dns: code optimize

README.md

@@ -17,7 +17,7 @@ we can set up local listeners as proxy servers, and forward requests to internet
 ## Features
 - Act as both proxy client and proxy server
 - Flexible proxy & protocol chains
-- Multiple forwarders support with the following scheduling algorithm:
+- Load balancing with the following scheduling algorithm:
   - rr: round robin
   - ha: high availability 
   - lha: latency based high availability
@@ -73,7 +73,6 @@ sudo pacman -S glider
 
 ## Usage
 
-help:
 ```bash
 glider -h
 ```
@@ -347,7 +346,7 @@ forward=tls://1.1.1.1:443,ws://,vmess://5a146038-0b56-4e95-b1dc-5c6f5a32cd98@?al
 - Chain protocols and servers:
 
 ``` bash
-forward=socks5://1.1.1.1:1080,tls://2.2.2.2:443,ws://,vmess://5a146038-0b56-4e95-b1dc-5c6f5a32cd98@?alterID=2
+forward=socks5://1.1.1.1:1080,tls://2.2.2.2:443,vmess://5a146038-0b56-4e95-b1dc-5c6f5a32cd98@?alterID=2
 ```
 
 - Chain protocols in listener: https proxy server

dns/client.go

@@ -89,8 +89,22 @@ func (c *Client) Exchange(reqBytes []byte, clientAddr string, preferTCP bool) ([
 		return respBytes, err
 	}
 
+	ips, ttl := c.extractAnswer(resp)
+
+	// add to cache only when there's a valid ip address
+	if len(ips) != 0 && ttl > 0 {
+		c.cache.Put(getKey(resp.Question), respBytes, ttl)
+	}
+
+	log.F("[dns] %s <-> %s(%s) via %s, type: %d, %s: %s",
+		clientAddr, dnsServer, network, dialerAddr, resp.Question.QTYPE, resp.Question.QNAME, strings.Join(ips, ","))
+
+	return respBytes, nil
+}
+
+func (c *Client) extractAnswer(resp *Message) ([]string, int) {
+	var ips []string
 	ttl := c.config.MinTTL
-	ips := []string{}
 	for _, answer := range resp.Answers {
 		if answer.TYPE == QTypeA || answer.TYPE == QTypeAAAA {
 			for _, h := range c.handlers {
@@ -111,15 +125,7 @@ func (c *Client) Exchange(reqBytes []byte, clientAddr string, preferTCP bool) ([
 		ttl = c.config.MinTTL
 	}
 
-	// add to cache only when there's a valid ip address
+	return ips, ttl
-	if len(ips) != 0 && ttl > 0 {
-		c.cache.Put(getKey(resp.Question), respBytes, ttl)
-	}
-
-	log.F("[dns] %s <-> %s(%s) via %s, type: %d, %s: %s",
-		clientAddr, dnsServer, network, dialerAddr, resp.Question.QTYPE, resp.Question.QNAME, strings.Join(ips, ","))
-
-	return respBytes, nil
 }
 
 // exchange choose a upstream dns server based on qname, communicate with it on the network.

dns/server.go

@@ -24,12 +24,15 @@ type Server struct {
 // NewServer returns a new dns server.
 func NewServer(addr string, p proxy.Proxy, config *Config) (*Server, error) {
 	c, err := NewClient(p, config)
+	if err != nil {
+		return nil, err
+	}
+
 	s := &Server{
 		addr:   addr,
 		Client: c,
 	}
-
+	return s, nil
-	return s, err
 }
 
 // Start starts the dns forwarding server.

proxy/trojan/packet.go

@@ -1,10 +1,3 @@
-// https://trojan-gfw.github.io/trojan/protocol
-// If the connection is a UDP ASSOCIATE, then each UDP packet has the following format:
-// +------+----------+----------+--------+---------+----------+
-// | ATYP | DST.ADDR | DST.PORT | Length |  CRLF   | Payload  |
-// +------+----------+----------+--------+---------+----------+
-// |  1   | Variable |    2     |   2    | X'0D0A' | Variable |
-// +------+----------+----------+--------+---------+----------+
 package trojan
 
 import (
@@ -25,6 +18,7 @@ type PktConn struct {
 	tgtAddr socks.Addr
 }
 
+// NewPktConn returns a PktConn.
 func NewPktConn(c net.Conn, tgtAddr socks.Addr) *PktConn {
 	pc := &PktConn{
 		Conn:    c,
@@ -33,6 +27,7 @@ func NewPktConn(c net.Conn, tgtAddr socks.Addr) *PktConn {
 	return pc
 }
 
+// ReadFrom implements the necessary function of net.PacketConn.
 func (pc *PktConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	// ATYP, DST.ADDR, DST.PORT
 	_, err := socks.ReadAddr(pc.Conn)
@@ -65,6 +60,7 @@ func (pc *PktConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	return n, nil, err
 }
 
+// ReadFrom implements the necessary function of net.PacketConn.
 func (pc *PktConn) WriteTo(b []byte, addr net.Addr) (int, error) {
 	var buf bytes.Buffer
 	buf.Write(pc.tgtAddr)

proxy/trojan/trojan.go

@@ -1,29 +1,5 @@
 // protocol spec:
 // https://trojan-gfw.github.io/trojan/protocol
-// +-----------------------+---------+----------------+---------+----------+
-// | hex(SHA224(password)) |  CRLF   | Trojan Request |  CRLF   | Payload  |
-// +-----------------------+---------+----------------+---------+----------+
-// |          56           | X'0D0A' |    Variable    | X'0D0A' | Variable |
-// +-----------------------+---------+----------------+---------+----------+
-
-// where Trojan Request is a SOCKS5-like request:
-
-// +-----+------+----------+----------+
-// | CMD | ATYP | DST.ADDR | DST.PORT |
-// +-----+------+----------+----------+
-// |  1  |  1   | Variable |    2     |
-// +-----+------+----------+----------+
-
-// where:
-//     o  CMD
-//         o  CONNECT X'01'
-//         o  UDP ASSOCIATE X'03'
-//     o  ATYP address type of following address
-//         o  IP V4 address: X'01'
-//         o  DOMAINNAME: X'03'
-//         o  IP V6 address: X'04'
-//     o  DST.ADDR desired destination address
-//     o  DST.PORT desired destination port in network octet order
 
 package trojan
 
@@ -91,7 +67,7 @@ func NewTrojan(s string, d proxy.Dialer, p proxy.Proxy) (*Trojan, error) {
 	t.tlsConfig = &tls.Config{
 		ServerName:         t.serverName,
 		InsecureSkipVerify: t.skipVerify,
-		NextProtos:         []string{"http/1.1"},
+		NextProtos:         []string{"http/1.1", "h2"},
 		ClientSessionCache: tls.NewLRUClientSessionCache(64),
 		MinVersion:         tls.VersionTLS10,
 	}