Line data    Source code

       1             : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2             : // Copyright (c) 2009-2022 The Bitcoin Core developers
       3             : // Distributed under the MIT software license, see the accompanying
       4             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       5             : 
       6             : #if defined(HAVE_CONFIG_H)
       7             : #include <config/bitcoin-config.h>
       8             : #endif
       9             : 
      10             : #include <randomenv.h>
      11             : 
      12             : #include <clientversion.h>
      13             : #include <compat/compat.h>
      14             : #include <compat/cpuid.h>
      15             : #include <crypto/sha512.h>
      16             : #include <support/cleanse.h>
      17             : #include <util/time.h>
      18             : 
      19             : #include <algorithm>
      20             : #include <atomic>
      21             : #include <cstdint>
      22             : #include <cstring>
      23             : #include <chrono>
      24             : #include <climits>
      25             : #include <thread>
      26             : #include <vector>
      27             : 
      28             : #include <sys/types.h> // must go before a number of other headers
      29             : 
      30             : #ifdef WIN32
      31             : #include <windows.h>
      32             : #include <winreg.h>
      33             : #else
      34             : #include <fcntl.h>
      35             : #include <netinet/in.h>
      36             : #include <sys/resource.h>
      37             : #include <sys/socket.h>
      38             : #include <sys/stat.h>
      39             : #include <sys/time.h>
      40             : #include <sys/utsname.h>
      41             : #include <unistd.h>
      42             : #endif
      43             : #if HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS
      44             : #include <ifaddrs.h>
      45             : #endif
      46             : #if HAVE_SYSCTL
      47             : #include <sys/sysctl.h>
      48             : #if HAVE_VM_VM_PARAM_H
      49             : #include <vm/vm_param.h>
      50             : #endif
      51             : #if HAVE_SYS_RESOURCES_H
      52             : #include <sys/resources.h>
      53             : #endif
      54             : #if HAVE_SYS_VMMETER_H
      55             : #include <sys/vmmeter.h>
      56             : #endif
      57             : #endif
      58             : #if defined(HAVE_STRONG_GETAUXVAL)
      59             : #include <sys/auxv.h>
      60             : #endif
      61             : 
      62             : extern char** environ; // NOLINT(readability-redundant-declaration): Necessary on some platforms
      63             : 
      64             : namespace {
      65             : 
      66           2 : void RandAddSeedPerfmon(CSHA512& hasher)
      67             : {
      68             : #ifdef WIN32
      69             :     // Seed with the entire set of perfmon data
      70             : 
      71             :     // This can take up to 2 seconds, so only do it every 10 minutes.
      72             :     // Initialize last_perfmon to 0 seconds, we don't skip the first call.
      73             :     static std::atomic<std::chrono::seconds> last_perfmon{0s};
      74             :     auto last_time = last_perfmon.load();
      75             :     auto current_time = GetTime<std::chrono::seconds>();
      76             :     if (current_time < last_time + std::chrono::minutes{10}) return;
      77             :     last_perfmon = current_time;
      78             : 
      79             :     std::vector<unsigned char> vData(250000, 0);
      80             :     long ret = 0;
      81             :     unsigned long nSize = 0;
      82             :     const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data
      83             :     while (true) {
      84             :         nSize = vData.size();
      85             :         ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", nullptr, nullptr, vData.data(), &nSize);
      86             :         if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize)
      87             :             break;
      88             :         vData.resize(std::min((vData.size() * 3) / 2, nMaxSize)); // Grow size of buffer exponentially
      89             :     }
      90             :     RegCloseKey(HKEY_PERFORMANCE_DATA);
      91             :     if (ret == ERROR_SUCCESS) {
      92             :         hasher.Write(vData.data(), nSize);
      93             :         memory_cleanse(vData.data(), nSize);
      94             :     } else {
      95             :         // Performance data is only a best-effort attempt at improving the
      96             :         // situation when the OS randomness (and other sources) aren't
      97             :         // adequate. As a result, failure to read it is isn't considered critical,
      98             :         // so we don't call RandFailure().
      99             :         // TODO: Add logging when the logger is made functional before global
     100             :         // constructors have been invoked.
     101             :     }
     102             : #endif
     103           2 : }
     104             : 
     105             : /** Helper to easily feed data into a CSHA512.
