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Add base64 encode Implementation

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Florian Märkl 2018-11-17 16:51:44 +01:00
commit d9d3990d32
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2 changed files with 78 additions and 1 deletions
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1
lib/include/chiaki/base64.h
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@ -28,6 +28,7 @@
extern "C" { extern "C" {
#endif #endif
CHIAKI_EXPORT ChiakiErrorCode chiaki_base64_encode(const uint8_t *in, size_t in_size, char *out, size_t out_size);
CHIAKI_EXPORT ChiakiErrorCode chiaki_base64_decode(const char *in, size_t in_size, uint8_t *out, size_t *out_size); CHIAKI_EXPORT ChiakiErrorCode chiaki_base64_decode(const char *in, size_t in_size, uint8_t *out, size_t *out_size);
#ifdef __cplusplus #ifdef __cplusplus

78
lib/src/base64.c
View file

@ -19,9 +19,85 @@
#include <stdint.h> #include <stdint.h>
// Implementation taken from // Implementations taken from
// https://en.wikibooks.org/wiki/Algorithm_Implementation/Miscellaneous/Base64 // https://en.wikibooks.org/wiki/Algorithm_Implementation/Miscellaneous/Base64
CHIAKI_EXPORT ChiakiErrorCode chiaki_base64_encode(const uint8_t *in, size_t in_size, char *out, size_t out_size)
{
const char base64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
size_t result_index = 0;
size_t x;
uint32_t n = 0;
size_t pad_count = in_size % 3;
uint8_t n0, n1, n2, n3;
// increment over the length of the string, three characters at a time
for(x = 0; x < in_size; x += 3)
{
// these three 8-bit (ASCII) characters become one 24-bit number
n = ((uint32_t)in[x]) << 16;
if((x+1) < in_size)
n += ((uint32_t)in[x+1]) << 8;
if((x+2) < in_size)
n += in[x+2];
// this 24-bit number gets separated into four 6-bit numbers
n0 = (uint8_t)(n >> 18) & 63;
n1 = (uint8_t)(n >> 12) & 63;
n2 = (uint8_t)(n >> 6) & 63;
n3 = (uint8_t)n & 63;
// if we have one byte available, then its encoding is spread
// out over two characters
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index++] = base64chars[n0];
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index++] = base64chars[n1];
// if we have only two bytes available, then their encoding is
// spread out over three chars
if((x+1) < in_size)
{
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index++] = base64chars[n2];
}
// if we have all three bytes available, then their encoding is spread
// out over four characters
if((x+2) < in_size)
{
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index++] = base64chars[n3];
}
}
// create and add padding that is required if we did not have a multiple of 3
// number of characters available
if (pad_count > 0)
{
for (; pad_count < 3; pad_count++)
{
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index++] = '=';
}
}
if(result_index >= out_size)
return CHIAKI_ERR_BUF_TOO_SMALL;
out[result_index] = 0;
return CHIAKI_ERR_SUCCESS;
}
#define WHITESPACE 64 #define WHITESPACE 64
#define EQUALS 65 #define EQUALS 65
#define INVALID 66 #define INVALID 66