sharpshooter

README

Sharpshooter

Reliable UDP transport protocol for Go

中文文档

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Sharpshooter is a reliable transport protocol built on UDP, implemented in Go. It provides TCP-like connection-oriented semantics without TCP's protocol fingerprint, making it suitable for bypassing protocol-based traffic detection and serving as a transport layer for P2P applications.

Features:

• TCP-like 3-way handshake
• ACK-based retransmission
• Adaptive sliding window congestion control
• Optional FEC (Forward Error Correction) via Reed-Solomon
• RTT/RTO auto-calibration
• Health check & timeout detection
• Implements net.Conn interface
• Zero external dependencies besides Reed-Solomon

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Quick Start

go get github.com/soyum2222/sharpshooter

Server

l, _ := sharpshooter.Listen(":8858")
conn, _ := l.Accept()
// conn implements net.Conn — use Read/Write directly

Client

conn, _ := sharpshooter.Dial("127.0.0.1:8858")
// Enable FEC (optional)
conn.(*sharpshooter.Sniper).OpenFec(10, 3)
conn.Write([]byte("hello"))

More examples in the example/ directory.

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API

Method	Description
Dial(addr) (net.Conn, error)	Connect to a remote listener
Listen(addr) (*headquarters, error)	Start a UDP listener
Accept() (net.Conn, error)	Accept a new connection
OpenFec(data, par)	Enable FEC (e.g. OpenFec(10, 3) tolerates 30% loss)
SetPackageSize(size)	Set packet payload size
SetSendWin(size) / SetRecWin(size)	Set send/receive window
OpenStaTraffic()	Enable traffic statistics
TrafficStatistics()	Get traffic stats snapshot

All standard net.Conn methods (Read, Write, Close, SetDeadline, etc.) are supported.

For protocol specification and detailed documentation, see docs/.

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File Transfer Tool

# Server (receive)
go run example/sharp_transfer.go -l 8858 -o output.dat

# Client (send)
go run example/sharp_transfer.go -addr 127.0.0.1:8858 -i input.dat

# Resume transfer
go run example/sharp_transfer.go -addr 127.0.0.1:8858 -i input.dat -o output.dat -c

# Compare with TCP
go run example/sharp_transfer.go -addr 127.0.0.1:8858 -i input.dat -t

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Related

• sharpshooter-tunel — TCP ↔ Sharpshooter bridge

License

MIT

Documentation

Index

• Constants
• Variables
• func Dial(addr string) (net.Conn, error)
• func Listen(addr string) (*headquarters, error)
• func NewHeadquarters() *headquarters
• type Sniper
  • func NewSniper(conn *net.UDPConn, aim *net.UDPAddr) *Sniper
  • func (s *Sniper) CleanStatistics()
  • func (s *Sniper) Close() error
  • func (s *Sniper) Debug()
  • func (s *Sniper) LocalAddr() net.Addr
  • func (s *Sniper) OpenFec(dataShards, parShards int)
  • func (s *Sniper) OpenStaTraffic()
  • func (s *Sniper) Read(b []byte) (n int, err error)
  • func (s *Sniper) RemoteAddr() net.Addr
  • func (s *Sniper) SetDeadline(t time.Time) error
  • func (s *Sniper) SetInterval(interval int64)
  • func (s *Sniper) SetPackageSize(size int64)
  • func (s *Sniper) SetReadDeadline(t time.Time) error
  • func (s *Sniper) SetRecWin(size int64)
  • func (s *Sniper) SetSendWin(size int32)
  • func (s *Sniper) SetWriteDeadline(t time.Time) error
  • func (s *Sniper) TrafficStatistics() Statistics
  • func (s *Sniper) Write(b []byte) (n int, err error)
• type Statistics
• type TimedSched
  • func NewTimedSched(parallel int) *TimedSched
  • func (ts *TimedSched) Close()
  • func (ts *TimedSched) Put(f func(), deadline time.Time)

