// Copyright (c) 2012 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.

// This file contains some protocol structures for use with SPDY 2 and 3
// The SPDY 2 spec can be found at:
// http://dev.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2
// The SPDY 3 spec can be found at:
// http://dev.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3

#ifndef NET_SPDY_SPDY_PROTOCOL_H_
#define NET_SPDY_SPDY_PROTOCOL_H_

#include <limits>
#include <map>
#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/strings/string_piece.h"
#include "base/sys_byteorder.h"
#include "net/base/net_export.h"
#include "net/spdy/spdy_bitmasks.h"

namespace net {

// The major versions of SPDY. Major version differences indicate
// framer-layer incompatibility, as opposed to minor version numbers
// which indicate application-layer incompatibility. Do not rely on
// the mapping from enum value SPDYn to the integer n.
enum SpdyMajorVersion {
  SPDY2 = 2,
  SPDY_MIN_VERSION = SPDY2,
  SPDY3 = 3,
  SPDY4 = 4,
  HTTP2 = SPDY4,
  SPDY_MAX_VERSION = SPDY4
};

// A SPDY stream id is a 31 bit entity.
typedef uint32 SpdyStreamId;

// Specifies the stream ID used to denote the current session (for
// flow control).
const SpdyStreamId kSessionFlowControlStreamId = 0;

// The maxmium possible control frame size allowed by the spec.
const int32 kSpdyMaxControlFrameSize = (1 << 24) - 1;

// The maximum control frame size we accept.
const int32 kControlFrameSizeLimit = 1 << 14;

// Maximum window size for a Spdy stream or session.
const int32 kSpdyMaximumWindowSize = 0x7FFFFFFF;  // Max signed 32bit int

// Maximum padding size in octets for one DATA or HEADERS or PUSH_PROMISE frame.
const int32 kPaddingSizePerFrame = 256;

// SPDY 2 dictionary.
// This is just a hacked dictionary to use for shrinking HTTP-like headers.
const char kV2Dictionary[] =
  "optionsgetheadpostputdeletetraceacceptaccept-charsetaccept-encodingaccept-"
  "languageauthorizationexpectfromhostif-modified-sinceif-matchif-none-matchi"
  "f-rangeif-unmodifiedsincemax-forwardsproxy-authorizationrangerefererteuser"
  "-agent10010120020120220320420520630030130230330430530630740040140240340440"
  "5406407408409410411412413414415416417500501502503504505accept-rangesageeta"
  "glocationproxy-authenticatepublicretry-afterservervarywarningwww-authentic"
  "ateallowcontent-basecontent-encodingcache-controlconnectiondatetrailertran"
  "sfer-encodingupgradeviawarningcontent-languagecontent-lengthcontent-locati"
  "oncontent-md5content-rangecontent-typeetagexpireslast-modifiedset-cookieMo"
  "ndayTuesdayWednesdayThursdayFridaySaturdaySundayJanFebMarAprMayJunJulAugSe"
  "pOctNovDecchunkedtext/htmlimage/pngimage/jpgimage/gifapplication/xmlapplic"
  "ation/xhtmltext/plainpublicmax-agecharset=iso-8859-1utf-8gzipdeflateHTTP/1"
  ".1statusversionurl";
const int kV2DictionarySize = arraysize(kV2Dictionary);

// SPDY 3 dictionary.
const char kV3Dictionary[] = {
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  0x2c, 0x74, 0x65, 0x78, 0x74, 0x2f, 0x70, 0x6c,  // .text.pl
  0x61, 0x69, 0x6e, 0x2c, 0x74, 0x65, 0x78, 0x74,  // ain.text
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  0x69, 0x70, 0x74, 0x2c, 0x70, 0x75, 0x62, 0x6c,  // ipt.publ
  0x69, 0x63, 0x70, 0x72, 0x69, 0x76, 0x61, 0x74,  // icprivat
  0x65, 0x6d, 0x61, 0x78, 0x2d, 0x61, 0x67, 0x65,  // emax-age
  0x3d, 0x67, 0x7a, 0x69, 0x70, 0x2c, 0x64, 0x65,  // .gzip.de
  0x66, 0x6c, 0x61, 0x74, 0x65, 0x2c, 0x73, 0x64,  // flate.sd
  0x63, 0x68, 0x63, 0x68, 0x61, 0x72, 0x73, 0x65,  // chcharse
  0x74, 0x3d, 0x75, 0x74, 0x66, 0x2d, 0x38, 0x63,  // t.utf-8c
  0x68, 0x61, 0x72, 0x73, 0x65, 0x74, 0x3d, 0x69,  // harset.i
  0x73, 0x6f, 0x2d, 0x38, 0x38, 0x35, 0x39, 0x2d,  // so-8859-
  0x31, 0x2c, 0x75, 0x74, 0x66, 0x2d, 0x2c, 0x2a,  // 1.utf-..
  0x2c, 0x65, 0x6e, 0x71, 0x3d, 0x30, 0x2e         // .enq.0.
};
const int kV3DictionarySize = arraysize(kV3Dictionary);

