1 | /*
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2 | * gen_uuid.c --- generate a DCE-compatible uuid
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3 | *
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4 | * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
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5 | *
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6 | * %Begin-Header%
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7 | * Redistribution and use in source and binary forms, with or without
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8 | * modification, are permitted provided that the following conditions
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9 | * are met:
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10 | * 1. Redistributions of source code must retain the above copyright
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11 | * notice, and the entire permission notice in its entirety,
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12 | * including the disclaimer of warranties.
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13 | * 2. Redistributions in binary form must reproduce the above copyright
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14 | * notice, this list of conditions and the following disclaimer in the
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15 | * documentation and/or other materials provided with the distribution.
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16 | * 3. The name of the author may not be used to endorse or promote
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17 | * products derived from this software without specific prior
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18 | * written permission.
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19 | *
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20 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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21 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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22 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
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23 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
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24 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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25 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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27 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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28 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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29 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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30 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
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31 | * DAMAGE.
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32 | * %End-Header%
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33 | */
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34 |
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35 | #include <unistd.h>
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36 | #include <stdlib.h>
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37 | #include <string.h>
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38 | #include <fcntl.h>
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39 | #include <errno.h>
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40 | #include <sys/types.h>
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41 | #include <sys/stat.h>
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42 | #include <sys/file.h>
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43 | #ifdef HAVE_SYS_IOCTL_H
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44 | #include <sys/ioctl.h>
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45 | #endif
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46 | #include <sys/socket.h>
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47 | #ifdef HAVE_SYS_SOCKIO_H
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48 | #include <sys/sockio.h>
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49 | #endif
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50 | #ifdef HAVE_NET_IF_H
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51 | #include <net/if.h>
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52 | #endif
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53 | #ifdef HAVE_NETINET_IN_H
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54 | #include <netinet/in.h>
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55 | #endif
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56 | #ifdef HAVE_NET_IF_DL_H
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57 | #include <net/if_dl.h>
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58 | #endif
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59 |
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60 | #include "uuidP.h"
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61 |
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62 | #ifdef HAVE_SRANDOM
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63 | #define srand(x) srandom(x)
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64 | #define rand() random()
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65 | #endif
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66 |
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67 | static int get_random_fd(void)
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68 | {
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69 | struct timeval tv;
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70 | static int fd = -2;
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71 | int i;
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72 |
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73 | if (fd == -2) {
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74 | gettimeofday(&tv, 0);
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75 | fd = open("/dev/urandom", O_RDONLY);
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76 | if (fd == -1)
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77 | fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
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78 | srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
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79 | }
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80 | /* Crank the random number generator a few times */
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81 | gettimeofday(&tv, 0);
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82 | for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
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83 | rand();
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84 | return fd;
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85 | }
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86 |
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87 |
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88 | /*
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89 | * Generate a series of random bytes. Use /dev/urandom if possible,
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90 | * and if not, use srandom/random.
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91 | */
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92 | static void get_random_bytes(void *buf, int nbytes)
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93 | {
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94 | int i, n = nbytes, fd = get_random_fd();
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95 | int lose_counter = 0;
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96 | unsigned char *cp = (unsigned char *) buf;
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97 |
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98 | if (fd >= 0) {
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99 | while (n > 0) {
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100 | i = read(fd, cp, n);
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101 | if (i <= 0) {
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102 | if (lose_counter++ > 16)
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103 | break;
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104 | continue;
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105 | }
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106 | n -= i;
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107 | cp += i;
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108 | lose_counter = 0;
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109 | }
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110 | }
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111 |
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112 | /*
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113 | * We do this all the time, but this is the only source of
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114 | * randomness if /dev/random/urandom is out to lunch.
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115 | */
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116 | for (cp = buf, i = 0; i < nbytes; i++)
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117 | *cp++ ^= (rand() >> 7) & 0xFF;
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118 | return;
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119 | }
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120 |
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121 | /*
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122 | * Get the ethernet hardware address, if we can find it...
