4 ms·

So if my IP is XXX.XXX.XXX.42 I can expect misconfigured clients to be trying to connect to me constantly? What could possible go wrong!

• zck 16y ago
  Well, only if someone tries to go to http://XXX.XXX.XXX.42 http://XXX.XXX.XXX.42, which seems rare. I can't think of a way to tell whether XXX.XXX.XXX.42 is an IP or a website from that string alone. You could require that no subdomain has four "parts" (i.e., A.B.C.42), but that's harsh. You could require that somewhere in the URL for a four-part numeric-TLD URL there be a character. You could also require that at least one of the parts of A.B.C.D be X<0 or 255<X. The last two suggestions are more lighthanded, but harder to implement. They'd all rule out URLs like 1.2.3.4, though. Quick, register your favorite sequence! (http://oeis.org/ http://oeis.org/)
  • etherealG 16y ago
    reading the rules from an rfc mentioned on the wiki, if XXX.XXX.XXX.42 is a valid IP address, the client should try to use that first, if not it should only then try to use DNS to resolve.
    • zck 16y ago
      That certainly works, but it seems like a large part of this market would want numeric-only URLs, and so you couldn't have e.g., 1.2.3.4, or 1.1.2.3, etc.
      • nickknw 16y ago
        > but it seems like a large part of this market would want numeric-only URLs Except for maybe douglasadams.42 ;)
    • qjz 16y ago
      Reference: http://tools.ietf.org/html/rfc1123#page-13 http://tools.ietf.org/html/rfc1123#page-13 But note that the RFC assumes there will never be a numeric TLD. Furthermore, it suggests checking the string syntactically to determine if it's in dotted decimal form, remaining somewhat ambiguous about what to do if the hostname looks like IPv4, but the connection fails (it seems unwise to do a DNS lookup for every IPv4 address that's offline). Since IPv4 is relatively easy to validate, it would have made a lot more sense for a numeric TLD to select a number outside the range of 0-255, such as 4200. Then it's obvious that 1.2.3.4200 is a hostname (or harmless typo), and not an IP address.
      • andfarm 16y ago
        A lot of parsers do support numbers outside 0-255, though, and treat them as "packed" addresses. For instance, 127.0.1, 32512.1 and 2130706433 are all sometimes treated as alternate representations of 127.0.0.1.
      • metageek 16y ago
        There's also RFC-1738 (URL syntax), which says: host The fully qualified domain name of a network host, or its IP address as a set of four decimal digit groups separated by ".". Fully qualified domain names take the form as described in Section 3.5 of RFC 1034 [13] and Section 2.1 of RFC 1123 [5]: a sequence of domain labels separated by ".", each domain label starting and ending with an alphanumerical character and possibly also containing "-" characters. The rightmost domain label will never start with a digit, though, which syntactically distinguishes all domain names from the IP addresses. http://www.ietf.org/rfc/rfc1738.txt http://www.ietf.org/rfc/rfc1738.txt