chore: code tidy and doc update

README.md

@@ -96,7 +96,7 @@ glider -verbose -listen :8443 -forward SCHEME://HOST:PORT
 #### Help
 
 <details>
-<summary> glider -help</summary>
+<summary><code>glider -help</code></summary>
 
 ```bash
 Usage: glider [-listen URL]... [-forward URL]... [OPTION]...
@@ -220,7 +220,7 @@ Help:
 
 see README.md and glider.conf.example for more details.
 --
-glider 0.16.0, https://github.com/nadoo/glider
+glider 0.16.0, https://github.com/nadoo/glider (glider.proxy@gmail.com)
 ```
 
 </details>
@@ -228,7 +228,7 @@ glider 0.16.0, https://github.com/nadoo/glider
 #### Schemes
 
 <details>
-<summary> glider -scheme all</summary>
+<summary><code>glider -scheme all</code></summary>
 
 ```bash
 KCP scheme:
@@ -343,7 +343,7 @@ TLS and Websocket with a specified proxy protocol:
 #### Examples
 
 <details>
-<summary> glider -example</summary>
+<summary><code>glider -example</code></summary>
 
 ```bash
 Examples:
@@ -392,13 +392,13 @@ Examples:
 
 ## Service
 
-- dhcpd: 
+- dhcpd / dhcpd-failover: 
   - service=dhcpd,INTERFACE,START_IP,END_IP,LEASE_MINUTES[,MAC=IP,MAC=IP...]
-      - service=dhcpd,eth1,192.168.1.100,192.168.1.199,720
-      - service=dhcpd,eth2,192.168.2.100,192.168.2.199,720,fc:23:34:9e:25:01=192.168.2.101
   - service=dhcpd-failover,INTERFACE,START_IP,END_IP,LEASE_MINUTES[,MAC=IP,MAC=IP...]
-      - note: only serve requests when there's no other dhcp server exists in lan
+    - service=dhcpd,eth1,192.168.1.100,192.168.1.199,720
-      - detect interval: 1min
+    - service=dhcpd-failover,eth2,192.168.2.100,192.168.2.199,720,fc:23:34:9e:25:01=192.168.2.101
+  - note: `dhcpd-failover` only serves requests when there's no other dhcp server exists in lan
+    - detect interval: 1min
 
 ## Linux Service
 

config.go

@@ -215,7 +215,7 @@ Help:
 
 see README.md and glider.conf.example for more details.
 --
-glider %s, https://github.com/nadoo/glider
+glider %s, https://github.com/nadoo/glider (glider.proxy@gmail.com)
 `
 
 var examples = `

dns/message.go

@@ -94,8 +94,7 @@ func (m *Message) AddAnswer(rr *RR) error {
 // Marshal marshals message struct to []byte.
 func (m *Message) Marshal() ([]byte, error) {
 	buf := &bytes.Buffer{}
-	_, err := m.MarshalTo(buf)
+	if _, err := m.MarshalTo(buf); err != nil {
-	if err != nil {
 		return nil, err
 	}
 	return buf.Bytes(), nil
@@ -137,8 +136,7 @@ func UnmarshalMessage(b []byte) (*Message, error) {
 	}
 
 	m := &Message{unMarshaled: b}
-	err := UnmarshalHeader(b[:HeaderLen], &m.Header)
+	if err := UnmarshalHeader(b[:HeaderLen], &m.Header); err != nil {
-	if err != nil {
 		return nil, err
 	}
 
@@ -285,14 +283,12 @@ func (q *Question) MarshalTo(w io.Writer) (n int, err error) {
 		return
 	}
 
-	err = binary.Write(w, binary.BigEndian, q.QTYPE)
+	if err = binary.Write(w, binary.BigEndian, q.QTYPE); err != nil {
-	if err != nil {
 		return
 	}
 	n += 2
 
-	err = binary.Write(w, binary.BigEndian, q.QCLASS)
+	if err = binary.Write(w, binary.BigEndian, q.QCLASS); err != nil {
-	if err != nil {
 		return
 	}
 	n += 2
@@ -375,20 +371,17 @@ func (rr *RR) MarshalTo(w io.Writer) (n int, err error) {
 		return
 	}
 
-	err = binary.Write(w, binary.BigEndian, rr.TYPE)
+	if err = binary.Write(w, binary.BigEndian, rr.TYPE); err != nil {
-	if err != nil {
 		return
 	}
 	n += 2
 
-	err = binary.Write(w, binary.BigEndian, rr.CLASS)
+	if err = binary.Write(w, binary.BigEndian, rr.CLASS); err != nil {
-	if err != nil {
 		return
 	}
 	n += 2
 
-	err = binary.Write(w, binary.BigEndian, rr.TTL)
+	if err = binary.Write(w, binary.BigEndian, rr.TTL); err != nil {
-	if err != nil {
 		return
 	}
 	n += 4
@@ -399,8 +392,7 @@ func (rr *RR) MarshalTo(w io.Writer) (n int, err error) {
 	}
 	n += 2
 
