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/*
* Base64 Encoder/Decoder
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/base64.h>
#include <botan/charset.h>
#include <botan/exceptn.h>
#include <algorithm>
namespace Botan {
/*
* Base64_Encoder Constructor
*/
Base64_Encoder::Base64_Encoder(bool breaks, u32bit length, bool t_n) :
line_length(breaks ? length : 0), trailing_newline(t_n)
{
in.create(48);
out.create(4);
counter = position = 0;
}
/*
* Base64 Encoding Operation
*/
void Base64_Encoder::encode(const byte in[3], byte out[4])
{
out[0] = BIN_TO_BASE64[((in[0] & 0xFC) >> 2)];
out[1] = BIN_TO_BASE64[((in[0] & 0x03) << 4) | (in[1] >> 4)];
out[2] = BIN_TO_BASE64[((in[1] & 0x0F) << 2) | (in[2] >> 6)];
out[3] = BIN_TO_BASE64[((in[2] & 0x3F) )];
}
/*
* Encode and send a block
*/
void Base64_Encoder::encode_and_send(const byte block[], u32bit length)
{
for(u32bit j = 0; j != length; j += 3)
{
encode(block + j, out);
do_output(out, 4);
}
}
/*
* Handle the output
*/
void Base64_Encoder::do_output(const byte input[], u32bit length)
{
if(line_length == 0)
send(input, length);
else
{
u32bit remaining = length, offset = 0;
while(remaining)
{
u32bit sent = std::min(line_length - counter, remaining);
send(input + offset, sent);
counter += sent;
remaining -= sent;
offset += sent;
if(counter == line_length)
{
send('\n');
counter = 0;
}
}
}
}
/*
* Convert some data into Base64
*/
void Base64_Encoder::write(const byte input[], u32bit length)
{
in.copy(position, input, length);
if(position + length >= in.size())
{
encode_and_send(in, in.size());
input += (in.size() - position);
length -= (in.size() - position);
while(length >= in.size())
{
encode_and_send(input, in.size());
input += in.size();
length -= in.size();
}
in.copy(input, length);
position = 0;
}
position += length;
}
/*
* Flush buffers
*/
void Base64_Encoder::end_msg()
{
u32bit start_of_last_block = 3 * (position / 3),
left_over = position % 3;
encode_and_send(in, start_of_last_block);
if(left_over)
{
SecureBuffer<byte, 3> remainder(in + start_of_last_block, left_over);
encode(remainder, out);
u32bit empty_bits = 8 * (3 - left_over), index = 4 - 1;
while(empty_bits >= 8)
{
out[index--] = '=';
empty_bits -= 6;
}
do_output(out, 4);
}
if(trailing_newline || (counter && line_length))
send('\n');
counter = position = 0;
}
/*
* Base64_Decoder Constructor
*/
Base64_Decoder::Base64_Decoder(Decoder_Checking c) : checking(c)
{
in.create(48);
out.create(3);
position = 0;
}
/*
* Check if a character is a valid Base64 char
*/
bool Base64_Decoder::is_valid(byte in)
{
return (BASE64_TO_BIN[in] != 0x80);
}
/*
* Base64 Decoding Operation
*/
void Base64_Decoder::decode(const byte in[4], byte out[3])
{
out[0] = ((BASE64_TO_BIN[in[0]] << 2) | (BASE64_TO_BIN[in[1]] >> 4));
out[1] = ((BASE64_TO_BIN[in[1]] << 4) | (BASE64_TO_BIN[in[2]] >> 2));
out[2] = ((BASE64_TO_BIN[in[2]] << 6) | (BASE64_TO_BIN[in[3]]));
}
/*
* Decode and send a block
*/
void Base64_Decoder::decode_and_send(const byte block[], u32bit length)
{
for(u32bit j = 0; j != length; j += 4)
{
decode(block + j, out);
send(out, 3);
}
}
/*
* Handle processing an invalid character
*/
void Base64_Decoder::handle_bad_char(byte c)
{
if(c == '=' || checking == NONE)
return;
if((checking == IGNORE_WS) && Charset::is_space(c))
return;
throw Decoding_Error(
std::string("Base64_Decoder: Invalid base64 character '") +
static_cast<char>(c) + "'"
);
}
/*
* Convert some data from Base64
*/
void Base64_Decoder::write(const byte input[], u32bit length)
{
for(u32bit j = 0; j != length; ++j)
{
if(is_valid(input[j]))
in[position++] = input[j];
else
handle_bad_char(input[j]);
if(position == in.size())
{
decode_and_send(in, in.size());
position = 0;
}
}
}
/*
* Flush buffers
*/
void Base64_Decoder::end_msg()
{
if(position != 0)
{
u32bit start_of_last_block = 4 * (position / 4),
left_over = position % 4;
decode_and_send(in, start_of_last_block);
if(left_over)
{
SecureBuffer<byte, 4> remainder(in + start_of_last_block, left_over);
decode(remainder, out);
send(out, ((left_over == 1) ? (1) : (left_over - 1)));
}
}
position = 0;
}
}
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