contrib/wpa/src/utils/base64.c

   1 /*
   2  * Base64 encoding/decoding (RFC1341)
   3  * Copyright (c) 2005-2019, 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 #include <stdint.h>
  11
  12 #include "os.h"
  13 #include "base64.h"
  14
  15 static const unsigned char base64_table[65] =
  16         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  17 static const unsigned char base64_url_table[65] =
  18         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
  19
  20
  21 static unsigned char * base64_gen_encode(const unsigned char *src, size_t len,
  22                                          size_t *out_len,
  23                                          const unsigned char *table,
  24                                          int add_pad)
  25 {
  26         unsigned char *out, *pos;
  27         const unsigned char *end, *in;
  28         size_t olen;
  29         int line_len;
  30
  31         if (len >= SIZE_MAX / 4)
  32                 return NULL;
  33         olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
  34         if (add_pad)
  35                 olen += olen / 72; /* line feeds */
  36         olen++; /* nul termination */
  37         if (olen < len)
  38                 return NULL; /* integer overflow */
  39         out = os_malloc(olen);
  40         if (out == NULL)
  41                 return NULL;
  42
  43         end = src + len;
  44         in = src;
  45         pos = out;
  46         line_len = 0;
  47         while (end - in >= 3) {
  48                 *pos++ = table[(in[0] >> 2) & 0x3f];
  49                 *pos++ = table[(((in[0] & 0x03) << 4) | (in[1] >> 4)) & 0x3f];
  50                 *pos++ = table[(((in[1] & 0x0f) << 2) | (in[2] >> 6)) & 0x3f];
  51                 *pos++ = table[in[2] & 0x3f];
  52                 in += 3;
  53                 line_len += 4;
  54                 if (add_pad && line_len >= 72) {
  55                         *pos++ = '\n';
  56                         line_len = 0;
  57                 }
  58         }
  59
  60         if (end - in) {
  61                 *pos++ = table[(in[0] >> 2) & 0x3f];
  62                 if (end - in == 1) {
  63                         *pos++ = table[((in[0] & 0x03) << 4) & 0x3f];
  64                         if (add_pad)
  65                                 *pos++ = '=';
  66                 } else {
  67                         *pos++ = table[(((in[0] & 0x03) << 4) |
  68                                         (in[1] >> 4)) & 0x3f];
  69                         *pos++ = table[((in[1] & 0x0f) << 2) & 0x3f];
  70                 }
  71                 if (add_pad)
  72                         *pos++ = '=';
  73                 line_len += 4;
  74         }
  75
  76         if (add_pad && line_len)
  77                 *pos++ = '\n';
  78
  79         *pos = '\0';
  80         if (out_len)
  81                 *out_len = pos - out;
  82         return out;
  83 }
  84
  85
  86 static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
  87                                          size_t *out_len,
  88                                          const unsigned char *table)
  89 {
  90         unsigned char dtable[256], *out, *pos, block[4], tmp;
  91         size_t i, count, olen;
  92         int pad = 0;
  93         size_t extra_pad;
  94
  95         os_memset(dtable, 0x80, 256);
  96         for (i = 0; i < sizeof(base64_table) - 1; i++)
  97                 dtable[table[i]] = (unsigned char) i;
  98         dtable['='] = 0;
  99
 100         count = 0;
 101         for (i = 0; i < len; i++) {
 102                 if (dtable[src[i]] != 0x80)
 103                         count++;
 104         }
 105
 106         if (count == 0)
 107                 return NULL;
 108         extra_pad = (4 - count % 4) % 4;
 109
 110         olen = (count + extra_pad) / 4 * 3;
 111         pos = out = os_malloc(olen);
 112         if (out == NULL)
 113                 return NULL;
 114
 115         count = 0;
 116         for (i = 0; i < len + extra_pad; i++) {
 117                 unsigned char val;
 118
 119                 if (i >= len)
 120                         val = '=';
 121                 else
 122                         val = src[i];
 123                 tmp = dtable[val];
 124                 if (tmp == 0x80)
 125                         continue;
 126
 127                 if (val == '=')
 128                         pad++;
 129                 block[count] = tmp;
 130                 count++;
 131                 if (count == 4) {
 132                         *pos++ = (block[0] << 2) | (block[1] >> 4);
 133                         *pos++ = (block[1] << 4) | (block[2] >> 2);
 134                         *pos++ = (block[2] << 6) | block[3];
 135                         count = 0;
 136                         if (pad) {
 137                                 if (pad == 1)
 138                                         pos--;
 139                                 else if (pad == 2)
 140                                         pos -= 2;
 141                                 else {
 142                                         /* Invalid padding */
 143                                         os_free(out);
 144                                         return NULL;
 145                                 }
 146                                 break;
 147                         }
 148                 }
 149         }
 150
 151         *out_len = pos - out;
 152         return out;
 153 }
 154
 155
 156 /**
 157  * base64_encode - Base64 encode
 158  * @src: Data to be encoded
 159  * @len: Length of the data to be encoded
 160  * @out_len: Pointer to output length variable, or %NULL if not used
 161  * Returns: Allocated buffer of out_len bytes of encoded data,
 162  * or %NULL on failure
 163  *
 164  * Caller is responsible for freeing the returned buffer. Returned buffer is
 165  * nul terminated to make it easier to use as a C string. The nul terminator is
 166  * not included in out_len.
 167  */
 168 unsigned char * base64_encode(const unsigned char *src, size_t len,
 169                               size_t *out_len)
 170 {
 171         return base64_gen_encode(src, len, out_len, base64_table, 1);
 172 }
 173
 174
 175 unsigned char * base64_url_encode(const unsigned char *src, size_t len,
 176                                   size_t *out_len, int add_pad)
 177 {
 178         return base64_gen_encode(src, len, out_len, base64_url_table, add_pad);
 179 }
 180
 181
 182 /**
 183  * base64_decode - Base64 decode
 184  * @src: Data to be decoded
 185  * @len: Length of the data to be decoded
 186  * @out_len: Pointer to output length variable
 187  * Returns: Allocated buffer of out_len bytes of decoded data,
 188  * or %NULL on failure
 189  *
 190  * Caller is responsible for freeing the returned buffer.
 191  */
 192 unsigned char * base64_decode(const unsigned char *src, size_t len,
 193                               size_t *out_len)
 194 {
 195         return base64_gen_decode(src, len, out_len, base64_table);
 196 }
 197
 198
 199 unsigned char * base64_url_decode(const unsigned char *src, size_t len,
 200                                   size_t *out_len)
 201 {
 202         return base64_gen_decode(src, len, out_len, base64_url_table);
 203 }