// The HTTP/2 connection header prefix, which must be the first bytes
// sent by the client upon starting an HTTP/2 connection, and which
// must be followed by a SETTINGS frame.
//
// Equivalent to the string "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
// (without the null terminator).
const char kHttp2ConnectionHeaderPrefix[] = {
  0x50, 0x52, 0x49, 0x20, 0x2a, 0x20, 0x48, 0x54,  // PRI * HT
  0x54, 0x50, 0x2f, 0x32, 0x2e, 0x30, 0x0d, 0x0a,  // TP/2.0..
  0x0d, 0x0a, 0x53, 0x4d, 0x0d, 0x0a, 0x0d, 0x0a   // ..SM....
};
const int kHttp2ConnectionHeaderPrefixSize =
    arraysize(kHttp2ConnectionHeaderPrefix);

const char kHttp2VersionString[] = "HTTP/1.1";

// Types of SPDY frames.
enum SpdyFrameType {
  DATA,
  SYN_STREAM,
  SYN_REPLY,
  RST_STREAM,
  SETTINGS,
  PING,
  GOAWAY,
  HEADERS,
  WINDOW_UPDATE,
  CREDENTIAL = 10,  // No longer valid.  Kept for identifiability.
  PUSH_PROMISE,
  CONTINUATION,
  PRIORITY,
  // BLOCKED and ALTSVC are recognized extensions.
  BLOCKED,
  ALTSVC,
};

// Flags on data packets.
enum SpdyDataFlags {
  DATA_FLAG_NONE = 0x00,
  DATA_FLAG_FIN = 0x01,
  DATA_FLAG_END_SEGMENT = 0x02,
  DATA_FLAG_PADDED = 0x08,
  DATA_FLAG_COMPRESSED = 0x20,
};

// Flags on control packets
enum SpdyControlFlags {
  CONTROL_FLAG_NONE = 0x00,
  CONTROL_FLAG_FIN = 0x01,
  CONTROL_FLAG_UNIDIRECTIONAL = 0x02,
};

enum SpdyPingFlags {
  PING_FLAG_ACK = 0x01,
};

// Used by HEADERS, PUSH_PROMISE, and CONTINUATION.
enum SpdyHeadersFlags {
  HEADERS_FLAG_END_SEGMENT = 0x02,
  HEADERS_FLAG_END_HEADERS = 0x04,
  HEADERS_FLAG_PADDED = 0x08,
  HEADERS_FLAG_PRIORITY = 0x20,
};

enum SpdyPushPromiseFlags {
  PUSH_PROMISE_FLAG_END_PUSH_PROMISE = 0x04,
  PUSH_PROMISE_FLAG_PADDED = 0x08,
};

// Flags on the SETTINGS control frame.
enum SpdySettingsControlFlags {
  SETTINGS_FLAG_CLEAR_PREVIOUSLY_PERSISTED_SETTINGS = 0x01,
};

enum Http2SettingsControlFlags {
  SETTINGS_FLAG_ACK = 0x01,
};

// Flags for settings within a SETTINGS frame.
enum SpdySettingsFlags {
  SETTINGS_FLAG_NONE = 0x00,
  SETTINGS_FLAG_PLEASE_PERSIST = 0x01,
  SETTINGS_FLAG_PERSISTED = 0x02,
};

// List of known settings. Avoid changing these enum values, as persisted
// settings are keyed on them, and they are also exposed in net-internals.
enum SpdySettingsIds {
  SETTINGS_UPLOAD_BANDWIDTH = 0x1,
  SETTINGS_DOWNLOAD_BANDWIDTH = 0x2,
  // Network round trip time in milliseconds.
  SETTINGS_ROUND_TRIP_TIME = 0x3,
  // The maximum number of simultaneous live streams in each direction.
  SETTINGS_MAX_CONCURRENT_STREAMS = 0x4,
  // TCP congestion window in packets.
  SETTINGS_CURRENT_CWND = 0x5,
  // Downstream byte retransmission rate in percentage.
  SETTINGS_DOWNLOAD_RETRANS_RATE = 0x6,
  // Initial window size in bytes
  SETTINGS_INITIAL_WINDOW_SIZE = 0x7,
  // HPACK header table maximum size.
  SETTINGS_HEADER_TABLE_SIZE = 0x8,
  // Whether or not server push (PUSH_PROMISE) is enabled.
  SETTINGS_ENABLE_PUSH = 0x9,
  // The size of the largest frame payload that a receiver is willing to accept.
  SETTINGS_MAX_FRAME_SIZE = 0xa,
  // The maximum size of header list that the sender is prepared to accept.
  SETTINGS_MAX_HEADER_LIST_SIZE = 0xb,
};

