snowflake_server

Documentation

Overview

Package snowflake_server implements the functionality necessary to accept Snowflake connections from Snowflake clients.

Included in the package is a Transport type that implements the Pluggable Transports v2.1 Go API specification. To start a TLS Snowflake server using the golang.org/x/crypto/acme/autocert library, configure a certificate manager for the server's domain name and then create a new Transport as follows:

// The snowflake server runs a websocket server. To run this securely, you will
// need a valid certificate.
certManager := &autocert.Manager{
	Prompt:     autocert.AcceptTOS,
	HostPolicy: autocert.HostWhitelist("snowflake.yourdomain.com"),
	Email:      "you@yourdomain.com",
}

transport := snowflake_server.NewSnowflakeServer(certManager.GetCertificate)

The Listen function starts a new listener, and Accept will return incoming Snowflake connections:

ln, err := transport.Listen(addr)
if err != nil {
	// handle error
}
for {
	conn, err := ln.Accept()
	if err != nil {
		// handle error
	}
	// handle conn
}

Index

• Constants
• type ClientMapAddr
  • func (addr ClientMapAddr) Network() string
  • func (addr ClientMapAddr) String() string
• type SnowflakeClientConn
  • func (conn *SnowflakeClientConn) Close() error
  • func (conn *SnowflakeClientConn) LocalAddr() net.Addr
  • func (conn *SnowflakeClientConn) Read(b []byte) (int, error)
  • func (conn *SnowflakeClientConn) RemoteAddr() net.Addr
  • func (conn *SnowflakeClientConn) SetDeadline(t time.Time) error
  • func (conn *SnowflakeClientConn) SetReadDeadline(t time.Time) error
  • func (conn *SnowflakeClientConn) SetWriteDeadline(t time.Time) error
  • func (conn *SnowflakeClientConn) Write(b []byte) (int, error)
  • func (conn *SnowflakeClientConn) WriteTo(w io.Writer) (int64, error)
• type SnowflakeListener
  • func (l *SnowflakeListener) Accept() (net.Conn, error)
  • func (l *SnowflakeListener) Addr() net.Addr
  • func (l *SnowflakeListener) Close() error
• type Transport
  • func NewSnowflakeServer(getCertificate func(*tls.ClientHelloInfo) (*tls.Certificate, error)) *Transport
  • func (t *Transport) Listen(addr net.Addr, numKCPInstances int) (*SnowflakeListener, error)

Constants

const (
	// WindowSize is the number of packets in the send and receive window of a KCP connection.
	WindowSize = 65535
	// StreamSize controls the maximum amount of in flight data between a client and server.
	StreamSize = 1048576 // 1MB
)

Types

type ClientMapAddr

type ClientMapAddr string

ClientMapAddr is a string that represents a connecting client.

func (ClientMapAddr) Network

func (addr ClientMapAddr) Network() string

func (ClientMapAddr) String

func (addr ClientMapAddr) String() string

type SnowflakeClientConn

type SnowflakeClientConn struct {
	// contains filtered or unexported fields
}

SnowflakeClientConn is a wrapper for the underlying turbotunnel conn (smux.Stream). It implements the net.Conn and io.WriterTo interfaces. The RemoteAddr method is overridden to refer to a real IP address, looked up from the client address map, rather than an abstract client ID.

func (*SnowflakeClientConn) Close

func (conn *SnowflakeClientConn) Close() error

func (*SnowflakeClientConn) LocalAddr

func (conn *SnowflakeClientConn) LocalAddr() net.Addr

func (*SnowflakeClientConn) Read

func (conn *SnowflakeClientConn) Read(b []byte) (int, error)

Forward net.Conn methods, other than RemoteAddr, to the inner stream.

func (*SnowflakeClientConn) RemoteAddr

func (conn *SnowflakeClientConn) RemoteAddr() net.Addr

RemoteAddr returns the mapped client address of the Snowflake connection.

func (*SnowflakeClientConn) SetDeadline

func (conn *SnowflakeClientConn) SetDeadline(t time.Time) error

func (*SnowflakeClientConn) SetReadDeadline

func (conn *SnowflakeClientConn) SetReadDeadline(t time.Time) error

func (*SnowflakeClientConn) SetWriteDeadline

func (conn *SnowflakeClientConn) SetWriteDeadline(t time.Time) error

func (*SnowflakeClientConn) Write

func (conn *SnowflakeClientConn) Write(b []byte) (int, error)

func (*SnowflakeClientConn) WriteTo

func (conn *SnowflakeClientConn) WriteTo(w io.Writer) (int64, error)

WriteTo implements the io.WriterTo interface by passing the call to the underlying smux.Stream.

type SnowflakeListener

type SnowflakeListener struct {
	// contains filtered or unexported fields
}

func (*SnowflakeListener) Accept

func (l *SnowflakeListener) Accept() (net.Conn, error)

Accept allows the caller to accept incoming Snowflake connections. We accept connections from a queue to accommodate both incoming smux Streams and legacy non-turbotunnel connections.

func (*SnowflakeListener) Addr

func (l *SnowflakeListener) Addr() net.Addr

Addr returns the address of the SnowflakeListener

func (*SnowflakeListener) Close

func (l *SnowflakeListener) Close() error

Close closes the Snowflake connection.

type Transport

type Transport struct {
	// contains filtered or unexported fields
}

Transport is a structure with methods that conform to the Go PT v2.1 API https://github.com/Pluggable-Transports/Pluggable-Transports-spec/blob/master/releases/PTSpecV2.1/Pluggable%20Transport%20Specification%20v2.1%20-%20Go%20Transport%20API.pdf

func NewSnowflakeServer

func NewSnowflakeServer(getCertificate func(*tls.ClientHelloInfo) (*tls.Certificate, error)) *Transport

NewSnowflakeServer returns a new server-side Transport for Snowflake.

func (*Transport) Listen

func (t *Transport) Listen(addr net.Addr, numKCPInstances int) (*SnowflakeListener, error)

Listen starts a listener on addr that will accept both turbotunnel and legacy Snowflake connections.