mirror of
https://github.com/arun11299/cpp-jwt.git
synced 2025-05-14 16:58:34 +00:00
311 lines
7.3 KiB
C++
311 lines
7.3 KiB
C++
#ifndef CPP_JWT_BASE64_HPP
|
|
#define CPP_JWT_BASE64_HPP
|
|
|
|
#include <array>
|
|
#include <cassert>
|
|
#include "jwt/string_view.hpp"
|
|
|
|
namespace jwt {
|
|
|
|
// Returns the maximum number of bytes required to
|
|
// encode an input byte string of length `n` to base64.
|
|
inline constexpr
|
|
size_t encoding_size(size_t n)
|
|
{
|
|
return 4 * ((n + 2) / 3);
|
|
}
|
|
|
|
|
|
// Returns the maximum number of bytes required
|
|
// to store a decoded base64 byte string.
|
|
inline constexpr
|
|
size_t decoding_size(size_t n)
|
|
{
|
|
return n / 4 * 3;
|
|
}
|
|
|
|
/**
|
|
* Encoding map.
|
|
* A constexpr helper class for performing base64
|
|
* encoding on the input byte string.
|
|
*/
|
|
class EMap
|
|
{
|
|
public:
|
|
constexpr EMap() = default;
|
|
|
|
public:
|
|
constexpr char at(size_t pos) const noexcept
|
|
{
|
|
assert (pos < chars_.size());
|
|
return chars_.at(pos);
|
|
}
|
|
|
|
private:
|
|
std::array<char, 64> chars_ = {
|
|
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
|
|
'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
|
|
'0','1','2','3','4','5','6','7','8','9',
|
|
'+','/',
|
|
};
|
|
};
|
|
|
|
/**
|
|
* Encodes a sequence of octet into base64 string.
|
|
* Returns std::string resized to contain only the
|
|
* encoded data (as usual without null terminator).
|
|
*
|
|
* The encoded string is atleast `encoding_size(input len)`
|
|
* in size.
|
|
*
|
|
* Arguments:
|
|
* @in : Input byte string to be encoded.
|
|
* @len : Length of the input byte string.
|
|
*/
|
|
std::string base64_encode(const char* in, size_t len)
|
|
{
|
|
std::string result;
|
|
const auto encoded_siz = encoding_size(len);
|
|
result.resize(encoded_siz);
|
|
|
|
constexpr static const EMap emap{};
|
|
|
|
int i = 0;
|
|
int j = 0;
|
|
for (; i < len - 2; i += 3) {
|
|
const auto first = in[i];
|
|
const auto second = in[i+1];
|
|
const auto third = in[i+2];
|
|
|
|
result[j++] = emap.at( (first >> 2) & 0x3F );
|
|
result[j++] = emap.at(((first & 0x03) << 4) | ((second & 0xF0) >> 4));
|
|
result[j++] = emap.at(((second & 0x0F) << 2) | ((third & 0xC0) >> 6));
|
|
result[j++] = emap.at( (third & 0x3F) );
|
|
}
|
|
|
|
switch (len % 3) {
|
|
case 2:
|
|
{
|
|
const auto first = in[i];
|
|
const auto second = in[i+1];
|
|
|
|
result[j++] = emap.at( (first >> 2) & 0x3F );
|
|
result[j++] = emap.at(((first & 0x03) << 4) | ((second & 0xF0) >> 4));
|
|
result[j++] = emap.at( (second & 0x0F) << 2 );
|
|
result[j++] = '=';
|
|
break;
|
|
}
|
|
case 1:
|
|
{
|
|
const auto first = in[i];
|
|
|
|
result[j++] = emap.at((first >> 2) & 0x3F);
|
|
result[j++] = emap.at((first & 0x03) << 4);
|
|
result[j++] = '=';
|
|
result[j++] = '=';
|
|
break;
|
|
}
|
|
case 0:
|
|
break;
|
|
};
|
|
|
|
result.resize(j);
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
|
|
//======================= Decoder ==========================
|
|
|
|
/**
|
|
* Decoding map.
|
|
* A helper constexpr class for providing interface
|
|
* to the decoding map for base64.
|
|
*/
|
|
class DMap
|
|
{
|
|
public:
|
|
constexpr DMap() = default;
|
|
|
|
public:
|
|
constexpr char at(size_t pos) const noexcept
|
|
{
|
|
assert (pos < map_.size());
|
|
return map_[pos];
|
|
}
|
|
|
|
private:
|
|
std::array<char, 256> map_ = {
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0-15
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 16-31
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, // 32-47
|
|
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, // 48-63
|
|
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 64-79
|
|
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, // 80-95
|
|
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 96-111
|
|
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, // 112-127
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 128-143
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 144-159
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 160-175
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 176-191
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 192-207
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 208-223
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 224-239
|
|
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 // 240-255
|
|
};
|
|
};
|
|
|
|
/**
|
|
* Decodes octet of base64 encoded byte string.
