Fix support for some non-standard subscription

Add Dockerfile for image auto update.

src/misc.cpp

@@ -124,7 +124,7 @@ unsigned char FromHex(unsigned char x)
     else if (x >= '0' && x <= '9')
         y = x - '0';
     else
-        assert(0);
+        y = x;
     return y;
 }
 
@@ -154,7 +154,7 @@ std::string UrlEncode(const std::string& str)
 
 std::string UrlDecode(const std::string& str)
 {
-    std::string strTemp = "";
+    std::string strTemp;
     size_t length = str.length();
     for (size_t i = 0; i < length; i++)
     {
@@ -164,9 +164,14 @@ std::string UrlDecode(const std::string& str)
         {
             if(i + 2 >= length)
                 return strTemp;
-            unsigned char high = FromHex((unsigned char)str[++i]);
-            unsigned char low = FromHex((unsigned char)str[++i]);
-            strTemp += high * 16 + low;
+            if(isalnum(str[i + 1]) && isalnum(str[i + 2]))
+            {
+                unsigned char high = FromHex((unsigned char)str[++i]);
+                unsigned char low = FromHex((unsigned char)str[++i]);
+                strTemp += high * 16 + low;
+            }
+            else
+                strTemp += str[i];
         }
         else
             strTemp += str[i];