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/* MiniDLNA project
*
* http://sourceforge.net/projects/minidlna/
*
* Much of this code and ideas for this code have been taken
* from Helge Deller's proposed Linux kernel patch (which
* apparently never made it upstream), and some from Busybox.
*
* MiniDLNA media server
* Copyright (C) 2009 Justin Maggard
*
* This file is part of MiniDLNA.
*
* MiniDLNA is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* MiniDLNA is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MiniDLNA. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <errno.h>
#include "getifaddr.h"
#include "log.h"
#define ETH_ALEN 6
#define NSEC_PER_SEC 1000000000L
#define NSEC_PER_MSEC 1000000L
static u_int32_t clock_seq;
static const u_int32_t clock_seq_max = 0x3fff; /* 14 bits */
static int clock_seq_initialized;
unsigned long long
monotonic_us(void)
{
struct timespec ts;
syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts);
return ts.tv_sec * 1000000ULL + ts.tv_nsec / 1000;
}
int
read_bootid_node(unsigned char *buf, size_t size)
{
FILE *boot_id;
if(size != 6)
return -1;
boot_id = fopen("/proc/sys/kernel/random/boot_id", "r");
if(!boot_id)
return -1;
if((fseek(boot_id, 24, SEEK_SET) < 0) ||
(fscanf(boot_id, "%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx",
&buf[0], &buf[1], &buf[2], &buf[3], &buf[4], &buf[5]) != 6))
{
fclose(boot_id);
return -1;
}
fclose(boot_id);
return 0;
}
static void
read_random_bytes(unsigned char *buf, size_t size)
{
int i;
pid_t pid;
i = open("/dev/urandom", O_RDONLY);
if(i >= 0)
{
read(i, buf, size);
close(i);
}
/* Paranoia. /dev/urandom may be missing.
* rand() is guaranteed to generate at least [0, 2^15) range,
* but lowest bits in some libc are not so "random". */
srand(monotonic_us());
pid = getpid();
while(1)
{
for(i = 0; i < size; i++)
buf[i] ^= rand() >> 5;
if(pid == 0)
break;
srand(pid);
pid = 0;
}
}
void
init_clockseq(void)
{
unsigned char buf[4];
read_random_bytes(buf, 4);
memcpy(&clock_seq, &buf, sizeof(clock_seq));
clock_seq &= clock_seq_max;
clock_seq_initialized = 1;
}
int
generate_uuid(unsigned char uuid_out[16])
{
static u_int64_t last_time_all;
static unsigned int clock_seq_started;
static char last_node[6] = { 0, 0, 0, 0, 0, 0 };
struct timespec ts;
u_int64_t time_all;
int inc_clock_seq = 0;
unsigned char mac[6];
int mac_error;
memset(&mac, '\0', sizeof(mac));
/* Get the spatially unique node identifier */
mac_error = getsyshwaddr((char *)mac, sizeof(mac));
if(!mac_error)
{
memcpy(&uuid_out[10], mac, ETH_ALEN);
}
else
{
/* use bootid's nodeID if no network interface found */
DPRINTF(E_INFO, L_HTTP, "Could not find MAC. Use bootid's nodeID.\n");
if( read_bootid_node(&uuid_out[10], 6) != 0)
{
DPRINTF(E_INFO, L_HTTP, "bootid node not successfully read.\n");
read_random_bytes(&uuid_out[10], 6);
}
}
if(memcmp(last_node, uuid_out+10, 6) != 0)
{
inc_clock_seq = 1;
memcpy(last_node, uuid_out+10, 6);
}
/* Determine 60-bit timestamp value. For UUID version 1, this is
* represented by Coordinated Universal Time (UTC) as a count of 100-
* nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of
* Gregorian reform to the Christian calendar).
*/
syscall(__NR_clock_gettime, CLOCK_REALTIME, &ts);
time_all = ((u_int64_t)ts.tv_sec) * (NSEC_PER_SEC / 100);
time_all += ts.tv_nsec / 100;
/* add offset from Gregorian Calendar to Jan 1 1970 */
time_all += 12219292800000ULL * (NSEC_PER_MSEC / 100);
time_all &= 0x0fffffffffffffffULL; /* limit to 60 bits */
/* Determine clock sequence (max. 14 bit) */
if(!clock_seq_initialized)
{
init_clockseq();
clock_seq_started = clock_seq;
}
else
{
if(inc_clock_seq || time_all <= last_time_all)
{
clock_seq = (clock_seq + 1) & clock_seq_max;
if(clock_seq == clock_seq_started)
{
clock_seq = (clock_seq - 1) & clock_seq_max;
}
}
else
clock_seq_started = clock_seq;
}
last_time_all = time_all;
/* Fill in timestamp and clock_seq values */
uuid_out[3] = (u_int8_t)time_all;
uuid_out[2] = (u_int8_t)(time_all >> 8);
uuid_out[1] = (u_int8_t)(time_all >> 16);
uuid_out[0] = (u_int8_t)(time_all >> 24);
uuid_out[5] = (u_int8_t)(time_all >> 32);
uuid_out[4] = (u_int8_t)(time_all >> 40);
uuid_out[7] = (u_int8_t)(time_all >> 48);
uuid_out[6] = (u_int8_t)(time_all >> 56);
uuid_out[8] = clock_seq >> 8;
uuid_out[9] = clock_seq & 0xff;
/* Set UUID version to 1 --- time-based generation */
uuid_out[6] = (uuid_out[6] & 0x0F) | 0x10;
/* Set the UUID variant to DCE */
uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
return 0;
}
/* Places a null-terminated 37-byte time-based UUID string in the buffer pointer to by buf.
* A large enough buffer must already be allocated. */
int
get_uuid_string(char *buf)
{
unsigned char uuid[16];
if( generate_uuid(uuid) != 0 )
return -1;
sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
uuid[0], uuid[1], uuid[2], uuid[3], uuid[4], uuid[5], uuid[6], uuid[7], uuid[8],
uuid[9], uuid[10], uuid[11], uuid[12], uuid[13], uuid[14], uuid[15]);
buf[36] = '\0';
return 0;
}