| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "spdy/core/hpack/hpack_encoder.h" |
| |
| #include <algorithm> |
| #include <limits> |
| #include <utility> |
| |
| #include "http2/hpack/huffman/hpack_huffman_encoder.h" |
| #include "common/platform/api/quiche_bug_tracker.h" |
| #include "common/platform/api/quiche_logging.h" |
| #include "spdy/core/hpack/hpack_constants.h" |
| #include "spdy/core/hpack/hpack_header_table.h" |
| #include "spdy/core/hpack/hpack_output_stream.h" |
| |
| namespace spdy { |
| |
| class HpackEncoder::RepresentationIterator { |
| public: |
| // |pseudo_headers| and |regular_headers| must outlive the iterator. |
| RepresentationIterator(const Representations& pseudo_headers, |
| const Representations& regular_headers) |
| : pseudo_begin_(pseudo_headers.begin()), |
| pseudo_end_(pseudo_headers.end()), |
| regular_begin_(regular_headers.begin()), |
| regular_end_(regular_headers.end()) {} |
| |
| // |headers| must outlive the iterator. |
| explicit RepresentationIterator(const Representations& headers) |
| : pseudo_begin_(headers.begin()), |
| pseudo_end_(headers.end()), |
| regular_begin_(headers.end()), |
| regular_end_(headers.end()) {} |
| |
| bool HasNext() { |
| return pseudo_begin_ != pseudo_end_ || regular_begin_ != regular_end_; |
| } |
| |
| const Representation Next() { |
| if (pseudo_begin_ != pseudo_end_) { |
| return *pseudo_begin_++; |
| } else { |
| return *regular_begin_++; |
| } |
| } |
| |
| private: |
| Representations::const_iterator pseudo_begin_; |
| Representations::const_iterator pseudo_end_; |
| Representations::const_iterator regular_begin_; |
| Representations::const_iterator regular_end_; |
| }; |
| |
| namespace { |
| |
| // The default header listener. |
| void NoOpListener(absl::string_view /*name*/, absl::string_view /*value*/) {} |
| |
| // The default HPACK indexing policy. |
| bool DefaultPolicy(absl::string_view name, absl::string_view /* value */) { |
| if (name.empty()) { |
| return false; |
| } |
| // :authority is always present and rarely changes, and has moderate |
| // length, therefore it makes a lot of sense to index (insert in the |
| // dynamic table). |
| if (name[0] == kPseudoHeaderPrefix) { |
| return name == ":authority"; |
| } |
| return true; |
| } |
| |
| } // namespace |
| |
| HpackEncoder::HpackEncoder() |
| : output_stream_(), |
| min_table_size_setting_received_(std::numeric_limits<size_t>::max()), |
| listener_(NoOpListener), |
| should_index_(DefaultPolicy), |
| enable_compression_(true), |
| should_emit_table_size_(false) {} |
| |
| HpackEncoder::~HpackEncoder() = default; |
| |
| std::string HpackEncoder::EncodeHeaderBlock(const SpdyHeaderBlock& header_set) { |
| // Separate header set into pseudo-headers and regular headers. |
| Representations pseudo_headers; |
| Representations regular_headers; |
| bool found_cookie = false; |
| for (const auto& header : header_set) { |
| if (!found_cookie && header.first == "cookie") { |
| // Note that there can only be one "cookie" header, because header_set is |
| // a map. |
| found_cookie = true; |
| CookieToCrumbs(header, ®ular_headers); |
| } else if (!header.first.empty() && |
| header.first[0] == kPseudoHeaderPrefix) { |
| DecomposeRepresentation(header, &pseudo_headers); |
| } else { |
| DecomposeRepresentation(header, ®ular_headers); |
| } |
| } |
| |
| RepresentationIterator iter(pseudo_headers, regular_headers); |
| return EncodeRepresentations(&iter); |
| } |
| |
| void HpackEncoder::ApplyHeaderTableSizeSetting(size_t size_setting) { |
| if (size_setting == header_table_.settings_size_bound()) { |
| return; |
| } |
| if (size_setting < header_table_.settings_size_bound()) { |
| min_table_size_setting_received_ = |
| std::min(size_setting, min_table_size_setting_received_); |
| } |
| header_table_.SetSettingsHeaderTableSize(size_setting); |
| should_emit_table_size_ = true; |
| } |
| |
| std::string HpackEncoder::EncodeRepresentations(RepresentationIterator* iter) { |
| MaybeEmitTableSize(); |
| while (iter->HasNext()) { |
| const auto header = iter->Next(); |
| listener_(header.first, header.second); |
| if (enable_compression_) { |
| size_t index = |
| header_table_.GetByNameAndValue(header.first, header.second); |
| if (index != kHpackEntryNotFound) { |
| EmitIndex(index); |
| } else if (should_index_(header.first, header.second)) { |
| EmitIndexedLiteral(header); |
| } else { |
| EmitNonIndexedLiteral(header, enable_compression_); |
