Add geosite protocol

common/geosite/reader.go

@@ -0,0 +1,97 @@
+package geosite
+
+import (
+	"io"
+	"sync"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/rw"
+)
+
+type Reader struct {
+	reader       io.ReadSeeker
+	access       sync.Mutex
+	metadataRead bool
+	domainIndex  map[string]int
+	domainLength map[string]int
+}
+
+func (r *Reader) readMetadata() error {
+	version, err := rw.ReadByte(r.reader)
+	if err != nil {
+		return err
+	}
+	if version != 0 {
+		return E.New("unknown version")
+	}
+	entryLength, err := rw.ReadUVariant(r.reader)
+	if err != nil {
+		return err
+	}
+	keys := make([]string, entryLength)
+	domainIndex := make(map[string]int)
+	domainLength := make(map[string]int)
+	for i := 0; i < int(entryLength); i++ {
+		var (
+			code       string
+			codeIndex  uint64
+			codeLength uint64
+		)
+		code, err = rw.ReadVString(r.reader)
+		if err != nil {
+			return err
+		}
+		keys[i] = code
+		codeIndex, err = rw.ReadUVariant(r.reader)
+		if err != nil {
+			return err
+		}
+		codeLength, err = rw.ReadUVariant(r.reader)
+		if err != nil {
+			return err
+		}
+		domainIndex[code] = int(codeIndex)
+		domainLength[code] = int(codeLength)
+	}
+	r.domainIndex = domainIndex
+	r.domainLength = domainLength
+	r.metadataRead = true
+	return nil
+}
+
+func (r *Reader) Read(code string) ([]Item, error) {
+	r.access.Lock()
+	defer r.access.Unlock()
+	if !r.metadataRead {
+		err := r.readMetadata()
+		if err != nil {
+			return nil, err
+		}
+	}
+	if _, exists := r.domainIndex[code]; !exists {
+		return nil, E.New("code ", code, " not exists!")
+	}
+	counter := &rw.ReadCounter{Reader: r.reader}
+	domain := make([]Item, r.domainLength[code])
+	for i := range domain {
+		var (
+			item Item
+			err  error
+		)
+		item.Type, err = rw.ReadByte(counter)
+		if err != nil {
+			return nil, err
+		}
+		item.Value, err = rw.ReadVString(counter)
+		if err != nil {
+			return nil, err
+		}
+		domain[i] = item
+	}
+	_, err := r.reader.Seek(int64(r.domainIndex[code])-counter.Count(), io.SeekCurrent)
+	return domain, err
+}
+
+func (r *Reader) Upstream() any {
+	return r.reader
+}