ws

type Dialer struct {
	// ReadBufferSize and WriteBufferSize is an I/O buffer sizes.
	// They used to read and write http data while upgrading to WebSocket.
	// Allocated buffers are pooled with sync.Pool to avoid extra allocations.
	//
	// If a size is zero then default value is used.
	ReadBufferSize, WriteBufferSize int

	// Timeout is the maximum amount of time a Dial() will wait for a connect
	// and an handshake to complete.
	//
	// The default is no timeout.
	Timeout time.Duration

	// Protocols is the list of subprotocols that the client wants to speak,
	// ordered by preference.
	//
	// See https://tools.ietf.org/html/rfc6455#section-4.1
	Protocols []string

	// Extensions is the list of extensions that client wants to speak.
	//
	// Note that if server decides to use some of this extensions, Dial() will
	// return Handshake struct containing a slice of items, which are the
	// shallow copies of the items from this list. That is, internals of
	// Extensions items are shared during Dial().
	//
	// See https://tools.ietf.org/html/rfc6455#section-4.1
	// See https://tools.ietf.org/html/rfc6455#section-9.1
	Extensions []httphead.Option

	// Header is the callback that will be called with io.Writer.
	// Write() calls to the given writer will put data in a request http
	// headers section.
	//
	// It used instead of http.Header mapping to avoid allocations in user land.
	Header func(io.Writer)

	// OnStatusError is the callback that will be called after receiving non
	// "101 Continue" HTTP response status. It receives an io.Reader object
	// representing server response bytes. That is, it gives ability to parse
	// HTTP response somehow (probably with http.ReadResponse call) and make a
	// decision of further logic.
	//
	// The arguments are only valid until the callback returns.
	OnStatusError func(status int, reason []byte, resp io.Reader)

	// OnHeader is the callback that will be called after successful parsing of
	// header, that is not used during WebSocket handshake procedure. That is,
	// it will be called with non-websocket headers, which could be relevant
	// for application-level logic.
	//
	// The arguments are only valid until the callback returns.
	//
	// Returned value could be used to prevent processing response.
	OnHeader func(key, value []byte) (err error)

	// NetDial is the function that is used to get plain tcp connection.
	// If it is not nil, then it is used instead of net.Dialer.
	NetDial func(ctx context.Context, network, addr string) (net.Conn, error)

	// TLSClient is the callback that will be called after succesful dial with
	// received connection and its remote host name. If it is nil, then the
	// default tls.Client() will be used.
	// If it is not nil, then TLSConfig field is ignored.
	TLSClient func(conn net.Conn, hostname string) net.Conn

	// TLSConfig is passed to tls.Client() to start TLS over established
	// connection. If TLSClient is not nil, then it is ignored. If TLSConfig is
	// non-nil and its ServerName is empty, then for every Dial() it will be
	// cloned and appropriate ServerName will be set.
	TLSConfig *tls.Config

	// WrapConn is the optional callback that will be called when connection is
	// ready for an i/o. That is, it will be called after successful dial and
	// TLS initialization (for "wss" schemes). It may be helpful for different
	// user land purposes such as end to end encryption.
	//
	// Note that for debugging purposes of an http handshake (e.g. sent request
	// and received response), there is an wsutil.DebugDialer struct.
	WrapConn func(conn net.Conn) net.Conn
}

type Frame struct {
	Header  Header
	Payload []byte
}

type HTTPUpgrader struct {
	// Timeout is the maximum amount of time an Upgrade() will spent while
	// writing handshake response.
	//
	// The default is no timeout.
	Timeout time.Duration

	// Protocol is the select function that is used to select subprotocol from
	// list requested by client. If this field is set, then the first matched
	// protocol is sent to a client as negotiated.
	Protocol func(string) bool

	// Extension is the select function that is used to select extensions from
	// list requested by client. If this field is set, then the all matched
	// extensions are sent to a client as negotiated.
	Extension func(httphead.Option) bool
}

type Handshake struct {
	// Protocol is the subprotocol selected during handshake.
	Protocol string

	// Extensions is the list of negotiated extensions.
	Extensions []httphead.Option
}

type Header struct {
	Fin    bool
	Rsv    byte
	OpCode OpCode
	Length int64
	Masked bool
	Mask   [4]byte
}

type OpCode byte

type ProtocolError string

type State uint8

type StatusCode uint16

type StatusCodeRange struct {
	Min, Max StatusCode
}

type StatusError int

type Upgrader struct {
	// ReadBufferSize and WriteBufferSize is an I/O buffer sizes.
	// They used to read and write http data while upgrading to WebSocket.
	// Allocated buffers are pooled with sync.Pool to avoid extra allocations.
	//
	// If a size is zero then default value is used.
	//
	// Usually it is useful to set read buffer size bigger than write buffer
	// size because incoming request could contain long header values, such as
	// Cookie. Response, in other way, could be big only if user write multiple
	// custom headers. Usually response takes less than 256 bytes.
	ReadBufferSize, WriteBufferSize int

	// Protocol is a select function that is used to select subprotocol
	// from list requested by client. If this field is set, then the first matched
	// protocol is sent to a client as negotiated.
	//
	// The argument is only valid until the callback returns.
	Protocol func([]byte) bool

	// ProtocolCustrom allow user to parse Sec-WebSocket-Protocol header manually.
	// Note that returned bytes must be valid until Upgrade returns.
	// If ProtocolCustom is set, it used instead of Protocol function.
	ProtocolCustom func([]byte) (string, bool)

	// Extension is a select function that is used to select extensions
	// from list requested by client. If this field is set, then the all matched
	// extensions are sent to a client as negotiated.
	//
	// The argument is only valid until the callback returns.
	//
	// According to the RFC6455 order of extensions passed by a client is
	// significant. That is, returning true from this function means that no
	// other extension with the same name should be checked because server
	// accepted the most preferable extension right now:
	// "Note that the order of extensions is significant.  Any interactions between
	// multiple extensions MAY be defined in the documents defining the extensions.
	// In the absence of such definitions, the interpretation is that the header
	// fields listed by the client in its request represent a preference of the
	// header fields it wishes to use, with the first options listed being most
	// preferable."
	Extension func(httphead.Option) bool

	// ExtensionCustorm allow user to parse Sec-WebSocket-Extensions header manually.
	// Note that returned options should be valid until Upgrade returns.
	// If ExtensionCustom is set, it used instead of Extension function.
	ExtensionCustom func([]byte, []httphead.Option) ([]httphead.Option, bool)

	// Header is a callback that will be called with io.Writer.
	// Write() calls that writer will put data in the response http headers
	// section.
	//
	// It used instead of http.Header mapping to avoid allocations in user land.
	//
	// Not that if present, this callback will be called for any result of
	// upgrading.
	Header func(io.Writer)

	// OnRequest is a callback that will be called after request line and
	// "Host" header successful parsing. Setting this field helps to implement
	// some application logic.
	//
	// The arguments are only valid until the callback returns.
	//
	// Returned value could be used to prevent processing request and response
	// with appropriate http status.
	OnRequest func(host, uri []byte) (err error, code int)

	// OnHeader is a callback that will be called after successful parsing of
	// header, that is not used during WebSocket handshake procedure. That is,
	// it will be called with non-websocket headers, which could be relevant
	// for application-level logic.
	//
	// The arguments are only valid until the callback returns.
	//
	// Returned value could be used to prevent processing request and response
	// with appropriate http status.
	OnHeader func(key, value []byte) (err error, code int)

	// OnBeforeUpgrade is a callback that will be called before sending
	// successful upgrade response.
	//
	// Setting OnBeforeUpgrade allows user to make final application-level
	// checks and decide whether this connection is allowed to successfully
	// upgrade to WebSocket. That is, the session checks and other application
	// logic could be contained inside this callback.
	//
	// OnBeforeUpgrade could return header writer callback, that will be called
	// to provide some user land http headers in response.
	//
	// If by some reason connection should not be upgraded then OnBeforeUpgrade
	// should return error and appropriate http status code.
	//
	// Note that header writer callback will be called even if err is non-nil.
	OnBeforeUpgrade func() (header func(io.Writer), err error, code int)
}