     106             :  *
     107             :  * Note that this does not serialize the passed object (like stream.h's << operators do).
     108             :  * Its raw memory representation is used directly.
     109             :  */
     110             : template<typename T>
     111         778 : CSHA512& operator<<(CSHA512& hasher, const T& data) {
     112             :     static_assert(!std::is_same<typename std::decay<T>::type, char*>::value, "Calling operator<<(CSHA512, char*) is probably not what you want");
     113             :     static_assert(!std::is_same<typename std::decay<T>::type, unsigned char*>::value, "Calling operator<<(CSHA512, unsigned char*) is probably not what you want");
     114             :     static_assert(!std::is_same<typename std::decay<T>::type, const char*>::value, "Calling operator<<(CSHA512, const char*) is probably not what you want");
     115             :     static_assert(!std::is_same<typename std::decay<T>::type, const unsigned char*>::value, "Calling operator<<(CSHA512, const unsigned char*) is probably not what you want");
     116         778 :     hasher.Write((const unsigned char*)&data, sizeof(data));
     117         778 :     return hasher;
     118             : }
     119             : 
     120             : #ifndef WIN32
     121          78 : void AddSockaddr(CSHA512& hasher, const struct sockaddr *addr)
     122             : {
     123          78 :     if (addr == nullptr) return;
     124          58 :     switch (addr->sa_family) {
     125             :     case AF_INET:
     126          18 :         hasher.Write((const unsigned char*)addr, sizeof(sockaddr_in));
     127          18 :         break;
     128             :     case AF_INET6:
     129          20 :         hasher.Write((const unsigned char*)addr, sizeof(sockaddr_in6));
     130          20 :         break;
     131             :     default:
     132          20 :         hasher.Write((const unsigned char*)&addr->sa_family, sizeof(addr->sa_family));
     133          20 :     }
     134          78 : }
     135             : 
     136          36 : void AddFile(CSHA512& hasher, const char *path)
     137             : {
     138          36 :     struct stat sb = {};
     139          36 :     int f = open(path, O_RDONLY);
     140          36 :     size_t total = 0;
     141          36 :     if (f != -1) {
     142             :         unsigned char fbuf[4096];
     143             :         int n;
     144          36 :         hasher.Write((const unsigned char*)&f, sizeof(f));
     145          36 :         if (fstat(f, &sb) == 0) hasher << sb;
     146          36 :         do {
     147          54 :             n = read(f, fbuf, sizeof(fbuf));
     148          54 :             if (n > 0) hasher.Write(fbuf, n);
     149          54 :             total += n;
     150             :             /* not bothering with EINTR handling. */
     151          54 :         } while (n == sizeof(fbuf) && total < 1048576); // Read only the first 1 Mbyte
     152          36 :         close(f);
     153          36 :     }
     154          36 : }
     155             : 
     156          10 : void AddPath(CSHA512& hasher, const char *path)
     157             : {
     158          10 :     struct stat sb = {};
     159          10 :     if (stat(path, &sb) == 0) {
     160          10 :         hasher.Write((const unsigned char*)path, strlen(path) + 1);
     161          10 :         hasher << sb;
     162          10 :     }
     163          10 : }
     164             : #endif
     165             : 
     166             : #if HAVE_SYSCTL
     167             : template<int... S>
     168             : void AddSysctl(CSHA512& hasher)
     169             : {
     170             :     int CTL[sizeof...(S)] = {S...};
     171             :     unsigned char buffer[65536];
     172             :     size_t siz = 65536;
     173             :     int ret = sysctl(CTL, sizeof...(S), buffer, &siz, nullptr, 0);
     174             :     if (ret == 0 || (ret == -1 && errno == ENOMEM)) {
     175             :         hasher << sizeof(CTL);
     176             :         hasher.Write((const unsigned char*)CTL, sizeof(CTL));
     177             :         if (siz > sizeof(buffer)) siz = sizeof(buffer);
     178             :         hasher << siz;
     179             :         hasher.Write(buffer, siz);
     180             :     }
     181             : }
