// Get retrieves a list of services from the registry that matches the given domain pattern:
//
// uuid.host.region.version.service.environment
// any of these positions may supply the wildcard "*", to have all values match in this position.
// additionally, you only need to specify as much of the domain as needed the domain version.service.environment is perfectly acceptable,
// and will assume "*" for all the ommited subdomain positions
func (r *DefaultRegistry) Get(domain string) ([]msg.Service, error) {
// TODO: account for version wildcards
r.mutex.Lock()
defer r.mutex.Unlock()
// Ensure we are using lowercase keys, as this is the way they are stored
domain = strings.ToLower(domain)
// DNS queries have a trailing .
if strings.HasSuffix(domain, ".") {
domain = domain[:len(domain)-1]
}
tree := dns.SplitDomainName(domain)
// Domains can be partial, and we should assume wildcards for the unsupplied portions
if len(tree) < 6 {
pad := 6 - len(tree)
t := make([]string, pad)
for i := 0; i < pad; i++ {
t[i] = "*"
}
tree = append(t, tree...)
}
return r.tree.get(tree)
}
// ToPunycode converts unicode domain names to DNS-appropriate punycode names.
// This function will return an empty string result for domain names with
// invalid unicode strings. This function expects domain names in lowercase.
func ToPunycode(s string) string {
// Early check to see if encoding is needed.
// This will prevent making heap allocations when not needed.
if !needToPunycode(s) {
return s
}
tokens := dns.SplitDomainName(s)
switch {
case s == "":
return ""
case tokens == nil: // s == .
return "."
case s[len(s)-1] == '.':
tokens = append(tokens, "")
}
for i := range tokens {
t := encode([]byte(tokens[i]))
if t == nil {
return ""
}
tokens[i] = string(t)
}
return strings.Join(tokens, ".")
}
func parent(name string) (string, bool) {
labels := dns.SplitDomainName(name)
if labels == nil {
return "", false
}
return toLowerFQDN(strings.Join(labels[1:], ".")), true
}
// NewNSEC3 returns the NSEC3 record need to denial qname, or gives back a NODATA NSEC3.
func (s *server) NewNSEC3(qname string) *dns.NSEC {
qlabels := dns.SplitDomainName(qname)
if len(qlabels) < s.domainLabels {
// TODO(miek): can not happen...?
}
// Strip the last s.domainLabels, return up to 4 before
// that. Four labels is the maximum qname we can handle.
ls := len(qlabels) - s.domainLabels
ls4 := ls - 4
if ls4 < 0 {
ls4 = 0
}
key := qlabels[ls4:ls]
key = key // TODO(miek)
// TODO etcd here
// prev, next := s.registry.GetNSEC(strings.Join(key, "."))
prev, next := "", ""
nsec := &dns.NSEC{Hdr: dns.RR_Header{Name: prev + s.config.Domain + ".", Rrtype: dns.TypeNSEC, Class: dns.ClassINET, Ttl: 60},
NextDomain: next + s.config.Domain + "."}
if prev == "" {
nsec.TypeBitMap = []uint16{dns.TypeA, dns.TypeSOA, dns.TypeNS, dns.TypeAAAA, dns.TypeRRSIG, dns.TypeNSEC, dns.TypeDNSKEY}
} else {
nsec.TypeBitMap = []uint16{dns.TypeA, dns.TypeAAAA, dns.TypeSRV, dns.TypeRRSIG, dns.TypeNSEC}
}
return nsec
}
func (d *Device) Hostname() string {
l := dns.SplitDomainName(d.Name)
if len(l) > 0 {
return l[0]
}
return d.Name
}
// Look in .../dns/stub/<domain>/xx for msg.Services. Loop through them
// extract <domain> and add them as forwarders (ip:port-combos) for
// the stub zones. Only numeric (i.e. IP address) hosts are used.
