Perform insensitive string compare of cookie SameSite attribute (#1706)

Co-authored-by: Omar Mohamed <omar@omar-laptop.lan>

lib/inc/drogon/Cookie.h

@@ -18,6 +18,7 @@
 #include <drogon/utils/string_view.h>
 #include <trantor/utils/Date.h>
 #include <trantor/utils/Logger.h>
+#include <cctype>
 #include <string>
 #include <limits>
 
@@ -295,25 +296,60 @@ class DROGON_EXPORT Cookie
         return sameSite_;
     }
 
+    /**
+     * @brief Compare two strings ignoring the their cases
+     *
+     * @param str1 string to check its value
+     * @param str2 string to check against, written in lower case
+     *
+     * @note the function is optimized to check for cookie's samesite value
+     * where we check if the value equals to a specific value we already know in
+     * str2. so the function doesn't apply tolower to the second argument
+     * str2 as it's always in lower case.
+     *
+     * @return 0 if both strings are equall ignoring case, negative value if lhs
+     * is smaller than rhs and vice versa
+     */
+    static int stricmp(const string_view str1, const string_view str2)
+    {
+        auto str1Len{str1.length()};
+        auto str2Len{str2.length()};
+
+        if (str1Len != str2Len)
+            return str1Len - str2Len;
+
+        for (size_t idx{0}; idx < str1Len; ++idx)
+        {
+            auto lowerChar{tolower(str1[idx])};
+
+            if (lowerChar != str2[idx])
+            {
+                return lowerChar - str2[idx];
+            }
+        }
+
+        return 0;
+    }
+
     /**
      * @brief Converts a string value to its associated enum class SameSite
      * value
      */
     static SameSite convertString2SameSite(const string_view &sameSite)
     {
-        if (sameSite == "Lax")
+        if (stricmp(sameSite, "lax") == 0)
         {
             return Cookie::SameSite::kLax;
         }
-        else if (sameSite == "Strict")
+        else if (stricmp(sameSite, "strict") == 0)
         {
             return Cookie::SameSite::kStrict;
         }
-        else if (sameSite == "None")
+        else if (stricmp(sameSite, "none") == 0)
         {
             return Cookie::SameSite::kNone;
         }
-        else if (sameSite != "Null")
+        else if (stricmp(sameSite, "null") != 0)
         {
             LOG_WARN
                 << "'" << sameSite