import from minilb repo

app/rproxy/proxy.go

@@ -0,0 +1,192 @@
+package rproxy
+
+import (
+	"context"
+	"errors"
+	"io"
+	"log"
+	"math/rand"
+	"net"
+	"strconv"
+	"sync"
+)
+
+type Proxy struct {
+	Forwarders []*Forwarder       `json:"forwarders"  yaml:"forwarders"`
+	ctx        context.Context    `json:"-"           yaml:"-"`
+	cancel     context.CancelFunc `json:"-"           yaml:"-"`
+	wg         sync.WaitGroup     `json:"-"           yaml:"-"`
+}
+
+func NewProxy() *Proxy {
+	ctx, cancel := context.WithCancel(context.Background())
+	return &Proxy{
+		Forwarders: make([]*Forwarder, 0),
+		ctx:        ctx,
+		cancel:     cancel,
+	}
+}
+
+func (bal *Proxy) AddForwarder(ctx context.Context, lport, dport uint32, addrs ...string) error {
+	var err error
+	forw, err := NewForwarder(ctx, lport, dport, addrs...)
+	if err != nil {
+		return err
+	}
+	bal.Forwarders = append(bal.Forwarders, forw)
+	bal.wg.Add(1)
+	go forw.Listen(&bal.wg)
+	return err
+}
+
+func (bal *Proxy) DeleteForwarder(ctx context.Context, lport uint32) error {
+	var err error
+	forwarders := make([]*Forwarder, 0)
+	for _, forw := range bal.Forwarders {
+		if forw.Lport == lport {
+			forw.Stop()
+			continue
+		}
+		forwarders = append(forwarders, forw)
+	}
+	bal.Forwarders = forwarders
+	return err
+}
+
+func (bal *Proxy) Start() error {
+	var err error
+	for _, forw := range bal.Forwarders {
+		bal.wg.Add(1)
+		go forw.Listen(&bal.wg)
+	}
+	bal.wg.Wait()
+	return err
+}
+
+func (bal *Proxy) Stop() error {
+	var err error
+	for _, forw := range bal.Forwarders {
+		forw.Stop()
+	}
+	return err
+}
+
+type Forwarder struct {
+	listen net.Listener       `json:"-"      yaml:"-"`
+	ctx    context.Context    `json:"-"      yaml:"-"`
+	cancel context.CancelFunc `json:"-"      yaml:"-"`
+	Lport  uint32             `json:"lport"  yaml:"lport"`
+	Dport  uint32             `json:"dport"  yaml:"dport"`
+	Dests  []*Destination     `json:"dests"  yaml:"dests"`
+}
+
+func NewForwarder(ctx context.Context, lport, dport uint32, addrs ...string) (*Forwarder, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	forw := &Forwarder{
+		Dests:  make([]*Destination, 0),
+		Lport:  lport,
+		Dport:  dport,
+		ctx:    ctx,
+		cancel: cancel,
+	}
+	for _, addr := range addrs {
+		dest := NewDestination(addr)
+		forw.Dests = append(forw.Dests, dest)
+	}
+	port := ":" + strconv.FormatUint(uint64(forw.Lport), 10)
+	listen, err := net.Listen("tcp", port)
+	if err != nil {
+		return forw, err
+	}
+	forw.listen = listen
+	return forw, err
+}
+
+func (forw *Forwarder) Listen(wg *sync.WaitGroup) {
+	log.Printf("Start listening on %d\n", forw.Lport)
+	defer wg.Done()
+	for {
+		conn, err := forw.listen.Accept()
+		if err != nil {
+			log.Printf("Listen err: %v\n", err)
+			return
+		}
+		go forw.handle(forw.ctx, conn)
+	}
+}
+
+func (forw *Forwarder) Stop() error {
+	return forw.listen.Close()
+}
+
+func (forw *Forwarder) handle(ctx context.Context, inconn net.Conn) {
+	log.Printf("Handler on %d started\n", forw.Lport)
+	defer inconn.Close()
+	if len(forw.Dests) == 0 {
+		return
+	}
+	addrnum := rand.Uint32() % uint32(len(forw.Dests))
+	ipaddr := forw.Dests[addrnum].Address
+	dstaddr := ipaddr + ":" + strconv.FormatUint(uint64(forw.Dport), 10)
+	outconn, err := net.Dial("tcp", dstaddr)
+	if err != nil {
+		return
+	}
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go forw.stream(&wg, inconn, outconn)
+	wg.Add(1)
+	go forw.stream(&wg, outconn, inconn)
+	wg.Wait()
+	log.Printf("Handler on %d stopped\n", forw.Lport)
+}
+
+func (forw *Forwarder) stream(wg *sync.WaitGroup, inconn io.Reader, outconn io.Writer) {
+	defer wg.Done()
+	_, err := copy(forw.ctx, outconn, inconn)
+	if err != nil {
+		log.Printf("Copy err: %v\n", err)
+	}
+}
+
+type Destination struct {
+	Address string `json:"address"  yaml:"address"`
+}
+
+func NewDestination(addr string) *Destination {
+	return &Destination{
+		Address: addr,
+	}
+}
+
+func copy(ctx context.Context, writer io.Writer, reader io.Reader) (int64, error) {
+	var err error
+	var size int64
+	var halt bool
+	buffer := make([]byte, 1024*4)
+	for {
+		select {
+		case <-ctx.Done():
+			err = errors.New("Break copy by context")
+			break
+		default:
+		}
+		rsize, err := reader.Read(buffer)
+		if err == io.EOF {
+			err = nil
+			halt = true
+		}
+		if err != nil {
+			return size, err
+		}
+		wsize, err := writer.Write(buffer[0:rsize])
+		size += int64(wsize)
+		if err != nil {
+			return size, err
+		}
+		if halt {
+			break
+		}
+	}
+	return size, err
+}