func (s *server) UpdateStubZones() {
stubmap := make(map[string][]string)
services, err := s.backend.Records("stub.dns."+s.config.Domain, false, net.IP{})
if err != nil {
logf("stub zone update failed: %s", err)
return
}
for _, serv := range services {
if serv.Port == 0 {
serv.Port = 53
}
ip := net.ParseIP(serv.Host)
if ip == nil {
logf("stub zone non-address %s seen for: %s", serv.Key, serv.Host)
continue
}
domain := msg.Domain(serv.Key)
// Chop of left most label, because that is used as the nameserver place holder
// and drop the right most labels that belong to localDomain.
labels := dns.SplitDomainName(domain)
domain = dns.Fqdn(strings.Join(labels[1:len(labels)-dns.CountLabel(s.config.localDomain)], "."))
// If the remaining name equals s.config.LocalDomain we ignore it.
if domain == s.config.localDomain {
logf("not adding stub zone for my own domain")
continue
}
stubmap[domain] = append(stubmap[domain], net.JoinHostPort(serv.Host, strconv.Itoa(serv.Port)))
}
s.config.stub = &stubmap
}
func getKey(domain string, rtype uint16) (r string, e error) {
if *debug {
Log.Printf("getKey: domain: %s, resource type: %d\n", domain, rtype)
}
if n, ok := dns.IsDomainName(domain); ok {
labels := dns.SplitDomainName(domain)
// Reverse domain, starting from top-level domain
// eg. ".com.mkaczanowski.test "
var tmp string
for i := 0; i < int(math.Floor(float64(n/2))); i++ {
tmp = labels[i]
labels[i] = labels[n-1]
labels[n-1] = tmp
}
reverseDomain := strings.Join(labels, ".")
r = strings.Join([]string{reverseDomain, strconv.Itoa(int(rtype))}, "_")
} else {
e = errors.New("Invailid domain: " + domain)
Log.Println(e.Error())
}
return r, e
}
// Path converts a domainname to an etcd path. If s looks like service.staging.skydns.local.,
// the resulting key will be /skydns/local/skydns/staging/service .
func Path(s string) string {
l := dns.SplitDomainName(s)
for i, j := 0, len(l)-1; i < j; i, j = i+1, j-1 {
l[i], l[j] = l[j], l[i]
}
return path.Join(append([]string{"/skydns/"}, l...)...)
}
func GetRootDomain(s string) string {
labels := dns.SplitDomainName(s)
if len(labels) < 2 {
return s
}
root := dns.Fqdn(strings.Join([]string{labels[len(labels)-2], labels[len(labels)-1]}, "."))
return root
}
// path converts a domainname to an etcd path. If s looks like service.staging.skydns.local.,
// the resulting key will be /skydns/local/skydns/staging/service .
func path(s string) string {
l := dns.SplitDomainName(s)
for i, j := 0, len(l)-1; i < j; i, j = i+1, j-1 {
l[i], l[j] = l[j], l[i]
}
// TODO(miek): escape slashes in s.
return "/skydns/" + strings.Join(l, "/")
}
func (h *handler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
defer w.WriteMsg(m)
if len(r.Question) != 1 {
return
}
q := r.Question[0]
if q.Qclass != dns.ClassINET {
return
}
if q.Qtype != dns.TypeA {
return
}
withID := false
labels := dns.SplitDomainName(q.Name)
for i, j := 0, len(labels)-1; i < j; i, j = i+1, j-1 {
labels[i], labels[j] = labels[j], labels[i]
}
if len(labels) > 0 && labels[0] == "" {
labels = labels[1:]
}
if len(labels) > 0 && labels[0] == "switch" {
labels = labels[1:]
}
if len(labels) > 0 && labels[0] == "id" {
labels = labels[1:]
withID = true
}
name := strings.Join(labels, "/")
var host *hosts.Host
if withID {
host = h.vnet.Hosts().GetTable().LookupByID(name)
} else {
host = h.vnet.Hosts().GetTable().LookupByName(name)
}
if host == nil {
return
}
for _, ip := range host.IPv4Addrs {
m.Answer = append(m.Answer, &dns.A{
Hdr: dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 60,
},
A: ip,
})
}
}
func GenerateParentDomain(d string) (string, *MyError.MyError) {
x := dns.SplitDomainName(d)
if cap(x) > 1 {
// fmt.Println(x)
return strings.Join(x[1:], "."), nil
} else {
return d, MyError.NewError(MyError.ERROR_NORESULT, d+" has no subdomain")
}
return d, MyError.NewError(MyError.ERROR_UNKNOWN, d+" unknown error")
}
func (s *Server) getSRVRecords(q dns.Question) (records []dns.RR, err error) {
var weight uint16
services := make([]msg.Service, 0)
key := strings.TrimSuffix(q.Name, s.domain+".")