// Status codes for RST_STREAM frames.
enum SpdyRstStreamStatus {
  RST_STREAM_INVALID = 0,
  RST_STREAM_PROTOCOL_ERROR = 1,
  RST_STREAM_INVALID_STREAM = 2,
  RST_STREAM_STREAM_CLOSED = 2,  // Equivalent to INVALID_STREAM
  RST_STREAM_REFUSED_STREAM = 3,
  RST_STREAM_UNSUPPORTED_VERSION = 4,
  RST_STREAM_CANCEL = 5,
  RST_STREAM_INTERNAL_ERROR = 6,
  RST_STREAM_FLOW_CONTROL_ERROR = 7,
  RST_STREAM_STREAM_IN_USE = 8,
  RST_STREAM_STREAM_ALREADY_CLOSED = 9,
  RST_STREAM_INVALID_CREDENTIALS = 10,
  // FRAME_TOO_LARGE (defined by SPDY versions 3.1 and below), and
  // FRAME_SIZE_ERROR (defined by HTTP/2) are mapped to the same internal
  // reset status.
  RST_STREAM_FRAME_TOO_LARGE = 11,
  RST_STREAM_FRAME_SIZE_ERROR = 11,
  RST_STREAM_SETTINGS_TIMEOUT = 12,
  RST_STREAM_CONNECT_ERROR = 13,
  RST_STREAM_ENHANCE_YOUR_CALM = 14,
  RST_STREAM_INADEQUATE_SECURITY = 15,
  RST_STREAM_HTTP_1_1_REQUIRED = 16,
  RST_STREAM_NUM_STATUS_CODES = 17
};

// Status codes for GOAWAY frames.
enum SpdyGoAwayStatus {
  GOAWAY_OK = 0,
  GOAWAY_NO_ERROR = GOAWAY_OK,
  GOAWAY_PROTOCOL_ERROR = 1,
  GOAWAY_INTERNAL_ERROR = 2,
  GOAWAY_FLOW_CONTROL_ERROR = 3,
  GOAWAY_SETTINGS_TIMEOUT = 4,
  GOAWAY_STREAM_CLOSED = 5,
  GOAWAY_FRAME_SIZE_ERROR = 6,
  GOAWAY_REFUSED_STREAM = 7,
  GOAWAY_CANCEL = 8,
  GOAWAY_COMPRESSION_ERROR = 9,
  GOAWAY_CONNECT_ERROR = 10,
  GOAWAY_ENHANCE_YOUR_CALM = 11,
  GOAWAY_INADEQUATE_SECURITY = 12,
  GOAWAY_HTTP_1_1_REQUIRED = 13
};

// A SPDY priority is a number between 0 and 7 (inclusive).
// SPDY priority range is version-dependent. For SPDY 2 and below, priority is a
// number between 0 and 3.
typedef uint8 SpdyPriority;

typedef std::map<std::string, std::string> SpdyNameValueBlock;

typedef uint64 SpdyPingId;

typedef std::string SpdyProtocolId;

enum class SpdyHeaderValidatorType { REQUEST, RESPONSE };

// TODO(hkhalil): Add direct testing for this? It won't increase coverage any,
// but is good to do anyway.
class NET_EXPORT_PRIVATE SpdyConstants {
 public:
  // Returns true if a given on-the-wire enumeration of a frame type is valid
  // for a given protocol version, false otherwise.
  static bool IsValidFrameType(SpdyMajorVersion version, int frame_type_field);

  // Parses a frame type from an on-the-wire enumeration of a given protocol
  // version.
  // Behavior is undefined for invalid frame type fields; consumers should first
  // use IsValidFrameType() to verify validity of frame type fields.
  static SpdyFrameType ParseFrameType(SpdyMajorVersion version,
                                      int frame_type_field);

  // Serializes a given frame type to the on-the-wire enumeration value for the
  // given protocol version.
  // Returns -1 on failure (I.E. Invalid frame type for the given version).
  static int SerializeFrameType(SpdyMajorVersion version,
                                SpdyFrameType frame_type);

  // Returns the frame type for non-control (i.e. data) frames
  // in the given SPDY version.
  static int DataFrameType(SpdyMajorVersion version);

  // Returns true if a given on-the-wire enumeration of a setting id is valid
  // for a given protocol version, false otherwise.
  static bool IsValidSettingId(SpdyMajorVersion version, int setting_id_field);

