Botan  1.10.9
es_egd.cpp
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1 /*
2 * EGD EntropySource
3 * (C) 1999-2009 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7 
8 #include <botan/internal/es_egd.h>
9 #include <botan/parsing.h>
10 #include <botan/exceptn.h>
11 #include <cstring>
12 #include <stdexcept>
13 
14 #include <sys/types.h>
15 #include <sys/stat.h>
16 #include <fcntl.h>
17 #include <unistd.h>
18 
19 #include <sys/socket.h>
20 #include <sys/un.h>
21 
22 #ifndef PF_LOCAL
23  #define PF_LOCAL PF_UNIX
24 #endif
25 
26 namespace Botan {
27 
28 EGD_EntropySource::EGD_Socket::EGD_Socket(const std::string& path) :
29  socket_path(path), m_fd(-1)
30  {
31  }
32 
33 /**
34 * Attempt a connection to an EGD/PRNGD socket
35 */
36 int EGD_EntropySource::EGD_Socket::open_socket(const std::string& path)
37  {
38  int fd = ::socket(PF_LOCAL, SOCK_STREAM, 0);
39 
40  if(fd >= 0)
41  {
42  sockaddr_un addr;
43  std::memset(&addr, 0, sizeof(addr));
44  addr.sun_family = PF_LOCAL;
45 
46  if(path.length() >= sizeof(addr.sun_path))
47  throw std::invalid_argument("EGD socket path is too long");
48 
49  std::strncpy(addr.sun_path, path.c_str(), sizeof(addr.sun_path));
50 
51  int len = sizeof(addr.sun_family) + std::strlen(addr.sun_path) + 1;
52 
53  if(::connect(fd, reinterpret_cast<struct ::sockaddr*>(&addr), len) < 0)
54  {
55  ::close(fd);
56  fd = -1;
57  }
58  }
59 
60  return fd;
61  }
62 
63 /**
64 * Attempt to read entropy from EGD
65 */
66 size_t EGD_EntropySource::EGD_Socket::read(byte outbuf[], size_t length)
67  {
68  if(length == 0)
69  return 0;
70 
71  if(m_fd < 0)
72  {
73  m_fd = open_socket(socket_path);
74  if(m_fd < 0)
75  return 0;
76  }
77 
78  try
79  {
80  // 1 == EGD command for non-blocking read
81  byte egd_read_command[2] = {
82  1, static_cast<byte>(std::min<size_t>(length, 255)) };
83 
84  if(::write(m_fd, egd_read_command, 2) != 2)
85  throw std::runtime_error("Writing entropy read command to EGD failed");
86 
87  byte out_len = 0;
88  if(::read(m_fd, &out_len, 1) != 1)
89  throw std::runtime_error("Reading response length from EGD failed");
90 
91  if(out_len > egd_read_command[1])
92  throw std::runtime_error("Bogus length field received from EGD");
93 
94  ssize_t count = ::read(m_fd, outbuf, out_len);
95 
96  if(count != out_len)
97  throw std::runtime_error("Reading entropy result from EGD failed");
98 
99  return static_cast<size_t>(count);
100  }
101  catch(std::exception)
102  {
103  this->close();
104  // Will attempt to reopen next poll
105  }
106 
107  return 0;
108  }
109 
110 void EGD_EntropySource::EGD_Socket::close()
111  {
112  if(m_fd > 0)
113  {
114  ::close(m_fd);
115  m_fd = -1;
116  }
117  }
118 
119 /**
120 * EGD_EntropySource constructor
121 */
122 EGD_EntropySource::EGD_EntropySource(const std::vector<std::string>& paths)
123  {
124  for(size_t i = 0; i != paths.size(); ++i)
125  sockets.push_back(EGD_Socket(paths[i]));
126  }
127 
129  {
130  for(size_t i = 0; i != sockets.size(); ++i)
131  sockets[i].close();
132  sockets.clear();
133  }
134 
135 /**
136 * Gather Entropy from EGD
137 */
139  {
140  size_t go_get = std::min<size_t>(accum.desired_remaining_bits() / 8, 32);
141 
142  MemoryRegion<byte>& io_buffer = accum.get_io_buffer(go_get);
143 
144  for(size_t i = 0; i != sockets.size(); ++i)
145  {
146  size_t got = sockets[i].read(&io_buffer[0], io_buffer.size());
147 
148  if(got)
149  {
150  accum.add(&io_buffer[0], got, 6);
151  break;
152  }
153  }
154  }
155 
156 }
EGD_EntropySource(const std::vector< std::string > &)
Definition: es_egd.cpp:122
MemoryRegion< byte > & get_io_buffer(size_t size)
Definition: entropy_src.h:38
void poll(Entropy_Accumulator &accum)
Definition: es_egd.cpp:138
void add(const void *bytes, size_t length, double entropy_bits_per_byte)
Definition: entropy_src.h:70
unsigned char byte
Definition: types.h:22
#define PF_LOCAL
Definition: es_egd.cpp:23
size_t desired_remaining_bits() const
Definition: entropy_src.h:56