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feat: add HTTP/1.1 chunked transfer decoder #14
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,243 @@ | ||
| #include "http/chunked_decoder.hpp" | ||
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| #include <algorithm> | ||
| #include <charconv> | ||
| #include <cstddef> | ||
| #include <string> | ||
| #include <string_view> | ||
| #include <system_error> | ||
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| #include <cpp_request/error.hpp> | ||
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| namespace cpp_request::detail::http { | ||
| namespace { | ||
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| [[nodiscard]] constexpr char ascii_lower(char ch) noexcept { | ||
| return ch >= 'A' && ch <= 'Z' | ||
| ? static_cast<char>(ch + ('a' - 'A')) | ||
| : ch; | ||
| } | ||
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| [[nodiscard]] bool ascii_iequals( | ||
| std::string_view lhs, | ||
| std::string_view rhs) noexcept { | ||
| if (lhs.size() != rhs.size()) { | ||
| return false; | ||
| } | ||
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| for (std::size_t index = 0; index < lhs.size(); ++index) { | ||
| if (ascii_lower(lhs[index]) != ascii_lower(rhs[index])) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| [[nodiscard]] constexpr bool is_tchar(unsigned char ch) noexcept { | ||
| if ((ch >= '0' && ch <= '9') | ||
| || (ch >= 'A' && ch <= 'Z') | ||
| || (ch >= 'a' && ch <= 'z')) { | ||
| return true; | ||
| } | ||
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| switch (ch) { | ||
| case '!': | ||
| case '#': | ||
| case '$': | ||
| case '%': | ||
| case '&': | ||
| case '\'': | ||
| case '*': | ||
| case '+': | ||
| case '-': | ||
| case '.': | ||
| case '^': | ||
| case '_': | ||
| case '`': | ||
| case '|': | ||
| case '~': | ||
| return true; | ||
| default: | ||
| return false; | ||
| } | ||
| } | ||
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| [[nodiscard]] bool valid_field_name(std::string_view name) noexcept { | ||
| if (name.empty()) { | ||
| return false; | ||
| } | ||
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| for (const unsigned char ch : name) { | ||
| if (!is_tchar(ch)) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| [[nodiscard]] bool valid_field_value(std::string_view value) noexcept { | ||
| for (const unsigned char ch : value) { | ||
| if (ch == '\t') { | ||
| continue; | ||
| } | ||
| if (ch < 0x20 || ch == 0x7f) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| [[nodiscard]] bool valid_chunk_extension(std::string_view extension) noexcept { | ||
| for (const unsigned char ch : extension) { | ||
| if (ch == '\t') { | ||
| continue; | ||
| } | ||
| if (ch < 0x20 || ch == 0x7f) { | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
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| [[nodiscard]] Result<std::size_t> parse_chunk_size(std::string_view line) noexcept { | ||
| const std::size_t semicolon = line.find(';'); | ||
| const std::string_view size_text = line.substr(0, semicolon); | ||
|
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When a server sends a chunk line such as Useful? React with 👍 / 👎. |
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| if (size_text.empty()) { | ||
| return Error{ErrorCode::InvalidChunkSize}; | ||
| } | ||
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| if (semicolon != std::string_view::npos | ||
| && !valid_chunk_extension(line.substr(semicolon + 1))) { | ||
| return Error{ErrorCode::InvalidChunkFraming}; | ||
| } | ||
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| std::size_t value = 0; | ||
| const char* const first = size_text.data(); | ||
| const char* const last = size_text.data() + size_text.size(); | ||
| const auto parsed = std::from_chars(first, last, value, 16); | ||
| if (parsed.ec != std::errc{} || parsed.ptr != last) { | ||
| return Error{ErrorCode::InvalidChunkSize}; | ||
| } | ||
| return value; | ||
| } | ||
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| [[nodiscard]] bool valid_trailer_line(std::string_view line) noexcept { | ||
| if (line.empty() || line.front() == ' ' || line.front() == '\t') { | ||
| return false; | ||
| } | ||
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| const std::size_t colon = line.find(':'); | ||
| if (colon == std::string_view::npos || colon == 0) { | ||
| return false; | ||
| } | ||
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| const std::string_view name = line.substr(0, colon); | ||
| const std::string_view value = line.substr(colon + 1); | ||
| if (!valid_field_name(name) || !valid_field_value(value)) { | ||
| return false; | ||
| } | ||
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| return !ascii_iequals(name, "Content-Length") | ||
| && !ascii_iequals(name, "Transfer-Encoding"); | ||
| } | ||
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| void consume_prefix(std::string& input, std::size_t count) { | ||