| } |
| } else { |
| EmitNonIndexedLiteral(header, enable_compression_); |
| } |
| } |
| |
| return output_stream_.TakeString(); |
| } |
| |
| void HpackEncoder::EmitIndex(size_t index) { |
| QUICHE_DVLOG(2) << "Emitting index " << index; |
| output_stream_.AppendPrefix(kIndexedOpcode); |
| output_stream_.AppendUint32(index); |
| } |
| |
| void HpackEncoder::EmitIndexedLiteral(const Representation& representation) { |
| QUICHE_DVLOG(2) << "Emitting indexed literal: (" << representation.first |
| << ", " << representation.second << ")"; |
| output_stream_.AppendPrefix(kLiteralIncrementalIndexOpcode); |
| EmitLiteral(representation); |
| header_table_.TryAddEntry(representation.first, representation.second); |
| } |
| |
| void HpackEncoder::EmitNonIndexedLiteral(const Representation& representation, |
| bool enable_compression) { |
| QUICHE_DVLOG(2) << "Emitting nonindexed literal: (" << representation.first |
| << ", " << representation.second << ")"; |
| output_stream_.AppendPrefix(kLiteralNoIndexOpcode); |
| size_t name_index = header_table_.GetByName(representation.first); |
| if (enable_compression && name_index != kHpackEntryNotFound) { |
| output_stream_.AppendUint32(name_index); |
| } else { |
| output_stream_.AppendUint32(0); |
| EmitString(representation.first); |
| } |
| EmitString(representation.second); |
| } |
| |
| void HpackEncoder::EmitLiteral(const Representation& representation) { |
| size_t name_index = header_table_.GetByName(representation.first); |
| if (name_index != kHpackEntryNotFound) { |
| output_stream_.AppendUint32(name_index); |
| } else { |
| output_stream_.AppendUint32(0); |
| EmitString(representation.first); |
| } |
| EmitString(representation.second); |
| } |
| |
| void HpackEncoder::EmitString(absl::string_view str) { |
| size_t encoded_size = |
| enable_compression_ ? http2::HuffmanSize(str) : str.size(); |
| if (encoded_size < str.size()) { |
| QUICHE_DVLOG(2) << "Emitted Huffman-encoded string of length " |
| << encoded_size; |
| output_stream_.AppendPrefix(kStringLiteralHuffmanEncoded); |
| output_stream_.AppendUint32(encoded_size); |
| http2::HuffmanEncodeFast(str, encoded_size, output_stream_.MutableString()); |
| } else { |
| QUICHE_DVLOG(2) << "Emitted literal string of length " << str.size(); |
| output_stream_.AppendPrefix(kStringLiteralIdentityEncoded); |
| output_stream_.AppendUint32(str.size()); |
| output_stream_.AppendBytes(str); |
| } |
| } |
| |
| void HpackEncoder::MaybeEmitTableSize() { |
| if (!should_emit_table_size_) { |
| return; |
| } |
| const size_t current_size = CurrentHeaderTableSizeSetting(); |
| QUICHE_DVLOG(1) << "MaybeEmitTableSize current_size=" << current_size; |
| QUICHE_DVLOG(1) << "MaybeEmitTableSize min_table_size_setting_received_=" |
| << min_table_size_setting_received_; |
| if (min_table_size_setting_received_ < current_size) { |
| output_stream_.AppendPrefix(kHeaderTableSizeUpdateOpcode); |
| output_stream_.AppendUint32(min_table_size_setting_received_); |
| } |
| output_stream_.AppendPrefix(kHeaderTableSizeUpdateOpcode); |
| output_stream_.AppendUint32(current_size); |
| min_table_size_setting_received_ = std::numeric_limits<size_t>::max(); |
| should_emit_table_size_ = false; |
| } |
| |
| // static |
| void HpackEncoder::CookieToCrumbs(const Representation& cookie, |
| Representations* out) { |
| // See Section 8.1.2.5. "Compressing the Cookie Header Field" in the HTTP/2 |
| // specification at https://tools.ietf.org/html/draft-ietf-httpbis-http2-14. |
| // Cookie values are split into individually-encoded HPACK representations. |
| absl::string_view cookie_value = cookie.second; |
| // Consume leading and trailing whitespace if present. |
| absl::string_view::size_type first = cookie_value.find_first_not_of(" \t"); |
| absl::string_view::size_type last = cookie_value.find_last_not_of(" \t"); |
| if (first == absl::string_view::npos) { |
| cookie_value = absl::string_view(); |
| } else { |
| cookie_value = cookie_value.substr(first, (last - first) + 1); |
| } |
| for (size_t pos = 0;;) { |
| size_t end = cookie_value.find(';', pos); |
| |
| if (end == absl::string_view::npos) { |
| out->push_back(std::make_pair(cookie.first, cookie_value.substr(pos))); |
| break; |
| } |
| out->push_back( |
| std::make_pair(cookie.first, cookie_value.substr(pos, end - pos))); |
| |
| // Consume next space if present. |
| pos = end + 1; |
| if (pos != cookie_value.size() && cookie_value[pos] == ' ') { |
