feat: add mrs format ipcidr ruleset

rules/provider/mrs_reader.go

@@ -0,0 +1,72 @@
+package provider
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/klauspost/compress/zstd"
+)
+
+var MrsMagicBytes = [4]byte{'M', 'R', 'S', 1} // MRSv1
+
+func rulesMrsParse(buf []byte, strategy ruleStrategy) (ruleStrategy, error) {
+	if _strategy, ok := strategy.(mrsRuleStrategy); ok {
+		reader, err := zstd.NewReader(bytes.NewReader(buf))
+		if err != nil {
+			return nil, err
+		}
+		defer reader.Close()
+
+		// header
+		var header [4]byte
+		_, err = io.ReadFull(reader, header[:])
+		if err != nil {
+			return nil, err
+		}
+		if header != MrsMagicBytes {
+			return nil, fmt.Errorf("invalid MrsMagic bytes")
+		}
+
+		// behavior
+		var _behavior [1]byte
+		_, err = io.ReadFull(reader, _behavior[:])
+		if err != nil {
+			return nil, err
+		}
+		if _behavior[0] != strategy.Behavior().Byte() {
+			return nil, fmt.Errorf("invalid behavior")
+		}
+
+		// count
+		var count int64
+		err = binary.Read(reader, binary.BigEndian, &count)
+		if err != nil {
+			return nil, err
+		}
+
+		// extra (reserved for future using)
+		var length int64
+		err = binary.Read(reader, binary.BigEndian, &length)
+		if err != nil {
+			return nil, err
+		}
+		if length < 0 {
+			return nil, errors.New("length is invalid")
+		}
+		if length > 0 {
+			extra := make([]byte, length)
+			_, err = io.ReadFull(reader, extra)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		err = _strategy.FromMrs(reader, int(count))
+		return strategy, err
+	} else {
+		return nil, ErrInvalidFormat
+	}
+}