Constants

const (
	DEFAULT_HEAD_SIZE                          = 20
	DEFAULT_INIT_SENDWIND                      = 64
	DEFAULT_INIT_RECEWIND                      = 1 << 10
	DEFAULT_INIT_PACKSIZE                      = 800
	DEFAULT_INIT_HEALTHTICKER                  = 1
	DEFAULT_INIT_HEALTHCHECK_TIMEOUT_TRY_COUNT = 10
	DEFAULT_INIT_HANDSHACK_TIMEOUT             = 6
	DEFAULT_INIT_RTO_UNIT                      = float64(200 * time.Millisecond)
	DEFAULT_INIT_DELAY_ACK                     = float64(200 * time.Millisecond)
	DEFAULT_INIT_INTERVAL                      = 500
)

const (
	STATUS_NONE = iota
	STATUS_SECONDHANDSHACK
	STATUS_THIRDHANDSHACK
	STATUS_NORMAL
	STATUS_CLOSEING1
	STATUS_CLOSEING2
	STATUS_CLOSEING3
)

Variables

var (
	CLOSEERROR         = errors.New("the connection is closed")
	HEALTHTIMEOUTERROR = errors.New("health monitor timeout ")
	TIMEOUERROR        = timeout(0)
	RCVAMMOBAGEMPTY    = make([]*protocol.Ammo, DEFAULT_INIT_RECEWIND)
)

Functions

func Dial

func Dial(addr string) (net.Conn, error)

func Listen

func Listen(addr string) (*headquarters, error)

func NewHeadquarters

func NewHeadquarters() *headquarters

Types

type Sniper

type Sniper struct {
	Statistics
	// contains filtered or unexported fields
}

func NewSniper

func NewSniper(conn *net.UDPConn, aim *net.UDPAddr) *Sniper

func (*Sniper) CleanStatistics

func (s *Sniper) CleanStatistics()

func (*Sniper) Close

func (s *Sniper) Close() error

func (*Sniper) Debug

func (s *Sniper) Debug()

func (*Sniper) LocalAddr

func (s *Sniper) LocalAddr() net.Addr

func (*Sniper) OpenFec

func (s *Sniper) OpenFec(dataShards, parShards int)

OpenFec use FEC algorithm in communication this will waste some traffic , but when the packet is lost there is a certain probability that the lost packet can be recovered

func (*Sniper) OpenStaTraffic

func (s *Sniper) OpenStaTraffic()

func (*Sniper) Read

func (s *Sniper) Read(b []byte) (n int, err error)

func (*Sniper) RemoteAddr

func (s *Sniper) RemoteAddr() net.Addr

func (*Sniper) SetDeadline

func (s *Sniper) SetDeadline(t time.Time) error

func (*Sniper) SetInterval

func (s *Sniper) SetInterval(interval int64)

func (*Sniper) SetPackageSize

func (s *Sniper) SetPackageSize(size int64)

func (*Sniper) SetReadDeadline

func (s *Sniper) SetReadDeadline(t time.Time) error

func (*Sniper) SetRecWin

func (s *Sniper) SetRecWin(size int64)

func (*Sniper) SetSendWin

func (s *Sniper) SetSendWin(size int32)

func (*Sniper) SetWriteDeadline

func (s *Sniper) SetWriteDeadline(t time.Time) error

func (*Sniper) TrafficStatistics

func (s *Sniper) TrafficStatistics() Statistics

func (*Sniper) Write

func (s *Sniper) Write(b []byte) (n int, err error)

type Statistics

type Statistics struct {
	TotalTraffic     int64
	EffectiveTraffic int64
	TotalPacket      int64
	EffectivePacket  int64
	RTT              int64
	RTO              int64
	SendWin          int64
	ReceiveWin       int64
}

type TimedSched

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

TimedSched represents the control struct for timed parallel scheduler

var SystemTimedSched *TimedSched = NewTimedSched(runtime.NumCPU())

SystemTimedSched is the library level timed-scheduler

func NewTimedSched

func NewTimedSched(parallel int) *TimedSched

NewTimedSched creates a parallel-scheduler with given parallelization

func (*TimedSched) Close

func (ts *TimedSched) Close()

Close terminates this scheduler

func (*TimedSched) Put

func (ts *TimedSched) Put(f func(), deadline time.Time)

Put a function 'f' awaiting to be executed at 'deadline'