Botan 2.19.1
Crypto and TLS for C&
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 107 of file entropy_srcs.cpp.

108 {
109#if defined(BOTAN_HAS_SYSTEM_RNG)
110 if(name == "system_rng" || name == "win32_cryptoapi")
111 {
112 return std::unique_ptr<Entropy_Source>(new System_RNG_EntropySource);
113 }
114#endif
115
116#if defined(BOTAN_HAS_PROCESSOR_RNG)
117 if(name == "hwrng" || name == "rdrand" || name == "p9_darn")
118 {
120 {
121 return std::unique_ptr<Entropy_Source>(new Processor_RNG_EntropySource);
122 }
123 }
124#endif
125
126#if defined(BOTAN_HAS_ENTROPY_SRC_RDSEED)
127 if(name == "rdseed")
128 {
129 return std::unique_ptr<Entropy_Source>(new Intel_Rdseed);
130 }
131#endif
132
133#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
134 if(name == "getentropy")
135 {
136 return std::unique_ptr<Entropy_Source>(new Getentropy);
137 }
138#endif
139
140#if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
141 if(name == "dev_random")
142 {
143 return std::unique_ptr<Entropy_Source>(new Device_EntropySource(BOTAN_SYSTEM_RNG_POLL_DEVICES));
144 }
145#endif
146
147#if defined(BOTAN_HAS_ENTROPY_SRC_PROC_WALKER)
148 if(name == "proc_walk" && OS::running_in_privileged_state() == false)
149 {
150 const std::string root_dir = BOTAN_ENTROPY_PROC_FS_PATH;
151 if(!root_dir.empty())
152 return std::unique_ptr<Entropy_Source>(new ProcWalking_EntropySource(root_dir));
153 }
154#endif
155
156#if defined(BOTAN_HAS_ENTROPY_SRC_WIN32)
157 if(name == "system_stats")
158 {
159 return std::unique_ptr<Entropy_Source>(new Win32_EntropySource);
160 }
161#endif
162
164 return std::unique_ptr<Entropy_Source>();
165 }
#define BOTAN_UNUSED(...)
Definition: assert.h:142
virtual std::string name() const =0
static bool available()
bool running_in_privileged_state()
Definition: os_utils.cpp:143

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

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

◆ 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: