Documentation
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Overview ¶
Package resolver implements a stub DNS resolver that can also serve records out of an internal local zone.
Index ¶
- func ShouldUseRoutes(knobs *controlknobs.Knobs) bool
- func WriteDNSResolver(w *bufio.Writer, r *dnstype.Resolver)
- func WriteDNSResolvers(w *bufio.Writer, resolvers []*dnstype.Resolver)
- func WriteIPPorts(w *bufio.Writer, vv []netip.AddrPort)
- func WriteRoutes(w *bufio.Writer, routes map[dnsname.FQDN][]*dnstype.Resolver)
- type Config
- type ForwardLinkSelector
- type Resolver
- func (r *Resolver) Close()
- func (r *Resolver) GetUpstreamResolvers(name dnsname.FQDN) []*dnstype.Resolver
- func (r *Resolver) HandlePeerDNSQuery(ctx context.Context, q []byte, from netip.AddrPort, ...) (res []byte, err error)
- func (r *Resolver) Query(ctx context.Context, bs []byte, family string, from netip.AddrPort) ([]byte, error)
- func (r *Resolver) SetConfig(cfg Config) error
- func (r *Resolver) TestOnlySetHook(hook func(Config))
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func ShouldUseRoutes ¶ added in v1.84.0
func ShouldUseRoutes(knobs *controlknobs.Knobs) bool
ShouldUseRoutes reports whether the DNS resolver should consider routes when dialing upstream nameservers via TCP.
If true, routes should be considered (tsdial.Dialer.UserDial), otherwise defer to the system routes (tsdial.Dialer.SystemDial).
TODO(nickkhyl): Update tsdial.Dialer to reuse the bart.Table we create in net/tstun.Wrapper to avoid having two bart tables in memory, especially on iOS. Once that's done, we can get rid of the nodeAttr/control knob and always use UserDial for DNS.
See tailscale/tailscale#12027.
func WriteDNSResolver ¶ added in v1.16.0
WriteDNSResolver writes r to w.
func WriteDNSResolvers ¶ added in v1.16.0
WriteDNSResolvers writes resolvers to w.
func WriteIPPorts ¶ added in v1.12.0
WriteIPPorts writes vv to w.
Types ¶
type Config ¶
type Config struct {
// Routes is a map of DNS name suffix to the resolvers to use for
// queries within that suffix.
// Queries only match the most specific suffix.
// To register a "default route", add an entry for ".".
Routes map[dnsname.FQDN][]*dnstype.Resolver
// LocalHosts is a map of FQDNs to corresponding IPs.
Hosts map[dnsname.FQDN][]netip.Addr
// LocalDomains is a list of DNS name suffixes that should not be
// routed to upstream resolvers.
LocalDomains []dnsname.FQDN
}
Config is a resolver configuration. Given a Config, queries are resolved in the following order: If the query is an exact match for an entry in LocalHosts, return that. Else if the query suffix matches an entry in LocalDomains, return NXDOMAIN. Else forward the query to the most specific matching entry in Routes. Else return SERVFAIL.
func (*Config) RoutesRequireNoCustomResolvers ¶ added in v1.68.0
RoutesRequireNoCustomResolvers returns true if this resolver.Config only contains routes that do not specify a set of custom resolver(s), i.e. they can be resolved by the local upstream DNS resolver.
func (*Config) WriteToBufioWriter ¶ added in v1.12.0
WriteToBufioWriter write a debug version of c for logs to w, omitting spammy stuff like *.arpa entries and replacing it with a total count.
type ForwardLinkSelector ¶ added in v1.10.0
type Resolver ¶
type Resolver struct {
// contains filtered or unexported fields
}
Resolver is a DNS resolver for nodes on the Tailscale network, associating them with domain names of the form <mynode>.<mydomain>.<root>. If it is asked to resolve a domain that is not of that form, it delegates to upstream nameservers if any are set.
func New ¶
func New(logf logger.Logf, linkSel ForwardLinkSelector, dialer *tsdial.Dialer, health *health.Tracker, knobs *controlknobs.Knobs) *Resolver
New returns a new resolver. dialer and health must be non-nil.
func (*Resolver) Close ¶
func (r *Resolver) Close()
Close shuts down the resolver and ensures poll goroutines have exited. The Resolver cannot be used again after Close is called.
func (*Resolver) GetUpstreamResolvers ¶ added in v1.76.0
GetUpstreamResolvers returns the resolvers that would be used to resolve the given FQDN.
func (*Resolver) HandlePeerDNSQuery ¶ added in v1.54.0
func (r *Resolver) HandlePeerDNSQuery(ctx context.Context, q []byte, from netip.AddrPort, allowName func(name string) bool) (res []byte, err error)
HandlePeerDNSQuery handles a DNS query that arrived from a peer via the peerapi's DoH server. This is used when the local node is being an exit node or an app connector.
The provided allowName callback is whether a DNS query for a name (as found by parsing q) is allowed.
In most (all?) cases, err will be nil. A bogus DNS query q will still result in a response DNS packet (saying there's a failure) and a nil error. TODO: figure out if we even need an error result.
Source Files