Feature: add load-balance group

adapters/outbound/loadbalance.go

@@ -0,0 +1,94 @@
+package adapters
+
+import (
+	"encoding/json"
+	"errors"
+	"net"
+
+	"github.com/Dreamacro/clash/common/murmur3"
+	C "github.com/Dreamacro/clash/constant"
+
+	"golang.org/x/net/publicsuffix"
+)
+
+type LoadBalance struct {
+	*Base
+	proxies  []C.Proxy
+	maxRetry int
+}
+
+func getKey(metadata *C.Metadata) string {
+	if metadata.Host != "" {
+		// ip host
+		if ip := net.ParseIP(metadata.Host); ip != nil {
+			return metadata.Host
+		}
+
+		if etld, err := publicsuffix.EffectiveTLDPlusOne(metadata.Host); err == nil {
+			return etld
+		}
+	}
+
+	if metadata.IP == nil {
+		return ""
+	}
+
+	return metadata.IP.String()
+}
+
+func jumpHash(key uint64, buckets int32) int32 {
+	var b, j int64
+
+	for j < int64(buckets) {
+		b = j
+		key = key*2862933555777941757 + 1
+		j = int64(float64(b+1) * (float64(int64(1)<<31) / float64((key>>33)+1)))
+	}
+
+	return int32(b)
+}
+
+func (lb *LoadBalance) Generator(metadata *C.Metadata) (net.Conn, error) {
+	key := uint64(murmur3.Sum32([]byte(getKey(metadata))))
+	buckets := int32(len(lb.proxies))
+	for i := 0; i < lb.maxRetry; i++ {
+		idx := jumpHash(key, buckets)
+		if proxy, err := lb.proxies[idx].Generator(metadata); err == nil {
+			return proxy, nil
+		}
+		key++
+	}
+
+	return lb.proxies[0].Generator(metadata)
+}
+
+func (lb *LoadBalance) MarshalJSON() ([]byte, error) {
+	var all []string
+	for _, proxy := range lb.proxies {
+		all = append(all, proxy.Name())
+	}
+	return json.Marshal(map[string]interface{}{
+		"type": lb.Type().String(),
+		"all":  all,
+	})
+}
+
+type LoadBalanceOption struct {
+	Name    string   `proxy:"name"`
+	Proxies []string `proxy:"proxies"`
+}
+
+func NewLoadBalance(name string, proxies []C.Proxy) (*LoadBalance, error) {
+	if len(proxies) == 0 {
+		return nil, errors.New("Provide at least one proxy")
+	}
+
+	return &LoadBalance{
+		Base: &Base{
+			name: name,
+			tp:   C.LoadBalance,
+		},
+		proxies:  proxies,
+		maxRetry: 3,
+	}, nil
+}