moved remove_double_dots_and_double_slashes() to string.c

build/src/string.c

@@ -243,3 +243,26 @@ static int match_prefix(const char *pattern, int pattern_len, const char *str) {
   return j;
 }
 
+// Protect against directory disclosure attack by removing '..',
+// excessive '/' and '\' characters
+static void remove_double_dots_and_double_slashes(char *s) {
+  char *p = s;
+
+  while (*s != '\0') {
+    *p++ = *s++;
+    if (s[-1] == '/' || s[-1] == '\\') {
+      // Skip all following slashes, backslashes and double-dots
+      while (s[0] != '\0') {
+        if (s[0] == '/' || s[0] == '\\') {
+          s++;
+        } else if (s[0] == '.' && s[1] == '.') {
+          s += 2;
+        } else {
+          break;
+        }
+      }
+    }
+  }
+  *p = '\0';
+}
+