crypto/quic_vlint.c

   1 #include "internal/quic_vlint.h"
   2 #include "internal/e_os.h"
   3
   4 void ossl_quic_vlint_encode_n(uint8_t *buf, uint64_t v, int n)
   5 {
   6     if (n == 1) {
   7         buf[0] = (uint8_t)v;
   8     } else if (n == 2) {
   9         buf[0] = (uint8_t)(0x40 | ((v >> 8) & 0x3F));
  10         buf[1] = (uint8_t)v;
  11     } else if (n == 4) {
  12         buf[0] = (uint8_t)(0x80 | ((v >> 24) & 0x3F));
  13         buf[1] = (uint8_t)(v >> 16);
  14         buf[2] = (uint8_t)(v >>  8);
  15         buf[3] = (uint8_t)v;
  16     } else {
  17         buf[0] = (uint8_t)(0xC0 | ((v >> 56) & 0x3F));
  18         buf[1] = (uint8_t)(v >> 48);
  19         buf[2] = (uint8_t)(v >> 40);
  20         buf[3] = (uint8_t)(v >> 32);
  21         buf[4] = (uint8_t)(v >> 24);
  22         buf[5] = (uint8_t)(v >> 16);
  23         buf[6] = (uint8_t)(v >>  8);
  24         buf[7] = (uint8_t)v;
  25     }
  26 }
  27
  28 void ossl_quic_vlint_encode(uint8_t *buf, uint64_t v)
  29 {
  30     ossl_quic_vlint_encode_n(buf, v, ossl_quic_vlint_encode_len(v));
  31 }
  32
  33 uint64_t ossl_quic_vlint_decode_unchecked(const unsigned char *buf)
  34 {
  35     uint8_t first_byte = buf[0];
  36     size_t sz = ossl_quic_vlint_decode_len(first_byte);
  37
  38     if (sz == 1)
  39         return first_byte & 0x3F;
  40
  41     if (sz == 2)
  42         return ((uint64_t)(first_byte & 0x3F) << 8)
  43              | buf[1];
  44
  45     if (sz == 4)
  46         return ((uint64_t)(first_byte & 0x3F) << 24)
  47              | ((uint64_t)buf[1] << 16)
  48              | ((uint64_t)buf[2] <<  8)
  49              |  buf[3];
  50
  51     return ((uint64_t)(first_byte & 0x3F) << 56)
  52          | ((uint64_t)buf[1] << 48)
  53          | ((uint64_t)buf[2] << 40)
  54          | ((uint64_t)buf[3] << 32)
  55          | ((uint64_t)buf[4] << 24)
  56          | ((uint64_t)buf[5] << 16)
  57          | ((uint64_t)buf[6] <<  8)
  58          |  buf[7];
  59 }
  60
  61 int ossl_quic_vlint_decode(const unsigned char *buf, size_t buf_len, uint64_t *v)
  62 {
  63     size_t dec_len;
  64     uint64_t x;
  65
  66     if (buf_len < 1)
  67         return 0;
  68
  69     dec_len = ossl_quic_vlint_decode_len(buf[0]);
  70     if (buf_len < dec_len)
  71         return 0;
  72
  73     x = ossl_quic_vlint_decode_unchecked(buf);
  74
  75     *v = x;
  76     return dec_len;
  77 }