lib/base64-decode.c

   1 /*
   2  * This code originally came from here
   3  *
   4  * http://base64.sourceforge.net/b64.c
   5  *
   6  * with the following license:
   7  *
   8  * LICENCE:        Copyright (c) 2001 Bob Trower, Trantor Standard Systems Inc.
   9  *
  10  *                Permission is hereby granted, free of charge, to any person
  11  *                obtaining a copy of this software and associated
  12  *                documentation files (the "Software"), to deal in the
  13  *                Software without restriction, including without limitation
  14  *                the rights to use, copy, modify, merge, publish, distribute,
  15  *                sublicense, and/or sell copies of the Software, and to
  16  *                permit persons to whom the Software is furnished to do so,
  17  *                subject to the following conditions:
  18  *
  19  *                The above copyright notice and this permission notice shall
  20  *                be included in all copies or substantial portions of the
  21  *                Software.
  22  *
  23  *                THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  24  *                KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  25  *                WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  26  *                PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
  27  *                OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  28  *                OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  29  *                OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  30  *                SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31  *
  32  * VERSION HISTORY:
  33  *               Bob Trower 08/04/01 -- Create Version 0.00.00B
  34  *
  35  * I cleaned it up quite a bit to match the (linux kernel) style of the rest
  36  * of libwebsockets; this version is under LGPL2.1 + SLE like the rest of lws
  37  * since he explicitly allows sublicensing, but I give the URL above so you can
  38  * get the original with Bob's super-liberal terms directly if you prefer.
  39  */
  40
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include "private-libwebsockets.h"
  44
  45 static const char encode[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
  46                              "abcdefghijklmnopqrstuvwxyz0123456789+/";
  47 static const char decode[] = "|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW"
  48                              "$$$$$$XYZ[\\]^_`abcdefghijklmnopq";
  49
  50 LWS_VISIBLE int
  51 lws_b64_encode_string(const char *in, int in_len, char *out, int out_size)
  52 {
  53         unsigned char triple[3];
  54         int i;
  55         int len;
  56         int line = 0;
  57         int done = 0;
  58
  59         while (in_len) {
  60                 len = 0;
  61                 for (i = 0; i < 3; i++) {
  62                         if (in_len) {
  63                                 triple[i] = *in++;
  64                                 len++;
  65                                 in_len--;
  66                         } else
  67                                 triple[i] = 0;
  68                 }
  69
  70                 if (done + 4 >= out_size)
  71                         return -1;
  72
  73                 *out++ = encode[triple[0] >> 2];
  74                 *out++ = encode[((triple[0] & 0x03) << 4) |
  75                                              ((triple[1] & 0xf0) >> 4)];
  76                 *out++ = (len > 1 ? encode[((triple[1] & 0x0f) << 2) |
  77                                              ((triple[2] & 0xc0) >> 6)] : '=');
  78                 *out++ = (len > 2 ? encode[triple[2] & 0x3f] : '=');
  79
  80                 done += 4;
  81                 line += 4;
  82         }
  83
  84         if (done + 1 >= out_size)
  85                 return -1;
  86
  87         *out++ = '\0';
  88
  89         return done;
  90 }
  91
  92 /*
  93  * returns length of decoded string in out, or -1 if out was too small
  94  * according to out_size
  95  */
  96
  97 LWS_VISIBLE int
  98 lws_b64_decode_string(const char *in, char *out, int out_size)
  99 {
 100         int len, i, c = 0, done = 0;
 101         unsigned char v, quad[4];
 102
 103         while (*in) {
 104
 105                 len = 0;
 106                 for (i = 0; i < 4 && *in; i++) {
 107
 108                         v = 0;
 109                         c = 0;
 110                         while (*in && !v) {
 111                                 c = v = *in++;
 112                                 v = (v < 43 || v > 122) ? 0 : decode[v - 43];
 113                                 if (v)
 114                                         v = (v == '$') ? 0 : v - 61;
 115                         }
 116                         if (c) {
 117                                 len++;
 118                                 if (v)
 119                                         quad[i] = v - 1;
 120                         } else
 121                                 quad[i] = 0;
 122                 }
 123
 124                 if (out_size < (done + len - 1))
 125                         /* out buffer is too small */
 126                         return -1;
 127
 128                 /*
 129                  * "The '==' sequence indicates that the last group contained
 130                  * only one byte, and '=' indicates that it contained two
 131                  * bytes." (wikipedia)
 132                  */
 133
 134                 if (!*in && c == '=')
 135                         len--;
 136
 137                 if (len >= 2)
 138                         *out++ = quad[0] << 2 | quad[1] >> 4;
 139                 if (len >= 3)
 140                         *out++ = quad[1] << 4 | quad[2] >> 2;
 141                 if (len >= 4)
 142                         *out++ = ((quad[2] << 6) & 0xc0) | quad[3];
 143
 144                 done += len - 1;
 145         }
 146
 147         if (done + 1 >= out_size)
 148                 return -1;
 149
 150         *out = '\0';
 151
 152         return done;
 153 }
 154
 155 #if 0
 156 int
 157 lws_b64_selftest(void)
 158 {
 159         char buf[64];
 160         unsigned int n,  r = 0;
 161         unsigned int test;
 162         /* examples from https://en.wikipedia.org/wiki/Base64 */
 163         static const char * const plaintext[] = {
 164                 "any carnal pleasure.",
 165                 "any carnal pleasure",
 166                 "any carnal pleasur",
 167                 "any carnal pleasu",
 168                 "any carnal pleas",
 169                 "Admin:kloikloi"
 170         };
 171         static const char * const coded[] = {
 172                 "YW55IGNhcm5hbCBwbGVhc3VyZS4=",
 173                 "YW55IGNhcm5hbCBwbGVhc3VyZQ==",
 174                 "YW55IGNhcm5hbCBwbGVhc3Vy",
 175                 "YW55IGNhcm5hbCBwbGVhc3U=",
 176                 "YW55IGNhcm5hbCBwbGVhcw==",
 177                 "QWRtaW46a2xvaWtsb2k="
 178         };
 179
 180         for (test = 0; test < sizeof plaintext / sizeof(plaintext[0]); test++) {
 181
 182                 buf[sizeof(buf) - 1] = '\0';
 183                 n = lws_b64_encode_string(plaintext[test],
 184                                       strlen(plaintext[test]), buf, sizeof buf);
 185                 if (n != strlen(coded[test]) || strcmp(buf, coded[test])) {
 186                         lwsl_err("Failed lws_b64 encode selftest "
 187                                            "%d result '%s' %d\n", test, buf, n);
 188                         r = -1;
 189                 }
 190
 191                 buf[sizeof(buf) - 1] = '\0';
 192                 n = lws_b64_decode_string(coded[test], buf, sizeof buf);
 193                 if (n != strlen(plaintext[test]) ||
 194                                                  strcmp(buf, plaintext[test])) {
 195                         lwsl_err("Failed lws_b64 decode selftest "
 196                                  "%d result '%s' / '%s', %d / %d\n",
 197                                  test, buf, plaintext[test], n, strlen(plaintext[test]));
 198                         r = -1;
 199                 }
 200         }
 201
 202         lwsl_notice("Base 64 selftests passed\n");
 203
 204         return r;
 205 }
 206 #endif