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//Chris Xiong 2022
//License: MPL-2.0
#include <string>
#include <cstdint>
#include <cstdlib>
#include "base64.hpp"
const char *base64_encoder::b64c = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
base64_encoder::base64_encoder() : counter(0), rem(0), ret(std::string()) {}
void base64_encoder::encode_data(const void *data, size_t len)
{
const uint8_t *u8d = (uint8_t*) data;
for (size_t i = 0; i < len; ++i)
{
++counter;
if (counter == 3) counter = 0;
switch (counter)
{
case 0:
rem |= (u8d[i] >> 6);
ret.push_back(b64c[rem]);
ret.push_back(b64c[u8d[i] & 0b111111]);
break;
case 1:
ret.push_back(b64c[u8d[i] >> 2]);
rem = (u8d[i] & 0b11) << 4;
break;
case 2:
rem |= (u8d[i] >> 4);
ret.push_back(b64c[rem]);
rem = (u8d[i] & 0b1111) << 2;
break;
}
}
}
std::string base64_encoder::finalize()
{
if (counter)
{
ret.push_back(b64c[rem]);
for (int i = 0; i < 3 - counter; ++i)
ret.push_back('=');
}
return ret;
}
const uint8_t base64_decoder::b64v[] = {
65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,
65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,65,
65,65,65,65,65,65,65,65,65,65,65,62,65,65,65,63,
52,53,54,55,56,57,58,59,60,61,65,65,65,64,65,65,
65, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
15,16,17,18,19,20,21,22,23,24,25,65,65,65,65,65,
65,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
41,42,43,44,45,46,47,48,49,50,51,65,65,65,65,65
};
base64_decoder::base64_decoder(std::string &&b) :
s(b),
invalid(false),
rem(0),
counter(0),
bp(0)
{
size_t npadd = 0;
for (auto ri = s.rbegin(); ri != s.rend(); ++ri)
if (*ri == '=')
++npadd;
else break;
dlen = (s.length() - npadd) / 4 * 3;
switch (npadd)
{
case 0: break;
case 1: dlen += 2; break;
case 2: dlen += 1; break;
default:
dlen = 0;
invalid = true;
}
}
size_t base64_decoder::decoded_length()
{
return dlen;
}
size_t base64_decoder::decode_data(const void *data, size_t len)
{
uint8_t *rp = (uint8_t*)data;
for (; bp < s.size(); ++bp)
{
++counter;
if (counter == 4) counter = 0;
if (s[bp] == '=') break;
if (s[bp] < 0 || b64v[s[bp]] > 64)
{
invalid = true;
return 0;
}
switch (counter)
{
case 0:
rem |= b64v[s[bp]];
*(rp++) = rem;
break;
case 1:
rem = b64v[s[bp]] << 2;
break;
case 2:
rem |= b64v[s[bp]] >> 4;
*(rp++) = rem;
rem = (b64v[s[bp]] & 0b1111) << 4;
break;
case 3:
rem |= b64v[s[bp]] >> 2;
*(rp++) = rem;
rem = (b64v[s[bp]] & 0b11) << 6;
break;
}
if (rp - (uint8_t*)data == len)
{
++bp;
break;
}
}
return rp - (uint8_t*)data;
}
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