  // Parses a setting id from an on-the-wire enumeration of a given protocol
  // version.
  // Behavior is undefined for invalid setting id fields; consumers should first
  // use IsValidSettingId() to verify validity of setting id fields.
  static SpdySettingsIds ParseSettingId(SpdyMajorVersion version,
                                        int setting_id_field);

  // Serializes a given setting id to the on-the-wire enumeration value for the
  // given protocol version.
  // Returns -1 on failure (I.E. Invalid setting id for the given version).
  static int SerializeSettingId(SpdyMajorVersion version, SpdySettingsIds id);

  // Returns true if a given on-the-wire enumeration of a RST_STREAM status code
  // is valid for a given protocol version, false otherwise.
  static bool IsValidRstStreamStatus(SpdyMajorVersion version,
                                     int rst_stream_status_field);

  // Parses a RST_STREAM status code from an on-the-wire enumeration of a given
  // protocol version.
  // Behavior is undefined for invalid RST_STREAM status code fields; consumers
  // should first use IsValidRstStreamStatus() to verify validity of RST_STREAM
  // status code fields..
  static SpdyRstStreamStatus ParseRstStreamStatus(SpdyMajorVersion version,
                                                  int rst_stream_status_field);

  // Serializes a given RST_STREAM status code to the on-the-wire enumeration
  // value for the given protocol version.
  // Returns -1 on failure (I.E. Invalid RST_STREAM status code for the given
  // version).
  static int SerializeRstStreamStatus(SpdyMajorVersion version,
                                      SpdyRstStreamStatus rst_stream_status);

  // Returns true if a given on-the-wire enumeration of a GOAWAY status code is
  // valid for the given protocol version, false otherwise.
  static bool IsValidGoAwayStatus(SpdyMajorVersion version,
                                  int goaway_status_field);

  // Parses a GOAWAY status from an on-the-wire enumeration of a given protocol
  // version.
  // Behavior is undefined for invalid GOAWAY status fields; consumers should
  // first use IsValidGoAwayStatus() to verify validity of GOAWAY status fields.
  static SpdyGoAwayStatus ParseGoAwayStatus(SpdyMajorVersion version,
                                            int goaway_status_field);

  // Serializes a given GOAWAY status to the on-the-wire enumeration value for
  // the given protocol version.
  // Returns -1 on failure (I.E. Invalid GOAWAY status for the given version).
  static int SerializeGoAwayStatus(SpdyMajorVersion version,
                                   SpdyGoAwayStatus status);

  // Size, in bytes, of the data frame header. Future versions of SPDY
  // will likely vary this, so we allow for the flexibility of a function call
  // for this value as opposed to a constant.
  static size_t GetDataFrameMinimumSize(SpdyMajorVersion version);

  // Size, in bytes, of the control frame header.
  static size_t GetControlFrameHeaderSize(SpdyMajorVersion version);

  static size_t GetPrefixLength(SpdyFrameType type, SpdyMajorVersion version);

  static size_t GetFrameMaximumSize(SpdyMajorVersion version);

  // Returns the size of a header block size field. Valid only for SPDY
  // versions <= 3.
  static size_t GetSizeOfSizeField(SpdyMajorVersion version);

  // Returns the size (in bytes) of a wire setting ID and value.
  static size_t GetSettingSize(SpdyMajorVersion version);

  // Initial window size for a stream in bytes.
  static int32 GetInitialStreamWindowSize(SpdyMajorVersion version);

  // Initial window size for a session in bytes.
  static int32 GetInitialSessionWindowSize(SpdyMajorVersion version);

  static SpdyMajorVersion ParseMajorVersion(int version_number);

  static int SerializeMajorVersion(SpdyMajorVersion version);

  static std::string GetVersionString(SpdyMajorVersion version);
};

class SpdyFrame;
typedef SpdyFrame SpdySerializedFrame;

class SpdyFrameVisitor;

// Intermediate representation for SPDY frames.
// TODO(hkhalil): Rename this class to SpdyFrame when the existing SpdyFrame is
// gone.
class NET_EXPORT_PRIVATE SpdyFrameIR {
 public:
  virtual ~SpdyFrameIR() {}

  virtual void Visit(SpdyFrameVisitor* visitor) const = 0;

 protected:
  SpdyFrameIR() {}

 private:
  DISALLOW_COPY_AND_ASSIGN(SpdyFrameIR);
};

