Botan  2.8.0
Crypto and TLS for C++11
Public Member Functions | Static Public Member Functions | List of all members
Botan::ProcWalking_EntropySource Class Referencefinal

#include <proc_walk.h>

Inheritance diagram for Botan::ProcWalking_EntropySource:
Botan::Entropy_Source

Public Member Functions

std::string name () const override
 
size_t poll (RandomNumberGenerator &rng) override
 
 ProcWalking_EntropySource (const std::string &root_dir)
 

Static Public Member Functions

static std::unique_ptr< Entropy_Sourcecreate (const std::string &type)
 

Detailed Description

File Tree Walking Entropy Source

Definition at line 26 of file proc_walk.h.

Constructor & Destructor Documentation

◆ ProcWalking_EntropySource()

Botan::ProcWalking_EntropySource::ProcWalking_EntropySource ( const std::string &  root_dir)
inlineexplicit

Definition at line 33 of file proc_walk.h.

33  :
34  m_path(root_dir), m_dir(nullptr) {}

Member Function Documentation

◆ create()

std::unique_ptr< Entropy_Source > Botan::Entropy_Source::create ( const std::string &  type)
staticinherited

Return a new entropy source of a particular type, or null Each entropy source may require substantial resources (eg, a file handle or socket instance), so try to share them among multiple RNGs, or just use the preconfigured global list accessed by Entropy_Sources::global_sources()

Definition at line 63 of file entropy_srcs.cpp.

References BOTAN_UNUSED, Botan::Entropy_Source::name(), and Botan::OS::running_in_privileged_state().

Referenced by Botan::Entropy_Sources::Entropy_Sources().

64  {
65 #if defined(BOTAN_HAS_SYSTEM_RNG)
66  if(name == "system_rng" || name == "win32_cryptoapi")
67  {
68  return std::unique_ptr<Entropy_Source>(new System_RNG_EntropySource);
69  }
70 #endif
71 
72 #if defined(BOTAN_HAS_ENTROPY_SRC_RDRAND)
73  if(name == "rdrand")
74  {
75  return std::unique_ptr<Entropy_Source>(new Intel_Rdrand);
76  }
77 #endif
78 
79 #if defined(BOTAN_HAS_ENTROPY_SRC_RDSEED)
80  if(name == "rdseed")
81  {
82  return std::unique_ptr<Entropy_Source>(new Intel_Rdseed);
83  }
84 #endif
85 
86 #if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
87  if(name == "getentropy")
88  {
89  return std::unique_ptr<Entropy_Source>(new Getentropy);
90  }
91 #endif
92 
93 #if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
94  if(name == "dev_random")
95  {
96  return std::unique_ptr<Entropy_Source>(new Device_EntropySource(BOTAN_SYSTEM_RNG_POLL_DEVICES));
97  }
98 #endif
99 
100 #if defined(BOTAN_HAS_ENTROPY_SRC_PROC_WALKER)
101  if(name == "proc_walk" && OS::running_in_privileged_state() == false)
102  {
103  const std::string root_dir = BOTAN_ENTROPY_PROC_FS_PATH;
104  if(!root_dir.empty())
105  return std::unique_ptr<Entropy_Source>(new ProcWalking_EntropySource(root_dir));
106  }
107 #endif
108 
109 #if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
110  if(name == "system_stats")
111  {
112  return std::unique_ptr<Entropy_Source>(new Win32_EntropySource);
113  }
114 #endif
115 
117  return std::unique_ptr<Entropy_Source>();
118  }
virtual std::string name() const =0
bool running_in_privileged_state()
Definition: os_utils.cpp:83
#define BOTAN_UNUSED(...)
Definition: assert.h:142

◆ name()

std::string Botan::ProcWalking_EntropySource::name ( ) const
inlineoverridevirtual
Returns
name identifying this entropy source

Implements Botan::Entropy_Source.

Definition at line 29 of file proc_walk.h.

29 { return "proc_walk"; }

◆ poll()

size_t Botan::ProcWalking_EntropySource::poll ( RandomNumberGenerator rng)
overridevirtual

Perform an entropy gathering poll

Parameters
rngwill be provided with entropy via calls to add_entropy
Returns
conservative estimate of actual entropy added to rng during poll

Implements Botan::Entropy_Source.

Definition at line 112 of file proc_walk.cpp.

113  {
114  const size_t MAX_FILES_READ_PER_POLL = 2048;
115 
116  lock_guard_type<mutex_type> lock(m_mutex);
117 
118  if(!m_dir)
119  m_dir.reset(new Directory_Walker(m_path));
120 
121  m_buf.resize(4096);
122 
123  size_t bits = 0;
124 
125  for(size_t i = 0; i != MAX_FILES_READ_PER_POLL; ++i)
126  {
127  int fd = m_dir->next_fd();
128 
129  // If we've exhaused this walk of the directory, halt the poll
130  if(fd == -1)
131  {
132  m_dir.reset();
133  break;
134  }
135 
136  ssize_t got = ::read(fd, m_buf.data(), m_buf.size());
137  ::close(fd);
138 
139  if(got > 0)
140  {
141  rng.add_entropy(m_buf.data(), static_cast<size_t>(got));
142 
143  // Conservative estimate of 4 bits per file
144  bits += 4;
145  }
146 
147  if(bits > 128)
148  break;
149  }
150 
151  return bits;
152  }

The documentation for this class was generated from the following files: