Improve sniffer

common/sniff/ssh.go

@@ -5,22 +5,26 @@ import (
 	"context"
 	"io"
 	"os"
-	"strings"
 
 	"github.com/sagernet/sing-box/adapter"
 	C "github.com/sagernet/sing-box/constant"
+	E "github.com/sagernet/sing/common/exceptions"
 )
 
 func SSH(_ context.Context, metadata *adapter.InboundContext, reader io.Reader) error {
-	scanner := bufio.NewScanner(reader)
-	if !scanner.Scan() {
+	const sshPrefix = "SSH-2.0-"
+	bReader := bufio.NewReader(reader)
+	prefix, err := bReader.Peek(len(sshPrefix))
+	if err != nil {
+		return E.Cause1(ErrNeedMoreData, err)
+	} else if string(prefix) != sshPrefix {
 		return os.ErrInvalid
 	}
-	fistLine := scanner.Text()
-	if !strings.HasPrefix(fistLine, "SSH-2.0-") {
-		return os.ErrInvalid
+	fistLine, _, err := bReader.ReadLine()
+	if err != nil {
+		return err
 	}
 	metadata.Protocol = C.ProtocolSSH
-	metadata.Client = fistLine[8:]
+	metadata.Client = string(fistLine)[8:]
 	return nil
 }