services, err = s.registry.Get(key)
if err != nil {
return
}
weight = 0
if len(services) > 0 {
weight = uint16(math.Floor(float64(100 / len(services))))
}
for _, serv := range services {
// TODO: Dynamically set weight
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL}, Priority: 10, Weight: weight, Port: serv.Port, Target: serv.Host + "."})
}
// Append matching entries in different region than requested with a higher priority
labels := dns.SplitDomainName(key)
pos := len(labels) - 4
if len(labels) >= 4 && labels[pos] != "any" && labels[pos] != "all" {
region := labels[pos]
labels[pos] = "any"
// TODO: This is pretty much a copy of the above, and should be abstracted
additionalServices := make([]msg.Service, len(services))
additionalServices, err = s.registry.Get(strings.Join(labels, "."))
if err != nil {
return
}
weight = 0
if len(additionalServices) <= len(services) {
return
}
weight = uint16(math.Floor(float64(100 / (len(additionalServices) - len(services)))))
for _, serv := range additionalServices {
// Exclude entries we already have
if strings.ToLower(serv.Region) == region {
continue
}
// TODO: Dynamically set priority and weight
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL}, Priority: 20, Weight: weight, Port: serv.Port, Target: serv.Host + "."})
}
}
return
}
// dispatch is used to parse a request and invoke the correct handler
func (d *DNSServer) dispatch(network string, req, resp *dns.Msg) {
// By default the query is in the default datacenter
datacenter := d.agent.config.Datacenter
// Get the QName without the domain suffix
qName := dns.Fqdn(req.Question[0].Name)
qName = strings.TrimSuffix(qName, d.domain)
// Split into the label parts
labels := dns.SplitDomainName(qName)
// The last label is either "node", "service" or a datacenter name
PARSE:
n := len(labels)
if n == 0 {
goto INVALID
}
switch labels[n-1] {
case "service":
if n == 1 {
goto INVALID
}
// Extract the service
service := labels[n-2]
// Support "." in the label, re-join all the parts
tag := ""
if n >= 3 {
tag = strings.Join(labels[:n-2], ".")
}
// Handle lookup with and without tag
d.serviceLookup(network, datacenter, service, tag, req, resp)
case "node":
if len(labels) == 1 {
goto INVALID
}
// Allow a "." in the node name, just join all the parts
node := strings.Join(labels[:n-1], ".")
d.nodeLookup(network, datacenter, node, req, resp)
default:
// Store the DC, and re-parse
datacenter = labels[n-1]
labels = labels[:n-1]
goto PARSE
}
return
INVALID:
d.logger.Printf("[WARN] dns: QName invalid: %s", qName)
resp.SetRcode(req, dns.RcodeNameError)
}
func (s HelixServer) getResponse(q dns.Question) (Response, error) {
addr := dns.SplitDomainName(q.Name)
path := []string{"helix"}
for i := len(addr) - 1; i >= 0; i-- {
path = append(path, addr[i])
}
path = append(path, dns.TypeToString[q.Qtype])
return s.Client.Get(strings.Join(path, "/"))
}
// As Path, but
// if a name contains wildcards (*), the name will be chopped of before the (first) wildcard, and
// we do a highler evel search and later find the matching names.
