Botan::ProcWalking_EntropySource Class Reference

#include <proc_walk.h>

Inheritance diagram for Botan::ProcWalking_EntropySource:

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_Source >	create (const std::string &type)

Detailed Description

File Tree Walking Entropy Source

Definition at line 26 of file proc_walk.h.

Constructor & Destructor Documentation

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

inlineexplicit

Definition at line 33 of file proc_walk.h.

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

Member Function Documentation

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 67 of file entropy_srcs.cpp.

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

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

   {
#if defined(BOTAN_HAS_SYSTEM_RNG)
   if(name == "system_rng" || name == "win32_cryptoapi")
      {
      return std::unique_ptr<Entropy_Source>(new System_RNG_EntropySource);
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_RDRAND)
   if(name == "rdrand")
      {
      return std::unique_ptr<Entropy_Source>(new Intel_Rdrand);
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_RDSEED)
   if(name == "rdseed")
      {
      return std::unique_ptr<Entropy_Source>(new Intel_Rdseed);
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_DARN)
   if(name == "p9_darn")
      {
      return std::unique_ptr<Entropy_Source>(new POWER9_DARN);
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
   if(name == "getentropy")
      {
      return std::unique_ptr<Entropy_Source>(new Getentropy);
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
   if(name == "dev_random")
      {
      return std::unique_ptr<Entropy_Source>(new Device_EntropySource(BOTAN_SYSTEM_RNG_POLL_DEVICES));
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_PROC_WALKER)
   if(name == "proc_walk" && OS::running_in_privileged_state() == false)
      {
      const std::string root_dir = BOTAN_ENTROPY_PROC_FS_PATH;
      if(!root_dir.empty())
         return std::unique_ptr<Entropy_Source>(new ProcWalking_EntropySource(root_dir));
      }
#endif

#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
   if(name == "system_stats")
      {
      return std::unique_ptr<Entropy_Source>(new Win32_EntropySource);
      }
#endif

   BOTAN_UNUSED(name);
   return std::unique_ptr<Entropy_Source>();
   }

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.

{ return "proc_walk"; }

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

overridevirtual

Perform an entropy gathering poll

Parameters

rng	will 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.

References Botan::RandomNumberGenerator::add_entropy(), and m_mutex.

   {
   const size_t MAX_FILES_READ_PER_POLL = 2048;

   lock_guard_type<mutex_type> lock(m_mutex);

   if(!m_dir)
      m_dir.reset(new Directory_Walker(m_path));

   m_buf.resize(4096);

   size_t bits = 0;

   for(size_t i = 0; i != MAX_FILES_READ_PER_POLL; ++i)
      {
      int fd = m_dir->next_fd();

      // If we've exhaused this walk of the directory, halt the poll
      if(fd == -1)
         {
         m_dir.reset();
         break;
         }

      ssize_t got = ::read(fd, m_buf.data(), m_buf.size());
      ::close(fd);

      if(got > 0)
         {
         rng.add_entropy(m_buf.data(), static_cast<size_t>(got));

         // Conservative estimate of 4 bits per file
         bits += 4;
         }

      if(bits > 128)
         break;
      }

   return bits;
   }

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

• src/lib/entropy/proc_walk/proc_walk.h
• src/lib/entropy/proc_walk/proc_walk.cpp