     182             : #endif
     183             : 
     184             : #ifdef HAVE_GETCPUID
     185         110 : void inline AddCPUID(CSHA512& hasher, uint32_t leaf, uint32_t subleaf, uint32_t& ax, uint32_t& bx, uint32_t& cx, uint32_t& dx)
     186             : {
     187         110 :     GetCPUID(leaf, subleaf, ax, bx, cx, dx);
     188         110 :     hasher << leaf << subleaf << ax << bx << cx << dx;
     189         110 : }
     190             : 
     191           2 : void AddAllCPUID(CSHA512& hasher)
     192             : {
     193             :     uint32_t ax, bx, cx, dx;
     194             :     // Iterate over all standard leaves
     195           2 :     AddCPUID(hasher, 0, 0, ax, bx, cx, dx); // Returns max leaf in ax
     196           2 :     uint32_t max = ax;
     197          34 :     for (uint32_t leaf = 1; leaf <= max && leaf <= 0xFF; ++leaf) {
     198          32 :         uint32_t maxsub = 0;
     199          42 :         for (uint32_t subleaf = 0; subleaf <= 0xFF; ++subleaf) {
     200          42 :             AddCPUID(hasher, leaf, subleaf, ax, bx, cx, dx);
     201             :             // Iterate subleafs for leaf values 4, 7, 11, 13
     202          42 :             if (leaf == 4) {
     203           2 :                 if ((ax & 0x1f) == 0) break;
     204          40 :             } else if (leaf == 7) {
     205           2 :                 if (subleaf == 0) maxsub = ax;
     206           2 :                 if (subleaf == maxsub) break;
     207          38 :             } else if (leaf == 11) {
     208           6 :                 if ((cx & 0xff00) == 0) break;
     209          36 :             } else if (leaf == 13) {
     210           8 :                 if (ax == 0 && bx == 0 && cx == 0 && dx == 0) break;
     211           6 :             } else {
     212             :                 // For any other leaf, stop after subleaf 0.
     213          24 :                 break;
     214             :             }
     215          10 :         }
     216          32 :     }
     217             :     // Iterate over all extended leaves
     218           2 :     AddCPUID(hasher, 0x80000000, 0, ax, bx, cx, dx); // Returns max extended leaf in ax
     219           2 :     uint32_t ext_max = ax;
     220          66 :     for (uint32_t leaf = 0x80000001; leaf <= ext_max && leaf <= 0x800000FF; ++leaf) {
     221          64 :         AddCPUID(hasher, leaf, 0, ax, bx, cx, dx);
     222          64 :     }
     223           2 : }
     224             : #endif
     225             : } // namespace
     226             : 
     227           2 : void RandAddDynamicEnv(CSHA512& hasher)
     228             : {
     229           2 :     RandAddSeedPerfmon(hasher);
     230             : 
     231             :     // Various clocks
     232             : #ifdef WIN32
     233             :     FILETIME ftime;
     234             :     GetSystemTimeAsFileTime(&ftime);
     235             :     hasher << ftime;
     236             : #else
     237           2 :     struct timespec ts = {};
     238             : #    ifdef CLOCK_MONOTONIC
     239           2 :     clock_gettime(CLOCK_MONOTONIC, &ts);
     240           2 :     hasher << ts;
     241             : #    endif
     242             : #    ifdef CLOCK_REALTIME
     243           2 :     clock_gettime(CLOCK_REALTIME, &ts);
     244           2 :     hasher << ts;
     245             : #    endif
     246             : #    ifdef CLOCK_BOOTTIME
     247           2 :     clock_gettime(CLOCK_BOOTTIME, &ts);
     248           2 :     hasher << ts;
     249             : #    endif
     250             :     // gettimeofday is available on all UNIX systems, but only has microsecond precision.
     251           2 :     struct timeval tv = {};
     252           2 :     gettimeofday(&tv, nullptr);
     253           2 :     hasher << tv;
     254             : #endif
     255             :     // Probably redundant, but also use all the standard library clocks:
     256           2 :     hasher << std::chrono::system_clock::now().time_since_epoch().count();
     257           2 :     hasher << std::chrono::steady_clock::now().time_since_epoch().count();
     258           2 :     hasher << std::chrono::high_resolution_clock::now().time_since_epoch().count();
     259             : 
     260             : #ifndef WIN32
     261             :     // Current resource usage.
