fix: loadbalance panic

adapter/outboundgroup/loadbalance.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"sync"
 	"time"
 
 	"github.com/Dreamacro/clash/adapter/outbound"
@@ -20,7 +21,7 @@ import (
 	"golang.org/x/net/publicsuffix"
 )
 
-type strategyFn = func(proxies []C.Proxy, metadata *C.Metadata) C.Proxy
+type strategyFn = func(proxies []C.Proxy, metadata *C.Metadata, touch bool) C.Proxy
 
 type LoadBalance struct {
 	*GroupBase
@@ -127,21 +128,23 @@ func (lb *LoadBalance) SupportUDP() bool {
 }
 
 func strategyRoundRobin() strategyFn {
-	flag := true
 	idx := 0
-	return func(proxies []C.Proxy, metadata *C.Metadata) C.Proxy {
+	idxMutex := sync.Mutex{}
+	return func(proxies []C.Proxy, metadata *C.Metadata, touch bool) C.Proxy {
+		id := idx // value could be wrong due to no lock, but don't care if we don't touch
+		if touch {
+			idxMutex.Lock()
+			defer idxMutex.Unlock()
+			id = idx // get again by lock's protect, so it must be right
+			defer func() {
+				idx = id
+			}()
+		}
+
 		length := len(proxies)
 		for i := 0; i < length; i++ {
-			flag = !flag
+			id = (id + 1) % length
-			if flag {
+			proxy := proxies[id]
-				idx = (idx - 1) % length
-			} else {
-				idx = (idx + 2) % length
-			}
-			if idx < 0 {
-				idx = idx + length
-			}
-			proxy := proxies[idx]
 			if proxy.Alive() {
 				return proxy
 			}
@@ -153,7 +156,7 @@ func strategyRoundRobin() strategyFn {
 
 func strategyConsistentHashing() strategyFn {
 	maxRetry := 5
-	return func(proxies []C.Proxy, metadata *C.Metadata) C.Proxy {
+	return func(proxies []C.Proxy, metadata *C.Metadata, touch bool) C.Proxy {
 		key := uint64(murmur3.Sum32([]byte(getKey(metadata))))
 		buckets := int32(len(proxies))
 		for i := 0; i < maxRetry; i, key = i+1, key+1 {
@@ -181,7 +184,7 @@ func strategyStickySessions() strategyFn {
 	lruCache := cache.New[uint64, int](
 		cache.WithAge[uint64, int](int64(ttl.Seconds())),
 		cache.WithSize[uint64, int](1000))
-	return func(proxies []C.Proxy, metadata *C.Metadata) C.Proxy {
+	return func(proxies []C.Proxy, metadata *C.Metadata, touch bool) C.Proxy {
 		key := uint64(murmur3.Sum32([]byte(getKeyWithSrcAndDst(metadata))))
 		length := len(proxies)
 		idx, has := lruCache.Get(key)
@@ -213,7 +216,7 @@ func strategyStickySessions() strategyFn {
 // Unwrap implements C.ProxyAdapter
 func (lb *LoadBalance) Unwrap(metadata *C.Metadata, touch bool) C.Proxy {
 	proxies := lb.GetProxies(touch)
-	return lb.strategyFn(proxies, metadata)
+	return lb.strategyFn(proxies, metadata, true)
 }
 
 // MarshalJSON implements C.ProxyAdapter

adapter/outboundgroup/relay.go

@@ -176,7 +176,7 @@ func (r *Relay) proxies(metadata *C.Metadata, touch bool) ([]C.Proxy, []C.Proxy)
 }
 
 func (r *Relay) Addr() string {
-	proxies, _ := r.proxies(nil, true)
+	proxies, _ := r.proxies(nil, false)
 	return proxies[len(proxies)-1].Addr()
 }