conn: add CopyN function

README.md

@@ -306,6 +306,10 @@ Examples:
 
   ./glider -verbose -dns=:53 -dnsserver=8.8.8.8:53 -dnsrecord=www.example.com/1.2.3.4
     -listen on :53 as dns server, forward dns requests to 8.8.8.8:53, return 1.2.3.4 when resolving www.example.com.
+
+Services:
+  dhcpd: service=dhcpd,INTERFACE,START_IP,END_IP
+    e.g.,service=dhcpd,en0,192.168.254.100,192.168.254.199
 ```
 
 </details>
@@ -367,7 +371,8 @@ glider -config CONFIGPATH -listen :8080 -verbose
 
 ## Service
 
-Scheme: 
+#### Scheme: 
+
 service=SERVICE_NAME[,SERVICE_CONFIG]
 
 - dhcpd(from v0.11.0): 

common/conn/conn.go

@@ -107,6 +107,19 @@ func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
 	return CopyBuffer(dst, src)
 }
 
+// CopyN copies n bytes (or until an error) from src to dst.
+func CopyN(dst io.Writer, src io.Reader, n int64) (written int64, err error) {
+	written, err = Copy(dst, io.LimitReader(src, n))
+	if written == n {
+		return n, nil
+	}
+	if written < n && err == nil {
+		// src stopped early; must have been EOF.
+		err = io.EOF
+	}
+	return
+}
+
 // CopyBuffer copies from src to dst with a userspace buffer.
 func CopyBuffer(dst io.Writer, src io.Reader) (written int64, err error) {
 	size := TCPBufSize

config.go

@@ -313,4 +313,9 @@ func usage() {
 	fmt.Fprintf(w, "  "+app+" -verbose -dns=:53 -dnsserver=8.8.8.8:53 -dnsrecord=www.example.com/1.2.3.4\n")
 	fmt.Fprintf(w, "    -listen on :53 as dns server, forward dns requests to 8.8.8.8:53, return 1.2.3.4 when resolving www.example.com.\n")
 	fmt.Fprintf(w, "\n")
+
+	fmt.Fprintf(w, "Services:\n")
+	fmt.Fprintf(w, "  dhcpd: service=dhcpd,INTERFACE,START_IP,END_IP\n")
+	fmt.Fprintf(w, "    e.g.,service=dhcpd,en0,192.168.254.100,192.168.254.199\n")
+	fmt.Fprintf(w, "\n")
 }

proxy/vless/client.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"strings"
 
+	"github.com/nadoo/glider/common/conn"
 	"github.com/nadoo/glider/common/pool"
 )
 
@@ -38,7 +39,7 @@ func NewConn(c net.Conn, uuid [16]byte, target string) (*Conn, error) {
 
 	buf.WriteByte(Version) // ver
 	buf.Write(uuid[:])     // uuid
-	buf.WriteByte(0)       // addinfo
+	buf.WriteByte(0)       // addLen
 	buf.WriteByte(CmdTCP)  // cmd
 
 	// target
@@ -67,8 +68,8 @@ func (c *Conn) Read(b []byte) (n int, err error) {
 			return n, errors.New("version not supported")
 		}
 
-		if addLen := int64(buf[1]); addLen != 0 {
-			io.CopyN(ioutil.Discard, c.Conn, addLen)
+		if addLen := int64(buf[1]); addLen > 0 {
+			conn.CopyN(ioutil.Discard, c.Conn, addLen)
 		}
 		c.rcved = true
 	}