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Addition of string_view support
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@sjanel
sjanel committed Aug 18, 2023
1 parent f3f091b commit 478a743
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Showing 11 changed files with 688 additions and 387 deletions.
3 changes: 2 additions & 1 deletion docs/traits.md
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,8 @@ struct my_favorite_json_library_traits {
static boolean_type as_boolean(const value_type &val);

// serialization and parsing
static bool parse(value_type &val, string_type str);
template <class string_t> // could be the json string_type, or std::string_view for instance
static bool parse(value_type &val, const string_t& str);
static string_type serialize(const value_type &val); // with no extra whitespace, padding or indentation
};
```
218 changes: 137 additions & 81 deletions include/jwt-cpp/base.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2,11 +2,11 @@
#define JWT_CPP_BASE_H

#include <algorithm>
#include <array>
#include <cstdint>
#include <stdexcept>
#include <string>
#include <vector>

#include "string_types.h"

#ifdef __has_cpp_attribute
#if __has_cpp_attribute(fallthrough)
Expand All @@ -18,6 +18,11 @@
#define JWT_FALLTHROUGH
#endif

#ifndef JWT_HAS_STRING_VIEW
#include <array>
#include <cstring>
#endif

namespace jwt {
/**
* \brief character maps when encoding and decoding
Expand All @@ -30,19 +35,31 @@ namespace jwt {
* base64-encoded as per [Section 4 of RFC4648](https://datatracker.ietf.org/doc/html/rfc4648#section-4)
*/
struct base64 {

#define JWT_BASE_ALPHABET \
'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'

#ifdef JWT_HAS_STRING_VIEW
// From C++17 it's perfectly fine to have inline static variables. No ODR violation in this case.
static constexpr char kData[]{JWT_BASE_ALPHABET, '+', '/'};

static constexpr std::string_view kFill[]{"="};
#else
// For pre C++17 standards, we need to use a method
static const std::array<char, 64>& data() {
static constexpr std::array<char, 64> data{
{'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', '+', '/'}};
return data;
static constexpr std::array<char, 64> kData{{JWT_BASE_ALPHABET, '+', '/'}};
return kData;
}
static const std::string& fill() {
static std::string fill{"="};
return fill;

static const std::array<const char*, 1>& fill() {
static constexpr std::array<const char*, 1> kFill{"="};
return kFill;
}
#endif
};

/**
* \brief valid list of character when working with [Base64URL](https://tools.ietf.org/html/rfc4648#section-5)
*
Expand All @@ -53,18 +70,24 @@ namespace jwt {
* > [Section 5 of RFC 4648 RFC4648](https://tools.ietf.org/html/rfc4648#section-5), with all trailing '=' characters omitted
*/
struct base64url {

#ifdef JWT_HAS_STRING_VIEW
static constexpr char kData[]{JWT_BASE_ALPHABET, '-', '_'};

static constexpr std::string_view kFill[]{"%3d"};
#else
// For pre C++17 standards, we need to use a method
static const std::array<char, 64>& data() {
static constexpr std::array<char, 64> data{
{'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', '-', '_'}};
return data;
static constexpr std::array<char, 64> kData{{JWT_BASE_ALPHABET, '-', '_'}};
return kData;
}
static const std::string& fill() {
static std::string fill{"%3d"};
return fill;

static const std::array<const char*, 1>& fill() {
static constexpr std::array<const char*, 1> kFill{"%3d"};
return kFill;
}

#endif
};
namespace helper {
/**
Expand All @@ -74,26 +97,35 @@ namespace jwt {
* This is useful in situations outside of JWT encoding/decoding and is provided as a helper
*/
struct base64url_percent_encoding {

#ifdef JWT_HAS_STRING_VIEW
static constexpr char kData[]{JWT_BASE_ALPHABET, '-', '_'};

static constexpr std::string_view kFill[]{"%3D", "%3d"};
#else
// For pre C++17 standards, we need to use a method
static const std::array<char, 64>& data() {
