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resolved: preferably route single-label lookups to unicast DNS scopes with search domains (#11485)

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Fixes: #11391
This commit is contained in:
Lennart Poettering
2019-01-22 09:57:49 +01:00
committed by Zbigniew Jędrzejewski-Szmek
parent a9bc94e558
commit fea46786ce
1 changed files with 23 additions and 7 deletions
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src/resolve/resolved-dns-scope.c
+23 -7
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@@ -527,6 +527,7 @@ DnsScopeMatch dns_scope_good_domain(
switch (s->protocol) {
case DNS_PROTOCOL_DNS: {
bool has_search_domains = false;
int n_best = -1;
/* Never route things to scopes that lack DNS servers */
@@ -536,7 +537,11 @@ DnsScopeMatch dns_scope_good_domain(
/* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
* we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
* won't be considered anymore. */
LIST_FOREACH(domains, d, dns_scope_get_search_domains(s))
LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) {
if (!d->route_only && !dns_name_is_root(d->name))
has_search_domains = true;
if (dns_name_endswith(domain, d->name) > 0) {
int c;
@@ -547,6 +552,13 @@ DnsScopeMatch dns_scope_good_domain(
if (c > n_best)
n_best = c;
}
}
/* If there's a true search domain defined for this scope, and the query is single-label,
* then let's resolve things here, prefereably. Note that LLMNR considers itself
* authoritative for single-label names too, at the same preference, see below. */
if (has_search_domains && dns_name_is_single_label(domain))
return DNS_SCOPE_YES_BASE + 1;
/* Let's return the number of labels in the best matching result */
if (n_best >= 0) {
@@ -606,12 +618,16 @@ DnsScopeMatch dns_scope_good_domain(
if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
!is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via LLMNR */
return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative for
* single-label names, i.e. one label. This is particular
* relevant as it means a "." route on some other scope won't
* pull all traffic away from us. (If people actually want to
* pull traffic away from us they should turn off LLMNR on the
* link) */
return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative
* for single-label names, i.e. one label. This is
* particular relevant as it means a "." route on some
* other scope won't pull all traffic away from
* us. (If people actually want to pull traffic away
* from us they should turn off LLMNR on the
* link). Note that unicast DNS scopes with search
* domains also consider themselves authoritative for
* single-label domains, at the same preference (see
* above). */
return DNS_SCOPE_NO;
}