uuid.c

   1 /*
   2  * Copyright (C) 2010 The Android Open Source Project
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <string.h>
  18
  19 #include <arpa/inet.h>
  20
  21 #include "ext4_utils.h"
  22 #include "sha1.h"
  23 #include "uuid.h"
  24
  25 /* Definition from RFC-4122 */
  26 struct uuid {
  27         u32 time_low;
  28         u16 time_mid;
  29         u16 time_hi_and_version;
  30         u8 clk_seq_hi_res;
  31         u8 clk_seq_low;
  32         u16 node0_1;
  33         u32 node2_5;
  34 };
  35
  36 static void sha1_hash(const char *namespace, const char *name,
  37         unsigned char sha1[SHA1_DIGEST_LENGTH])
  38 {
  39         SHA1_CTX ctx;
  40         SHA1Init(&ctx);
  41         SHA1Update(&ctx, (const u8*)namespace, strlen(namespace));
  42         SHA1Update(&ctx, (const u8*)name, strlen(name));
  43         SHA1Final(sha1, &ctx);
  44 }
  45
  46 void generate_uuid(const char *namespace, const char *name, u8 result[16])
  47 {
  48         unsigned char sha1[SHA1_DIGEST_LENGTH];
  49         struct uuid *uuid = (struct uuid *)result;
  50
  51         sha1_hash(namespace, name, (unsigned char*)sha1);
  52         memcpy(uuid, sha1, sizeof(struct uuid));
  53
  54         uuid->time_low = ntohl(uuid->time_low);
  55         uuid->time_mid = ntohs(uuid->time_mid);
  56         uuid->time_hi_and_version = ntohs(uuid->time_hi_and_version);
  57         uuid->time_hi_and_version &= 0x0FFF;
  58         uuid->time_hi_and_version |= (5 << 12);
  59         uuid->clk_seq_hi_res &= ~(1 << 6);
  60         uuid->clk_seq_hi_res |= 1 << 7;
  61 }