// Abstract class intended to be inherited by IRs that have a stream associated
// to them.
class NET_EXPORT_PRIVATE SpdyFrameWithStreamIdIR : public SpdyFrameIR {
 public:
  ~SpdyFrameWithStreamIdIR() override {}
  SpdyStreamId stream_id() const { return stream_id_; }
  void set_stream_id(SpdyStreamId stream_id) {
    DCHECK_EQ(0u, stream_id & ~kStreamIdMask);
    stream_id_ = stream_id;
  }

 protected:
  explicit SpdyFrameWithStreamIdIR(SpdyStreamId stream_id) {
    set_stream_id(stream_id);
  }

 private:
  SpdyStreamId stream_id_;

  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithStreamIdIR);
};

// Abstract class intended to be inherited by IRs that have the option of a FIN
// flag. Implies SpdyFrameWithStreamIdIR.
class NET_EXPORT_PRIVATE SpdyFrameWithFinIR : public SpdyFrameWithStreamIdIR {
 public:
  ~SpdyFrameWithFinIR() override {}
  bool fin() const { return fin_; }
  void set_fin(bool fin) { fin_ = fin; }

 protected:
  explicit SpdyFrameWithFinIR(SpdyStreamId stream_id)
      : SpdyFrameWithStreamIdIR(stream_id),
        fin_(false) {}

 private:
  bool fin_;

  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithFinIR);
};

// Abstract class intended to be inherited by IRs that contain a name-value
// block. Implies SpdyFrameWithFinIR.
class NET_EXPORT_PRIVATE SpdyFrameWithNameValueBlockIR
    : public NON_EXPORTED_BASE(SpdyFrameWithFinIR) {
 public:
  const SpdyNameValueBlock& name_value_block() const {
    return name_value_block_;
  }
  void set_name_value_block(const SpdyNameValueBlock& name_value_block) {
    // Deep copy.
    name_value_block_ = name_value_block;
  }
  void SetHeader(base::StringPiece name, base::StringPiece value) {
    name_value_block_[name.as_string()] = value.as_string();
  }
  SpdyNameValueBlock* mutable_name_value_block() {
    return &name_value_block_;
  }

 protected:
  explicit SpdyFrameWithNameValueBlockIR(SpdyStreamId stream_id);
  ~SpdyFrameWithNameValueBlockIR() override;

 private:
  SpdyNameValueBlock name_value_block_;

  DISALLOW_COPY_AND_ASSIGN(SpdyFrameWithNameValueBlockIR);
};

class NET_EXPORT_PRIVATE SpdyDataIR
    : public NON_EXPORTED_BASE(SpdyFrameWithFinIR) {
 public:
  // Performs deep copy on data.
  SpdyDataIR(SpdyStreamId stream_id, base::StringPiece data);

  // Use in conjunction with SetDataShallow() for shallow-copy on data.
  explicit SpdyDataIR(SpdyStreamId stream_id);

  ~SpdyDataIR() override;

  base::StringPiece data() const { return data_; }

  bool padded() const { return padded_; }

  int padding_payload_len() const { return padding_payload_len_; }

  void set_padding_len(int padding_len) {
    DCHECK_GT(padding_len, 0);
    DCHECK_LE(padding_len, kPaddingSizePerFrame);
    padded_ = true;
    // The pad field takes one octet on the wire.
    padding_payload_len_ = padding_len - 1;
  }

  // Deep-copy of data (keep private copy).
  void SetDataDeep(base::StringPiece data) {
    data_store_.reset(new std::string(data.data(), data.length()));
    data_ = *(data_store_.get());
  }

  // Shallow-copy of data (do not keep private copy).
  void SetDataShallow(base::StringPiece data) {
    data_store_.reset();
    data_ = data;
  }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  // Used to store data that this SpdyDataIR should own.
  scoped_ptr<std::string> data_store_;
  base::StringPiece data_;

  bool padded_;
  // padding_payload_len_ = desired padding length - len(padding length field).
  int padding_payload_len_;

  DISALLOW_COPY_AND_ASSIGN(SpdyDataIR);
};

class NET_EXPORT_PRIVATE SpdySynStreamIR
    : public SpdyFrameWithNameValueBlockIR {
 public:
  explicit SpdySynStreamIR(SpdyStreamId stream_id)
      : SpdyFrameWithNameValueBlockIR(stream_id),
        associated_to_stream_id_(0),
        priority_(0),
        unidirectional_(false) {}
  SpdyStreamId associated_to_stream_id() const {
    return associated_to_stream_id_;
  }
  void set_associated_to_stream_id(SpdyStreamId stream_id) {
    associated_to_stream_id_ = stream_id;
  }
  SpdyPriority priority() const { return priority_; }
  void set_priority(SpdyPriority priority) { priority_ = priority; }
  bool unidirectional() const { return unidirectional_; }
  void set_unidirectional(bool unidirectional) {
    unidirectional_ = unidirectional;
  }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  SpdyStreamId associated_to_stream_id_;
  SpdyPriority priority_;
  bool unidirectional_;