| pos++; |
| } |
| } |
| } |
| |
| // static |
| void HpackEncoder::DecomposeRepresentation(const Representation& header_field, |
| Representations* out) { |
| size_t pos = 0; |
| size_t end = 0; |
| while (end != absl::string_view::npos) { |
| end = header_field.second.find('\0', pos); |
| out->push_back(std::make_pair( |
| header_field.first, |
| header_field.second.substr( |
| pos, end == absl::string_view::npos ? end : end - pos))); |
| pos = end + 1; |
| } |
| } |
| |
| // Iteratively encodes a SpdyHeaderBlock. |
| class HpackEncoder::Encoderator : public ProgressiveEncoder { |
| public: |
| Encoderator(const SpdyHeaderBlock& header_set, HpackEncoder* encoder); |
| Encoderator(const Representations& representations, HpackEncoder* encoder); |
| |
| // Encoderator is neither copyable nor movable. |
| Encoderator(const Encoderator&) = delete; |
| Encoderator& operator=(const Encoderator&) = delete; |
| |
| // Returns true iff more remains to encode. |
| bool HasNext() const override { return has_next_; } |
| |
| // Encodes and returns up to max_encoded_bytes of the current header block. |
| std::string Next(size_t max_encoded_bytes) override; |
| |
| private: |
| HpackEncoder* encoder_; |
| std::unique_ptr<RepresentationIterator> header_it_; |
| Representations pseudo_headers_; |
| Representations regular_headers_; |
| bool has_next_; |
| }; |
| |
| HpackEncoder::Encoderator::Encoderator(const SpdyHeaderBlock& header_set, |
| HpackEncoder* encoder) |
| : encoder_(encoder), has_next_(true) { |
| // Separate header set into pseudo-headers and regular headers. |
| bool found_cookie = false; |
| for (const auto& header : header_set) { |
| if (!found_cookie && header.first == "cookie") { |
| // Note that there can only be one "cookie" header, because header_set |
| // is a map. |
| found_cookie = true; |
| CookieToCrumbs(header, ®ular_headers_); |
| } else if (!header.first.empty() && |
| header.first[0] == kPseudoHeaderPrefix) { |
| DecomposeRepresentation(header, &pseudo_headers_); |
| } else { |
| DecomposeRepresentation(header, ®ular_headers_); |
| } |
| } |
| header_it_ = std::make_unique<RepresentationIterator>(pseudo_headers_, |
| regular_headers_); |
| |
| encoder_->MaybeEmitTableSize(); |
| } |
| |
| HpackEncoder::Encoderator::Encoderator(const Representations& representations, |
| HpackEncoder* encoder) |
| : encoder_(encoder), has_next_(true) { |
| for (const auto& header : representations) { |
| if (header.first == "cookie") { |
| CookieToCrumbs(header, ®ular_headers_); |
| } else if (!header.first.empty() && |
| header.first[0] == kPseudoHeaderPrefix) { |
| pseudo_headers_.push_back(header); |
| } else { |
| regular_headers_.push_back(header); |
| } |
| } |
| header_it_ = std::make_unique<RepresentationIterator>(pseudo_headers_, |
| regular_headers_); |
| |
| encoder_->MaybeEmitTableSize(); |
| } |
| |
| std::string HpackEncoder::Encoderator::Next(size_t max_encoded_bytes) { |
| QUICHE_BUG_IF(spdy_bug_61_1, !has_next_) |
| << "Encoderator::Next called with nothing left to encode."; |
| const bool enable_compression = encoder_->enable_compression_; |
| |
| // Encode up to max_encoded_bytes of headers. |
| while (header_it_->HasNext() && |
| encoder_->output_stream_.size() <= max_encoded_bytes) { |
| const Representation header = header_it_->Next(); |
| encoder_->listener_(header.first, header.second); |
| if (enable_compression) { |
| size_t index = encoder_->header_table_.GetByNameAndValue(header.first, |
| header.second); |
| if (index != kHpackEntryNotFound) { |
| encoder_->EmitIndex(index); |
| } else if (encoder_->should_index_(header.first, header.second)) { |
| encoder_->EmitIndexedLiteral(header); |
| } else { |
| encoder_->EmitNonIndexedLiteral(header, enable_compression); |
| } |
| } else { |
| encoder_->EmitNonIndexedLiteral(header, enable_compression); |
| } |
| } |
| |
| has_next_ = encoder_->output_stream_.size() > max_encoded_bytes; |
| return encoder_->output_stream_.BoundedTakeString(max_encoded_bytes); |
| } |
| |
| std::unique_ptr<HpackEncoder::ProgressiveEncoder> HpackEncoder::EncodeHeaderSet( |
| const SpdyHeaderBlock& header_set) { |
| return std::make_unique<Encoderator>(header_set, this); |
| } |
| |
| std::unique_ptr<HpackEncoder::ProgressiveEncoder> |
| HpackEncoder::EncodeRepresentations(const Representations& representations) { |
| return std::make_unique<Encoderator>(representations, this); |
| } |
| |
| } // namespace spdy |