Add support for ::13.1.68.3

Fix #9

src/isinetaddr6.c

@@ -27,8 +27,12 @@ isinetaddr6(const char *str)
     if (has_consecutive_chars(&str[i], SEP, 3)) {
       return 0;
     } else if (has_consecutive_chars(&str[i], SEP, 2)) {
+      if (i == 0 && isinetaddr4(&str[3])) {
+        return 1;
+      } else {
         char new_str[MAX_STRLEN];
         return isinetaddr6(expand(str, len, new_str, i));
+      }
     } else if (str[i] == SEP) {
       digitlen = 0;
     } else if (isxdigit(str[i])) {

test/isinetaddr6_test.c

@@ -36,6 +36,7 @@ const char *valid[] = {
   "FF01::101",
   "::ffff:192.168.2.1",
   "::FFFF:192.168.2.1",
+  "::13.1.68.3",
   "::",
   "::1",
 };