static constexpr std::array<char, 64> data{
{'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', '-', '_'}};
return data;
static constexpr std::array<char, 64> kData{{JWT_BASE_ALPHABET, '-', '_'}};
return kData;
}
static const std::initializer_list<std::string>& fill() {
static std::initializer_list<std::string> fill{"%3D", "%3d"};
return fill;

static const std::array<const char*, 2>& fill() {
static constexpr std::array<const char*, 2> kFill{"%3D", "%3d"};
return kFill;
}
#endif
};
} // namespace helper

inline uint32_t index(const std::array<char, 64>& alphabet, char symbol) {
auto itr = std::find_if(alphabet.cbegin(), alphabet.cend(), [symbol](char c) { return c == symbol; });
if (itr == alphabet.cend()) { throw std::runtime_error("Invalid input: not within alphabet"); }
template<class char_it>
inline uint32_t index(char_it alphabetBeg, char_it alphabetEnd, char symbol) {
if (symbol >= 'A' && symbol <= 'Z') { return static_cast<uint32_t>(symbol - 'A'); }
if (symbol >= 'a' && symbol <= 'z') { return static_cast<uint32_t>(26 + symbol - 'a'); }
if (symbol >= '0' && symbol <= '9') { return static_cast<uint32_t>(52 + symbol - '0'); }
auto itr = std::find(std::next(alphabetBeg, 62U), alphabetEnd, symbol);
if (itr == alphabetEnd) { throw std::runtime_error("Invalid input: not within alphabet"); }

return std::distance(alphabet.cbegin(), itr);
return static_cast<uint32_t>(std::distance(alphabetBeg, itr));
}
} // namespace alphabet

Expand All @@ -108,39 +140,44 @@ namespace jwt {
size_t length = 0;

padding() = default;
padding(size_t count, size_t length) : count(count), length(length) {}

padding operator+(const padding& p) { return padding(count + p.count, length + p.length); }
padding(size_t c, size_t l) : count(c), length(l) {}

friend bool operator==(const padding& lhs, const padding& rhs) {
return lhs.count == rhs.count && lhs.length == rhs.length;
}
padding operator+(const padding& p) const { return padding{count + p.count, length + p.length}; }
};

inline padding count_padding(const std::string& base, const std::vector<std::string>& fills) {
for (const auto& fill : fills) {
if (base.size() < fill.size()) continue;
// Does the end of the input exactly match the fill pattern?
if (base.substr(base.size() - fill.size()) == fill) {
return padding{1, fill.length()} +
count_padding(base.substr(0, base.size() - fill.size()), fills);
inline std::size_t string_len(string_view str) { return str.size(); }

template<class str_input_it>
padding count_padding(string_view base, str_input_it fillStart, str_input_it fillEnd) {
for (str_input_it fillIt = fillStart; fillIt != fillEnd; ++fillIt) {
std::size_t fillLen = string_len(*fillIt);
if (base.size() >= fillLen) {
std::size_t deltaLen = base.size() - fillLen;
// Does the end of the input exactly match the fill pattern?
if (base.substr(deltaLen) == *fillIt) {
return padding{1UL, fillLen} + count_padding(base.substr(0, deltaLen), fillStart, fillEnd);
}
}
}

return {};
}

inline std::string encode(const std::string& bin, const std::array<char, 64>& alphabet,
const std::string& fill) {
inline std::string encode(string_view bin, const char* alphabet, string_view fill) {
size_t size = bin.size();
std::string res;

res.reserve((4UL * size) / 3UL);

// clear incomplete bytes
size_t fast_size = size - size % 3;
for (size_t i = 0; i < fast_size;) {
uint32_t octet_a = static_cast<unsigned char>(bin[i++]);
uint32_t octet_b = static_cast<unsigned char>(bin[i++]);
uint32_t octet_c = static_cast<unsigned char>(bin[i++]);
size_t mod = size % 3;

size_t fast_size = size - mod;
for (size_t i = 0; i < fast_size; i += 3) {
uint32_t octet_a = static_cast<unsigned char>(bin[i]);
uint32_t octet_b = static_cast<unsigned char>(bin[i + 1]);
uint32_t octet_c = static_cast<unsigned char>(bin[i + 2]);

uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;

