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#ifndef QUICHE_SPDY_CORE_METADATA_EXTENSION_H_
#define QUICHE_SPDY_CORE_METADATA_EXTENSION_H_
#include <memory>
#include <string>
#include <vector>
#include "absl/container/flat_hash_map.h"
#include "quiche/spdy/core/http2_frame_decoder_adapter.h"
#include "quiche/spdy/core/spdy_header_block.h"
#include "quiche/spdy/core/spdy_protocol.h"
#include "quiche/spdy/core/zero_copy_output_buffer.h"
namespace spdy {
// An implementation of the ExtensionVisitorInterface that can parse
// METADATA frames. METADATA is a non-standard HTTP/2 extension developed and
// used internally at Google. A peer advertises support for METADATA by sending
// a setting with a setting ID of kMetadataExtensionId and a value of 1.
//
// Metadata is represented as a HPACK header block with literal encoding.
class MetadataVisitor : public spdy::ExtensionVisitorInterface {
public:
using MetadataPayload = spdy::SpdyHeaderBlock;
static_assert(!std::is_copy_constructible<MetadataPayload>::value,
"MetadataPayload should be a move-only type!");
using OnMetadataSupport = std::function<void(bool)>;
using OnCompletePayload =
std::function<void(spdy::SpdyStreamId, MetadataPayload)>;
// The HTTP/2 SETTINGS ID that is used to indicate support for METADATA
// frames.
static const spdy::SpdySettingsId kMetadataExtensionId;
// The 8-bit frame type code for a METADATA frame.
static const uint8_t kMetadataFrameType;
// The flag that indicates the end of a logical metadata block. Due to frame
// size limits, a single metadata block may be emitted as several HTTP/2
// frames.
static const uint8_t kEndMetadataFlag;
// |on_payload| is invoked whenever a complete metadata payload is received.
// |on_support| is invoked whenever the peer's advertised support for metadata
// changes.
MetadataVisitor(OnCompletePayload on_payload, OnMetadataSupport on_support);
~MetadataVisitor() override;
MetadataVisitor(const MetadataVisitor&) = delete;
MetadataVisitor& operator=(const MetadataVisitor&) = delete;
// Interprets the non-standard setting indicating support for METADATA.
void OnSetting(spdy::SpdySettingsId id, uint32_t value) override;
// Returns true iff |type| indicates a METADATA frame.
bool OnFrameHeader(spdy::SpdyStreamId stream_id, size_t length, uint8_t type,
uint8_t flags) override;
// Consumes a METADATA frame payload. Invokes the registered callback when a
// complete payload has been received.
void OnFramePayload(const char* data, size_t len) override;
// Returns true if the peer has advertised support for METADATA via the
// appropriate setting.
bool PeerSupportsMetadata() const {
return peer_supports_metadata_ == MetadataSupportState::SUPPORTED;
}
private:
enum class MetadataSupportState : uint8_t {
UNSPECIFIED,
SUPPORTED,
NOT_SUPPORTED,
};
struct MetadataPayloadState;
using StreamMetadataMap =
absl::flat_hash_map<spdy::SpdyStreamId,
std::unique_ptr<MetadataPayloadState>>;
OnCompletePayload on_payload_;
OnMetadataSupport on_support_;
StreamMetadataMap metadata_map_;
spdy::SpdyStreamId current_stream_;
MetadataSupportState peer_supports_metadata_;
};
// A class that serializes metadata blocks as sequences of frames.
class MetadataSerializer {
public:
using MetadataPayload = spdy::SpdyHeaderBlock;
class FrameSequence {
public:
virtual ~FrameSequence() {}
// Returns nullptr once the sequence has been exhausted.
virtual std::unique_ptr<spdy::SpdyFrameIR> Next() = 0;
};
MetadataSerializer() {}
MetadataSerializer(const MetadataSerializer&) = delete;
MetadataSerializer& operator=(const MetadataSerializer&) = delete;
// Returns nullptr on failure.
std::unique_ptr<FrameSequence> FrameSequenceForPayload(
spdy::SpdyStreamId stream_id, MetadataPayload payload);
};
} // namespace spdy
#endif // QUICHE_SPDY_CORE_METADATA_EXTENSION_H_
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