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123 | */
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124 | static int get_node_id(unsigned char *node_id)
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125 | {
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126 | #ifdef HAVE_NET_IF_H
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127 | int sd;
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128 | struct ifreq ifr, *ifrp;
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129 | struct ifconf ifc;
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130 | char buf[1024];
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131 | int n, i;
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132 | unsigned char *a;
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133 | #ifdef HAVE_NET_IF_DL_H
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134 | struct sockaddr_dl *sdlp;
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135 | #endif
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136 |
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137 | /*
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138 | * BSD 4.4 defines the size of an ifreq to be
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139 | * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
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140 | * However, under earlier systems, sa_len isn't present, so the size is
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141 | * just sizeof(struct ifreq)
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142 | */
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143 | #ifdef HAVE_SA_LEN
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144 | #ifndef max
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145 | #define max(a,b) ((a) > (b) ? (a) : (b))
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146 | #endif
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147 | #define ifreq_size(i) max(sizeof(struct ifreq),\
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148 | sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
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149 | #else
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150 | #define ifreq_size(i) sizeof(struct ifreq)
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151 | #endif /* HAVE_SA_LEN*/
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152 |
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153 | sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
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154 | if (sd < 0) {
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155 | return -1;
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156 | }
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157 | memset(buf, 0, sizeof(buf));
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158 | ifc.ifc_len = sizeof(buf);
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159 | ifc.ifc_buf = buf;
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160 | if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
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161 | close(sd);
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162 | return -1;
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163 | }
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164 | n = ifc.ifc_len;
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165 | for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
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166 | ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
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167 | strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
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168 | #ifdef SIOCGIFHWADDR
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169 | if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
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170 | continue;
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171 | a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
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172 | #else
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173 | #ifdef SIOCGENADDR
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174 | if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
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175 | continue;
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176 | a = (unsigned char *) ifr.ifr_enaddr;
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177 | #else
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178 | #ifdef HAVE_NET_IF_DL_H
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179 | sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
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180 | if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
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181 | continue;
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182 | a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
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183 | #else
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184 | /*
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185 | * XXX we don't have a way of getting the hardware
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186 | * address
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187 | */
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188 | close(sd);
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189 | return 0;
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190 | #endif /* HAVE_NET_IF_DL_H */
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191 | #endif /* SIOCGENADDR */
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192 | #endif /* SIOCGIFHWADDR */
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193 | if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
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194 | continue;
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195 | if (node_id) {
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196 | memcpy(node_id, a, 6);
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197 | close(sd);
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198 | return 1;
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199 | }
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200 | }
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201 | close(sd);
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202 | #endif
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203 | return 0;
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204 | }
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205 |
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206 | /* Assume that the gettimeofday() has microsecond granularity */
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207 | #define MAX_ADJUSTMENT 10
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208 |
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209 | static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
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210 | {
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211 | static int adjustment = 0;
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212 | static struct timeval last = {0, 0};
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213 | static uint16_t clock_seq;
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214 | struct timeval tv;
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215 | unsigned long long clock_reg;
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216 |
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217 | try_again:
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218 | gettimeofday(&tv, 0);
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219 | if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
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220 | get_random_bytes(&clock_seq, sizeof(clock_seq));
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221 | clock_seq &= 0x3FFF;
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222 | last = tv;
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223 | last.tv_sec--;
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224 | }
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225 | if ((tv.tv_sec < last.tv_sec) ||
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226 | ((tv.tv_sec == last.tv_sec) &&
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227 | (tv.tv_usec < last.tv_usec))) {
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228 | clock_seq = (clock_seq+1) & 0x3FFF;
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229 | adjustment = 0;
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230 | last = tv;
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231 | } else if ((tv.tv_sec == last.tv_sec) &&
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232 | (tv.tv_usec == last.tv_usec)) {
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233 | if (adjustment >= MAX_ADJUSTMENT)
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234 | goto try_again;
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235 | adjustment++;
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236 | } else {
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237 | adjustment = 0;
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238 | last = tv;
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239 | }
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240 |
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241 | clock_reg = tv.tv_usec*10 + adjustment;
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242 | clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
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243 | clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
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244 |
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245 | *clock_high = clock_reg >> 32;
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246 | *clock_low = clock_reg;
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247 | *ret_clock_seq = clock_seq;
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248 | return 0;
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249 | }
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250 |
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251 | void uuid_generate_time(uuid_t out)
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252 | {
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253 | static unsigned char node_id[6];
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254 | static int has_init = 0;
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255 | struct uuid uu;
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256 | uint32_t clock_mid;
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257 |
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258 | if (!has_init) {
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259 | if (get_node_id(node_id) <= 0) {
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260 | get_random_bytes(node_id, 6);
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261 | /*
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262 | * Set multicast bit, to prevent conflicts
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263 | * with IEEE 802 addresses obtained from
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264 | * network cards
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265 | */
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266 | node_id[0] |= 0x01;
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267 | }
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268 | has_init = 1;
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269 | }
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270 | get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
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271 | uu.clock_seq |= 0x8000;
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272 | uu.time_mid = (uint16_t) clock_mid;
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273 | uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
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274 | memcpy(uu.node, node_id, 6);
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275 | uuid_pack(&uu, out);
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276 | }
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277 |
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278 | void uuid_generate_random(uuid_t out)
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279 | {
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280 | uuid_t buf;
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281 | struct uuid uu;
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282 |
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283 | get_random_bytes(buf, sizeof(buf));
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284 | uuid_unpack(buf, &uu);
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285 |
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286 | uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
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287 | uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
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288 | uuid_pack(&uu, out);
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289 | }
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290 |
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291 | /*
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292 | * This is the generic front-end to uuid_generate_random and
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293 | * uuid_generate_time. It uses uuid_generate_random only if
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294 | * /dev/urandom is available, since otherwise we won't have
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295 | * high-quality randomness.
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296 | */
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297 | void uuid_generate(uuid_t out)
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298 | {
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299 | if (get_random_fd() >= 0)
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300 | uuid_generate_random(out);
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301 | else
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302 | uuid_generate_time(out);
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303 | }
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