support server plugin feature

models/plugin/client/plugin.go

@@ -0,0 +1,92 @@
+// Copyright 2017 fatedier, fatedier@gmail.com
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package plugin
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"sync"
+
+	"github.com/fatedier/golib/errors"
+)
+
+// Creators is used for create plugins to handle connections.
+var creators = make(map[string]CreatorFn)
+
+// params has prefix "plugin_"
+type CreatorFn func(params map[string]string) (Plugin, error)
+
+func Register(name string, fn CreatorFn) {
+	creators[name] = fn
+}
+
+func Create(name string, params map[string]string) (p Plugin, err error) {
+	if fn, ok := creators[name]; ok {
+		p, err = fn(params)
+	} else {
+		err = fmt.Errorf("plugin [%s] is not registered", name)
+	}
+	return
+}
+
+type Plugin interface {
+	Name() string
+
+	// extraBufToLocal will send to local connection first, then join conn with local connection
+	Handle(conn io.ReadWriteCloser, realConn net.Conn, extraBufToLocal []byte)
+	Close() error
+}
+
+type Listener struct {
+	conns  chan net.Conn
+	closed bool
+	mu     sync.Mutex
+}
+
+func NewProxyListener() *Listener {
+	return &Listener{
+		conns: make(chan net.Conn, 64),
+	}
+}
+
+func (l *Listener) Accept() (net.Conn, error) {
+	conn, ok := <-l.conns
+	if !ok {
+		return nil, fmt.Errorf("listener closed")
+	}
+	return conn, nil
+}
+
+func (l *Listener) PutConn(conn net.Conn) error {
+	err := errors.PanicToError(func() {
+		l.conns <- conn
+	})
+	return err
+}
+
+func (l *Listener) Close() error {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if !l.closed {
+		close(l.conns)
+		l.closed = true
+	}
+	return nil
+}
+
+func (l *Listener) Addr() net.Addr {
+	return (*net.TCPAddr)(nil)
+}