libeap/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
  17 /**
  18  * base64_encode - Base64 encode
  19  * @src: Data to be encoded
  20  * @len: Length of the data to be encoded
  21  * @out_len: Pointer to output length variable, or %NULL if not used
  22  * Returns: Allocated buffer of out_len bytes of encoded data,
  23  * or %NULL on failure
  24  *
  25  * Caller is responsible for freeing the returned buffer. Returned buffer is
  26  * nul terminated to make it easier to use as a C string. The nul terminator is
  27  * not included in out_len.
  28  */
  29 unsigned char * base64_encode(const unsigned char *src, size_t len,
  30                               size_t *out_len)
  31 {
  32         unsigned char *out, *pos;
  33         const unsigned char *end, *in;
  34         size_t olen;
  35         int line_len;
  36
  37         olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
  38         olen += olen / 72; /* line feeds */
  39         olen++; /* nul termination */
  40         if (olen < len)
  41                 return NULL; /* integer overflow */
  42         out = os_malloc(olen);
  43         if (out == NULL)
  44                 return NULL;
  45
  46         end = src + len;
  47         in = src;
  48         pos = out;
  49         line_len = 0;
  50         while (end - in >= 3) {
  51                 *pos++ = base64_table[(in[0] >> 2) & 0x3f];
  52                 *pos++ = base64_table[(((in[0] & 0x03) << 4) |
  53                                        (in[1] >> 4)) & 0x3f];
  54                 *pos++ = base64_table[(((in[1] & 0x0f) << 2) |
  55                                        (in[2] >> 6)) & 0x3f];
  56                 *pos++ = base64_table[in[2] & 0x3f];
  57                 in += 3;
  58                 line_len += 4;
  59                 if (line_len >= 72) {
  60                         *pos++ = '\n';
  61                         line_len = 0;
  62                 }
  63         }
  64
  65         if (end - in) {
  66                 *pos++ = base64_table[(in[0] >> 2) & 0x3f];
  67                 if (end - in == 1) {
  68                         *pos++ = base64_table[((in[0] & 0x03) << 4) & 0x3f];
  69                         *pos++ = '=';
  70                 } else {
  71                         *pos++ = base64_table[(((in[0] & 0x03) << 4) |
  72                                                (in[1] >> 4)) & 0x3f];
  73                         *pos++ = base64_table[((in[1] & 0x0f) << 2) & 0x3f];
  74                 }
  75                 *pos++ = '=';
  76                 line_len += 4;
  77         }
  78
  79         if (line_len)
  80                 *pos++ = '\n';
  81
  82         *pos = '\0';
  83         if (out_len)
  84                 *out_len = pos - out;
  85         return out;
  86 }
  87
  88
  89 /**
  90  * base64_decode - Base64 decode
  91  * @src: Data to be decoded
  92  * @len: Length of the data to be decoded
  93  * @out_len: Pointer to output length variable
  94  * Returns: Allocated buffer of out_len bytes of decoded data,
  95  * or %NULL on failure
  96  *
  97  * Caller is responsible for freeing the returned buffer.
  98  */
  99 unsigned char * base64_decode(const unsigned char *src, size_t len,
 100                               size_t *out_len)
 101 {
 102         unsigned char dtable[256], *out, *pos, block[4], tmp;
 103         size_t i, count, olen;
 104         int pad = 0;
 105
 106         os_memset(dtable, 0x80, 256);
 107         for (i = 0; i < sizeof(base64_table) - 1; i++)
 108                 dtable[base64_table[i]] = (unsigned char) i;
 109         dtable['='] = 0;
 110
 111         count = 0;
 112         for (i = 0; i < len; i++) {
 113                 if (dtable[src[i]] != 0x80)
 114                         count++;
 115         }
 116
 117         if (count == 0 || count % 4)
 118                 return NULL;
 119
 120         olen = count / 4 * 3;
 121         pos = out = os_malloc(olen);
 122         if (out == NULL)
 123                 return NULL;
 124
 125         count = 0;
 126         for (i = 0; i < len; i++) {
 127                 tmp = dtable[src[i]];
 128                 if (tmp == 0x80)
 129                         continue;
 130
 131                 if (src[i] == '=')
 132                         pad++;
 133                 block[count] = tmp;
 134                 count++;
 135                 if (count == 4) {
 136                         *pos++ = (block[0] << 2) | (block[1] >> 4);
 137                         *pos++ = (block[1] << 4) | (block[2] >> 2);
 138                         *pos++ = (block[2] << 6) | block[3];
 139                         count = 0;
 140                         if (pad) {
 141                                 if (pad == 1)
 142                                         pos--;
 143                                 else if (pad == 2)
 144                                         pos -= 2;
 145                                 else {
 146                                         /* Invalid padding */
 147                                         os_free(out);
 148                                         return NULL;
 149                                 }
 150                                 break;
 151                         }
 152                 }
 153         }
 154
 155         *out_len = pos - out;
 156         return out;
 157 }