src/library/crandom.cpp

   1 #include "arch-detect.hpp"
   2 #include "crandom.hpp"
   3 #include <stdexcept>
   4 #include <iostream>
   5
   6 #if defined(_WIN32) || defined(_WIN64)
   7 #include <windows.h>
   8
   9 namespace
  10 {
  11         typedef BOOLEAN (WINAPI *rtlgenrandom_t)(PVOID buf, ULONG buflen);
  12         HMODULE advapi;
  13         rtlgenrandom_t rtlgenrandom_fn;
  14 }
  15
  16 namespace crandom
  17 {
  18 void init()
  19 {
  20         if(rtlgenrandom_fn) return;
  21         advapi = LoadLibraryA("advapi32.dll");
  22         if(!advapi)
  23                 throw std::runtime_error("Can't load advapi32.dll");
  24         rtlgenrandom_fn = (rtlgenrandom_t)GetProcAddress(advapi, "SystemFunction036");
  25         if(!rtlgenrandom_fn)
  26                 throw std::runtime_error("Can't find rtlgenrandom");
  27 }
  28
  29 void generate(void* buffer, size_t buffersize)
  30 {
  31         if(!rtlgenrandom_fn)
  32                 init();
  33         while(!rtlgenrandom_fn(buffer, buffersize));
  34 }
  35 }
  36
  37 #else
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40 #include <cerrno>
  41
  42 namespace
  43 {
  44         int fd = -1;
  45         void try_file(const char* name)
  46         {
  47                 int err = 0;
  48                 while(fd < 0 && err != ENOENT && err != ENXIO) {
  49                         fd = open(name, O_RDONLY);
  50                         if(fd < 0) err = errno;
  51                 }
  52         }
  53 }
  54
  55 namespace crandom
  56 {
  57 void init()
  58 {
  59         if(fd < 0) try_file("/dev/urandom");
  60         if(fd < 0) try_file("/dev/random");
  61         if(fd < 0) throw std::runtime_error("Can't open /dev/urandom");
  62 }
  63
  64 void generate(void* buffer, size_t buffersize)
  65 {
  66         if(fd < 0)
  67                 init();
  68         size_t out = 0;
  69         while(out < buffersize) {
  70                 ssize_t r = read(fd, (char*)buffer + out, buffersize - out);
  71                 if(r > 0) out += r;
  72         }
  73 }
  74 }
  75
  76 #endif
  77
  78 namespace crandom
  79 {
  80 uint64_t arch_get_tsc()
  81 {
  82 #ifdef ARCH_IS_I386
  83         uint32_t a, b;
  84         asm volatile("rdtsc" : "=a"(a), "=d"(b));
  85         return ((uint64_t)b << 32) | a;
  86 #else
  87         return 0;
  88 #endif
  89 }
  90
  91 uint64_t arch_get_random()
  92 {
  93 #ifdef ARCH_IS_I386
  94         uint32_t r;
  95         asm volatile (".byte 0xb8, 0x01, 0x00, 0x00, 0x00, 0x0f, 0xa2, 0xf7, 0xc1, 0x00, 0x00, 0x00, 0x40, "
  96                 "0x74, 0x05, 0x0f, 0xc7, 0xf0, 0xeb, 0x02, 0x31, 0xc0" : "=a"(r) : : "ebx", "ecx", "edx");
  97         return r;
  98 #else
  99         return 0;
 100 #endif
 101 }
 102 }