diff options
Diffstat (limited to 'lib/lib.c')
| -rw-r--r-- | lib/lib.c | 23 |
1 files changed, 8 insertions, 15 deletions
@@ -1138,29 +1138,22 @@ int qstrcmp(const void *a, const void *b) return strcmp(*(char **)a, *(char **)b); } -// According to http://www.opengroup.org/onlinepubs/9629399/apdxa.htm -// we should generate a uuid structure by reading a clock with 100 nanosecond -// precision, normalizing it to the start of the gregorian calendar in 1582, -// and looking up our eth0 mac address. -// -// On the other hand, we have 128 bits to come up with a unique identifier, of -// which 6 have a defined value. /dev/urandom it is. - +// See https://tools.ietf.org/html/rfc4122, specifically section 4.4 +// "Algorithms for Creating a UUID from Truly Random or Pseudo-Random +// Numbers". void create_uuid(char *uuid) { - // Read 128 random bits + // "Set all the ... bits to randomly (or pseudo-randomly) chosen values". int fd = xopenro("/dev/urandom"); xreadall(fd, uuid, 16); close(fd); - // Claim to be a DCE format UUID. + // "Set the four most significant bits ... of the time_hi_and_version + // field to the 4-bit version number [4]". uuid[6] = (uuid[6] & 0x0F) | 0x40; + // "Set the two most significant bits (bits 6 and 7) of + // clock_seq_hi_and_reserved to zero and one, respectively". uuid[8] = (uuid[8] & 0x3F) | 0x80; - - // rfc2518 section 6.4.1 suggests if we're not using a macaddr, we should - // set bit 1 of the node ID, which is the mac multicast bit. This means we - // should never collide with anybody actually using a macaddr. - uuid[11] |= 128; } char *show_uuid(char *uuid) |