  DISALLOW_COPY_AND_ASSIGN(SpdySynStreamIR);
};

class NET_EXPORT_PRIVATE SpdySynReplyIR : public SpdyFrameWithNameValueBlockIR {
 public:
  explicit SpdySynReplyIR(SpdyStreamId stream_id)
      : SpdyFrameWithNameValueBlockIR(stream_id) {}

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  DISALLOW_COPY_AND_ASSIGN(SpdySynReplyIR);
};

class NET_EXPORT_PRIVATE SpdyRstStreamIR : public SpdyFrameWithStreamIdIR {
 public:
  SpdyRstStreamIR(SpdyStreamId stream_id, SpdyRstStreamStatus status,
                  base::StringPiece description);

  ~SpdyRstStreamIR() override;

  SpdyRstStreamStatus status() const {
    return status_;
  }
  void set_status(SpdyRstStreamStatus status) {
    status_ = status;
  }

  base::StringPiece description() const { return description_; }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  SpdyRstStreamStatus status_;
  base::StringPiece description_;

  DISALLOW_COPY_AND_ASSIGN(SpdyRstStreamIR);
};

class NET_EXPORT_PRIVATE SpdySettingsIR : public SpdyFrameIR {
 public:
  // Associates flags with a value.
  struct Value {
    Value() : persist_value(false),
              persisted(false),
              value(0) {}
    bool persist_value;
    bool persisted;
    int32 value;
  };
  typedef std::map<SpdySettingsIds, Value> ValueMap;

  SpdySettingsIR();

  ~SpdySettingsIR() override;

  // Overwrites as appropriate.
  const ValueMap& values() const { return values_; }
  void AddSetting(SpdySettingsIds id,
                  bool persist_value,
                  bool persisted,
                  int32 value) {
    values_[id].persist_value = persist_value;
    values_[id].persisted = persisted;
    values_[id].value = value;
  }

  bool clear_settings() const { return clear_settings_; }
  bool is_ack() const { return is_ack_; }
  void set_is_ack(bool is_ack) {
    is_ack_ = is_ack;
  }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  ValueMap values_;
  bool clear_settings_;
  bool is_ack_;

  DISALLOW_COPY_AND_ASSIGN(SpdySettingsIR);
};

class NET_EXPORT_PRIVATE SpdyPingIR : public SpdyFrameIR {
 public:
  explicit SpdyPingIR(SpdyPingId id) : id_(id), is_ack_(false) {}
  SpdyPingId id() const { return id_; }

  // ACK logic is valid only for SPDY versions 4 and above.
  bool is_ack() const { return is_ack_; }
  void set_is_ack(bool is_ack) { is_ack_ = is_ack; }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  SpdyPingId id_;
  bool is_ack_;

  DISALLOW_COPY_AND_ASSIGN(SpdyPingIR);
};

class NET_EXPORT_PRIVATE SpdyGoAwayIR : public SpdyFrameIR {
 public:
  SpdyGoAwayIR(SpdyStreamId last_good_stream_id,
               SpdyGoAwayStatus status,
               base::StringPiece description);
  ~SpdyGoAwayIR() override;
  SpdyStreamId last_good_stream_id() const { return last_good_stream_id_; }
  void set_last_good_stream_id(SpdyStreamId last_good_stream_id) {
    DCHECK_LE(0u, last_good_stream_id);
    DCHECK_EQ(0u, last_good_stream_id & ~kStreamIdMask);
    last_good_stream_id_ = last_good_stream_id;
  }
  SpdyGoAwayStatus status() const { return status_; }
  void set_status(SpdyGoAwayStatus status) {
    // TODO(hkhalil): Check valid ranges of status?
    status_ = status;
  }

  const base::StringPiece& description() const;

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  SpdyStreamId last_good_stream_id_;
  SpdyGoAwayStatus status_;
  const base::StringPiece description_;

  DISALLOW_COPY_AND_ASSIGN(SpdyGoAwayIR);
};

class NET_EXPORT_PRIVATE SpdyHeadersIR : public SpdyFrameWithNameValueBlockIR {
 public:
  explicit SpdyHeadersIR(SpdyStreamId stream_id)
      : SpdyFrameWithNameValueBlockIR(stream_id),
        has_priority_(false),
        priority_(0),
        padded_(false),
        padding_payload_len_(0) {}

  void Visit(SpdyFrameVisitor* visitor) const override;

  bool has_priority() const { return has_priority_; }
  void set_has_priority(bool has_priority) { has_priority_ = has_priority; }
  uint32 priority() const { return priority_; }
  void set_priority(SpdyPriority priority) { priority_ = priority; }

  bool padded() const { return padded_; }
  int padding_payload_len() const { return padding_payload_len_; }
  void set_padding_len(int padding_len) {
    DCHECK_GT(padding_len, 0);
    DCHECK_LE(padding_len, kPaddingSizePerFrame);
    padded_ = true;
    // The pad field takes one octet on the wire.
    padding_payload_len_ = padding_len - 1;
  }

 private:
  bool has_priority_;
  // 31-bit priority.
  uint32 priority_;

  bool padded_;
  int padding_payload_len_;