// So service.*.skydns.local, will look for all services under skydns.local and will later check
// for names that match service.*.skydns.local. If a wildcard is found the returned bool is true.
func PathWithWildcard(s string) (string, bool) {
l := dns.SplitDomainName(s)
for i, j := 0, len(l)-1; i < j; i, j = i+1, j-1 {
l[i], l[j] = l[j], l[i]
}
for i, k := range l {
if k == "*" {
return path.Join(append([]string{"/skydns/"}, l[:i]...)...), true
}
}
return path.Join(append([]string{"/skydns/"}, l...)...), false
}
// FromPunycode returns unicode domain name from provided punycode string.
func FromPunycode(s string) string {
tokens := dns.SplitDomainName(s)
switch {
case s == "":
return ""
case tokens == nil: // s == .
return "."
case s[len(s)-1] == '.':
tokens = append(tokens, "")
}
for i := range tokens {
tokens[i] = string(decode([]byte(tokens[i])))
}
return strings.Join(tokens, ".")
}
// getZoneForName returns the zone string that matches the name and a
// list of the DNS labels from name that are within the zone.
// For example, if "coredns.local" is a zone configured for the
// Kubernetes middleware, then getZoneForName("a.b.coredns.local")
// will return ("coredns.local", ["a", "b"]).
func (g Kubernetes) getZoneForName(name string) (string, []string) {
var zone string
var serviceSegments []string
for _, z := range g.Zones {
if dns.IsSubDomain(z, name) {
zone = z
serviceSegments = dns.SplitDomainName(name)
serviceSegments = serviceSegments[:len(serviceSegments)-dns.CountLabel(zone)]
break
}
}
return zone, serviceSegments
}
// Look in .../dns/stub/<zone>/xx for msg.Services. Loop through them
// extract <zone> and add them as forwarders (ip:port-combos) for
// the stub zones. Only numeric (i.e. IP address) hosts are used.
// Only the first zone configured on e is used for the lookup.
func (e *Etcd) updateStubZones() {
zone := e.Zones[0]
services, err := e.Records(stubDomain+"."+zone, false)
if err != nil {
return
}
stubmap := make(map[string]proxy.Proxy)
// track the nameservers on a per domain basis, but allow a list on the domain.
nameservers := map[string][]string{}
for _, serv := range services {
if serv.Port == 0 {
serv.Port = 53
}
ip := net.ParseIP(serv.Host)
if ip == nil {
log.Printf("[WARNING] Non IP address stub nameserver: %s", serv.Host)
continue
}
domain := msg.Domain(serv.Key)
labels := dns.SplitDomainName(domain)
// If the remaining name equals any of the zones we have, we ignore it.
for _, z := range e.Zones {
// Chop of left most label, because that is used as the nameserver place holder
// and drop the right most labels that belong to zone.
// We must *also* chop of dns.stub. which means cutting two more labels.
domain = dns.Fqdn(strings.Join(labels[1:len(labels)-dns.CountLabel(z)-2], "."))
