MOD: Add multi-upstream plugin

Makefile

@@ -7,4 +7,4 @@ build :
 clean :
 	rm *.coverprofile
 
-.PHONY: test build clean
+.PHONY: build clean

README.md

@@ -1,19 +1,20 @@
 # ΛPΞX [WIP]
+ΛPΞX is a DNS server written in Go, help you connect to the real Internet.
+
 [![Build Status](https://travis-ci.org/oif/apex.svg?branch=master)](https://travis-ci.org/oif/apex)
 [![Coverage Status](https://coveralls.io/repos/github/oif/apex/badge.svg?branch=master)](https://coveralls.io/github/oif/apex?branch=master)
 [![Go Report Card](https://goreportcard.com/badge/github.com/oif/apex)](https://goreportcard.com/report/github.com/oif/apex)
 
-ΛPΞX is a DNS server written in Go, help you connect to the real Internet.
 
 # Feature
 * edns-client-subnet
 * Multiple DNS upstream
-    * DNS Over TLS
-    * UDP/TCP DNS
 * Hosts
 * DNSSEC
 * Cache
 
+# Official Plugins
+
 # Package Management
 Apex uses the Go community [dep](https://github.com/golang/dep) project for package management, but it's young so maybe will cause some unexcepted issue occurred during building. For more information about dep project status, check [dep - Current status](https://github.com/golang/dep#current-status)
 

cmd/apexd/main.go

@@ -4,6 +4,7 @@ import (
 	engine "github.com/oif/apex/pkg/engine/v1"
 	"github.com/oif/apex/plugin/cache"
 	"github.com/oif/apex/plugin/gdns"
+	"github.com/oif/apex/plugin/mupstream"
 	"github.com/oif/apex/plugin/statistics"
 
 	log "github.com/Sirupsen/logrus"
@@ -21,7 +22,11 @@ func main() {
 	}())
 	s.RegisterPlugins(func() *cache.Plugin {
 		plugin := new(cache.Plugin)
-		plugin.CacheSize = 512
+		plugin.CacheSize = 1024
+		return plugin
+	}())
+	s.RegisterPlugins(func() *mupstream.Plugin {
+		plugin := new(mupstream.Plugin)
 		return plugin
 	}())
 	s.RegisterPlugins(func() *gdns.Plugin {

plugin/mupstream/plugin.go

@@ -0,0 +1,64 @@
+package mupstream
+
+import (
+	"github.com/Sirupsen/logrus"
+	plugin "github.com/oif/apex/pkg/plugin/v1"
+)
+
+// PluginName for plugin
+const PluginName = "Multi-upstream Plugin"
+
+// Plugin implements pkg/plugin/v1
+type Plugin struct {
+	upstreams []*upstream
+}
+
+// Name return the name of this plugin
+func (p *Plugin) Name() string {
+	return PluginName
+}
+
+// Initialize Google DNS Plugin
+func (p *Plugin) Initialize() error {
+	p.upstreams = append(p.upstreams, newUpstream("119.29.29.29:53"))
+	p.upstreams = append(p.upstreams, newUpstream("223.5.5.5:53"))
+	p.upstreams = append(p.upstreams, newUpstream("114.114.114.114:53"))
+	return nil
+}
+
+func (p *Plugin) Warmup(c *plugin.Context)                   {}
+func (p *Plugin) AfterResponse(c *plugin.Context, err error) {}
+
+func (p *Plugin) Patch(c *plugin.Context) {
+	up := p.bestUpstream()
+	resp, rtt, err := up.forward(c.Msg)
+	if err != nil {
+		c.Error(err)
+		return
+	}
+	resp.CopyTo(c.Msg)
+	c.Logger().WithFields(logrus.Fields{
+		"rtt":      rtt,
+		"upstream": up,
+	}).Debug("Exchange message")
+
+	c.Abort() // stop other patch steps
+}
+
+func (p *Plugin) bestUpstream() *upstream {
+	best := 0
+	for i := 0; i < len(p.upstreams); i++ {
+		if p.upstreams[i].srtt < p.upstreams[0].srtt {
+			best = i
+		}
+	}
+	go func(selected int) { // lost decay
+		for i := 0; i < len(p.upstreams); i++ {
+			if i != selected {
+				p.upstreams[i].srttAttenuation()
+			}
+		}
+	}(best)
+
+	return p.upstreams[best]
+}

plugin/mupstream/upstream.go

@@ -0,0 +1,55 @@
+package mupstream
+
+import (
+	"net"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+var checkClient = &dns.Client{
+	Net:          "tcp",
+	ReadTimeout:  2 * time.Second,
+	WriteTimeout: 2 * time.Second,
+}
+
+type upstream struct {
+	addr   string
+	srtt   float32
+	fails  uint32
+	client *dns.Client
+}
+
+func newUpstream(addr string) *upstream {
+	return &upstream{
+		addr: addr,
+		client: &dns.Client{
+			Net: "udp",
+			Dialer: &net.Dialer{
+				KeepAlive: time.Minute,
+			},
+			Timeout: time.Second,
+		},
+	}
+}
+
+func (u *upstream) String() string {
+	return u.addr
+}
+
+func (u *upstream) srttAttenuation() {
+	u.srtt *= 0.98
+}
+
+func (u *upstream) forward(m *dns.Msg) (*dns.Msg, time.Duration, error) {
+	resp, rtt, err := u.client.Exchange(m, u.addr)
+	if err != nil { //
+		u.srtt = u.srtt + 200
+	} else { // success
+		if rtt > 300 {
+			rtt = 300
+		}
+		u.srtt = u.srtt*0.7 + float32(rtt)*0.3
+	}
+	return resp, rtt, err
+}