
 124     /* if padding is used, then the message must be at least
 125        4 chars and be a multiple of 4.
 126        there can be at most 2 pad chars at the end */
 127     if (len < 4 || (len % 4 != 0)) return -1;
 128     if (src[len-1] == CHARPAD) {
 129         len--;
 130         if (src[len -1] == CHARPAD) {
 131             len--;
 132         }
 133     }
 134 #endif  /* DOPAD */
 135
 136     int i;
 137     int leftover = len % 4;
 138     int chunks = (leftover == 0) ? len / 4 - 1 : len /4;
 139
 140     uint8_t* p = (uint8_t*) dest;
 141     uint32_t x = 0;
 142     uint32_t* destInt = (uint32_t*) p;
 143     uint32_t* srcInt = (uint32_t*) src;
 144     uint32_t y = *srcInt++;
 145     for (i = 0; i < chunks; ++i) {
 146         x = d0[y >> 24 & 0xff] | d1[y >> 16 & 0xff] |
 147             d2[y >> 8 & 0xff] | d3[y & 0xff];
 148
 149         if (x >= BADCHAR)  return -1;
 150         *destInt = x << 8;
 151         p += 3;
 152         destInt = (uint32_t*)p;
 153         y = *srcInt++;
 154     }
 155
 156     switch (leftover) {
 157     case 0:
 158         x = d0[y >> 24 & 0xff] | d1[y >> 16 & 0xff] |
 159             d2[y >>  8 & 0xff] | d3[y & 0xff];
 160         if (x >= BADCHAR)  return -1;
 161         *p++ = ((uint8_t*)&x)[1];
 162         *p++ = ((uint8_t*)&x)[2];
 163         *p = ((uint8_t*)&x)[3];
 164         return (chunks+1)*3;
 165     case 1:
 166         x = d3[y >> 24];
 167         *p =  (uint8_t)x;
 168         break;
 169     case 2:
 170         x = d3[y >> 24] *64 + d3[(y >> 16) & 0xff];
 171         *p =  (uint8_t)(x >> 4);
 172         break;
 173     default:  /* case 3 */
 174         x = (d3[y >> 24] *64 + d3[(y >> 16) & 0xff])*64 +
 175             d3[(y >> 8) & 0xff];
 176         *p++ = (uint8_t) (x >> 10);
 177         *p = (uint8_t) (x >> 2);
 178         break;
 179     }
 180
 181     if (x >= BADCHAR) return -1;
 182     return 3*chunks + (6*leftover)/8;
 183 }
 184
 185 #else /* LITTLE  ENDIAN -- INTEL AND FRIENDS */
 186
 187 int modp_b64_decode(char* dest, const char* src, int len)
 188 {
 189     if (len == 0) return 0;
 190
 191 #ifdef DOPAD
 192     /*
 193      * if padding is used, then the message must be at least
 194      * 4 chars and be a multiple of 4
 195      */
 196     if (len < 4 || (len % 4 != 0)) return -1; /* error */
 197     /* there can be at most 2 pad chars at the end */
 198     if (src[len-1] == CHARPAD) {
 199         len--;
 200         if (src[len -1] == CHARPAD) {
 201             len--;
 202         }
 203     }
 204 #endif
 205
 206     int i;
 207     int leftover = len % 4;
 208     int chunks = (leftover == 0) ? len / 4 - 1 : len /4;
 209
 210     uint8_t* p = (uint8_t*)dest;
 211     uint32_t x = 0;
 212     uint32_t* destInt = (uint32_t*) p;
 213     uint32_t* srcInt = (uint32_t*) src;
 214     uint32_t y = *srcInt++;
 215     for (i = 0; i < chunks; ++i) {
 216         x = d0[y & 0xff] |
 217             d1[(y >> 8) & 0xff] |
 218             d2[(y >> 16) & 0xff] |
 219             d3[(y >> 24) & 0xff];
 220
 221         if (x >= BADCHAR) return -1;
 222         *destInt = x ;
 223         p += 3;
 224         destInt = (uint32_t*)p;
 225         y = *srcInt++;}
 226
 227
 228     switch (leftover) {
 229     case 0:
 230         x = d0[y & 0xff] |
 231             d1[(y >> 8) & 0xff] |
 232             d2[(y >> 16) & 0xff] |
 233             d3[(y >> 24) & 0xff];
 234
 235         if (x >= BADCHAR) return -1;
 236         *p++ =  ((uint8_t*)(&x))[0];
 237         *p++ =  ((uint8_t*)(&x))[1];
 238         *p =    ((uint8_t*)(&x))[2];
 239         return (chunks+1)*3;
 240         break;
 241     case 1:  /* with padding this is an impossible case */
 242         x = d0[y & 0xff];
 243         *p = *((uint8_t*)(&x)); // i.e. first char/byte in int
 244         break;
 245     case 2: // * case 2, 1  output byte */
 246         x = d0[y & 0xff] | d1[y >> 8 & 0xff];
 247         *p = *((uint8_t*)(&x)); // i.e. first char
 248         break;
 249     default: /* case 3, 2 output bytes */
 250         x = d0[y & 0xff] |
 251             d1[y >> 8 & 0xff ] |
 252             d2[y >> 16 & 0xff];  /* 0x3c */
 253         *p++ =  ((uint8_t*)(&x))[0];
 254         *p =  ((uint8_t*)(&x))[1];
 255         break;
 256     }
 257
 258     if (x >= BADCHAR) return -1;
 259
 260     return 3*chunks + (6*leftover)/8;
 261 }
 262
 263 #endif  /* if bigendian / else / endif */