forked from rus-cert/socks-router
/
multiplexer.go
109 lines (99 loc) · 2.56 KB
/
multiplexer.go
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package main
import (
"fmt"
"io"
"net"
"time"
"github.com/Jcd1230/socks-router/connpeeker"
"github.com/Jcd1230/socks-router/log"
"github.com/Jcd1230/socks-router/routing"
)
// Dialer is imported from routing/
type Dialer routing.Dialer
// ConnHandler describe anything capable of handling connections
type ConnHandler interface {
ServeConn(conn net.Conn) error
}
// ProtocolHandler detects certain protocols and returns a handler if detected
type ProtocolHandler interface {
Detect(peek []byte) (ConnHandler, error)
}
// ProtocolMultiplexer uses a list of ProtocolHandlers to handle many
// protocols on the same TCP socket
type ProtocolMultiplexer struct {
MaxPeek int
Handlers []ProtocolHandler
}
// Close closes all ProtocolHandlers which implement io.Closer
func (pm ProtocolMultiplexer) Close() error {
// return first error or nil
var err error
for _, h := range pm.Handlers {
if c, ok := h.(io.Closer); ok {
if herr := c.Close(); nil != herr && nil == err {
err = herr
}
}
}
return err
}
// ListenTCP accepts and handles TCP connections
func (pm ProtocolMultiplexer) ListenTCP(l *net.TCPListener) error {
var tempDelay time.Duration
for {
if conn, err := l.AcceptTCP(); err != nil {
if ne, ok := err.(net.Error); ok && ne.Temporary() {
if tempDelay == 0 {
tempDelay = 5 * time.Millisecond
} else {
tempDelay *= 2
}
if max := 1 * time.Second; tempDelay > max {
tempDelay = max
}
log.Error.Printf("Accept error: %v; retrying in %v", err, tempDelay)
time.Sleep(tempDelay)
continue
}
return err
} else {
tempDelay = 0
go func() {
pm.LogError(conn, pm.ServeTCP(conn))
}()
}
}
}
// LogError logs errors in connection context
func (pm ProtocolMultiplexer) LogError(conn net.Conn, err error) {
if nil != err {
log.Error.Printf("Error in %v -> %v: %v", conn.RemoteAddr(), conn.LocalAddr(), err)
}
}
// ServeTCP handle a single TCP connection
func (pm ProtocolMultiplexer) ServeTCP(conn *net.TCPConn) error {
pConn := &connpeeker.PeekTCPConn{Conn: conn}
maxPeek := pm.MaxPeek
if 0 == maxPeek {
maxPeek = 1024
}
for {
if err := pConn.Peek(maxPeek); nil != err {
conn.Close()
return err
}
for _, h := range pm.Handlers {
if connHandler, err := h.Detect(pConn.ReadBuffer); nil != err {
conn.Close()
return err
} else if nil != connHandler {
return connHandler.ServeConn(pConn)
}
// otherwise continue search for handler
}
if maxPeek == len(pConn.ReadBuffer) {
conn.Close()
return fmt.Errorf("Couldn't find handler within %v bytes", maxPeek)
}
}
}