     262           2 :     struct rusage usage = {};
     263           2 :     if (getrusage(RUSAGE_SELF, &usage) == 0) hasher << usage;
     264             : #endif
     265             : 
     266             : #ifdef __linux__
     267           2 :     AddFile(hasher, "/proc/diskstats");
     268           2 :     AddFile(hasher, "/proc/vmstat");
     269           2 :     AddFile(hasher, "/proc/schedstat");
     270           2 :     AddFile(hasher, "/proc/zoneinfo");
     271           2 :     AddFile(hasher, "/proc/meminfo");
     272           2 :     AddFile(hasher, "/proc/softirqs");
     273           2 :     AddFile(hasher, "/proc/stat");
     274           2 :     AddFile(hasher, "/proc/self/schedstat");
     275           2 :     AddFile(hasher, "/proc/self/status");
     276             : #endif
     277             : 
     278             : #if HAVE_SYSCTL
     279             : #  ifdef CTL_KERN
     280             : #    if defined(KERN_PROC) && defined(KERN_PROC_ALL)
     281             :     AddSysctl<CTL_KERN, KERN_PROC, KERN_PROC_ALL>(hasher);
     282             : #    endif
     283             : #  endif
     284             : #  ifdef CTL_HW
     285             : #    ifdef HW_DISKSTATS
     286             :     AddSysctl<CTL_HW, HW_DISKSTATS>(hasher);
     287             : #    endif
     288             : #  endif
     289             : #  ifdef CTL_VM
     290             : #    ifdef VM_LOADAVG
     291             :     AddSysctl<CTL_VM, VM_LOADAVG>(hasher);
     292             : #    endif
     293             : #    ifdef VM_TOTAL
     294             :     AddSysctl<CTL_VM, VM_TOTAL>(hasher);
     295             : #    endif
     296             : #    ifdef VM_METER
     297             :     AddSysctl<CTL_VM, VM_METER>(hasher);
     298             : #    endif
     299             : #  endif
     300             : #endif
     301             : 
     302             :     // Stack and heap location
     303           2 :     void* addr = malloc(4097);
     304           2 :     hasher << &addr << addr;
     305           2 :     free(addr);
     306           2 : }
     307             : 
     308           2 : void RandAddStaticEnv(CSHA512& hasher)
     309             : {
     310             :     // Some compile-time static properties
     311           2 :     hasher << (CHAR_MIN < 0) << sizeof(void*) << sizeof(long) << sizeof(int);
     312             : #if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
     313           2 :     hasher << __GNUC__ << __GNUC_MINOR__ << __GNUC_PATCHLEVEL__;
     314             : #endif
     315             : #ifdef _MSC_VER
     316             :     hasher << _MSC_VER;
     317             : #endif
     318           2 :     hasher << __cplusplus;
     319             : #ifdef _XOPEN_VERSION
     320           2 :     hasher << _XOPEN_VERSION;
     321             : #endif
     322             : #ifdef __VERSION__
     323           2 :     const char* COMPILER_VERSION = __VERSION__;
     324           2 :     hasher.Write((const unsigned char*)COMPILER_VERSION, strlen(COMPILER_VERSION) + 1);
     325             : #endif
     326             : 
     327             :     // Bitcoin client version
     328           2 :     hasher << CLIENT_VERSION;
     329             : 
     330             : #if defined(HAVE_STRONG_GETAUXVAL)
     331             :     // Information available through getauxval()
     332             : #  ifdef AT_HWCAP
     333           2 :     hasher << getauxval(AT_HWCAP);
     334             : #  endif
     335             : #  ifdef AT_HWCAP2
     336           2 :     hasher << getauxval(AT_HWCAP2);
     337             : #  endif
     338             : #  ifdef AT_RANDOM
     339           2 :     const unsigned char* random_aux = (const unsigned char*)getauxval(AT_RANDOM);
     340           2 :     if (random_aux) hasher.Write(random_aux, 16);
     341             : #  endif
     342             : #  ifdef AT_PLATFORM
     343           2 :     const char* platform_str = (const char*)getauxval(AT_PLATFORM);
