Enhance Base64 validation in isLikelyBase64 function to include UTF-8 check and improve decoding logic.

parser/common.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"strconv"
 	"strings"
+	"unicode/utf8"
 
 	P "github.com/bestnite/sub2clash/model/proxy"
 )
@@ -32,8 +33,13 @@ func ParsePort(portStr string) (int, error) {
 	return port, nil
 }
 
+// isLikelyBase64 不严格判断是否是合法的 Base64, 很多分享链接不符合 Base64 规范
 func isLikelyBase64(s string) bool {
-	if len(s)%4 == 0 && strings.HasSuffix(s, "=") && !strings.Contains(strings.TrimSuffix(s, "="), "=") {
+	if strings.TrimSpace(s) == "" {
+		return false
+	}
+
+	if !strings.Contains(strings.TrimSuffix(s, "="), "=") {
 		s = strings.TrimSuffix(s, "=")
 		chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
 		for _, c := range s {
@@ -41,17 +47,25 @@ func isLikelyBase64(s string) bool {
 				return false
 			}
 		}
-		return true
 	}
+
+	decoded, err := DecodeBase64(s)
+	if err != nil {
 		return false
 	}
+	if !utf8.ValidString(decoded) {
+		return false
+	}
+
+	return true
+}
 
 func DecodeBase64(s string) (string, error) {
 	s = strings.TrimSpace(s)
 
 	if strings.Contains(s, "-") || strings.Contains(s, "_") {
-		s = strings.Replace(s, "-", "+", -1)
+		s = strings.ReplaceAll(s, "-", "+")
-		s = strings.Replace(s, "_", "/", -1)
+		s = strings.ReplaceAll(s, "_", "/")
 	}
 	if len(s)%4 != 0 {
 		s += strings.Repeat("=", 4-len(s)%4)

server/static/index.html

@@ -55,7 +55,7 @@
             <label for="endpoint">客户端类型:</label>
             <select class="form-control" id="endpoint" name="endpoint">
                 <option value="clash">Clash</option>
-                <option value="meta">Clash.Meta</option>
+                <option value="meta" selected>Clash.Meta</option>
             </select>
         </div>
         <!-- Template -->
@@ -75,9 +75,9 @@
         </div>
         <!-- User Agent -->
         <div class="form-group mb-3">
-            <label for="user-agent">ua标识:</label>
+            <label for="user-agent">UA 标识:</label>
             <textarea class="form-control" id="user-agent" name="user-agent"
-                placeholder="用于获取订阅的http请求中的user-agent标识(可选)" rows="3"></textarea>
+                placeholder="用于获取订阅的 http 请求中的 User-Agent 标识（可选）" rows="3"></textarea>
         </div>
         <!-- Refresh -->
         <div class="form-check mb-3">