  DISALLOW_COPY_AND_ASSIGN(SpdyHeadersIR);
};

class NET_EXPORT_PRIVATE SpdyWindowUpdateIR : public SpdyFrameWithStreamIdIR {
 public:
  SpdyWindowUpdateIR(SpdyStreamId stream_id, int32 delta)
      : SpdyFrameWithStreamIdIR(stream_id) {
    set_delta(delta);
  }
  int32 delta() const { return delta_; }
  void set_delta(int32 delta) {
    DCHECK_LT(0, delta);
    DCHECK_LE(delta, kSpdyMaximumWindowSize);
    delta_ = delta;
  }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  int32 delta_;

  DISALLOW_COPY_AND_ASSIGN(SpdyWindowUpdateIR);
};

class NET_EXPORT_PRIVATE SpdyBlockedIR
    : public NON_EXPORTED_BASE(SpdyFrameWithStreamIdIR) {
 public:
  explicit SpdyBlockedIR(SpdyStreamId stream_id)
      : SpdyFrameWithStreamIdIR(stream_id) {}

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  DISALLOW_COPY_AND_ASSIGN(SpdyBlockedIR);
};

class NET_EXPORT_PRIVATE SpdyPushPromiseIR
    : public SpdyFrameWithNameValueBlockIR {
 public:
  SpdyPushPromiseIR(SpdyStreamId stream_id, SpdyStreamId promised_stream_id)
      : SpdyFrameWithNameValueBlockIR(stream_id),
        promised_stream_id_(promised_stream_id),
        padded_(false),
        padding_payload_len_(0) {}
  SpdyStreamId promised_stream_id() const { return promised_stream_id_; }

  void Visit(SpdyFrameVisitor* visitor) const override;

  bool padded() const { return padded_; }
  int padding_payload_len() const { return padding_payload_len_; }
  void set_padding_len(int padding_len) {
    DCHECK_GT(padding_len, 0);
    DCHECK_LE(padding_len, kPaddingSizePerFrame);
    padded_ = true;
    // The pad field takes one octet on the wire.
    padding_payload_len_ = padding_len - 1;
  }

 private:
  SpdyStreamId promised_stream_id_;

  bool padded_;
  int padding_payload_len_;

  DISALLOW_COPY_AND_ASSIGN(SpdyPushPromiseIR);
};

// TODO(jgraettinger): This representation needs review. SpdyContinuationIR
// needs to frame a portion of a single, arbitrarily-broken encoded buffer.
class NET_EXPORT_PRIVATE SpdyContinuationIR
    : public SpdyFrameWithNameValueBlockIR {
 public:
  explicit SpdyContinuationIR(SpdyStreamId stream_id)
      : SpdyFrameWithNameValueBlockIR(stream_id),
        end_headers_(false) {}

  void Visit(SpdyFrameVisitor* visitor) const override;

  bool end_headers() const { return end_headers_; }
  void set_end_headers(bool end_headers) {end_headers_ = end_headers;}

 private:
  bool end_headers_;
  DISALLOW_COPY_AND_ASSIGN(SpdyContinuationIR);
};

// TODO(bnc): Add probability.
// TODO(bnc): Separate (protocol, port, host, max_age, probability) tuple into
// struct, have a vector of that struct.  A single HTTP/1.1 header field or
// HTTP/2 or QUIC frame can define multiple such tuples.
class NET_EXPORT_PRIVATE SpdyAltSvcIR : public SpdyFrameWithStreamIdIR {
 public:
  explicit SpdyAltSvcIR(SpdyStreamId stream_id);

  uint32 max_age() const { return max_age_; }
  uint16 port() const { return port_; }
  SpdyProtocolId protocol_id() const {
    return protocol_id_;
  }
  std::string host() const { return host_; }
  std::string origin() const { return origin_; }

  void set_max_age(uint32 max_age) { max_age_ = max_age; }
  void set_port(uint16 port) { port_ = port; }
  void set_protocol_id(SpdyProtocolId protocol_id) {
    protocol_id_ = protocol_id;
  }
  void set_host(std::string host) { host_ = host; }
  void set_origin(std::string origin) { origin_ = origin; }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  uint32 max_age_;
  uint16 port_;
  SpdyProtocolId protocol_id_;
  std::string host_;
  std::string origin_;
  DISALLOW_COPY_AND_ASSIGN(SpdyAltSvcIR);
};

