fs/ceph/armor.c

   1
   2 #include <linux/errno.h>
   3
   4 /*
   5  * base64 encode/decode.
   6  */
   7
   8 const char *pem_key = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   9
  10 static int encode_bits(int c)
  11 {
  12         return pem_key[c];
  13 }
  14
  15 static int decode_bits(char c)
  16 {
  17         if (c >= 'A' && c <= 'Z')
  18                 return c - 'A';
  19         if (c >= 'a' && c <= 'z')
  20                 return c - 'a' + 26;
  21         if (c >= '0' && c <= '9')
  22                 return c - '0' + 52;
  23         if (c == '+')
  24                 return 62;
  25         if (c == '/')
  26                 return 63;
  27         if (c == '=')
  28                 return 0; /* just non-negative, please */
  29         return -EINVAL;
  30 }
  31
  32 int ceph_armor(char *dst, const char *src, const char *end)
  33 {
  34         int olen = 0;
  35         int line = 0;
  36
  37         while (src < end) {
  38                 unsigned char a, b, c;
  39
  40                 a = *src++;
  41                 *dst++ = encode_bits(a >> 2);
  42                 if (src < end) {
  43                         b = *src++;
  44                         *dst++ = encode_bits(((a & 3) << 4) | (b >> 4));
  45                         if (src < end) {
  46                                 c = *src++;
  47                                 *dst++ = encode_bits(((b & 15) << 2) |
  48                                                      (c >> 6));
  49                                 *dst++ = encode_bits(c & 63);
  50                         } else {
  51                                 *dst++ = encode_bits((b & 15) << 2);
  52                                 *dst++ = '=';
  53                         }
  54                 } else {
  55                         *dst++ = encode_bits(((a & 3) << 4));
  56                         *dst++ = '=';
  57                         *dst++ = '=';
  58                 }
  59                 olen += 4;
  60                 line += 4;
  61                 if (line == 64) {
  62                         line = 0;
  63                         *(dst++) = '\n';
  64                         olen++;
  65                 }
  66         }
  67         return olen;
  68 }
  69
  70 int ceph_unarmor(char *dst, const char *src, const char *end)
  71 {
  72         int olen = 0;
  73
  74         while (src < end) {
  75                 int a, b, c, d;
  76
  77                 if (src < end && src[0] == '\n')
  78                         src++;
  79                 if (src + 4 > end)
  80                         return -EINVAL;
  81                 a = decode_bits(src[0]);
  82                 b = decode_bits(src[1]);
  83                 c = decode_bits(src[2]);
  84                 d = decode_bits(src[3]);
  85                 if (a < 0 || b < 0 || c < 0 || d < 0)
  86                         return -EINVAL;
  87
  88                 *dst++ = (a << 2) | (b >> 4);
  89                 if (src[2] == '=')
  90                         return olen + 1;
  91                 *dst++ = ((b & 15) << 4) | (c >> 2);
  92                 if (src[3] == '=')
  93                         return olen + 2;
  94                 *dst++ = ((c & 3) << 6) | d;
  95                 olen += 3;
  96                 src += 4;
  97         }
  98         return olen;
  99 }