net/ceph/armor.c

   1
   2 #include <linux/errno.h>
   3
   4 int ceph_armor(char *dst, const char *src, const char *end);
   5 int ceph_unarmor(char *dst, const char *src, const char *end);
   6
   7 /*
   8  * base64 encode/decode.
   9  */
  10
  11 static const char *pem_key =
  12         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  13
  14 static int encode_bits(int c)
  15 {
  16         return pem_key[c];
  17 }
  18
  19 static int decode_bits(char c)
  20 {
  21         if (c >= 'A' && c <= 'Z')
  22                 return c - 'A';
  23         if (c >= 'a' && c <= 'z')
  24                 return c - 'a' + 26;
  25         if (c >= '0' && c <= '9')
  26                 return c - '0' + 52;
  27         if (c == '+')
  28                 return 62;
  29         if (c == '/')
  30                 return 63;
  31         if (c == '=')
  32                 return 0; /* just non-negative, please */
  33         return -EINVAL;
  34 }
  35
  36 int ceph_armor(char *dst, const char *src, const char *end)
  37 {
  38         int olen = 0;
  39         int line = 0;
  40
  41         while (src < end) {
  42                 unsigned char a, b, c;
  43
  44                 a = *src++;
  45                 *dst++ = encode_bits(a >> 2);
  46                 if (src < end) {
  47                         b = *src++;
  48                         *dst++ = encode_bits(((a & 3) << 4) | (b >> 4));
  49                         if (src < end) {
  50                                 c = *src++;
  51                                 *dst++ = encode_bits(((b & 15) << 2) |
  52                                                      (c >> 6));
  53                                 *dst++ = encode_bits(c & 63);
  54                         } else {
  55                                 *dst++ = encode_bits((b & 15) << 2);
  56                                 *dst++ = '=';
  57                         }
  58                 } else {
  59                         *dst++ = encode_bits(((a & 3) << 4));
  60                         *dst++ = '=';
  61                         *dst++ = '=';
  62                 }
  63                 olen += 4;
  64                 line += 4;
  65                 if (line == 64) {
  66                         line = 0;
  67                         *(dst++) = '\n';
  68                         olen++;
  69                 }
  70         }
  71         return olen;
  72 }
  73
  74 int ceph_unarmor(char *dst, const char *src, const char *end)
  75 {
  76         int olen = 0;
  77
  78         while (src < end) {
  79                 int a, b, c, d;
  80
  81                 if (src < end && src[0] == '\n')
  82                         src++;
  83                 if (src + 4 > end)
  84                         return -EINVAL;
  85                 a = decode_bits(src[0]);
  86                 b = decode_bits(src[1]);
  87                 c = decode_bits(src[2]);
  88                 d = decode_bits(src[3]);
  89                 if (a < 0 || b < 0 || c < 0 || d < 0)
  90                         return -EINVAL;
  91
  92                 *dst++ = (a << 2) | (b >> 4);
  93                 if (src[2] == '=')
  94                         return olen + 1;
  95                 *dst++ = ((b & 15) << 4) | (c >> 2);
  96                 if (src[3] == '=')
  97                         return olen + 2;
  98                 *dst++ = ((c & 3) << 6) | d;
  99                 olen += 3;
 100                 src += 4;
 101         }
 102         return olen;
 103 }