|
|
*
|
|
* Returns a std::string with the decoded byte string.
|
|
*
|
|
* Arguments:
|
|
* @in : Encoded base64 byte string.
|
|
* @len : Length of the encoded input byte string.
|
|
*/
|
|
std::string base64_decode(const char* in, size_t len)
|
|
{
|
|
std::string result;
|
|
const auto decoded_siz = decoding_size(len);
|
|
result.resize(decoded_siz);
|
|
|
|
int i = 0;
|
|
size_t bytes_rem = len;
|
|
size_t bytes_wr = 0;
|
|
|
|
constexpr static const DMap dmap{};
|
|
|
|
while (dmap.at(in[bytes_rem - 1]) == -1) { bytes_rem--; }
|
|
|
|
while (bytes_rem > 4)
|
|
{
|
|
// Error case in input
|
|
if (dmap.at(*in) == -1) return result;
|
|
|
|
const auto first = dmap.at(in[0]);
|
|
const auto second = dmap.at(in[1]);
|
|
const auto third = dmap.at(in[2]);
|
|
const auto fourth = dmap.at(in[3]);
|
|
|
|
result[i] = (first << 2) | (second >> 4);
|
|
result[i + 1] = (second << 4) | (third >> 2);
|
|
result[i + 2] = (third << 6) | fourth;
|
|
|
|
bytes_rem -= 4;
|
|
i += 3;
|
|
in += 4;
|
|
}
|
|
bytes_wr = i;
|
|
|
|
switch(bytes_rem) {
|
|
case 4:
|
|
{
|
|
const auto third = dmap.at(in[2]);
|
|
const auto fourth = dmap.at(in[3]);
|
|
result[i + 2] = (third << 6) | fourth;
|
|
bytes_wr++;
|
|
//FALLTHROUGH
|
|
}
|
|
case 3:
|
|
{
|
|
const auto second = dmap.at(in[1]);
|
|
const auto third = dmap.at(in[2]);
|
|
result[i + 1] = (second << 4) | (third >> 2);
|
|
bytes_wr++;
|
|
//FALLTHROUGH
|
|
}
|
|
case 2:
|
|
{
|
|
const auto first = dmap.at(in[0]);
|
|
const auto second = dmap.at(in[1]);
|
|
result[i] = (first << 2) | (second >> 4);
|
|
bytes_wr++;
|
|
}
|
|
};
|
|
|
|
result.resize(bytes_wr);
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Makes the base64 encoded byte string URL safe.
|
|
* Overwrites/skips few URL unsafe characters
|
|
* from the input sequence.
|
|
*
|
|
* Arguments:
|
|
* @data : Base64 encoded byte string.
|
|
* @len : Length of the base64 byte string.
|
|
*
|
|
* Returns:
|
|
* Length of the URL safe base64 encoded byte string.
|
|
*/
|
|
size_t base64_uri_encode(char* data, size_t len) noexcept
|
|
{
|
|
size_t i = 0;
|
|
size_t j = 0;
|
|
|
|
for (; i < len; ++i) {
|
|
switch (data[i]) {
|
|
case '+':
|
|
data[j++] = '-';
|
|
break;
|
|
case '/':
|
|
data[j++] = '_';
|
|
break;
|
|
case '=':
|
|
break;
|
|
default:
|
|
data[j++] = data[i];
|
|
};
|
|
}
|
|
|
|
return j;
|
|
}
|
|
|
|
/**
|
|
* Decodes an input URL safe base64 encoded byte string.
|
|
*
|
|
* NOTE: To be used only for decoding URL safe base64 encoded
|
|
* byte string.
|
|
*
|
|
* Arguments:
|
|
* @data : URL safe base64 encoded byte string.
|
|
* @len : Length of the input byte string.
|
|
*/
|
|
std::string base64_uri_decode(const char* data, size_t len)
|
|
{
|
|
std::string uri_dec;
|
|
uri_dec.resize(len + 4);
|
|
|
|
size_t i = 0;
|
|
|
|
for (; i < len; ++i) {
|
|
switch (data[i]) {
|
|
case '-':
|
|
uri_dec[i] = '+';
|
|
break;
|
|
case '_':
|
|
uri_dec[i] = '/';
|
|
break;
|
|
default:
|
|
uri_dec[i] = data[i];
|
|
};
|
|
}
|
|
|
|
size_t trailer = 4 - (i % 4);
|
|
if (trailer && trailer < 4) {
|
|
while (trailer--) {
|
|
uri_dec[i++] = '=';
|
|
}
|
|
}
|
|
|
|
return base64_decode(uri_dec.c_str(), uri_dec.length());
|
|
}
|
|
|
|
} // END namespace jwt
|
|
|
|
|
|
#endif
|