Add domain sniffer

common/sniff/sniff.go

@@ -0,0 +1,36 @@
+package sniff
+
+import (
+	"context"
+	"io"
+	"os"
+
+	"github.com/sagernet/sing-box/adapter"
+)
+
+type (
+	StreamSniffer = func(ctx context.Context, reader io.Reader) (*adapter.InboundContext, error)
+	PacketSniffer = func(ctx context.Context, packet []byte) (*adapter.InboundContext, error)
+)
+
+func PeekStream(ctx context.Context, reader io.Reader, sniffers ...StreamSniffer) (*adapter.InboundContext, error) {
+	for _, sniffer := range sniffers {
+		sniffMetadata, err := sniffer(ctx, reader)
+		if err != nil {
+			return nil, err
+		}
+		return sniffMetadata, nil
+	}
+	return nil, os.ErrInvalid
+}
+
+func PeekPacket(ctx context.Context, packet []byte, sniffers ...PacketSniffer) (*adapter.InboundContext, error) {
+	for _, sniffer := range sniffers {
+		sniffMetadata, err := sniffer(ctx, packet)
+		if err != nil {
+			return nil, err
+		}
+		return sniffMetadata, nil
+	}
+	return nil, os.ErrInvalid
+}