Expand All @@ -152,8 +189,6 @@ namespace jwt {

if (fast_size == size) return res;

size_t mod = size % 3;

uint32_t octet_a = fast_size < size ? static_cast<unsigned char>(bin[fast_size++]) : 0;
uint32_t octet_b = fast_size < size ? static_cast<unsigned char>(bin[fast_size++]) : 0;
uint32_t octet_c = fast_size < size ? static_cast<unsigned char>(bin[fast_size++]) : 0;
Expand All @@ -179,9 +214,10 @@ namespace jwt {
return res;
}

inline std::string decode(const std::string& base, const std::array<char, 64>& alphabet,
const std::vector<std::string>& fill) {
const auto pad = count_padding(base, fill);
template<class char_it, class str_input_it>
inline std::string decode(string_view base, char_it alphabetBeg, char_it alphabetEnd,
str_input_it fillStart, str_input_it fillEnd) {
const auto pad = count_padding(base, fillStart, fillEnd);
if (pad.count > 2) throw std::runtime_error("Invalid input: too much fill");

const size_t size = base.size() - pad.length;
Expand All @@ -191,7 +227,9 @@ namespace jwt {
std::string res;
res.reserve(out_size);

auto get_sextet = [&](size_t offset) { return alphabet::index(alphabet, base[offset]); };
auto get_sextet = [&](size_t offset) {
return alphabet::index(alphabetBeg, alphabetEnd, base[offset]);
};

size_t fast_size = size - size % 4;
for (size_t i = 0; i < fast_size;) {
Expand Down Expand Up @@ -225,46 +263,64 @@ namespace jwt {
return res;
}

inline std::string decode(const std::string& base, const std::array<char, 64>& alphabet,
const std::string& fill) {
return decode(base, alphabet, std::vector<std::string>{fill});
}

inline std::string pad(const std::string& base, const std::string& fill) {
std::string padding;
switch (base.size() % 4) {
case 1: padding += fill; JWT_FALLTHROUGH;
case 2: padding += fill; JWT_FALLTHROUGH;
case 3: padding += fill; JWT_FALLTHROUGH;
inline std::string pad(string_view base, string_view fill) {
std::string res(base);
switch (res.size() % 4) {
case 1: res += fill; JWT_FALLTHROUGH;
case 2: res += fill; JWT_FALLTHROUGH;
case 3: res += fill; JWT_FALLTHROUGH;
default: break;
}

return base + padding;
return res;
}

inline std::string trim(const std::string& base, const std::string& fill) {
inline std::string trim(string_view base, string_view fill) {
auto pos = base.find(fill);
return base.substr(0, pos);
return static_cast<std::string>(base.substr(0, pos));
}
} // namespace details

#ifdef JWT_HAS_STRING_VIEW
template<typename T>
std::string encode(const std::string& bin) {
return details::encode(bin, T::data(), T::fill());
std::string encode(string_view bin) {
return details::encode(bin, T::kData, T::kFill[0]);
}
template<typename T>
std::string decode(const std::string& base) {
return details::decode(base, T::data(), T::fill());
std::string decode(string_view base) {
return details::decode(base, std::begin(T::kData), std::end(T::kData), std::begin(T::kFill),
std::end(T::kFill));
}
template<typename T>
std::string pad(const std::string& base) {
return details::pad(base, T::fill());
std::string pad(string_view base) {
return details::pad(base, T::kFill[0]);
}
template<typename T>
std::string trim(const std::string& base) {
return details::trim(base, T::fill());
std::string trim(string_view base) {
return details::trim(base, T::kFill[0]);
}

#else
template<typename T>
std::string encode(string_view bin) {
return details::encode(bin, T::data().data(), T::fill()[0]);
}
template<typename T>
std::string decode(string_view base) {
return details::decode(base, std::begin(T::data()), std::end(T::data()), std::begin(T::fill()),
std::end(T::fill()));
}
template<typename T>
std::string pad(string_view base) {
return details::pad(base, T::fill()[0]);
}
template<typename T>
std::string trim(string_view base) {
return details::trim(base, T::fill()[0]);
}
#endif
} // namespace base
} // namespace jwt

#undef JWT_BASE_ALPHABET

#endif
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