fix dtls connection

dialer/dtls/dialer.go

@@ -8,6 +8,7 @@ import (
 	"github.com/go-gost/core/dialer"
 	"github.com/go-gost/core/logger"
 	md "github.com/go-gost/core/metadata"
+	xdtls "github.com/go-gost/x/internal/util/dtls"
 	"github.com/go-gost/x/registry"
 	"github.com/pion/dtls/v2"
 )
@@ -65,5 +66,9 @@ func (d *dtlsDialer) Dial(ctx context.Context, addr string, opts ...dialer.DialO
 		MTU:                  d.md.mtu,
 	}
 
-	return dtls.ClientWithContext(ctx, conn, &config)
+	c, err := dtls.ClientWithContext(ctx, conn, &config)
+	if err != nil {
+		return nil, err
+	}
+	return xdtls.Conn(c, d.md.bufferSize), nil
 }

dialer/dtls/metadata.go

@@ -7,18 +7,22 @@ import (
 	mdutil "github.com/go-gost/core/metadata/util"
 )
 
+const (
+	defaultBufferSize = 1200
+)
+
 type metadata struct {
 	mtu            int
+	bufferSize     int
 	flightInterval time.Duration
 }
 
 func (d *dtlsDialer) parseMetadata(md mdata.Metadata) (err error) {
-	const (
-		mtu            = "mtu"
-		flightInterval = "flightInterval"
-	)
-
-	d.md.mtu = mdutil.GetInt(md, mtu)
-	d.md.flightInterval = mdutil.GetDuration(md, flightInterval)
+	d.md.mtu = mdutil.GetInt(md, "dtls.mtu", "mtu")
+	d.md.bufferSize = mdutil.GetInt(md, "dtls.bufferSize", "bufferSize")
+	if d.md.bufferSize <= 0 {
+		d.md.bufferSize = defaultBufferSize
+	}
+	d.md.flightInterval = mdutil.GetDuration(md, "dtls.flightInterval", "flightInterval")
 	return
 }