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b64.c
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b64.c
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#include <stdio.h>
#include <stdlib.h>
/*
base64.h - c header for a base64 encoding and decoding algorithm
This is part of the libb64 project, and has been placed in the public domain.
For details, see http://sourceforge.net/projects/libb64
*/
#ifndef BASE64_ENCDEC_H
#define BASE64_ENCDEC_H
typedef enum
{
step_A, step_B, step_C
} base64_encodestep;
typedef struct
{
base64_encodestep step;
char result;
int stepcount;
} base64_encodestate;
void base64_init_encodestate(base64_encodestate* state_in);
char base64_encode_value(char value_in);
size_t base64_encode_block(const char* plaintext_in, size_t length_in, char* code_out, base64_encodestate* state_in);
size_t base64_encode_blockend(char* code_out, base64_encodestate* state_in);
typedef enum
{
step_a, step_b, step_c, step_d
} base64_decodestep;
typedef struct
{
base64_decodestep step;
char plainchar;
} base64_decodestate;
void base64_init_decodestate(base64_decodestate* state_in);
int base64_decode_value(char value_in);
size_t base64_decode_block(const char* code_in, const size_t length_in, char* plaintext_out, base64_decodestate* state_in);
#endif /* BASE64_ENCDEC_H */
/*
cencoder.c - c source to a base64 encoding algorithm implementation
This is part of the libb64 project, and has been placed in the public domain.
For details, see http://sourceforge.net/projects/libb64
*/
const int CHARS_PER_LINE = 72;
void base64_init_encodestate(base64_encodestate* state_in)
{
state_in->step = step_A;
state_in->result = 0;
state_in->stepcount = 0;
}
char base64_encode_value(char value_in)
{
static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
if (value_in > 63) return '=';
return encoding[(int)value_in];
}
size_t base64_encode_block(const char* plaintext_in, size_t length_in, char* code_out, base64_encodestate* state_in)
{
const char* plainchar = plaintext_in;
const char* const plaintextend = plaintext_in + length_in;
char* codechar = code_out;
char result;
char fragment;
result = state_in->result;
switch (state_in->step)
{
while (1)
{
case step_A:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_A;
return codechar - code_out;
}
fragment = *plainchar++;
result = (fragment & 0x0fc) >> 2;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x003) << 4;
case step_B:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_B;
return codechar - code_out;
}
fragment = *plainchar++;
result |= (fragment & 0x0f0) >> 4;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x00f) << 2;
case step_C:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_C;
return codechar - code_out;
}
fragment = *plainchar++;
result |= (fragment & 0x0c0) >> 6;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x03f) >> 0;
*codechar++ = base64_encode_value(result);
++(state_in->stepcount);
if (state_in->stepcount == CHARS_PER_LINE/4)
{
/**codechar++ = '\n';*/
state_in->stepcount = 0;
}
}
}
/* control should not reach here */
return codechar - code_out;
}
size_t base64_encode_blockend(char* code_out, base64_encodestate* state_in)
{
char* codechar = code_out;
switch (state_in->step)
{
case step_B:
*codechar++ = base64_encode_value(state_in->result);
*codechar++ = '=';
*codechar++ = '=';
break;
case step_C:
*codechar++ = base64_encode_value(state_in->result);
*codechar++ = '=';
break;
case step_A:
break;
}
/**codechar++ = '\n';*/
return codechar - code_out;
}
/*
cdecoder.c - c source to a base64 decoding algorithm implementation
This is part of the libb64 project, and has been placed in the public domain.
For details, see http://sourceforge.net/projects/libb64
*/
int base64_decode_value(char value_in)
{
static const char decoding[] = {62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51};
static const char decoding_size = sizeof(decoding);
value_in -= 43;
if (value_in < 0 || value_in > decoding_size) return -1;
return decoding[(int)value_in];
}
void base64_init_decodestate(base64_decodestate* state_in)
{
state_in->step = step_a;
state_in->plainchar = 0;
}
size_t base64_decode_block(const char* code_in, const size_t length_in, char* plaintext_out, base64_decodestate* state_in)
{
const char* codechar = code_in;
char* plainchar = plaintext_out;
char fragment;
*plainchar = state_in->plainchar;
switch (state_in->step)
{
while (1)
{
case step_a:
do {
if (codechar == code_in+length_in)
{
state_in->step = step_a;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar = (fragment & 0x03f) << 2;
case step_b:
do {
if (codechar == code_in+length_in)
{
state_in->step = step_b;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x030) >> 4;
*plainchar = (fragment & 0x00f) << 4;
case step_c:
do {
if (codechar == code_in+length_in)
{
state_in->step = step_c;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x03c) >> 2;
*plainchar = (fragment & 0x003) << 6;
case step_d:
do {
if (codechar == code_in+length_in)
{
state_in->step = step_d;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (char)base64_decode_value(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x03f);
}
}
/* control should not reach here */
return plainchar - plaintext_out;
}
#include "b64.h"
size_t
b64_encode( const char* in, size_t insize, char* out )
{
const char* start = out;
size_t len = 0;
base64_encodestate state;
base64_init_encodestate( &state );
len = base64_encode_block( in, insize, out, &state );
out += len;
len = base64_encode_blockend( out, &state );
out += len;
return out - start;
}
size_t
b64_decode( const char* in, size_t insize, char* out )
{
base64_decodestate state;
base64_init_decodestate( &state );
return base64_decode_block( in, insize, out, &state );
}