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#include "base64.h"
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <errno.h>
#define LOG_MODULE "base64"
#define LOG_ENABLE_DBG 0
#include "log.h"
#include "debug.h"
enum {
P = 1 << 6, // Padding byte (=)
I = 1 << 7, // Invalid byte ([^A-Za-z0-9+/=])
};
static const uint8_t reverse_lookup[256] = {
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, 62, I, I, I, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, I, I, I, P, I, I,
I, 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, I, I, I, I, I,
I, 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, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I
};
static const char lookup[64] = {
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/"
};
char *
base64_decode(const char *s, size_t *size)
{
const size_t len = strlen(s);
if (unlikely(len % 4 != 0)) {
errno = EINVAL;
return NULL;
}
char *ret = malloc(len / 4 * 3 + 1);
if (unlikely(ret == NULL))
return NULL;
if (unlikely(size != NULL))
*size = len / 4 * 3;
for (size_t i = 0, o = 0; i < len; i += 4, o += 3) {
unsigned a = reverse_lookup[(unsigned char)s[i + 0]];
unsigned b = reverse_lookup[(unsigned char)s[i + 1]];
unsigned c = reverse_lookup[(unsigned char)s[i + 2]];
unsigned d = reverse_lookup[(unsigned char)s[i + 3]];
unsigned u = a | b | c | d;
if (unlikely(u & I))
goto invalid;
if (unlikely(u & P)) {
if (unlikely(i + 4 != len || (a | b) & P || (c & P && !(d & P))))
goto invalid;
if (unlikely(size != NULL)) {
if (c & P)
*size = len / 4 * 3 - 2;
else
*size = len / 4 * 3 - 1;
}
c &= 63;
d &= 63;
}
uint32_t v = a << 18 | b << 12 | c << 6 | d << 0;
char x = (v >> 16) & 0xff;
char y = (v >> 8) & 0xff;
char z = (v >> 0) & 0xff;
LOG_DBG("%c%c%c", x, y, z);
ret[o + 0] = x;
ret[o + 1] = y;
ret[o + 2] = z;
}
ret[len / 4 * 3] = '\0';
return ret;
invalid:
free(ret);
errno = EINVAL;
return NULL;
}
char *
base64_encode(const uint8_t *data, size_t size)
{
xassert(size % 3 == 0);
if (unlikely(size % 3 != 0))
return NULL;
char *ret = malloc(size / 3 * 4 + 1);
if (unlikely(ret == NULL))
return NULL;
for (size_t i = 0, o = 0; i < size; i += 3, o += 4) {
int x = data[i + 0];
int y = data[i + 1];
int z = data[i + 2];
uint32_t v = x << 16 | y << 8 | z << 0;
unsigned a = (v >> 18) & 0x3f;
unsigned b = (v >> 12) & 0x3f;
unsigned c = (v >> 6) & 0x3f;
unsigned d = (v >> 0) & 0x3f;
char c0 = lookup[a];
char c1 = lookup[b];
char c2 = lookup[c];
char c3 = lookup[d];
ret[o + 0] = c0;
ret[o + 1] = c1;
ret[o + 2] = c2;
ret[o + 3] = c3;
LOG_DBG("base64: encode: %c%c%c%c", c0, c1, c2, c3);
}
ret[size / 3 * 4] = '\0';
return ret;
}
void
base64_encode_final(const uint8_t *data, size_t size, char result[4])
{
xassert(size > 0);
xassert(size < 3);
uint32_t v = 0;
if (size >= 1)
v |= data[0] << 16;
if (size >= 2)
v |= data[1] << 8;
unsigned a = (v >> 18) & 0x3f;
unsigned b = (v >> 12) & 0x3f;
unsigned c = (v >> 6) & 0x3f;
char c0 = lookup[a];
char c1 = lookup[b];
char c2 = size == 2 ? lookup[c] : '=';
char c3 = '=';
result[0] = c0;
result[1] = c1;
result[2] = c2;
result[3] = c3;
LOG_DBG("base64: encode: %c%c%c%c", c0, c1, c2, c3);
}
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