-	_, err = w.Write(rr.RDATA)
+	if _, err = w.Write(rr.RDATA); err != nil {
-	if err != nil {
 		return
 	}
 	n += len(rr.RDATA)
@@ -493,8 +485,7 @@ func (m *Message) UnmarshalDomainTo(sb *strings.Builder, b []byte) (int, error)
 			}
 
 			offset := binary.BigEndian.Uint16(b[idx : idx+2])
-			err := m.UnmarshalDomainPointTo(sb, int(offset&0x3FFF))
+			if err := m.UnmarshalDomainPointTo(sb, int(offset&0x3FFF)); err != nil {
-			if err != nil {
 				return 0, err
 			}
 

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/nadoo/ipset v0.4.1-0.20220218075046-ca3cdce74266
 	github.com/xtaci/kcp-go/v5 v5.6.1
 	golang.org/x/crypto v0.0.0-20220214200702-86341886e292
-	golang.org/x/sys v0.0.0-20220224120231-95c6836cb0e7
+	golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9
 )
 
 require (

go.sum

@@ -49,6 +49,7 @@ github.com/jsimonetti/rtnetlink v0.0.0-20201009170750-9c6f07d100c1/go.mod h1:hqo
 github.com/jsimonetti/rtnetlink v0.0.0-20201110080708-d2c240429e6c/go.mod h1:huN4d1phzjhlOsNIjFsw2SVRbwIHj3fJDMEU2SDPTmg=
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/klauspost/cpuid v1.2.4/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
+github.com/klauspost/cpuid v1.3.1 h1:5JNjFYYQrZeKRJ0734q51WCEEn2huer72Dc7K+R/b6s=
 github.com/klauspost/cpuid v1.3.1/go.mod h1:bYW4mA6ZgKPob1/Dlai2LviZJO7KGI3uoWLd42rAQw4=
 github.com/klauspost/cpuid/v2 v2.0.6/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/klauspost/cpuid/v2 v2.0.11 h1:i2lw1Pm7Yi/4O6XCSyJWqEHI2MDw2FzUK6o/D21xn2A=
@@ -164,8 +165,8 @@ golang.org/x/sys v0.0.0-20201101102859-da207088b7d1/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210525143221-35b2ab0089ea/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220209214540-3681064d5158/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220224120231-95c6836cb0e7 h1:BXxu8t6QN0G1uff4bzZzSkpsax8+ALqTGUtz08QrV00=
+golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 h1:nhht2DYV/Sn3qOayu8lM+cU1ii9sTLUeBQwQQfUHtrs=
-golang.org/x/sys v0.0.0-20220224120231-95c6836cb0e7/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 h1:JGgROgKl9N8DuW20oFS5gxc+lE67/N3FcwmBPMe7ArY=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=

proxy/conn.go

@@ -178,9 +178,9 @@ func CopyBuffer(dst io.Writer, src io.Reader) (written int64, err error) {
 // CopyUDP copys from src to dst at target with read timeout.
 // if step sets to non-zero value,
 // the read timeout will be increased from 0 to timeout by step in every read operation.
-func CopyUDP(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout time.Duration, step time.Duration) error {
+func CopyUDP(dst net.PacketConn, writeTo net.Addr, src net.PacketConn, timeout time.Duration, step time.Duration) error {
-	b := pool.GetBuffer(UDPBufSize)
+	buf := pool.GetBuffer(UDPBufSize)
-	defer pool.PutBuffer(b)
+	defer pool.PutBuffer(buf)
 
 	var t time.Duration
 	for {
@@ -189,12 +189,16 @@ func CopyUDP(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout ti
 		}
 
 		src.SetReadDeadline(time.Now().Add(t))
-		n, _, err := src.ReadFrom(b)
+		n, addr, err := src.ReadFrom(buf)
 		if err != nil {
 			return err
 		}
 
-		_, err = dst.WriteTo(b[:n], target)
+		if writeTo != nil {
+			addr = writeTo
+		}
+
+		_, err = dst.WriteTo(buf[:n], addr)
 		if err != nil {
 			return err
 		}

proxy/smux/client.go

@@ -1,7 +1,6 @@
 package smux
 
 import (
-	"errors"
 	"net"
 	"net/url"
 	"sync"
@@ -66,7 +65,7 @@ func (s *SmuxClient) Dial(network, addr string) (net.Conn, error) {
 
 // DialUDP connects to the given address via the proxy.
 func (s *SmuxClient) DialUDP(network, addr string) (net.PacketConn, net.Addr, error) {
-	return nil, nil, errors.New("smux client does not support udp now")
+	return nil, nil, proxy.ErrNotSupported
 }
 
 func (s *SmuxClient) initConn() error {