Re: [libvirt] [PATCH] network: don't add "no-resolv" if we still need DNS servers from resolv.conf

On Fri, Mar 17, 2017 at 12:33:14 -0400, Laine Stump wrote: > It was pointed out here: > > https://bugzilla.redhat.com/show_bug.cgi?id=1331796#c4 > > that we shouldn't be adding a "no-resolv" to the dnsmasq.conf file for > a network if there isn't any <forwarder> element that specifies an IP > address but no qualifying domain. If there is such an element, it will > handle all DNS requests that weren't otherwise handled by one of the > forwarder entries with a matching domain attribute. If not, then DNS > requests that don't match the domain of any <forwarder> would not be > resolved if we added no-resolv. > > So, only add "no-resolv" when there is at least one <forwarder> > element that specifies an IP address but no qualifying domain. ... > diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c > index c5ec282..32c5ab7 100644 > --- a/src/network/bridge_driver.c > +++ b/src/network/bridge_driver.c > @@ -1085,7 +1085,15 @@ networkDnsmasqConfContents(virNetworkObjPtr network, > virBufferAddLit(&configbuf, "port=0\n"); > > if (wantDNS && network->def->dns.forwarders) { > - virBufferAddLit(&configbuf, "no-resolv\n"); > + /* addNoResolv should be set to true if there are any entries > + * that specify an IP address for requests, but no domain > + * qualifier (implying that all requests otherwise "unclaimed" > + * should be sent to that address). if it is still false when > + * we've looked at all entries, it means we still need the > + * host's resolv.conf for some cases. > + */ > + bool addNoResolv = false; > + > for (i = 0; i < network->def->dns.nfwds; i++) { > virNetworkDNSForwarderPtr fwd = &network->def->dns.forwarders[i]; > > @@ -1099,11 +1107,15 @@ networkDnsmasqConfContents(virNetworkObjPtr network, > goto cleanup; > virBufferAsprintf(&configbuf, "%s\n", addr); > VIR_FREE(addr); > + if (!fwd->domain) > + addNoResolv = true; > } else { > /* "don't forward requests for this domain" */ > virBufferAddLit(&configbuf, "#\n"); > } > } > + if (addNoResolv) > + virBufferAddLit(&configbuf, "no-resolv\n"); > } > > if (network->def->domain) { So what if the network is isolated and supposed to only resolve names according to its database. Such network does not have any <forwarder/> element and yet no-resolve should be added in the configuration.