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/*
* (C) 2015,2017 Jack Lloyd
* (C) 2021 René Fischer
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/ffi.h>
#include <botan/internal/ffi_util.h>
#include <botan/internal/ffi_rng.h>
#include <botan/system_rng.h>
#include <botan/auto_rng.h>
#include <functional>
#if defined(BOTAN_HAS_PROCESSOR_RNG)
#include <botan/processor_rng.h>
#endif
extern "C" {
using namespace Botan_FFI;
int botan_rng_init(botan_rng_t* rng_out, const char* rng_type)
{
return ffi_guard_thunk(__func__, [=]() -> int {
if(rng_out == nullptr)
return BOTAN_FFI_ERROR_NULL_POINTER;
const std::string rng_type_s(rng_type ? rng_type : "system");
std::unique_ptr<Botan::RandomNumberGenerator> rng;
if(rng_type_s == "system")
{
rng.reset(new Botan::System_RNG);
}
else if(rng_type_s == "user" || rng_type_s == "user-threadsafe")
{
rng.reset(new Botan::AutoSeeded_RNG);
}
else if(rng_type_s == "null")
{
rng.reset(new Botan::Null_RNG);
}
#if defined(BOTAN_HAS_PROCESSOR_RNG)
else if((rng_type_s == "rdrand" || rng_type_s == "hwrng") && Botan::Processor_RNG::available())
{
rng.reset(new Botan::Processor_RNG);
}
#endif
if(!rng)
{
return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
}
*rng_out = new botan_rng_struct(rng.release());
return BOTAN_FFI_SUCCESS;
});
}
int botan_rng_init_custom(botan_rng_t* rng_out, const char* rng_name, void* context,
int(* get_cb)(void* context, uint8_t* out, size_t out_len),
int(* add_entropy_cb)(void* context, const uint8_t input[], size_t length),
void(* destroy_cb)(void* context))
{
return ffi_guard_thunk(__func__,[=]() -> int {
if(rng_out == nullptr)
return BOTAN_FFI_ERROR_NULL_POINTER;
if(rng_name == nullptr)
return BOTAN_FFI_ERROR_NULL_POINTER;
if(get_cb == nullptr)
return BOTAN_FFI_ERROR_NULL_POINTER;
class Custom_RNG : public Botan::RandomNumberGenerator
{
public:
Custom_RNG(const std::string& name, void* context,
int(* get_cb)(void* context, uint8_t* out, size_t out_len),
int(* add_entropy_cb)(void* context, const uint8_t input[], size_t length),
void(* destroy_cb)(void* context)) :
m_name(name)
{
m_context = context;
m_get_cb = get_cb;
m_add_entropy_cb = add_entropy_cb;
m_destroy_cb = destroy_cb;
}
~Custom_RNG()
{
if(m_destroy_cb)
{
m_destroy_cb(m_context);
}
}
void randomize(uint8_t output[], size_t length) override
{
int rc = m_get_cb(m_context, output, length);
if(rc)
{
throw Botan::Invalid_State("Failed to get random from C callback, rc=" + std::to_string(rc));
}
}
bool accepts_input() const override
{
return m_add_entropy_cb != nullptr;
}
void add_entropy(const uint8_t input[], size_t length) override
{
if(m_add_entropy_cb == nullptr)
{
return;
}
int rc = m_add_entropy_cb(m_context, input, length);
if(rc)
{
throw Botan::Invalid_State("Failed to add entropy via C callback, rc=" + std::to_string(rc));
}
}
std::string name() const override
{
return m_name;
}
void clear() override
{
}
bool is_seeded() const override
{
return true;
}
private:
std::string m_name;
void* m_context;
std::function<int(void* context, uint8_t* out, size_t out_len)> m_get_cb;
std::function<int(void* context, const uint8_t input[], size_t length)> m_add_entropy_cb;
std::function<void(void* context)> m_destroy_cb;
};
std::unique_ptr<Botan::RandomNumberGenerator> rng(new Custom_RNG(rng_name, context, get_cb, add_entropy_cb, destroy_cb));
*rng_out = new botan_rng_struct(rng.release());
return BOTAN_FFI_SUCCESS;
});
}
int botan_rng_destroy(botan_rng_t rng)
{
return BOTAN_FFI_CHECKED_DELETE(rng);
}
int botan_rng_get(botan_rng_t rng, uint8_t* out, size_t out_len)
{
return BOTAN_FFI_DO(Botan::RandomNumberGenerator, rng, r, { r.randomize(out, out_len); });
}
int botan_rng_reseed(botan_rng_t rng, size_t bits)
{
return BOTAN_FFI_DO(Botan::RandomNumberGenerator, rng, r, { r.reseed_from_rng(Botan::system_rng(), bits); });
}
int botan_rng_add_entropy(botan_rng_t rng, const uint8_t* input, size_t len)
{
return BOTAN_FFI_DO(Botan::RandomNumberGenerator, rng, r, { r.add_entropy(input, len); });
}
int botan_rng_reseed_from_rng(botan_rng_t rng, botan_rng_t source_rng, size_t bits)
{
return BOTAN_FFI_DO(Botan::RandomNumberGenerator, rng, r, { r.reseed_from_rng(safe_get(source_rng), bits); });
}
}
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