| if (count != 0) { | ||
| input.erase(0, count); | ||
| } | ||
| } | ||
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| } // namespace | ||
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| Result<ChunkDecodeProgress> ChunkedDecoder::process( | ||
| std::string& input, | ||
| std::string& output) { | ||
| std::size_t cursor = 0; | ||
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| while (true) { | ||
| switch (stage_) { | ||
| case Stage::SizeLine: { | ||
| const std::size_t line_end = input.find("\r\n", cursor); | ||
| if (line_end == std::string::npos) { | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::NeedMore; | ||
| } | ||
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| const std::string_view line{ | ||
| input.data() + cursor, | ||
| line_end - cursor}; | ||
| auto size = parse_chunk_size(line); | ||
| if (!size) { | ||
| return size.error(); | ||
| } | ||
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| cursor = line_end + 2; | ||
| chunk_remaining_ = size.value(); | ||
| stage_ = chunk_remaining_ == 0 | ||
| ? Stage::Trailers | ||
| : Stage::Data; | ||
| continue; | ||
| } | ||
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| case Stage::Data: { | ||
| const std::size_t available = input.size() - cursor; | ||
| const std::size_t amount = std::min(chunk_remaining_, available); | ||
| if (amount != 0) { | ||
| output.append(input.data() + cursor, amount); | ||
| cursor += amount; | ||
| chunk_remaining_ -= amount; | ||
| } | ||
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| if (chunk_remaining_ != 0) { | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::NeedMore; | ||
| } | ||
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| stage_ = Stage::DataCrlf; | ||
| continue; | ||
| } | ||
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| case Stage::DataCrlf: | ||
| if (input.size() - cursor < 2) { | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::NeedMore; | ||
| } | ||
| if (input[cursor] != '\r' || input[cursor + 1] != '\n') { | ||
| return Error{ErrorCode::InvalidChunkFraming}; | ||
| } | ||
| cursor += 2; | ||
| stage_ = Stage::SizeLine; | ||
| continue; | ||
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| case Stage::Trailers: { | ||
| const std::size_t line_end = input.find("\r\n", cursor); | ||
| if (line_end == std::string::npos) { | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::NeedMore; | ||
| } | ||
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| const std::string_view line{ | ||
| input.data() + cursor, | ||
| line_end - cursor}; | ||
| cursor = line_end + 2; | ||
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| if (line.empty()) { | ||
| stage_ = Stage::Complete; | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::Complete; | ||
| } | ||
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| if (!valid_trailer_line(line)) { | ||
| return Error{ErrorCode::InvalidHeader}; | ||
| } | ||
| continue; | ||
| } | ||
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| case Stage::Complete: | ||
| consume_prefix(input, cursor); | ||
| return ChunkDecodeProgress::Complete; | ||
| } | ||
| } | ||
| } | ||
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| } // namespace cpp_request::detail::http | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,34 @@ | ||
| #pragma once | ||
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| #include <cstddef> | ||
| #include <string> | ||
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| #include <cpp_request/result.hpp> | ||
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| namespace cpp_request::detail::http { | ||
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| enum class ChunkDecodeProgress { | ||
| NeedMore, | ||
| Complete | ||
| }; | ||
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| class ChunkedDecoder final { | ||
| public: | ||
| [[nodiscard]] Result<ChunkDecodeProgress> process( | ||
| std::string& input, | ||
| std::string& output); | ||
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| private: | ||
| enum class Stage { | ||
| SizeLine, | ||
| Data, | ||
| DataCrlf, | ||
| Trailers, | ||
| Complete | ||
| }; | ||
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| Stage stage_{Stage::SizeLine}; | ||
| std::size_t chunk_remaining_{0}; | ||
| }; | ||
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| } // namespace cpp_request::detail::http |
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When a malformed peer sends an extension such as
4;\r\nor4;foo="unterminated\r\n, this validator accepts it because it only rejects control bytes, and the response completes successfully. Chunk extensions require a nonempty token name and, when present, a token or valid quoted-string value, so the decoder needs to validate that grammar to satisfy its malformed-framing error contract.Useful? React with 👍 / 👎.