Skip to content

Commit

Permalink
Allow caller to supply output buffer for base64 decode
Browse files Browse the repository at this point in the history
  • Loading branch information
@Sainan
Sainan committed Dec 2, 2024
1 parent 6d4e24b commit 13cfa0c
Show file tree
Hide file tree
Showing 2 changed files with 75 additions and 36 deletions.
97 changes: 66 additions & 31 deletions soup/base64.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,14 +92,14 @@ NAMESPACE_SOUP
return encode(out, data, size, pad, table_encode_base64url);
}

std::string base64::encode(const char* const data, const size_t size, const bool pad, const char* table) SOUP_EXCAL
std::string base64::encode(const char* const data, const size_t size, const bool pad, const char table[64]) SOUP_EXCAL
{
std::string enc(getEncodedSize(size, pad), '\0');
encode(enc.data(), data, size, pad, table);
return enc;
}

void base64::encode(char* out, const char* data, const size_t size, const bool pad, const char* table) noexcept
void base64::encode(char* out, const char* data, const size_t size, const bool pad, const char table[64]) noexcept
{
size_t i = 0;

Expand Down Expand Up @@ -156,9 +156,30 @@ NAMESPACE_SOUP
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
};

std::string base64::decode(std::string enc) SOUP_EXCAL
size_t base64::getDecodedSize(const char* data, size_t size) noexcept
{
return decode(std::move(enc), table_decode_base64);
// Ignore pad bytes
while (size != 0 && data[size - 1] == '=')
{
size--;
}

size_t out_len = size / 4 * 3;
if (auto remainder = (size % 4))
{
out_len += (remainder - 1);
}
return out_len;
}

std::string base64::decode(const std::string& enc) SOUP_EXCAL
{
return decode(enc, table_decode_base64);
}

void base64::decode(char* out, const char* data, size_t size) noexcept
{
return decode(out, data, size, table_decode_base64);
}

static constexpr unsigned char table_decode_base64url[] = {
Expand All @@ -180,42 +201,56 @@ NAMESPACE_SOUP
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
};

std::string base64::urlDecode(std::string enc) SOUP_EXCAL
std::string base64::urlDecode(const std::string& enc) SOUP_EXCAL
{
return decode(std::move(enc), table_decode_base64url);
return decode(enc, table_decode_base64url);
}

std::string base64::decode(std::string&& enc, const unsigned char* table) SOUP_EXCAL
void base64::urlDecode(char* out, const char* data, size_t size) noexcept
{
std::string out{};
if (!enc.empty())
{
size_t in_len;
while (in_len = enc.size(), in_len % 4 != 0)
{
enc.push_back('=');
}
return decode(out, data, size, table_decode_base64url);
}

size_t out_len = in_len / 4 * 3;
if (enc[in_len - 1] == '=') out_len--;
if (enc[in_len - 2] == '=') out_len--;
std::string base64::decode(const std::string& enc, const unsigned char table[256]) SOUP_EXCAL
{
std::string out(getDecodedSize(enc.data(), enc.size()), '\0');
decode(out.data(), enc.data(), enc.size(), table);
return out;
}

out.resize(out_len);
void base64::decode(char* out, const char* data, size_t size, const unsigned char table[256]) noexcept
{
// Ignore pad bytes
while (size != 0 && data[size - 1] == '=')
{
size--;
}

for (size_t i = 0, j = 0; i < in_len; )
{
uint32_t a = enc[i] == '=' ? 0 & i++ : table[static_cast<uint8_t>(enc[i++])];
uint32_t b = enc[i] == '=' ? 0 & i++ : table[static_cast<uint8_t>(enc[i++])];
uint32_t c = enc[i] == '=' ? 0 & i++ : table[static_cast<uint8_t>(enc[i++])];
uint32_t d = enc[i] == '=' ? 0 & i++ : table[static_cast<uint8_t>(enc[i++])];
size_t i = 0;
size_t j = 0;
const size_t aligned_size = (size / 4) * 4;
while (i != aligned_size)
{
uint32_t a = table[static_cast<uint8_t>(data[i++])];
uint32_t b = table[static_cast<uint8_t>(data[i++])];
uint32_t c = table[static_cast<uint8_t>(data[i++])];
uint32_t d = table[static_cast<uint8_t>(data[i++])];
uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6);
out[j++] = (triple >> 2 * 8) & 0xFF;
out[j++] = (triple >> 1 * 8) & 0xFF;
out[j++] = (triple >> 0 * 8) & 0xFF;
}

uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6);
if (auto remainder = (size % 4))
{
auto extra = (remainder - 1);

if (j < out_len) out[j++] = (triple >> 2 * 8) & 0xFF;
if (j < out_len) out[j++] = (triple >> 1 * 8) & 0xFF;
if (j < out_len) out[j++] = (triple >> 0 * 8) & 0xFF;
}
uint32_t a = i != size ? table[static_cast<uint8_t>(data[i++])] : 0;
uint32_t b = i != size ? table[static_cast<uint8_t>(data[i++])] : 0;
uint32_t c = i != size ? table[static_cast<uint8_t>(data[i++])] : 0;
uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6);
if (extra--) out[j++] = (triple >> 2 * 8) & 0xFF;
if (extra--) out[j++] = (triple >> 1 * 8) & 0xFF;
}
return out;
}
}
14 changes: 9 additions & 5 deletions soup/base64.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,12 +44,16 @@ NAMESPACE_SOUP
[[nodiscard]] static std::string urlEncode(const char* const data, const size_t size, const bool pad = false) SOUP_EXCAL;
static void urlEncode(char* out, const char* const data, const size_t size, const bool pad) noexcept;

[[nodiscard]] static std::string encode(const char* const data, const size_t size, const bool pad, const char* table) SOUP_EXCAL;
static void encode(char* out, const char* data, const size_t size, const bool pad, const char* table) noexcept;
[[nodiscard]] static std::string encode(const char* const data, const size_t size, const bool pad, const char table[64]) SOUP_EXCAL;
static void encode(char* out, const char* data, const size_t size, const bool pad, const char table[64]) noexcept;

[[nodiscard]] static std::string decode(std::string enc) SOUP_EXCAL;
[[nodiscard]] static std::string urlDecode(std::string enc) SOUP_EXCAL;
[[nodiscard]] static std::string decode(std::string&& enc, const unsigned char* table) SOUP_EXCAL;
[[nodiscard]] static size_t getDecodedSize(const char* data, size_t size) noexcept;
[[nodiscard]] static std::string decode(const std::string& enc) SOUP_EXCAL;
static void decode(char* out, const char* data, size_t size) noexcept;
[[nodiscard]] static std::string urlDecode(const std::string& enc) SOUP_EXCAL;
static void urlDecode(char* out, const char* data, size_t size) noexcept;
[[nodiscard]] static std::string decode(const std::string& enc, const unsigned char table[256]) SOUP_EXCAL;
static void decode(char* out, const char* data, size_t size, const unsigned char table[256]) noexcept;

template <typename T>
static bool decode(T& out, std::string enc) SOUP_EXCAL
Expand Down

0 comments on commit 13cfa0c

Please sign in to comment.