Botan::ProcWalking_EntropySource Class Reference

#include <proc_walk.h>

Inheritance diagram for Botan::ProcWalking_EntropySource:

List of all members.

Public Member Functions
std::string	name () const
void	poll (Entropy_Accumulator &accum)
	ProcWalking_EntropySource (const std::string &root_dir)
Static Public Member Functions
static void	poll_available_sources (class Entropy_Accumulator &accum)

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Detailed Description

File Tree Walking Entropy Source

Definition at line 26 of file proc_walk.h.

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Constructor & Destructor Documentation

Botan::ProcWalking_EntropySource::ProcWalking_EntropySource

(

const std::string &

root_dir

)

[inline]

Definition at line 33 of file proc_walk.h.

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

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Member Function Documentation

std::string Botan::ProcWalking_EntropySource::name

(

)

const [inline, virtual]

Returns:

name identifying this entropy source

Implements Botan::EntropySource.

Definition at line 29 of file proc_walk.h.

{ return "Proc Walker"; }

void Botan::ProcWalking_EntropySource::poll

(

Entropy_Accumulator &

accum

)

[virtual]

Perform an entropy gathering poll

Parameters:

accum

is an accumulator object that will be given entropy

Implements Botan::EntropySource.

Definition at line 113 of file proc_walk.cpp.

References Botan::Entropy_Accumulator::add(), Botan::Entropy_Accumulator::get_io_buffer(), m_mutex, and Botan::Entropy_Accumulator::polling_goal_achieved().

   {
   const size_t MAX_FILES_READ_PER_POLL = 2048;
   const double ENTROPY_ESTIMATE = 1.0 / (8*1024);

   std::lock_guard<std::mutex> lock(m_mutex);

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

   secure_vector<byte>& io_buffer = accum.get_io_buffer(4096);

   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, &io_buffer[0], io_buffer.size());
      ::close(fd);

      if(got > 0)
         accum.add(&io_buffer[0], got, ENTROPY_ESTIMATE);

      if(accum.polling_goal_achieved())
         break;
      }
   }

void Botan::EntropySource::poll_available_sources

(

class Entropy_Accumulator &

accum

)

[static, inherited]

Definition at line 108 of file entropy_srcs.cpp.

References Botan::Entropy_Accumulator::polling_goal_achieved().

Referenced by Botan::HMAC_RNG::reseed().

   {
   static std::vector<std::unique_ptr<EntropySource>> g_sources(get_default_entropy_sources());

   if(g_sources.empty())
      throw std::runtime_error("No entropy sources enabled at build time, poll failed");

   size_t poll_attempt = 0;

   while(!accum.polling_goal_achieved() && poll_attempt < 16)
      {
      const size_t src_idx = poll_attempt % g_sources.size();
      g_sources[src_idx]->poll(accum);
      ++poll_attempt;
      }
   }

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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