proxy/http2/HTTP2.h

/** @file
 *
 *  Fundamental HTTP/2 protocol definitions and parsers.
 *
 *  @section license License
 *
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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 __HTTP2_H__
#define __HTTP2_H__

#include "ink_defs.h"
#include "ink_memory.h"
#include "HPACK.h"
#include "MIME.h"

class HTTPHdr;

typedef unsigned Http2StreamId;

// 6.9.2 Initial Flow Control Window Size - the flow control window can be come negative
// so we need to track it with a signed type.
typedef int32_t Http2WindowSize;

extern const char *const HTTP2_CONNECTION_PREFACE;
const size_t HTTP2_CONNECTION_PREFACE_LEN = 24;

const size_t HTTP2_FRAME_HEADER_LEN = 9;
const size_t HTTP2_DATA_PADLEN_LEN = 1;
const size_t HTTP2_HEADERS_PADLEN_LEN = 1;
const size_t HTTP2_PRIORITY_LEN = 5;
const size_t HTTP2_RST_STREAM_LEN = 4;
const size_t HTTP2_PING_LEN = 8;
const size_t HTTP2_GOAWAY_LEN = 8;
const size_t HTTP2_WINDOW_UPDATE_LEN = 4;
const size_t HTTP2_SETTINGS_PARAMETER_LEN = 6;

// SETTINGS initial values. NOTE: These should not be modified
// unless the protocol changes! Do not change this thinking you
// are changing server defaults. that is done via RecordsConfig.cc
const uint32_t HTTP2_MAX_CONCURRENT_STREAMS = 100;
const uint32_t HTTP2_INITIAL_WINDOW_SIZE = 65535;
const uint32_t HTTP2_MAX_FRAME_SIZE = 16384;
const uint32_t HTTP2_HEADER_TABLE_SIZE = 4096;
const uint32_t HTTP2_MAX_HEADER_LIST_SIZE = UINT_MAX;

// 6.9.1 The Flow Control Window
static const Http2WindowSize HTTP2_MAX_WINDOW_SIZE = 0x7FFFFFFF;

enum Http2ErrorCode {
  HTTP2_ERROR_NO_ERROR = 0,
  HTTP2_ERROR_PROTOCOL_ERROR = 1,
  HTTP2_ERROR_INTERNAL_ERROR = 2,
  HTTP2_ERROR_FLOW_CONTROL_ERROR = 3,
  HTTP2_ERROR_SETTINGS_TIMEOUT = 4,
  HTTP2_ERROR_STREAM_CLOSED = 5,
  HTTP2_ERROR_FRAME_SIZE_ERROR = 6,
  HTTP2_ERROR_REFUSED_STREAM = 7,
  HTTP2_ERROR_CANCEL = 8,
  HTTP2_ERROR_COMPRESSION_ERROR = 9,
  HTTP2_ERROR_CONNECT_ERROR = 10,
  HTTP2_ERROR_ENHANCE_YOUR_CALM = 11,
  HTTP2_ERROR_INADEQUATE_SECURITY = 12,
  HTTP2_ERROR_HTTP_1_1_REQUIRED = 13,

  HTTP2_ERROR_MAX,
};

// 5.1. Stream States
enum Http2StreamState {
  HTTP2_STREAM_STATE_IDLE,
  HTTP2_STREAM_STATE_RESERVED_LOCAL,
  HTTP2_STREAM_STATE_RESERVED_REMOTE,
  HTTP2_STREAM_STATE_OPEN,
  HTTP2_STREAM_STATE_HALF_CLOSED_LOCAL,
  HTTP2_STREAM_STATE_HALF_CLOSED_REMOTE,
  HTTP2_STREAM_STATE_CLOSED
};

enum Http2FrameType {
  HTTP2_FRAME_TYPE_DATA = 0,
  HTTP2_FRAME_TYPE_HEADERS = 1,
  HTTP2_FRAME_TYPE_PRIORITY = 2,
  HTTP2_FRAME_TYPE_RST_STREAM = 3,
  HTTP2_FRAME_TYPE_SETTINGS = 4,
  HTTP2_FRAME_TYPE_PUSH_PROMISE = 5,
  HTTP2_FRAME_TYPE_PING = 6,
  HTTP2_FRAME_TYPE_GOAWAY = 7,
  HTTP2_FRAME_TYPE_WINDOW_UPDATE = 8,
  HTTP2_FRAME_TYPE_CONTINUATION = 9,

  HTTP2_FRAME_TYPE_MAX,
};

// 6.1 Data
enum Http2FrameFlagsData {
  HTTP2_FLAGS_DATA_END_STREAM = 0x01,
  HTTP2_FLAGS_DATA_PADDED = 0x08,

  HTTP2_FLAGS_DATA_MASK = 0x2B,
};

// 6.2 Headers
enum Http2FrameFlagsHeaders {
  HTTP2_FLAGS_HEADERS_END_STREAM = 0x01,
  HTTP2_FLAGS_HEADERS_END_HEADERS = 0x04,
  HTTP2_FLAGS_HEADERS_PADDED = 0x08,
  HTTP2_FLAGS_HEADERS_PRIORITY = 0x20,

  HTTP2_FLAGS_HEADERS_MASK = 0x2B,
};

// 6.3 Priority
enum Http2FrameFlagsPriority {
  HTTP2_FLAGS_PRIORITY_MASK = 0x00,
};

// 6.3 Rst Stream
enum Http2FrameFlagsRstStream {
  HTTP2_FLAGS_RST_STREAM_MASK = 0x00,
};

// 6.4 Settings
enum Http2FrameFlagsSettings {
  HTTP2_FLAGS_SETTINGS_ACK = 0x01,