if domain == z {
log.Printf("[WARNING] Skipping nameserver for domain we are authoritative for: %s", domain)
continue
}
nameservers[domain] = append(nameservers[domain], net.JoinHostPort(serv.Host, strconv.Itoa(serv.Port)))
}
}
for domain, nss := range nameservers {
stubmap[domain] = proxy.New(nss)
}
// atomic swap (at least that's what we hope it is)
if len(stubmap) > 0 {
e.Stubmap = &stubmap
}
return
}
// dispatch is used to parse a request and invoke the correct handler
func (d *DNSServer) dispatch(network string, req, resp *dns.Msg) {
// By default the query is in the default datacenter
datacenter := d.agent.config.Datacenter
// Get the QName without the domain suffix
qName := dns.Fqdn(req.Question[0].Name)
qName = strings.TrimSuffix(qName, d.domain)
// Split into the label parts
labels := dns.SplitDomainName(qName)
// The last label is either "node", "service" or a datacenter name
PARSE:
if len(labels) == 0 {
goto INVALID
}
switch labels[len(labels)-1] {
case "service":
// Handle lookup with and without tag
switch len(labels) {
case 2:
d.serviceLookup(network, datacenter, labels[0], "", req, resp)
case 3:
d.serviceLookup(network, datacenter, labels[1], labels[0], req, resp)
default:
goto INVALID
}
case "node":
if len(labels) != 2 {
goto INVALID
}
d.nodeLookup(network, datacenter, labels[0], req, resp)
default:
// Store the DC, and re-parse
datacenter = labels[len(labels)-1]
labels = labels[:len(labels)-1]
goto PARSE
}
return
INVALID:
d.logger.Printf("[WARN] dns: QName invalid: %s", qName)
resp.SetRcode(req, dns.RcodeNameError)
}
func (x *DNSTransportUpstreamCodec) Decode(msg string) ([]byte, DNSCodecHeader) {
var ret []byte
var header DNSCodecHeader
labels := dns.SplitDomainName(msg)
if len(labels) < 1+x.domain_label_count {
return nil, header
}
header_bytes, err := base32.StdEncoding.DecodeString(labels[0])
if err != nil {
return nil, header
}
x.header_codec.DecodeFromBytes(header_bytes, &header)
labels = labels[1 : len(labels)-x.domain_label_count]
for _, label := range labels {
var data []byte
data, err = base32.StdEncoding.DecodeString(label)
if err == nil {
ret = append(ret, data...)
}
}
return ret, header
}
func getQuestionName(z *Zone, req *dns.Msg) string {
lx := dns.SplitDomainName(req.Question[0].Name)
ql := lx[0 : len(lx)-z.LabelCount]
return strings.ToLower(strings.Join(ql, "."))
}
// dispatch is used to parse a request and invoke the correct handler
func (d *DNSServer) dispatch(network string, req, resp *dns.Msg) {
// By default the query is in the default datacenter
datacenter := d.agent.config.Datacenter
// Get the QName without the domain suffix
qName := strings.ToLower(dns.Fqdn(req.Question[0].Name))
qName = strings.TrimSuffix(qName, d.domain)
// Split into the label parts
labels := dns.SplitDomainName(qName)
// The last label is either "node", "service" or a datacenter name
PARSE:
n := len(labels)
if n == 0 {
goto INVALID
}
switch labels[n-1] {
case "service":
if n == 1 {
goto INVALID
}
// Support RFC 2782 style syntax
if n == 3 && strings.HasPrefix(labels[n-2], "_") && strings.HasPrefix(labels[n-3], "_") {
// Grab the tag since we make nuke it if it's tcp
tag := labels[n-2][1:]
// Treat _name._tcp.service.consul as a default, no need to filter on that tag
if tag == "tcp" {
tag = ""
}
// _name._tag.service.consul
d.serviceLookup(network, datacenter, labels[n-3][1:], tag, req, resp)
// Consul 0.3 and prior format for SRV queries
} else {
// Support "." in the label, re-join all the parts
tag := ""
if n >= 3 {
tag = strings.Join(labels[:n-2], ".")
}
// tag[.tag].name.service.consul
d.serviceLookup(network, datacenter, labels[n-2], tag, req, resp)
}
case "node":
if len(labels) == 1 {
goto INVALID
}
// Allow a "." in the node name, just join all the parts
node := strings.Join(labels[:n-1], ".")
