src/third_party/tlslite/tlslite/utils/entropy.c

   1
   2 #include "Python.h"
   3
   4
   5 #ifdef MS_WINDOWS
   6
   7 /* The following #define is not needed on VC6 with the Platform SDK, and it
   8 may not be needed on VC7, I'm not sure.  I don't think it hurts anything.*/
   9 #define _WIN32_WINNT 0x0400
  10
  11 #include <windows.h>
  12
  13
  14 typedef BOOL (WINAPI *CRYPTACQUIRECONTEXTA)(HCRYPTPROV *phProv,\
  15               LPCSTR pszContainer, LPCSTR pszProvider, DWORD dwProvType,\
  16               DWORD dwFlags );
  17 typedef BOOL (WINAPI *CRYPTGENRANDOM)(HCRYPTPROV hProv, DWORD dwLen,\
  18               BYTE *pbBuffer );
  19 typedef BOOL (WINAPI *CRYPTRELEASECONTEXT)(HCRYPTPROV hProv,\
  20               DWORD dwFlags);
  21
  22
  23 static PyObject* entropy(PyObject *self, PyObject *args)
  24 {
  25     int howMany = 0;
  26     HINSTANCE hAdvAPI32 = NULL;
  27     CRYPTACQUIRECONTEXTA pCryptAcquireContextA = NULL;
  28     CRYPTGENRANDOM pCryptGenRandom = NULL;
  29     CRYPTRELEASECONTEXT pCryptReleaseContext = NULL;
  30     HCRYPTPROV hCryptProv = 0;
  31     unsigned char* bytes = NULL;
  32     PyObject* returnVal = NULL;
  33
  34
  35     /* Read arguments */
  36     if (!PyArg_ParseTuple(args, "i", &howMany))
  37         return(NULL);
  38
  39         /* Obtain handle to the DLL containing CryptoAPI
  40            This should not fail */
  41         if( (hAdvAPI32 = GetModuleHandle("advapi32.dll")) == NULL) {
  42         PyErr_Format(PyExc_SystemError,
  43             "Advapi32.dll not found");
  44         return NULL;
  45         }
  46
  47         /* Obtain pointers to the CryptoAPI functions
  48            This will fail on some early version of Win95 */
  49         pCryptAcquireContextA = (CRYPTACQUIRECONTEXTA)GetProcAddress(hAdvAPI32,\
  50                                 "CryptAcquireContextA");
  51         pCryptGenRandom = (CRYPTGENRANDOM)GetProcAddress(hAdvAPI32,\
  52                           "CryptGenRandom");
  53         pCryptReleaseContext = (CRYPTRELEASECONTEXT) GetProcAddress(hAdvAPI32,\
  54                                "CryptReleaseContext");
  55         if (pCryptAcquireContextA == NULL || pCryptGenRandom == NULL ||
  56                                              pCryptReleaseContext == NULL) {
  57         PyErr_Format(PyExc_NotImplementedError,
  58             "CryptoAPI not available on this version of Windows");
  59         return NULL;
  60         }
  61
  62     /* Allocate bytes */
  63     if ((bytes = (unsigned char*)PyMem_Malloc(howMany)) == NULL)
  64         return PyErr_NoMemory();
  65
  66
  67     /* Acquire context */
  68     if(!pCryptAcquireContextA(&hCryptProv, NULL, NULL, PROV_RSA_FULL,
  69                             CRYPT_VERIFYCONTEXT)) {
  70         PyErr_Format(PyExc_SystemError,
  71                      "CryptAcquireContext failed, error %d", GetLastError());
  72         PyMem_Free(bytes);
  73         return NULL;
  74     }
  75
  76     /* Get random data */
  77     if(!pCryptGenRandom(hCryptProv, howMany, bytes)) {
  78         PyErr_Format(PyExc_SystemError,
  79                      "CryptGenRandom failed, error %d", GetLastError());
  80         PyMem_Free(bytes);
  81         CryptReleaseContext(hCryptProv, 0);
  82         return NULL;
  83     }
  84
  85     /* Build return value */
  86     returnVal = Py_BuildValue("s#", bytes, howMany);
  87     PyMem_Free(bytes);
  88
  89     /* Release context */
  90     if (!pCryptReleaseContext(hCryptProv, 0)) {
  91         PyErr_Format(PyExc_SystemError,
  92                      "CryptReleaseContext failed, error %d", GetLastError());
  93         return NULL;
  94     }
  95
  96     return returnVal;
  97 }
  98
  99 #elif defined(HAVE_UNISTD_H) && defined(HAVE_FCNTL_H)
 100
 101 #include <unistd.h>
 102 #include <fcntl.h>
 103
 104 static PyObject* entropy(PyObject *self, PyObject *args)
 105 {
 106     int howMany;
 107     int fd;
 108     unsigned char* bytes = NULL;
 109     PyObject* returnVal = NULL;
 110
 111
 112     /* Read arguments */
 113     if (!PyArg_ParseTuple(args, "i", &howMany))
 114         return(NULL);
 115
 116     /* Allocate bytes */
 117     if ((bytes = (unsigned char*)PyMem_Malloc(howMany)) == NULL)
 118         return PyErr_NoMemory();
 119
 120     /* Open device */
 121     if ((fd = open("/dev/urandom", O_RDONLY, 0)) == -1) {
 122         PyErr_Format(PyExc_NotImplementedError,
 123             "No entropy source found");
 124         PyMem_Free(bytes);
 125         return NULL;
 126     }
 127
 128     /* Get random data */
 129     if (read(fd, bytes, howMany) < howMany) {
 130         PyErr_Format(PyExc_SystemError,
 131             "Reading from /dev/urandom failed");
 132         PyMem_Free(bytes);
 133         close(fd);
 134         return NULL;
 135     }
 136
 137     /* Build return value */
 138     returnVal = Py_BuildValue("s#", bytes, howMany);
 139     PyMem_Free(bytes);
 140
 141     /* Close device */
 142     close(fd);
 143
 144     return returnVal;
 145 }
 146
 147 #else
 148
 149 static PyObject* entropy(PyObject *self, PyObject *args)
 150 {
 151     PyErr_Format(PyExc_NotImplementedError,
 152             "Function not supported");
 153     return NULL;
 154 }
 155
 156 #endif
 157
 158
 159
 160 /* List of functions exported by this module */
 161
 162 static struct PyMethodDef entropy_functions[] = {
 163     {"entropy", (PyCFunction)entropy, METH_VARARGS, "Return a string of random bytes produced by a platform-specific\nentropy source."},
 164     {NULL,  NULL}        /* Sentinel */
 165 };
 166
 167
 168 /* Initialize this module. */
 169
 170 PyMODINIT_FUNC initentropy(void)
 171 {
 172     Py_InitModule("entropy", entropy_functions);
 173 }