http2

const (
	// ErrCodeNoError is no error, a graceful shutdown or a discarded stream.
	ErrCodeNoError ErrCode = iota
	// ErrCodeProtocol is an unspecific protocol violation.
	ErrCodeProtocol
	// ErrCodeInternal is an unexpected internal failure of the endpoint.
	ErrCodeInternal
	// ErrCodeFlowControl is a flow-control violation.
	ErrCodeFlowControl
	// ErrCodeSettingsTimeout is a SETTINGS frame unanswered in time.
	ErrCodeSettingsTimeout
	// ErrCodeStreamClosed is a frame received on a closed stream.
	ErrCodeStreamClosed
	// ErrCodeFrameSize is a frame of the wrong size.
	ErrCodeFrameSize
	// ErrCodeRefusedStream is a stream refused before any processing.
	ErrCodeRefusedStream
	// ErrCodeCancel is a stream no longer wanted.
	ErrCodeCancel
	// ErrCodeCompression is a field block the connection's compression state
	// cannot survive.
	ErrCodeCompression
	// ErrCodeConnect is a CONNECT tunnel's failure.
	ErrCodeConnect
	// ErrCodeEnhanceYourCalm is a peer exhibiting excessive load.
	ErrCodeEnhanceYourCalm
	// ErrCodeInadequateSecurity is a transport below the minimum.
	ErrCodeInadequateSecurity
	// ErrCodeHTTP11Required asks the client to retry over HTTP/1.1.
	ErrCodeHTTP11Required
)

const (
	// ErrorTypeProtocol counts an error answered PROTOCOL_ERROR, an unspecific protocol violation.
	ErrorTypeProtocol ErrorType = iota + 1
	// ErrorTypeInternal counts an error answered INTERNAL_ERROR, the endpoint's own failure.
	ErrorTypeInternal
	// ErrorTypeFlowControl counts an error answered FLOW_CONTROL_ERROR, a window overrun or overflowed.
	ErrorTypeFlowControl
	// ErrorTypeSettingsTimeout counts an error answered SETTINGS_TIMEOUT, a SETTINGS frame unanswered in time.
	ErrorTypeSettingsTimeout
	// ErrorTypeStreamClosed counts an error answered STREAM_CLOSED, a frame on a closed stream.
	ErrorTypeStreamClosed
	// ErrorTypeFrameSize counts an error answered FRAME_SIZE_ERROR, a frame of the wrong length.
	ErrorTypeFrameSize
	// ErrorTypeRefusedStream counts an error answered REFUSED_STREAM, a stream past the open-stream bound.
	ErrorTypeRefusedStream
	// ErrorTypeCancel counts an error answered CANCEL, a stream the endpoint no longer wanted.
	ErrorTypeCancel
	// ErrorTypeCompression counts an error answered COMPRESSION_ERROR, a field block HPACK refused.
	ErrorTypeCompression
	// ErrorTypeConnect counts an error answered CONNECT_ERROR, a CONNECT request's failure.
	ErrorTypeConnect
	// ErrorTypeEnhanceYourCalm counts an error answered ENHANCE_YOUR_CALM, a flood the codec cut short.
	ErrorTypeEnhanceYourCalm
	// ErrorTypeInadequateSecurity counts an error answered INADEQUATE_SECURITY, a transport below the minimum.
	ErrorTypeInadequateSecurity
	// ErrorTypeHTTP11Required counts an error answered HTTP_1_1_REQUIRED, a request HTTP/1.1 must carry.
	ErrorTypeHTTP11Required
	// ErrorTypeHeaderList counts a header list past the group's bound: answered 431
	// or refused, it is no RFC 9113 error code.
	ErrorTypeHeaderList
	// ErrorTypePingTimeout counts a connection closed because a PING sent on its
	// silence went unanswered (ADR 0195 §D3).
	ErrorTypePingTimeout
	// ErrorTypeOther counts an error the engine named outside this vocabulary.
	ErrorTypeOther
)

const (
	// FlagAck acknowledges a SETTINGS or a PING frame.
	FlagAck FrameFlags = 0x1
	// FlagEndStream marks the last frame of a stream on DATA and HEADERS.
	FlagEndStream FrameFlags = 0x1
	// FlagEndHeaders marks the last frame of a field block.
	FlagEndHeaders FrameFlags = 0x4
	// FlagPadded marks a frame carrying a pad length and padding.
	FlagPadded FrameFlags = 0x8
	// FlagPriority marks a HEADERS frame carrying a priority field.
	FlagPriority FrameFlags = 0x20
)

const (
	// FrameData carries a stream's content, RFC 9113 §6.1.
	FrameData FrameType = iota
	// FrameHeaders opens a stream and carries its field block, §6.2.
	FrameHeaders
	// FramePriority is the deprecated priority signal, §6.3; ignored.
	FramePriority
	// FrameRSTStream ends a stream at once, §6.4.
	FrameRSTStream
	// FrameSettings carries or acknowledges a connection's settings, §6.5.
	FrameSettings
	// FramePushPromise reserves a server-initiated stream, §6.6.
	FramePushPromise
	// FramePing measures the round trip and checks liveness, §6.7.
	FramePing
	// FrameGoAway ends a connection gracefully or with an error, §6.8.
	FrameGoAway
	// FrameWindowUpdate grants flow-control credit, §6.9.
	FrameWindowUpdate
	// FrameContinuation extends a field block past one frame, §6.10.
	FrameContinuation
)

const (
	// SettingHeaderTableSize bounds the peer's HPACK dynamic table.
	SettingHeaderTableSize SettingID = 0x1
	// SettingEnablePush says whether the peer may push.
	SettingEnablePush SettingID = 0x2
	// SettingMaxConcurrentStreams bounds the peer's open streams.
	SettingMaxConcurrentStreams SettingID = 0x3
	// SettingInitialWindowSize is the peer's initial stream window.
	SettingInitialWindowSize SettingID = 0x4
	// SettingMaxFrameSize is the largest frame the peer accepts.
	SettingMaxFrameSize SettingID = 0x5
	// SettingMaxHeaderListSize bounds the header list the peer accepts.
	SettingMaxHeaderListSize SettingID = 0x6
	// SettingEnableConnectProtocol enables RFC 8441's extended CONNECT.
	SettingEnableConnectProtocol SettingID = 0x8
)