     344           2 :     if (platform_str) hasher.Write((const unsigned char*)platform_str, strlen(platform_str) + 1);
     345             : #  endif
     346             : #  ifdef AT_EXECFN
     347           2 :     const char* exec_str = (const char*)getauxval(AT_EXECFN);
     348           2 :     if (exec_str) hasher.Write((const unsigned char*)exec_str, strlen(exec_str) + 1);
     349             : #  endif
     350             : #endif // HAVE_STRONG_GETAUXVAL
     351             : 
     352             : #ifdef HAVE_GETCPUID
     353           2 :     AddAllCPUID(hasher);
     354             : #endif
     355             : 
     356             :     // Memory locations
     357           2 :     hasher << &hasher << &RandAddStaticEnv << &malloc << &errno << &environ;
     358             : 
     359             :     // Hostname
     360             :     char hname[256];
     361           2 :     if (gethostname(hname, 256) == 0) {
     362           2 :         hasher.Write((const unsigned char*)hname, strnlen(hname, 256));
     363           2 :     }
     364             : 
     365             : #if HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS
     366             :     // Network interfaces
     367           2 :     struct ifaddrs *ifad = nullptr;
     368           2 :     getifaddrs(&ifad);
     369           2 :     struct ifaddrs *ifit = ifad;
     370          28 :     while (ifit != nullptr) {
     371          26 :         hasher.Write((const unsigned char*)&ifit, sizeof(ifit));
     372          26 :         hasher.Write((const unsigned char*)ifit->ifa_name, strlen(ifit->ifa_name) + 1);
     373          26 :         hasher.Write((const unsigned char*)&ifit->ifa_flags, sizeof(ifit->ifa_flags));
     374          26 :         AddSockaddr(hasher, ifit->ifa_addr);
     375          26 :         AddSockaddr(hasher, ifit->ifa_netmask);
     376          26 :         AddSockaddr(hasher, ifit->ifa_dstaddr);
     377          26 :         ifit = ifit->ifa_next;
     378             :     }
     379           2 :     freeifaddrs(ifad);
     380             : #endif
     381             : 
     382             : #ifndef WIN32
     383             :     // UNIX kernel information
     384             :     struct utsname name;
     385           2 :     if (uname(&name) != -1) {
     386           2 :         hasher.Write((const unsigned char*)&name.sysname, strlen(name.sysname) + 1);
     387           2 :         hasher.Write((const unsigned char*)&name.nodename, strlen(name.nodename) + 1);
     388           2 :         hasher.Write((const unsigned char*)&name.release, strlen(name.release) + 1);
     389           2 :         hasher.Write((const unsigned char*)&name.version, strlen(name.version) + 1);
     390           2 :         hasher.Write((const unsigned char*)&name.machine, strlen(name.machine) + 1);
     391           2 :     }
     392             : 
     393             :     /* Path and filesystem provided data */
     394           2 :     AddPath(hasher, "/");
     395           2 :     AddPath(hasher, ".");
     396           2 :     AddPath(hasher, "/tmp");
     397           2 :     AddPath(hasher, "/home");
     398           2 :     AddPath(hasher, "/proc");
     399             : #ifdef __linux__
     400           2 :     AddFile(hasher, "/proc/cmdline");
     401           2 :     AddFile(hasher, "/proc/cpuinfo");
     402           2 :     AddFile(hasher, "/proc/version");
     403             : #endif
     404           2 :     AddFile(hasher, "/etc/passwd");
     405           2 :     AddFile(hasher, "/etc/group");
     406           2 :     AddFile(hasher, "/etc/hosts");
     407           2 :     AddFile(hasher, "/etc/resolv.conf");
     408           2 :     AddFile(hasher, "/etc/timezone");
     409           2 :     AddFile(hasher, "/etc/localtime");
     410             : #endif
     411             : 
     412             :     // For MacOS/BSDs, gather data through sysctl instead of /proc. Not all of these
     413             :     // will exist on every system.
