add request rate limiter

handler/option.go

@@ -7,6 +7,7 @@ import (
 	"github.com/go-gost/core/auth"
 	"github.com/go-gost/core/bypass"
 	"github.com/go-gost/core/chain"
+	"github.com/go-gost/core/limiter/rate"
 	"github.com/go-gost/core/logger"
 	"github.com/go-gost/core/metadata"
 )
@@ -16,6 +17,7 @@ type Options struct {
 	Router      *chain.Router
 	Auth        *url.Userinfo
 	Auther      auth.Authenticator
+	RateLimiter rate.RateLimiter
 	TLSConfig   *tls.Config
 	Logger      logger.Logger
 }
@@ -46,6 +48,12 @@ func AutherOption(auther auth.Authenticator) Option {
 	}
 }
 
+func RateLimiterOption(limiter rate.RateLimiter) Option {
+	return func(opts *Options) {
+		opts.RateLimiter = limiter
+	}
+}
+
 func TLSConfigOption(tlsConfig *tls.Config) Option {
 	return func(opts *Options) {
 		opts.TLSConfig = tlsConfig

limiter/rate/limiter.go

@@ -0,0 +1,10 @@
+package rate
+
+type Limiter interface {
+	Allow(n int) bool
+	Limit() float64
+}
+
+type RateLimiter interface {
+	Limiter(key string) Limiter
+}

metadata/util/util.go

@@ -49,6 +49,8 @@ func GetFloat(md metadata.Metadata, key string) (v float64) {
 	}
 
 	switch vv := md.Get(key).(type) {
+	case float64:
+		return vv
 	case int:
 		return float64(vv)
 	case string: