Funkce pro overeni Base64 kodovaneho retezce

src/encString.cpp

@@ -3,6 +3,23 @@
 #include <libb64/cdecode.h>
 #include <cutils.hpp>
 
+bool isBase64(const char *p)
+{
+    char c;
+
+    if (strlen(p) % 4 != 0)
+        return false;
+    do {
+        c = *p;
+        if (isalnum(c))   // alphanumberics are OK
+            continue;
+        if (c == '/' || c == '+' || c == '=')   // + or / or = is OK.
+            continue;
+        return false;
+    } while (*++p != 0);
+    return true;
+}
+
 void strEncode(String &str)
 {
 
@@ -41,9 +58,11 @@ void strDecode(String &str)
     uint32_t cid = ESP_getChipId();
     uint32_t *pkey = (uint32_t *)&key[0];
     uint8_t data[str.length()];
-    unsigned int clen = base64_decode_chars(src, str.length(), (char *)data);
     String result = F("");
 
+    if (isBase64(str.c_str())) {
+        unsigned int clen = base64_decode_chars(src, str.length(), (char *)data);
+
         if (0 != clen) {
             *pkey = cid;
             for (i = 0; i < clen; i++) {
@@ -54,5 +73,6 @@ void strDecode(String &str)
                 result.concat(char(b));
             }
         }
+    }
     str = result;
 }

src/encString.hpp

@@ -16,4 +16,13 @@ void strEncode(String &str);
  */
 void strDecode(String &str);
 
+/**
+ * @brief Overeni, ze je retezec Base64
+ * 
+ * @param p Ukazatel na retezec
+ * @return true Retezec je kodovany pomoci Base64
+ * @return false Retezec neni kodovany pomoci Base64
+ */
+bool isBase64(const char *p);
+
 #endif