Don't allow banning in singleplayer

[minetest.git] / src / util / base64.cpp

diff --git a/src/util/base64.cpp b/src/util/base64.cpp
index c75f98598137ae9511ce73186457e48f7f31869b..0c245522234435e7da1750991d6606a6a74641a4 100644 (file)
--- a/src/util/base64.cpp
+++ b/src/util/base64.cpp
@@ -33,17 +33,39 @@ static const std::string base64_chars =
                "abcdefghijklmnopqrstuvwxyz"
                "0123456789+/";
 
+static const std::string base64_chars_padding_1 = "AEIMQUYcgkosw048";
+static const std::string base64_chars_padding_2 = "AQgw";
 
-static inline bool is_base64(unsigned char c) {
-       return (isalnum(c) || (c == '+') || (c == '/'));
+static inline bool is_base64(unsigned char c)
+{
+       return (c >= '0' && c <= '9')
+                       || (c >= 'A' && c <= 'Z')
+                       || (c >= 'a' && c <= 'z')
+                       || c == '+' || c == '/';
 }
 
 bool base64_is_valid(std::string const& s)
 {
-       for (char i : s)
-               if (!is_base64(i))
+       size_t i = 0;
+       for (; i < s.size(); ++i)
+               if (!is_base64(s[i]))
+                       break;
+       unsigned char padding = 3 - ((i + 3) % 4);
+       if ((padding == 1 && base64_chars_padding_1.find(s[i - 1]) == std::string::npos)
+                       || (padding == 2 && base64_chars_padding_2.find(s[i - 1]) == std::string::npos)
+                       || padding == 3)
+               return false;
+       int actual_padding = s.size() - i;
+       // omission of padding characters is allowed
+       if (actual_padding == 0)
+               return true;
+
+       // remaining characters (max. 2) may only be padding
+       for (; i < s.size(); ++i)
+               if (s[i] != '=')
                        return false;
-       return true;
+       // number of padding characters needs to match
+       return padding == actual_padding;
 }
 
 std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {