1/* MiniDLNA project 2 * 3 * http://sourceforge.net/projects/minidlna/ 4 * 5 * Much of this code and ideas for this code have been taken 6 * from Helge Deller's proposed Linux kernel patch (which 7 * apparently never made it upstream), and some from Busybox. 8 * 9 * MiniDLNA media server 10 * Copyright (C) 2009 Justin Maggard 11 * 12 * This file is part of MiniDLNA. 13 * 14 * MiniDLNA is free software; you can redistribute it and/or modify 15 * it under the terms of the GNU General Public License version 2 as 16 * published by the Free Software Foundation. 17 * 18 * MiniDLNA is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with MiniDLNA. If not, see <http://www.gnu.org/licenses/>. 25 */ 26#include <stdio.h> 27#include <stdlib.h> 28#include <time.h> 29#include <fcntl.h> 30#include <unistd.h> 31#include <sys/syscall.h> 32#include <string.h> 33#include <net/if.h> 34#include <sys/ioctl.h> 35#include <sys/time.h> 36#include <errno.h> 37 38#include "getifaddr.h" 39#include "log.h" 40 41#define ETH_ALEN 6 42#define NSEC_PER_SEC 1000000000L 43#define NSEC_PER_MSEC 1000000L 44 45static u_int32_t clock_seq; 46static const u_int32_t clock_seq_max = 0x3fff; /* 14 bits */ 47static int clock_seq_initialized; 48 49unsigned long long 50monotonic_us(void) 51{ 52 struct timespec ts; 53 54 syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts); 55 return ts.tv_sec * 1000000ULL + ts.tv_nsec / 1000; 56} 57 58int 59read_bootid_node(unsigned char *buf, size_t size) 60{ 61 FILE *boot_id; 62 63 if(size != 6) 64 return -1; 65 66 boot_id = fopen("/proc/sys/kernel/random/boot_id", "r"); 67 if(!boot_id) 68 return -1; 69 if((fseek(boot_id, 24, SEEK_SET) < 0) || 70 (fscanf(boot_id, "%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx", 71 &buf[0], &buf[1], &buf[2], &buf[3], &buf[4], &buf[5]) != 6)) 72 { 73 fclose(boot_id); 74 return -1; 75 } 76 77 fclose(boot_id); 78 return 0; 79} 80 81static void 82read_random_bytes(unsigned char *buf, size_t size) 83{ 84 int i; 85 pid_t pid; 86 87 i = open("/dev/urandom", O_RDONLY); 88 if(i >= 0) 89 { 90 read(i, buf, size); 91 close(i); 92 } 93 /* Paranoia. /dev/urandom may be missing. 94 * rand() is guaranteed to generate at least [0, 2^15) range, 95 * but lowest bits in some libc are not so "random". */ 96 srand(monotonic_us()); 97 pid = getpid(); 98 while(1) 99 { 100 for(i = 0; i < size; i++) 101 buf[i] ^= rand() >> 5; 102 if(pid == 0) 103 break; 104 srand(pid); 105 pid = 0; 106 } 107} 108 109void 110init_clockseq(void) 111{ 112 unsigned char buf[4]; 113 114 read_random_bytes(buf, 4); 115 memcpy(&clock_seq, &buf, sizeof(clock_seq)); 116 clock_seq &= clock_seq_max; 117 clock_seq_initialized = 1; 118} 119 120int 121generate_uuid(unsigned char uuid_out[16]) 122{ 123 static u_int64_t last_time_all; 124 static unsigned int clock_seq_started; 125 static char last_node[6] = { 0, 0, 0, 0, 0, 0 }; 126 127 struct timespec ts; 128 u_int64_t time_all; 129 int inc_clock_seq = 0; 130 131 unsigned char mac[6]; 132 int mac_error; 133 134 memset(&mac, '\0', sizeof(mac)); 135 /* Get the spatially unique node identifier */ 136 137 mac_error = getsyshwaddr((char *)mac, sizeof(mac)); 138 139 if(!mac_error) 140 { 141 memcpy(&uuid_out[10], mac, ETH_ALEN); 142 } 143 else 144 { 145 /* use bootid's nodeID if no network interface found */ 146 DPRINTF(E_INFO, L_HTTP, "Could not find MAC. Use bootid's nodeID.\n"); 147 if( read_bootid_node(&uuid_out[10], 6) != 0) 148 { 149 DPRINTF(E_INFO, L_HTTP, "bootid node not successfully read.\n"); 150 read_random_bytes(&uuid_out[10], 6); 151 } 152 } 153 154 if(memcmp(last_node, uuid_out+10, 6) != 0) 155 { 156 inc_clock_seq = 1; 157 memcpy(last_node, uuid_out+10, 6); 158 } 159 160 /* Determine 60-bit timestamp value. For UUID version 1, this is 161 * represented by Coordinated Universal Time (UTC) as a count of 100- 162 * nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of 163 * Gregorian reform to the Christian calendar). 164 */ 165 syscall(__NR_clock_gettime, CLOCK_REALTIME, &ts); 166 time_all = ((u_int64_t)ts.tv_sec) * (NSEC_PER_SEC / 100); 167 time_all += ts.tv_nsec / 100; 168 169 /* add offset from Gregorian Calendar to Jan 1 1970 */ 170 time_all += 12219292800000ULL * (NSEC_PER_MSEC / 100); 171 time_all &= 0x0fffffffffffffffULL; /* limit to 60 bits */ 172 173 /* Determine clock sequence (max. 14 bit) */ 174 if(!clock_seq_initialized) 175 { 176 init_clockseq(); 177 clock_seq_started = clock_seq; 178 } 179 else 180 { 181 if(inc_clock_seq || time_all <= last_time_all) 182 { 183 clock_seq = (clock_seq + 1) & clock_seq_max; 184 if(clock_seq == clock_seq_started) 185 { 186 clock_seq = (clock_seq - 1) & clock_seq_max; 187 } 188 } 189 else 190 clock_seq_started = clock_seq; 191 } 192 last_time_all = time_all; 193 194 /* Fill in timestamp and clock_seq values */ 195 uuid_out[3] = (u_int8_t)time_all; 196 uuid_out[2] = (u_int8_t)(time_all >> 8); 197 uuid_out[1] = (u_int8_t)(time_all >> 16); 198 uuid_out[0] = (u_int8_t)(time_all >> 24); 199 uuid_out[5] = (u_int8_t)(time_all >> 32); 200 uuid_out[4] = (u_int8_t)(time_all >> 40); 201 uuid_out[7] = (u_int8_t)(time_all >> 48); 202 uuid_out[6] = (u_int8_t)(time_all >> 56); 203 204 uuid_out[8] = clock_seq >> 8; 205 uuid_out[9] = clock_seq & 0xff; 206 207 /* Set UUID version to 1 --- time-based generation */ 208 uuid_out[6] = (uuid_out[6] & 0x0F) | 0x10; 209 /* Set the UUID variant to DCE */ 210 uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; 211 212 return 0; 213} 214 215/* Places a null-terminated 37-byte time-based UUID string in the buffer pointer to by buf. 216 * A large enough buffer must already be allocated. */ 217int 218get_uuid_string(char *buf) 219{ 220 unsigned char uuid[16]; 221 222 if( generate_uuid(uuid) != 0 ) 223 return -1; 224 225 sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x", 226 uuid[0], uuid[1], uuid[2], uuid[3], uuid[4], uuid[5], uuid[6], uuid[7], uuid[8], 227 uuid[9], uuid[10], uuid[11], uuid[12], uuid[13], uuid[14], uuid[15]); 228 buf[36] = '\0'; 229 230 return 0; 231} 232