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// Copyright 2015 gRPC authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_H
#define GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_H
#include <grpc/support/port_platform.h>
#include <cstdint>
#include <string>
#include <vector>
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "absl/types/span.h"
#include "absl/types/variant.h"
#include "src/core/lib/slice/slice.h"
#include "src/core/lib/slice/slice_buffer.h"
namespace grpc_core {
///////////////////////////////////////////////////////////////////////////////
// Frame types
//
// Define structs for each kind of frame that chttp2 reasons about.
//
// Each struct gets the members defined by the HTTP/2 spec for that frame type
// *that the semantic layers of chttp2 neead to reason about*.
//
// That means, for instance, that we drop padding and prioritization data from
// these structs, as they are handled by the HTTP/2 framing layer and are
// meaningless to the semantic layers above.
//
// If a frame type is associated with a stream, it has a stream_id member.
// If that frame type is only used at the channel layer it does not.
//
// Instead of carrying bitfields of flags like the wire format, we instead
// declare a bool per flag to make producing/consuming code easier to write.
//
// Equality operators are defined for use in unit tests.
// DATA frame
struct Http2DataFrame {
uint32_t stream_id = 0;
bool end_stream = false;
SliceBuffer payload;
bool operator==(const Http2DataFrame& other) const {
return stream_id == other.stream_id && end_stream == other.end_stream &&
payload.JoinIntoString() == other.payload.JoinIntoString();
}
};
// HEADER frame
struct Http2HeaderFrame {
uint32_t stream_id = 0;
bool end_headers = false;
bool end_stream = false;
SliceBuffer payload;
bool operator==(const Http2HeaderFrame& other) const {
return stream_id == other.stream_id && end_headers == other.end_headers &&
end_stream == other.end_stream &&
payload.JoinIntoString() == other.payload.JoinIntoString();
}
};
// CONTINUATION frame
struct Http2ContinuationFrame {
uint32_t stream_id = 0;
bool end_headers = false;
SliceBuffer payload;
bool operator==(const Http2ContinuationFrame& other) const {
return stream_id == other.stream_id && end_headers == other.end_headers &&
payload.JoinIntoString() == other.payload.JoinIntoString();
}
};
// RST_STREAM frame
struct Http2RstStreamFrame {
uint32_t stream_id = 0;
uint32_t error_code = 0;
bool operator==(const Http2RstStreamFrame& other) const {
return stream_id == other.stream_id && error_code == other.error_code;
}
};
// SETTINGS frame
struct Http2SettingsFrame {
struct Setting {
uint16_t id;
uint32_t value;
bool operator==(const Setting& other) const {
return id == other.id && value == other.value;
}
};
bool ack = false;
std::vector<Setting> settings;
bool operator==(const Http2SettingsFrame& other) const {
return ack == other.ack && settings == other.settings;
}
};
// PING frame
struct Http2PingFrame {
bool ack = false;
uint64_t opaque = 0;
bool operator==(const Http2PingFrame& other) const {
return ack == other.ack && opaque == other.opaque;
}
};
// GOAWAY frame
struct Http2GoawayFrame {
uint32_t last_stream_id = 0;
uint32_t error_code = 0;
Slice debug_data;
bool operator==(const Http2GoawayFrame& other) const {
return last_stream_id == other.last_stream_id &&
error_code == other.error_code &&
debug_data.as_string_view() == other.debug_data.as_string_view();
}
};
// WINDOW_UPDATE frame
struct Http2WindowUpdateFrame {
uint32_t stream_id;
uint32_t increment;
bool operator==(const Http2WindowUpdateFrame& other) const {
return stream_id == other.stream_id && increment == other.increment;
}
};
// Type of frame was unknown (and should be ignored)
struct Http2UnknownFrame {
bool operator==(const Http2UnknownFrame&) const { return true; }
};
///////////////////////////////////////////////////////////////////////////////
// Frame variant
//
// A union of all the frame types above, so that we may pass around an
// arbitrary frame between layers as appropriate.
using Http2Frame =
absl::variant<Http2DataFrame, Http2HeaderFrame, Http2ContinuationFrame,
Http2RstStreamFrame, Http2SettingsFrame, Http2PingFrame,
Http2GoawayFrame, Http2WindowUpdateFrame, Http2UnknownFrame>;
///////////////////////////////////////////////////////////////////////////////
// Frame header
//
// Define a struct for the frame header.
// Parsing this type is the first step in parsing a frame.
// No validation on the header is done during parsing - the fields should be
// instead interpreted by the frame type parser.
struct Http2FrameHeader {
uint32_t length;
uint8_t type;
uint8_t flags;
uint32_t stream_id;
// Serialize header to 9 byte long buffer output
// Crashes if length > 16777215 (as this is unencodable)
void Serialize(uint8_t* output) const;
// Parse header from 9 byte long buffer input
static Http2FrameHeader Parse(const uint8_t* input);
std::string ToString() const;
bool operator==(const Http2FrameHeader& other) const {
return length == other.length && type == other.type &&
flags == other.flags && stream_id == other.stream_id;
}
};
///////////////////////////////////////////////////////////////////////////////
// Parsing & serialization
// Given a frame header and a payload, parse the payload into a frame and
// return it.
// If this function returns an error, that should be considered a connection
// error.
// If a frame should simply be ignored, this function returns a
// Http2UnknownFrame.
// It is expected that hdr.length == payload.Length().
absl::StatusOr<Http2Frame> ParseFramePayload(const Http2FrameHeader& hdr,
SliceBuffer payload);
// Serialize frame and append to out, leaves frames in an unknown state (may
// move things out of frames)
void Serialize(absl::Span<Http2Frame> frames, SliceBuffer& out);
} // namespace grpc_core
#endif // GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_FRAME_H
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