class NET_EXPORT_PRIVATE SpdyPriorityIR : public SpdyFrameWithStreamIdIR {
 public:
  explicit SpdyPriorityIR(SpdyStreamId stream_id)
      : SpdyFrameWithStreamIdIR(stream_id),
        parent_stream_id_(0),
        weight_(1),
        exclusive_(false) {}
  SpdyPriorityIR(SpdyStreamId stream_id,
                 SpdyStreamId parent_stream_id,
                 uint8 weight,
                 bool exclusive)
      : SpdyFrameWithStreamIdIR(stream_id),
        parent_stream_id_(parent_stream_id),
        weight_(weight),
        exclusive_(exclusive) {}
  SpdyStreamId parent_stream_id() const { return parent_stream_id_; }
  void set_parent_stream_id(SpdyStreamId id) { parent_stream_id_ = id; }
  uint8 weight() const { return weight_; }
  void set_weight(uint8 weight) { weight_ = weight; }
  bool exclusive() const { return exclusive_; }
  void set_exclusive(bool exclusive) { exclusive_ = exclusive; }

  void Visit(SpdyFrameVisitor* visitor) const override;

 private:
  SpdyStreamId parent_stream_id_;
  uint8 weight_;
  bool exclusive_;
  DISALLOW_COPY_AND_ASSIGN(SpdyPriorityIR);
};

// -------------------------------------------------------------------------
// Wrapper classes for various SPDY frames.

// All Spdy Frame types derive from this SpdyFrame class.
class SpdyFrame {
 public:
  // Create a SpdyFrame using a pre-created buffer.
  // If |owns_buffer| is true, this class takes ownership of the buffer
  // and will delete it on cleanup.  The buffer must have been created using
  // new char[].
  // If |owns_buffer| is false, the caller retains ownership of the buffer and
  // is responsible for making sure the buffer outlives this frame.  In other
  // words, this class does NOT create a copy of the buffer.
  SpdyFrame(char* data, size_t size, bool owns_buffer)
      : frame_(data),
        size_(size),
        owns_buffer_(owns_buffer) {
    DCHECK(frame_);
  }

  ~SpdyFrame() {
    if (owns_buffer_) {
      delete [] frame_;
    }
    frame_ = NULL;
  }

  // Provides access to the frame bytes, which is a buffer containing
  // the frame packed as expected for sending over the wire.
  char* data() const { return frame_; }

  // Returns the actual size of the underlying buffer.
  size_t size() const { return size_; }

 protected:
  char* frame_;

 private:
  size_t size_;
  bool owns_buffer_;
  DISALLOW_COPY_AND_ASSIGN(SpdyFrame);
};

// This interface is for classes that want to process SpdyFrameIRs without
// having to know what type they are.  An instance of this interface can be
// passed to a SpdyFrameIR's Visit method, and the appropriate type-specific
// method of this class will be called.
class SpdyFrameVisitor {
 public:
  virtual void VisitSynStream(const SpdySynStreamIR& syn_stream) = 0;
  virtual void VisitSynReply(const SpdySynReplyIR& syn_reply) = 0;
  virtual void VisitRstStream(const SpdyRstStreamIR& rst_stream) = 0;
  virtual void VisitSettings(const SpdySettingsIR& settings) = 0;
  virtual void VisitPing(const SpdyPingIR& ping) = 0;
  virtual void VisitGoAway(const SpdyGoAwayIR& goaway) = 0;
  virtual void VisitHeaders(const SpdyHeadersIR& headers) = 0;
  virtual void VisitWindowUpdate(const SpdyWindowUpdateIR& window_update) = 0;
  virtual void VisitBlocked(const SpdyBlockedIR& blocked) = 0;
  virtual void VisitPushPromise(const SpdyPushPromiseIR& push_promise) = 0;
  virtual void VisitContinuation(const SpdyContinuationIR& continuation) = 0;
  virtual void VisitAltSvc(const SpdyAltSvcIR& altsvc) = 0;
  virtual void VisitPriority(const SpdyPriorityIR& priority) = 0;
  virtual void VisitData(const SpdyDataIR& data) = 0;

 protected:
  SpdyFrameVisitor() {}
  virtual ~SpdyFrameVisitor() {}

 private:
  DISALLOW_COPY_AND_ASSIGN(SpdyFrameVisitor);
};

}  // namespace net

#endif  // NET_SPDY_SPDY_PROTOCOL_H_