initial commit

server.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/hex"
+	"flag"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"sync"
+)
+
+func genKey() string {
+	b := make([]byte, 8)
+	rand.Read(b)
+	return hex.EncodeToString(b)
+}
+
+type srv struct {
+	sync.Mutex
+	conns map[string]*conn
+}
+
+func (s *srv) Conn(key string) *conn {
+	s.Lock()
+	defer s.Unlock()
+	return s.conns[key]
+}
+
+type conn struct {
+	R *buf
+	W *buf
+	C net.Conn
+}
+
+func newConn(c net.Conn) *conn {
+	return &conn{newBuf(), newBuf(), c}
+}
+
+type buf struct {
+	sync.Mutex
+	b *bytes.Buffer
+}
+
+func newBuf() *buf {
+	return &buf{b: bytes.NewBuffer(nil)}
+}
+
+func (b *buf) Read(buf []byte) (int, error) {
+	b.Lock()
+	defer b.Unlock()
+	return b.b.Read(buf)
+}
+
+func (b *buf) Write(buf []byte) (int, error) {
+	b.Lock()
+	defer b.Unlock()
+	return b.b.Write(buf)
+}
+
+func (s *srv) NewConn(key, addr string) error {
+	c, err := net.Dial("tcp", addr)
+	if err != nil {
+		return err
+	}
+	conn := newConn(c)
+	go func() {
+		for {
+			if conn.R == nil {
+				return
+			}
+			_, err := io.Copy(conn.R, c)
+			if err == io.EOF {
+				return
+			}
+		}
+	}()
+	go func() {
+		for {
+			if conn.W == nil {
+				return
+			}
+			io.Copy(c, conn.W)
+		}
+	}()
+	s.Lock()
+	defer s.Unlock()
+	s.conns[key] = conn
+	return nil
+}
+
+func (s *srv) Remove(key string) {
+	s.Lock()
+	defer s.Unlock()
+	conn := s.conns[key]
+	if conn != nil {
+		conn.R = nil
+		conn.W = nil
+		conn.C.Close()
+	}
+	delete(s.conns, key)
+}
+
+func (s *srv) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	p := r.URL.Path
+	switch p {
+	case "/new":
+		addr, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		key := genKey()
+		err = s.NewConn(key, string(addr))
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.Write([]byte(key))
+	case "/close":
+		s.Remove(r.Header.Get("Key"))
+	default:
+		conn := s.Conn(r.Header.Get("Key"))
+		_, err := io.Copy(conn.W, r.Body)
+		log.Println("client", err)
+		r.Body.Close()
+		w.Header().Set("Content-Type", "application/octet-stream")
+		_, err = io.Copy(w, conn.R)
+		log.Println("remote", err)
+	}
+}
+
+func main() {
+	var listen string
+	flag.StringVar(&listen, "listen", ":8080", "server listen address")
+	flag.Parse()
+	if err := http.ListenAndServe(listen, &srv{conns: make(map[string]*conn)}); err != nil {
+		panic(err)
+	}
+}