contrib/wpa/src/utils/base64.c

   1 /*
   2  * Base64 encoding/decoding (RFC1341)
   3  * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "os.h"
  12 #include "base64.h"
  13
  14 static const unsigned char base64_table[65] =
  15         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  16 static const unsigned char base64_url_table[65] =
  17         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
  18
  19
  20 static unsigned char * base64_gen_encode(const unsigned char *src, size_t len,
  21                                          size_t *out_len,
  22                                          const unsigned char *table,
  23                                          int add_pad)
  24 {
  25         unsigned char *out, *pos;
  26         const unsigned char *end, *in;
  27         size_t olen;
  28         int line_len;
  29
  30         olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
  31         if (add_pad)
  32                 olen += olen / 72; /* line feeds */
  33         olen++; /* nul termination */
  34         if (olen < len)
  35                 return NULL; /* integer overflow */
  36         out = os_malloc(olen);
  37         if (out == NULL)
  38                 return NULL;
  39
  40         end = src + len;
  41         in = src;
  42         pos = out;
  43         line_len = 0;
  44         while (end - in >= 3) {
  45                 *pos++ = table[(in[0] >> 2) & 0x3f];
  46                 *pos++ = table[(((in[0] & 0x03) << 4) | (in[1] >> 4)) & 0x3f];
  47                 *pos++ = table[(((in[1] & 0x0f) << 2) | (in[2] >> 6)) & 0x3f];
  48                 *pos++ = table[in[2] & 0x3f];
  49                 in += 3;
  50                 line_len += 4;
  51                 if (add_pad && line_len >= 72) {
  52                         *pos++ = '\n';
  53                         line_len = 0;
  54                 }
  55         }
  56
  57         if (end - in) {
  58                 *pos++ = table[(in[0] >> 2) & 0x3f];
  59                 if (end - in == 1) {
  60                         *pos++ = table[((in[0] & 0x03) << 4) & 0x3f];
  61                         if (add_pad)
  62                                 *pos++ = '=';
  63                 } else {
  64                         *pos++ = table[(((in[0] & 0x03) << 4) |
  65                                         (in[1] >> 4)) & 0x3f];
  66                         *pos++ = table[((in[1] & 0x0f) << 2) & 0x3f];
  67                 }
  68                 if (add_pad)
  69                         *pos++ = '=';
  70                 line_len += 4;
  71         }
  72
  73         if (add_pad && line_len)
  74                 *pos++ = '\n';
  75
  76         *pos = '\0';
  77         if (out_len)
  78                 *out_len = pos - out;
  79         return out;
  80 }
  81
  82
  83 static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
  84                                          size_t *out_len,
  85                                          const unsigned char *table)
  86 {
  87         unsigned char dtable[256], *out, *pos, block[4], tmp;
  88         size_t i, count, olen;
  89         int pad = 0;
  90         size_t extra_pad;
  91
  92         os_memset(dtable, 0x80, 256);
  93         for (i = 0; i < sizeof(base64_table) - 1; i++)
  94                 dtable[table[i]] = (unsigned char) i;
  95         dtable['='] = 0;
  96
  97         count = 0;
  98         for (i = 0; i < len; i++) {
  99                 if (dtable[src[i]] != 0x80)
 100                         count++;
 101         }
 102
 103         if (count == 0)
 104                 return NULL;
 105         extra_pad = (4 - count % 4) % 4;
 106
 107         olen = (count + extra_pad) / 4 * 3;
 108         pos = out = os_malloc(olen);
 109         if (out == NULL)
 110                 return NULL;
 111
 112         count = 0;
 113         for (i = 0; i < len + extra_pad; i++) {
 114                 unsigned char val;
 115
 116                 if (i >= len)
 117                         val = '=';
 118                 else
 119                         val = src[i];
 120                 tmp = dtable[val];
 121                 if (tmp == 0x80)
 122                         continue;
 123
 124                 if (val == '=')
 125                         pad++;
 126                 block[count] = tmp;
 127                 count++;
 128                 if (count == 4) {
 129                         *pos++ = (block[0] << 2) | (block[1] >> 4);
 130                         *pos++ = (block[1] << 4) | (block[2] >> 2);
 131                         *pos++ = (block[2] << 6) | block[3];
 132                         count = 0;
 133                         if (pad) {
 134                                 if (pad == 1)
 135                                         pos--;
 136                                 else if (pad == 2)
 137                                         pos -= 2;
 138                                 else {
 139                                         /* Invalid padding */
 140                                         os_free(out);
 141                                         return NULL;
 142                                 }
 143                                 break;
 144                         }
 145                 }
 146         }
 147
 148         *out_len = pos - out;
 149         return out;
 150 }
 151
 152
 153 /**
 154  * base64_encode - Base64 encode
 155  * @src: Data to be encoded
 156  * @len: Length of the data to be encoded
 157  * @out_len: Pointer to output length variable, or %NULL if not used
 158  * Returns: Allocated buffer of out_len bytes of encoded data,
 159  * or %NULL on failure
 160  *
 161  * Caller is responsible for freeing the returned buffer. Returned buffer is
 162  * nul terminated to make it easier to use as a C string. The nul terminator is
 163  * not included in out_len.
 164  */
 165 unsigned char * base64_encode(const unsigned char *src, size_t len,
 166                               size_t *out_len)
 167 {
 168         return base64_gen_encode(src, len, out_len, base64_table, 1);
 169 }
 170
 171
 172 unsigned char * base64_url_encode(const unsigned char *src, size_t len,
 173                                   size_t *out_len, int add_pad)
 174 {
 175         return base64_gen_encode(src, len, out_len, base64_url_table, add_pad);
 176 }
 177
 178
 179 /**
 180  * base64_decode - Base64 decode
 181  * @src: Data to be decoded
 182  * @len: Length of the data to be decoded
 183  * @out_len: Pointer to output length variable
 184  * Returns: Allocated buffer of out_len bytes of decoded data,
 185  * or %NULL on failure
 186  *
 187  * Caller is responsible for freeing the returned buffer.
 188  */
 189 unsigned char * base64_decode(const unsigned char *src, size_t len,
 190                               size_t *out_len)
 191 {
 192         return base64_gen_decode(src, len, out_len, base64_table);
 193 }
 194
 195
 196 unsigned char * base64_url_decode(const unsigned char *src, size_t len,
 197                                   size_t *out_len)
 198 {
 199         return base64_gen_decode(src, len, out_len, base64_url_table);
 200 }