  HTTP2_FLAGS_SETTINGS_MASK = 0x01
};

// 6.6 Push Promise
enum Http2FrameFlagsPushPromise {
  HTTP2_FLAGS_PUSH_PROMISE_END_HEADERS = 0x04,
  HTTP2_FLAGS_PUSH_PROMISE_PAD_LOW = 0x08,
  HTTP2_FLAGS_PUSH_PROMISE_PAD_HIGH = 0x10,

  HTTP2_FLAGS_PUSH_PROMISE_MASK = 0x1C,
};

// 6.7 Ping
enum Http2FrameFlagsPing {
  HTTP2_FLAGS_PING_ACK = 0x01,

  HTTP2_FLAGS_PING_MASK = 0x01
};

// 6.8 Goaway
enum Http2FrameFlagsGoaway {
  HTTP2_FLAGS_GOAWAY_MASK = 0x00,
};

// 6.9 Window Update
enum Http2FrameFlagsWindowUpdate {
  HTTP2_FLAGS_WINDOW_UPDATE_MASK = 0x00,
};

// 6.10 Continuation
enum Http2FrameFlagsContinuation {
  HTTP2_FLAGS_CONTINUATION_END_HEADERS = 0x04,
  HTTP2_FLAGS_CONTINUATION_PAD_LOW = 0x08,
  HTTP2_FLAGS_CONTINUATION_PAD_HIGH = 0x10,

  HTTP2_FLAGS_CONTINUATION_MASK = 0x1C,
};

// 6.5.2 Defined SETTINGS Parameters
enum Http2SettingsIdentifier {
  HTTP2_SETTINGS_HEADER_TABLE_SIZE = 1,
  HTTP2_SETTINGS_ENABLE_PUSH = 2,
  HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS = 3,
  HTTP2_SETTINGS_INITIAL_WINDOW_SIZE = 4,
  HTTP2_SETTINGS_MAX_FRAME_SIZE = 5,
  HTTP2_SETTINGS_MAX_HEADER_LIST_SIZE = 6,

  HTTP2_SETTINGS_MAX
};

// 4.1. Frame Format
struct Http2FrameHeader {
  uint32_t length;
  uint8_t type;
  uint8_t flags;
  Http2StreamId streamid;
};

// 6.5.1. SETTINGS Format
struct Http2SettingsParameter {
  uint16_t id;
  uint32_t value;
};

// 6.3 PRIORITY
struct Http2Priority {
  uint32_t stream_dependency;
  uint8_t weight;
};

// 6.2 HEADERS Format
struct Http2HeadersParameter {
  uint8_t pad_length;
  Http2Priority priority;
};

// 6.8 GOAWAY Format
struct Http2Goaway {
  Http2Goaway() : last_streamid(0), error_code(0) {}

  Http2StreamId last_streamid;
  uint32_t error_code;

  // NOTE: we don't (de)serialize the variable length debug data at this layer because there's
  // really nothing we can do with it without some out of band agreement. Trying to deal with it
  // just complicates memory management.
};

// 6.4 RST_STREAM Format
struct Http2RstStream {
  uint32_t error_code;
};

static inline bool
http2_is_client_streamid(Http2StreamId streamid)
{
  return (streamid & 0x1u) == 0x1u;
}

static inline bool
http2_is_server_streamid(Http2StreamId streamid)
{
  return (streamid & 0x1u) == 0x0u && streamid != 0x0u;
}

bool http2_parse_frame_header(IOVec, Http2FrameHeader &);

bool http2_write_frame_header(const Http2FrameHeader &, IOVec);

bool http2_write_data(const uint8_t *, size_t, const IOVec &);

bool http2_write_headers(const uint8_t *, size_t, const IOVec &);

bool http2_write_rst_stream(uint32_t, IOVec);

bool http2_write_settings(const Http2SettingsParameter &, IOVec);

bool http2_write_ping(const uint8_t *, IOVec);

bool http2_write_goaway(const Http2Goaway &, IOVec);

bool http2_write_window_update(const uint32_t new_size, const IOVec &);

bool http2_frame_header_is_valid(const Http2FrameHeader &, unsigned);

bool http2_settings_parameter_is_valid(const Http2SettingsParameter &);

bool http2_parse_headers_parameter(IOVec, Http2HeadersParameter &);

bool http2_parse_priority_parameter(IOVec, Http2Priority &);

bool http2_parse_rst_stream(IOVec, Http2RstStream &);

bool http2_parse_settings_parameter(IOVec, Http2SettingsParameter &);

bool http2_parse_goaway(IOVec, Http2Goaway &);

bool http2_parse_window_update(IOVec, uint32_t &);

int64_t http2_parse_header_fragment(HTTPHdr *, IOVec, Http2DynamicTable &, bool);

MIMEParseResult convert_from_2_to_1_1_header(HTTPHdr *);

int64_t http2_write_psuedo_headers(HTTPHdr *, uint8_t *, uint64_t, Http2DynamicTable &);

int64_t http2_write_header_fragment(HTTPHdr *, MIMEFieldIter &, uint8_t *, uint64_t, Http2DynamicTable &, bool &);


// Not sure where else to put this, but figure this is as good of a start as anything else.
// Right now, only the static init() is available, which sets up some basic librecords
// dependencies.
class Http2
{
public:
  static uint32_t max_concurrent_streams;
  static uint32_t initial_window_size;
  static uint32_t max_frame_size;
  static uint32_t header_table_size;
  static uint32_t max_header_list_size;

  static void init();
};

#endif /* __HTTP2_H__ */