Botan  1.11.15
src/lib/entropy/hres_timer/hres_timer.cpp
Go to the documentation of this file.
00001 /*
00002 * High Resolution Timestamp Entropy Source
00003 * (C) 1999-2009,2011,2014 Jack Lloyd
00004 *
00005 * Botan is released under the Simplified BSD License (see license.txt)
00006 */
00007 
00008 #include <botan/internal/hres_timer.h>
00009 #include <botan/cpuid.h>
00010 #include <chrono>
00011 
00012 #if defined(BOTAN_TARGET_OS_HAS_QUERY_PERF_COUNTER)
00013   #include <windows.h>
00014   #undef min
00015   #undef max
00016 #endif
00017 
00018 #if defined(BOTAN_TARGET_OS_HAS_CLOCK_GETTIME)
00019   #include <time.h>
00020 #endif
00021 
00022 namespace Botan {
00023 
00024 /*
00025 * Get the timestamp
00026 */
00027 void High_Resolution_Timestamp::poll(Entropy_Accumulator& accum)
00028    {
00029    // Don't count any timestamps as contributing any entropy
00030    const double ESTIMATED_ENTROPY_PER_BYTE = 0.0;
00031 
00032 #if defined(BOTAN_TARGET_OS_HAS_CLOCK_GETTIME)
00033 
00034 #define CLOCK_GETTIME_POLL(src)                              \
00035    do {                                                      \
00036      struct timespec ts;                                     \
00037      ::clock_gettime(src, &ts);                              \
00038      accum.add(&ts, sizeof(ts), ESTIMATED_ENTROPY_PER_BYTE); \
00039    } while(0)
00040 
00041 #if defined(CLOCK_REALTIME)
00042    CLOCK_GETTIME_POLL(CLOCK_REALTIME);
00043 #endif
00044 
00045 #if defined(CLOCK_MONOTONIC)
00046    CLOCK_GETTIME_POLL(CLOCK_MONOTONIC);
00047 #endif
00048 
00049 #if defined(CLOCK_MONOTONIC_RAW)
00050    CLOCK_GETTIME_POLL(CLOCK_MONOTONIC_RAW);
00051 #endif
00052 
00053 #if defined(CLOCK_PROCESS_CPUTIME_ID)
00054    CLOCK_GETTIME_POLL(CLOCK_PROCESS_CPUTIME_ID);
00055 #endif
00056 
00057 #if defined(CLOCK_THREAD_CPUTIME_ID)
00058    CLOCK_GETTIME_POLL(CLOCK_THREAD_CPUTIME_ID);
00059 #endif
00060 
00061 #undef CLOCK_GETTIME_POLL
00062 
00063 #else
00064 
00065 #define STD_CHRONO_POLL(clock)                                  \
00066    do {                                                         \
00067       auto timestamp = clock::now().time_since_epoch().count(); \
00068       accum.add(timestamp, ESTIMATED_ENTROPY_PER_BYTE);         \
00069    } while(0)
00070 
00071   STD_CHRONO_POLL(std::chrono::high_resolution_clock);
00072   STD_CHRONO_POLL(std::chrono::system_clock);
00073 
00074 #undef STD_CHRONO_POLL
00075 
00076 #endif
00077 
00078 #if BOTAN_USE_GCC_INLINE_ASM
00079 
00080    u64bit rtc = 0;
00081 
00082 #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
00083    if(CPUID::has_rdtsc()) // not availble on all x86 CPUs
00084       {
00085       u32bit rtc_low = 0, rtc_high = 0;
00086       asm volatile("rdtsc" : "=d" (rtc_high), "=a" (rtc_low));
00087       rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;
00088       }
00089 
00090 #elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)
00091    u32bit rtc_low = 0, rtc_high = 0;
00092    asm volatile("mftbu %0; mftb %1" : "=r" (rtc_high), "=r" (rtc_low));
00093    rtc = (static_cast<u64bit>(rtc_high) << 32) | rtc_low;
00094 
00095 #elif defined(BOTAN_TARGET_ARCH_IS_ALPHA)
00096    asm volatile("rpcc %0" : "=r" (rtc));
00097 
00098 #elif defined(BOTAN_TARGET_ARCH_IS_SPARC64) && !defined(BOTAN_TARGET_OS_IS_OPENBSD)
00099    asm volatile("rd %%tick, %0" : "=r" (rtc));
00100 
00101 #elif defined(BOTAN_TARGET_ARCH_IS_IA64)
00102    asm volatile("mov %0=ar.itc" : "=r" (rtc));
00103 
00104 #elif defined(BOTAN_TARGET_ARCH_IS_S390X)
00105    asm volatile("stck 0(%0)" : : "a" (&rtc) : "memory", "cc");
00106 
00107 #elif defined(BOTAN_TARGET_ARCH_IS_HPPA)
00108    asm volatile("mfctl 16,%0" : "=r" (rtc)); // 64-bit only?
00109 
00110 #endif
00111 
00112    accum.add(rtc, ESTIMATED_ENTROPY_PER_BYTE);
00113 
00114 #endif
00115 
00116 #if defined(BOTAN_TARGET_OS_HAS_QUERY_PERF_COUNTER)
00117    {
00118    LARGE_INTEGER tv;
00119    ::QueryPerformanceCounter(&tv);
00120    accum.add(tv.QuadPart, ESTIMATED_ENTROPY_PER_BYTE);
00121    }
00122 #endif
00123    }
00124 
00125 }