Botan  2.6.0
Crypto and TLS for C++11
Public Member Functions | Protected Member Functions | List of all members
Botan::Buffered_Filter Class Referenceabstract

#include <buf_filt.h>

Inheritance diagram for Botan::Buffered_Filter:
Botan::Cipher_Mode_Filter Botan::AEAD_Filter

Public Member Functions

 Buffered_Filter (size_t block_size, size_t final_minimum)
 
void end_msg ()
 
void write (const uint8_t in[], size_t length)
 
template<typename Alloc >
void write (const std::vector< uint8_t, Alloc > &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 19 of file buf_filt.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_sizethe function buffered_block will be called with inputs which are a multiple of this size
final_minimumthe function buffered_final will be called with at least this many bytes.

Definition at line 18 of file buf_filt.cpp.

18  :
19  m_main_block_mod(b), m_final_minimum(f)
20  {
21  if(m_main_block_mod == 0)
22  throw Invalid_Argument("m_main_block_mod == 0");
23 
24  if(m_final_minimum > m_main_block_mod)
25  throw Invalid_Argument("m_final_minimum > m_main_block_mod");
26 
27  m_buffer.resize(2 * m_main_block_mod);
28  m_buffer_pos = 0;
29  }

◆ ~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 83 of file buf_filt.h.

83 { 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
inputsome input bytes
lengththe 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 73 of file buf_filt.h.

73 { 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
inputsome input bytes
lengththe 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 78 of file buf_filt.h.

78 { 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 82 of file buf_filt.cpp.

References buffered_block(), and buffered_final().

83  {
84  if(m_buffer_pos < m_final_minimum)
85  throw Exception("Buffered filter end_msg without enough input");
86 
87  size_t spare_blocks = (m_buffer_pos - m_final_minimum) / m_main_block_mod;
88 
89  if(spare_blocks)
90  {
91  size_t spare_bytes = m_main_block_mod * spare_blocks;
92  buffered_block(m_buffer.data(), spare_bytes);
93  buffered_final(&m_buffer[spare_bytes], m_buffer_pos - spare_bytes);
94  }
95  else
96  {
97  buffered_final(m_buffer.data(), m_buffer_pos);
98  }
99 
100  m_buffer_pos = 0;
101  }
virtual void buffered_block(const uint8_t input[], size_t length)=0
virtual void buffered_final(const uint8_t input[], size_t length)=0

◆ write() [1/2]

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
inthe input bytes
lengthof in in bytes

Definition at line 34 of file buf_filt.cpp.

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

35  {
36  if(!input_size)
37  return;
38 
39  if(m_buffer_pos + input_size >= m_main_block_mod + m_final_minimum)
40  {
41  size_t to_copy = std::min<size_t>(m_buffer.size() - m_buffer_pos, input_size);
42 
43  copy_mem(&m_buffer[m_buffer_pos], input, to_copy);
44  m_buffer_pos += to_copy;
45 
46  input += to_copy;
47  input_size -= to_copy;
48 
49  size_t total_to_consume =
50  round_down(std::min(m_buffer_pos,
51  m_buffer_pos + input_size - m_final_minimum),
52  m_main_block_mod);
53 
54  buffered_block(m_buffer.data(), total_to_consume);
55 
56  m_buffer_pos -= total_to_consume;
57 
58  copy_mem(m_buffer.data(), m_buffer.data() + total_to_consume, m_buffer_pos);
59  }
60 
61  if(input_size >= m_final_minimum)
62  {
63  size_t full_blocks = (input_size - m_final_minimum) / m_main_block_mod;
64  size_t to_copy = full_blocks * m_main_block_mod;
65 
66  if(to_copy)
67  {
68  buffered_block(input, to_copy);
69 
70  input += to_copy;
71  input_size -= to_copy;
72  }
73  }
74 
75  copy_mem(&m_buffer[m_buffer_pos], input, input_size);
76  m_buffer_pos += input_size;
77  }
T round_down(T n, T align_to)
Definition: rounding.h:37
virtual void buffered_block(const uint8_t input[], size_t length)=0
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:108

◆ write() [2/2]

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

Definition at line 31 of file buf_filt.h.

32  {
33  write(in.data(), length);
34  }
void write(const uint8_t in[], size_t length)
Definition: buf_filt.cpp:34

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