     414             : #if HAVE_SYSCTL
     415             : #  ifdef CTL_HW
     416             : #    ifdef HW_MACHINE
     417             :     AddSysctl<CTL_HW, HW_MACHINE>(hasher);
     418             : #    endif
     419             : #    ifdef HW_MODEL
     420             :     AddSysctl<CTL_HW, HW_MODEL>(hasher);
     421             : #    endif
     422             : #    ifdef HW_NCPU
     423             :     AddSysctl<CTL_HW, HW_NCPU>(hasher);
     424             : #    endif
     425             : #    ifdef HW_PHYSMEM
     426             :     AddSysctl<CTL_HW, HW_PHYSMEM>(hasher);
     427             : #    endif
     428             : #    ifdef HW_USERMEM
     429             :     AddSysctl<CTL_HW, HW_USERMEM>(hasher);
     430             : #    endif
     431             : #    ifdef HW_MACHINE_ARCH
     432             :     AddSysctl<CTL_HW, HW_MACHINE_ARCH>(hasher);
     433             : #    endif
     434             : #    ifdef HW_REALMEM
     435             :     AddSysctl<CTL_HW, HW_REALMEM>(hasher);
     436             : #    endif
     437             : #    ifdef HW_CPU_FREQ
     438             :     AddSysctl<CTL_HW, HW_CPU_FREQ>(hasher);
     439             : #    endif
     440             : #    ifdef HW_BUS_FREQ
     441             :     AddSysctl<CTL_HW, HW_BUS_FREQ>(hasher);
     442             : #    endif
     443             : #    ifdef HW_CACHELINE
     444             :     AddSysctl<CTL_HW, HW_CACHELINE>(hasher);
     445             : #    endif
     446             : #  endif
     447             : #  ifdef CTL_KERN
     448             : #    ifdef KERN_BOOTFILE
     449             :      AddSysctl<CTL_KERN, KERN_BOOTFILE>(hasher);
     450             : #    endif
     451             : #    ifdef KERN_BOOTTIME
     452             :      AddSysctl<CTL_KERN, KERN_BOOTTIME>(hasher);
     453             : #    endif
     454             : #    ifdef KERN_CLOCKRATE
     455             :      AddSysctl<CTL_KERN, KERN_CLOCKRATE>(hasher);
     456             : #    endif
     457             : #    ifdef KERN_HOSTID
     458             :      AddSysctl<CTL_KERN, KERN_HOSTID>(hasher);
     459             : #    endif
     460             : #    ifdef KERN_HOSTUUID
     461             :      AddSysctl<CTL_KERN, KERN_HOSTUUID>(hasher);
     462             : #    endif
     463             : #    ifdef KERN_HOSTNAME
     464             :      AddSysctl<CTL_KERN, KERN_HOSTNAME>(hasher);
     465             : #    endif
     466             : #    ifdef KERN_OSRELDATE
     467             :      AddSysctl<CTL_KERN, KERN_OSRELDATE>(hasher);
     468             : #    endif
     469             : #    ifdef KERN_OSRELEASE
     470             :      AddSysctl<CTL_KERN, KERN_OSRELEASE>(hasher);
     471             : #    endif
     472             : #    ifdef KERN_OSREV
     473             :      AddSysctl<CTL_KERN, KERN_OSREV>(hasher);
     474             : #    endif
     475             : #    ifdef KERN_OSTYPE
     476             :      AddSysctl<CTL_KERN, KERN_OSTYPE>(hasher);
     477             : #    endif
     478             : #    ifdef KERN_POSIX1
     479             :      AddSysctl<CTL_KERN, KERN_OSREV>(hasher);
     480             : #    endif
     481             : #    ifdef KERN_VERSION
     482             :      AddSysctl<CTL_KERN, KERN_VERSION>(hasher);
     483             : #    endif
     484             : #  endif
     485             : #endif
     486             : 
     487             :     // Env variables
     488           2 :     if (environ) {
     489           6 :         for (size_t i = 0; environ[i]; ++i) {
     490           4 :             hasher.Write((const unsigned char*)environ[i], strlen(environ[i]));
     491           4 :         }
     492           2 :     }
     493             : 
     494             :     // Process, thread, user, session, group, ... ids.
     495             : #ifdef WIN32
     496             :     hasher << GetCurrentProcessId() << GetCurrentThreadId();
     497             : #else
     498           2 :     hasher << getpid() << getppid() << getsid(0) << getpgid(0) << getuid() << geteuid() << getgid() << getegid();
     499             : #endif
     500           2 :     hasher << std::this_thread::get_id();
     501           2 : }