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libuuid: fix name-based UUIDs 

The current version is not fully compatible with RFC4122. It
incorrectly encodes UUID variant

	xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

where M is UUID version and N is UUID variant.

 $ python -c "import uuid ; print(uuid.uuid5(uuid.UUID(int=0), 'foo'))"
 aa752cea-8222-5bc8-acd9-555b090c0ccb
                    ^^

Old version:

 $ uuidgen --namespace 00000000-0000-0000-0000-000000000000 --name 'foo' --sha1
 aa752cea-8222-5bc8-8cd9-555b090c0ccb
                    ^^

Fixed version:
 ./uuidgen --namespace 00000000-0000-0000-0000-000000000000 --name 'foo' --sha1;
 aa752cea-8222-5bc8-acd9-555b090c0ccb
                    ^^

The patch uses uuid_unpack and uuid_pack. It makes code more readable
and allow to access proper octens. The same way we already use for
time and random based UUIDs.

Addresses: https://github.com/karelzak/util-linux/issues/683
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2018-08-31 12:27:32 +02:00
parent 9a312758ee
commit d6ddf07d31
1 changed files with 16 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
libuuid/src/gen_uuid.c
View File

@ -96,9 +96,6 @@
#define THREAD_LOCAL static
#endif
/* index with UUID_VARIANT_xxx and shift 5 bits */
static unsigned char variant_bits[] = { 0x00, 0x04, 0x06, 0x07 };
#ifdef _WIN32
static void gettimeofday (struct timeval *tv, void *dummy)
{
@ -566,21 +563,22 @@ void uuid_generate_md5(uuid_t out, const uuid_t ns, const char *name, size_t len
{
UL_MD5_CTX ctx;
char hash[UL_MD5LENGTH];
uuid_t buf;
struct uuid uu;
ul_MD5Init(&ctx);
/* hash concatenation of well-known UUID with name */
ul_MD5Update(&ctx, ns, sizeof(uuid_t));
ul_MD5Update(&ctx, (const unsigned char *)name, len);
ul_MD5Final((unsigned char *)hash, &ctx);
memcpy(out, hash, sizeof(uuid_t));
assert(sizeof(buf) <= sizeof(hash));
out[6] &= ~(UUID_TYPE_MASK << UUID_TYPE_SHIFT);
out[6] |= (UUID_TYPE_DCE_MD5 << UUID_TYPE_SHIFT);
memcpy(buf, hash, sizeof(buf));
uuid_unpack(buf, &uu);
out[8] &= ~(UUID_VARIANT_MASK << UUID_VARIANT_SHIFT);
out[8] |= (variant_bits[UUID_VARIANT_DCE] << UUID_VARIANT_SHIFT);
uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x3000;
uuid_pack(&uu, out);
}
/*
@ -591,20 +589,20 @@ void uuid_generate_sha1(uuid_t out, const uuid_t ns, const char *name, size_t le
{
UL_SHA1_CTX ctx;
char hash[UL_SHA1LENGTH];
uuid_t buf;
struct uuid uu;
ul_SHA1Init(&ctx);
/* hash concatenation of well-known UUID with name */
ul_SHA1Update(&ctx, ns, sizeof(uuid_t));
ul_SHA1Update(&ctx, (const unsigned char *)name, len);
ul_SHA1Final((unsigned char *)hash, &ctx);
memcpy(out, hash, sizeof(uuid_t));
assert(sizeof(buf) <= sizeof(hash));
out[6] &= ~(UUID_TYPE_MASK << UUID_TYPE_SHIFT);
out[6] |= (UUID_TYPE_DCE_SHA1 << UUID_TYPE_SHIFT);
memcpy(buf, hash, sizeof(buf));
uuid_unpack(buf, &uu);
out[8] &= ~(UUID_VARIANT_MASK << UUID_VARIANT_SHIFT);
out[8] |= (variant_bits[UUID_VARIANT_DCE] << UUID_VARIANT_SHIFT);
uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x5000;
uuid_pack(&uu, out);
}