Botan::Buffered_Filter Class Reference

#include <filters.h>

Inheritance diagram for Botan::Buffered_Filter:

Public Member Functions
	Buffered_Filter (size_t block_size, size_t final_minimum)
void	end_msg ()
template<typename Alloc >
void	write (const std::vector< uint8_t, Alloc > &in, size_t length)
void	write (const uint8_t in[], size_t length)
virtual	~Buffered_Filter ()=default

Protected Member Functions
void	buffer_reset ()
virtual void	buffered_block (const uint8_t input[], size_t length)=0
size_t	buffered_block_size () const
virtual void	buffered_final (const uint8_t input[], size_t length)=0
size_t	current_position () const

Detailed Description

Filter mixin that breaks input into blocks, useful for cipher modes

Definition at line 40 of file filters.h.

Constructor & Destructor Documentation

Buffered_Filter()

Botan::Buffered_Filter::Buffered_Filter	(	size_t	block_size,
		size_t	final_minimum )

Initialize a Buffered_Filter

Parameters

block_size	the function buffered_block will be called with inputs which are a multiple of this size
final_minimum	the function buffered_final will be called with at least this many bytes.

Definition at line 18 of file buf_filt.cpp.

                                                   : m_main_block_mod(b), m_final_minimum(f) {
   if(m_main_block_mod == 0) {
      throw Invalid_Argument("m_main_block_mod == 0");
   }
 
   if(m_final_minimum > m_main_block_mod) {
      throw Invalid_Argument("m_final_minimum > m_main_block_mod");
   }
 
   m_buffer.resize(2 * m_main_block_mod);
   m_buffer_pos = 0;
}

~Buffered_Filter()

virtual Botan::Buffered_Filter::~Buffered_Filter ( )

virtualdefault

Member Function Documentation

buffer_reset()

void Botan::Buffered_Filter::buffer_reset ( )

inlineprotected

Reset the buffer position

Definition at line 103 of file filters.h.

{ m_buffer_pos = 0; }

buffered_block()

virtual void Botan::Buffered_Filter::buffered_block ( const uint8_t input[], size_t length )

protectedpure virtual

The block processor, implemented by subclasses

Parameters

input	some input bytes
length	the size of input, guaranteed to be a multiple of block_size

Referenced by end_msg(), and write().

buffered_block_size()

size_t Botan::Buffered_Filter::buffered_block_size ( ) const

inlineprotected

Returns

block size of inputs

Definition at line 93 of file filters.h.

{ return m_main_block_mod; }

buffered_final()

virtual void Botan::Buffered_Filter::buffered_final ( const uint8_t input[], size_t length )

protectedpure virtual

The final block, implemented by subclasses

Parameters

input	some input bytes
length	the size of input, guaranteed to be at least final_minimum bytes

Referenced by end_msg().

current_position()

size_t Botan::Buffered_Filter::current_position ( ) const

inlineprotected

Returns

current position in the buffer

Definition at line 98 of file filters.h.

{ return m_buffer_pos; }

end_msg()

void Botan::Buffered_Filter::end_msg

(

)

Finish a message, emitting to buffered_block and buffered_final Will throw an exception if less than final_minimum bytes were written into the filter.

Definition at line 79 of file buf_filt.cpp.

                              {
   if(m_buffer_pos < m_final_minimum) {
      throw Invalid_State("Buffered filter end_msg without enough input");
   }
 
   size_t spare_blocks = (m_buffer_pos - m_final_minimum) / m_main_block_mod;
 
   if(spare_blocks) {
      size_t spare_bytes = m_main_block_mod * spare_blocks;
      buffered_block(m_buffer.data(), spare_bytes);
      buffered_final(&m_buffer[spare_bytes], m_buffer_pos - spare_bytes);
   } else {
      buffered_final(m_buffer.data(), m_buffer_pos);
   }
 
   m_buffer_pos = 0;
}

References buffered_block(), and buffered_final().

write() [1/2]

template<typename Alloc >

void Botan::Buffered_Filter::write ( const std::vector< uint8_t, Alloc > & in, size_t length )

inline

Definition at line 51 of file filters.h.

                                                                     {
         write(in.data(), length);
      }

write() [2/2]

void Botan::Buffered_Filter::write	(	const uint8_t	in[],
		size_t	length )

Write bytes into the buffered filter, which will them emit them in calls to buffered_block in the subclass

Parameters

in	the input bytes
length	of in in bytes

Definition at line 34 of file buf_filt.cpp.

                                                                    {
   if(!input_size) {
      return;
   }
 
   if(m_buffer_pos + input_size >= m_main_block_mod + m_final_minimum) {
      size_t to_copy = std::min<size_t>(m_buffer.size() - m_buffer_pos, input_size);
 
      copy_mem(&m_buffer[m_buffer_pos], input, to_copy);
      m_buffer_pos += to_copy;
 
      input += to_copy;
      input_size -= to_copy;
 
      const size_t available = std::min(m_buffer_pos, m_buffer_pos + input_size - m_final_minimum);
 
      // Size down to available block size
      const size_t total_to_consume = available - (available % m_main_block_mod);
 
      buffered_block(m_buffer.data(), total_to_consume);
 
      m_buffer_pos -= total_to_consume;
 
      copy_mem(m_buffer.data(), m_buffer.data() + total_to_consume, m_buffer_pos);
   }
 
   if(input_size >= m_final_minimum) {
      size_t full_blocks = (input_size - m_final_minimum) / m_main_block_mod;
      size_t to_copy = full_blocks * m_main_block_mod;
 
      if(to_copy) {
         buffered_block(input, to_copy);
 
         input += to_copy;
         input_size -= to_copy;
      }
   }
 
   copy_mem(&m_buffer[m_buffer_pos], input, input_size);
   m_buffer_pos += input_size;
}

References buffered_block(), and Botan::copy_mem().

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

• src/lib/filters/filters.h
• src/lib/filters/buf_filt.cpp