net/dns: always offer MagicDNS records at 100.100.100.100.

Fixes #1886.

Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson
2021-05-17 15:18:25 -07:00
committed by Dave Anderson
parent dd0b690e7b
commit 6690f86ef4
4 changed files with 110 additions and 125 deletions

View File

@@ -1696,7 +1696,42 @@ func (b *LocalBackend) authReconfig() {
var dcfg dns.Config
// If CorpDNS is false, dcfg remains the zero value.
// Populate MagicDNS records. We do this unconditionally so that
// quad-100 can always respond to MagicDNS queries, even if the OS
// isn't configured to make MagicDNS resolution truly
// magic. Details in
// https://github.com/tailscale/tailscale/issues/1886.
set := func(name string, addrs []netaddr.IPPrefix) {
if len(addrs) == 0 || name == "" {
return
}
fqdn, err := dnsname.ToFQDN(name)
if err != nil {
return // TODO: propagate error?
}
var ips []netaddr.IP
for _, addr := range addrs {
// Remove IPv6 addresses for now, as we don't
// guarantee that the peer node actually can speak
// IPv6 correctly.
//
// https://github.com/tailscale/tailscale/issues/1152
// tracks adding the right capability reporting to
// enable AAAA in MagicDNS.
if addr.IP().Is6() {
continue
}
ips = append(ips, addr.IP())
}
dcfg.Hosts[fqdn] = ips
}
dcfg.AuthoritativeSuffixes = magicDNSRootDomains(nm)
dcfg.Hosts = map[dnsname.FQDN][]netaddr.IP{}
set(nm.Name, nm.Addresses)
for _, peer := range nm.Peers {
set(peer.Name, peer.Addresses)
}
if uc.CorpDNS {
addDefault := func(resolvers []tailcfg.DNSResolver) {
for _, resolver := range resolvers {
@@ -1734,36 +1769,9 @@ func (b *LocalBackend) authReconfig() {
}
dcfg.SearchDomains = append(dcfg.SearchDomains, fqdn)
}
set := func(name string, addrs []netaddr.IPPrefix) {
if len(addrs) == 0 || name == "" {
return
}
fqdn, err := dnsname.ToFQDN(name)
if err != nil {
return // TODO: propagate error?
}
var ips []netaddr.IP
for _, addr := range addrs {
// Remove IPv6 addresses for now, as we don't
// guarantee that the peer node actually can speak
// IPv6 correctly.
//
// https://github.com/tailscale/tailscale/issues/1152
// tracks adding the right capability reporting to
// enable AAAA in MagicDNS.
if addr.IP().Is6() {
continue
}
ips = append(ips, addr.IP())
}
dcfg.Hosts[fqdn] = ips
}
if nm.DNS.Proxied { // actually means "enable MagicDNS"
dcfg.AuthoritativeSuffixes = magicDNSRootDomains(nm)
dcfg.Hosts = map[dnsname.FQDN][]netaddr.IP{}
set(nm.Name, nm.Addresses)
for _, peer := range nm.Peers {
set(peer.Name, peer.Addresses)
for _, dom := range dcfg.AuthoritativeSuffixes {
dcfg.Routes[dom] = []netaddr.IPPort{netaddr.IPPortFrom(tsaddr.TailscaleServiceIP(), 53)}
}
}