sorry, "supercalifragilisticexpialidocioussupercalifragilisticexpialidocious" was a bad example. it would not be valid since it is longer than a label.
On Sun, Apr 12, 2015 at 9:37 AM, Lennart Poettering <lenn...@poettering.net> wrote: > On Sun, 12.04.15 09:21, Nick Owens (misch...@offblast.org) wrote: > >> On Sun, Apr 12, 2015 at 6:35 AM, Lennart Poettering >> <lenn...@poettering.net> wrote: >> > On Fri, 10.04.15 13:03, Nick Owens (misch...@offblast.org) wrote: >> > >> >> From: mischief <misch...@offblast.org> >> >> >> >> The maximum domain name size is larger than the maximum host name size. >> >> The smaller limit causes valid domains provided by DHCP or .network >> >> files to be silently ignored. >> > >> > Hmm? >> > >> > Can you give an example? >> >> if you set the Domains key in the [Network] section of a >> systemd.network file to a domain longer than a label, then it will be >> ignored. the same is true if your DHCP server sends a domain in option >> 15 (domain name) that is longer than a label. it will be ignored too. >> both of these code paths call 'hostname_is_valid', which will fail if >> passed something larger than a label, which a domain name can be. > > "longer than a label"? What do you mean by that? The function should > perfectly consider multi-label names valid? Are you saying you cannot > set the domain name "foo.bar."? a multi-label name is valid. however, hostname_is_valid will reject any domain name (multi-label or not) longer than HOST_NAME_MAX, the size of a label. > > Hmm, so the DHCP spec explicitly declares that options 15 and 12 are > about the DNS hostname, where RFC 1035 is normative. Our function > hostname_is_valid() currently does not validate host names according > to RFC 1035, but is in some way stricter (by enforcing Linux' own semantics > on the length, and by limiting the charset drastically) and in other > ways less strict (by not enforce label length.) > > I am pretty sure we should leave hostname_is_valid() the way it is, to > be used when setting local hostnames and things like that. However, > the DHCP code should really validate according to RFC 1035 instead, > since that's what the spec says... > > Implementation-wise this probably means we should move > src/resolve/resolved-dns-domain.[ch] into src/shared/dns-domain.[ch] > and then add a call there that works similar to dns_name_normalize() > but doesn't actually normalize, but simply validates. the intention of the domainname_is_valid function in this patch is to validate domain names, which can be up to 255 octets. there appears to be no standardized macro for this size, so i added one. > > Hope that makes sense? > > Lennart > > -- > Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
