1 // Copyright 2017 PDFium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6
7 #include "core/fxcrt/fx_random.h"
8
9 #include "core/fxcrt/fx_memory.h"
10 #include "core/fxcrt/fx_string.h"
11 #include "core/fxcrt/fx_system.h"
12
13 #define MT_N 848
14 #define MT_M 456
15 #define MT_Matrix_A 0x9908b0df
16 #define MT_Upper_Mask 0x80000000
17 #define MT_Lower_Mask 0x7fffffff
18
19 #if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
20 #include <wincrypt.h>
21 #else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
22 #include <sys/time.h>
23 #include <unistd.h>
24 #endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
25
26 namespace {
27
28 struct MTContext {
29 uint32_t mti;
30 uint32_t mt[MT_N];
31 };
32
33 bool g_bHaveGlobalSeed = false;
34 uint32_t g_nGlobalSeed = 0;
35
36 #if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
GenerateSeedFromCryptoRandom(uint32_t * pSeed)37 bool GenerateSeedFromCryptoRandom(uint32_t* pSeed) {
38 HCRYPTPROV hCP = 0;
39 if (!::CryptAcquireContext(&hCP, nullptr, nullptr, PROV_RSA_FULL, 0) ||
40 !hCP) {
41 return false;
42 }
43 ::CryptGenRandom(hCP, sizeof(uint32_t), reinterpret_cast<uint8_t*>(pSeed));
44 ::CryptReleaseContext(hCP, 0);
45 return true;
46 }
47 #endif
48
GenerateSeedFromEnvironment()49 uint32_t GenerateSeedFromEnvironment() {
50 char c;
51 uintptr_t p = reinterpret_cast<uintptr_t>(&c);
52 uint32_t seed = ~static_cast<uint32_t>(p >> 3);
53 #if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
54 SYSTEMTIME st;
55 GetSystemTime(&st);
56 seed ^= static_cast<uint32_t>(st.wSecond) * 1000000;
57 seed ^= static_cast<uint32_t>(st.wMilliseconds) * 1000;
58 seed ^= GetCurrentProcessId();
59 #else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
60 struct timeval tv;
61 gettimeofday(&tv, 0);
62 seed ^= static_cast<uint32_t>(tv.tv_sec) * 1000000;
63 seed ^= static_cast<uint32_t>(tv.tv_usec);
64 seed ^= static_cast<uint32_t>(getpid());
65 #endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
66 return seed;
67 }
68
ContextFromNextGlobalSeed()69 void* ContextFromNextGlobalSeed() {
70 if (!g_bHaveGlobalSeed) {
71 #if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
72 if (!GenerateSeedFromCryptoRandom(&g_nGlobalSeed))
73 g_nGlobalSeed = GenerateSeedFromEnvironment();
74 #else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
75 g_nGlobalSeed = GenerateSeedFromEnvironment();
76 #endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
77 g_bHaveGlobalSeed = true;
78 }
79 return FX_Random_MT_Start(++g_nGlobalSeed);
80 }
81
82 } // namespace
83
FX_Random_MT_Start(uint32_t dwSeed)84 void* FX_Random_MT_Start(uint32_t dwSeed) {
85 MTContext* pContext = FX_Alloc(MTContext, 1);
86 uint32_t* pBuf = pContext->mt;
87 pBuf[0] = dwSeed;
88 for (uint32_t i = 1; i < MT_N; i++)
89 pBuf[i] = (1812433253UL * (pBuf[i - 1] ^ (pBuf[i - 1] >> 30)) + i);
90
91 pContext->mti = MT_N;
92 return pContext;
93 }
94
FX_Random_MT_Generate(void * pContext)95 uint32_t FX_Random_MT_Generate(void* pContext) {
96 MTContext* pMTC = static_cast<MTContext*>(pContext);
97 uint32_t* pBuf = pMTC->mt;
98 uint32_t v;
99 if (pMTC->mti >= MT_N) {
100 static const uint32_t mag[2] = {0, MT_Matrix_A};
101 uint32_t kk;
102 for (kk = 0; kk < MT_N - MT_M; kk++) {
103 v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
104 pBuf[kk] = pBuf[kk + MT_M] ^ (v >> 1) ^ mag[v & 1];
105 }
106 for (; kk < MT_N - 1; kk++) {
107 v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
108 pBuf[kk] = pBuf[kk + (MT_M - MT_N)] ^ (v >> 1) ^ mag[v & 1];
109 }
110 v = (pBuf[MT_N - 1] & MT_Upper_Mask) | (pBuf[0] & MT_Lower_Mask);
111 pBuf[MT_N - 1] = pBuf[MT_M - 1] ^ (v >> 1) ^ mag[v & 1];
112 pMTC->mti = 0;
113 }
114 v = pBuf[pMTC->mti++];
115 v ^= (v >> 11);
116 v ^= (v << 7) & 0x9d2c5680UL;
117 v ^= (v << 15) & 0xefc60000UL;
118 v ^= (v >> 18);
119 return v;
120 }
121
FX_Random_MT_Close(void * pContext)122 void FX_Random_MT_Close(void* pContext) {
123 FX_Free(pContext);
124 }
125
FX_Random_GenerateMT(uint32_t * pBuffer,int32_t iCount)126 void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount) {
127 void* pContext = ContextFromNextGlobalSeed();
128 while (iCount-- > 0)
129 *pBuffer++ = FX_Random_MT_Generate(pContext);
130
131 FX_Random_MT_Close(pContext);
132 }
133