d.nodeLookup(network, datacenter, node, req, resp)
default:
// Store the DC, and re-parse
datacenter = labels[n-1]
labels = labels[:n-1]
goto PARSE
}
return
INVALID:
d.logger.Printf("[WARN] dns: QName invalid: %s", qName)
d.addSOA(d.domain, resp)
resp.SetRcode(req, dns.RcodeNameError)
}
// dispatch is used to parse a request and invoke the correct handler
func (d *DNSServer) dispatch(network string, req, resp *dns.Msg) {
// By default the query is in the default datacenter
datacenter := d.agent.config.Datacenter
// Get the QName without the domain suffix
qName := strings.ToLower(dns.Fqdn(req.Question[0].Name))
qName = strings.TrimSuffix(qName, d.domain)
// Split into the label parts
labels := dns.SplitDomainName(qName)
// The last label is either "node", "service", "query", or a datacenter name
PARSE:
n := len(labels)
if n == 0 {
goto INVALID
}
switch labels[n-1] {
case "service":
if n == 1 {
goto INVALID
}
// Support RFC 2782 style syntax
if n == 3 && strings.HasPrefix(labels[n-2], "_") && strings.HasPrefix(labels[n-3], "_") {
// Grab the tag since we make nuke it if it's tcp
tag := labels[n-2][1:]
// Treat _name._tcp.service.consul as a default, no need to filter on that tag
if tag == "tcp" {
tag = ""
}
// _name._tag.service.consul
d.serviceLookup(network, datacenter, labels[n-3][1:], tag, req, resp)
// Consul 0.3 and prior format for SRV queries
} else {
// Support "." in the label, re-join all the parts
tag := ""
if n >= 3 {
tag = strings.Join(labels[:n-2], ".")
}
// tag[.tag].name.service.consul
d.serviceLookup(network, datacenter, labels[n-2], tag, req, resp)
}
case "node":
if n == 1 {
goto INVALID
}
// Allow a "." in the node name, just join all the parts
node := strings.Join(labels[:n-1], ".")
d.nodeLookup(network, datacenter, node, req, resp)
case "query":
if n == 1 {
goto INVALID
}
// Allow a "." in the query name, just join all the parts.
query := strings.Join(labels[:n-1], ".")
d.preparedQueryLookup(network, datacenter, query, req, resp)
case "addr":
if n != 2 {
goto INVALID
}
switch len(labels[0]) / 2 {
// IPv4
case 4:
ip, err := hex.DecodeString(labels[0])
if err != nil {
goto INVALID
}
resp.Answer = append(resp.Answer, &dns.A{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: uint32(d.config.NodeTTL / time.Second),
},
A: ip,
})
// IPv6
case 16:
ip, err := hex.DecodeString(labels[0])
if err != nil {
goto INVALID
}
resp.Answer = append(resp.Answer, &dns.AAAA{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: uint32(d.config.NodeTTL / time.Second),
},
AAAA: ip,
})
}
default:
// Store the DC, and re-parse
datacenter = labels[n-1]
labels = labels[:n-1]
goto PARSE
}
return
INVALID:
d.logger.Printf("[WARN] dns: QName invalid: %s", qName)
d.addSOA(d.domain, resp)
resp.SetRcode(req, dns.RcodeNameError)
}
func (s *Server) getSRVRecords(q dns.Question) (records []dns.RR, extra []dns.RR, err error) {
var weight uint16
services := make([]msg.Service, 0)
key := strings.TrimSuffix(q.Name, s.domain+".")
services, err = s.registry.Get(key)
if err != nil {
return
}
weight = 0
if len(services) > 0 {
weight = uint16(math.Floor(float64(100 / len(services))))
}
for _, serv := range services {
// TODO: Dynamically set weight
// a Service may have an IP as its Host"name", in this case
// substitute UUID + "." + s.domain+"." an add an A record
// with the name and IP in the additional section.
// TODO(miek): check if resolvers actually grok this
ip := net.ParseIP(serv.Host)
switch {
case ip == nil:
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 10, Weight: weight, Port: serv.Port, Target: serv.Host + "."})
continue
case ip.To4() != nil:
extra = append(extra, &dns.A{Hdr: dns.RR_Header{Name: serv.UUID + "." + s.domain + ".", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: serv.TTL}, A: ip.To4()})
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 10, Weight: weight, Port: serv.Port, Target: serv.UUID + "." + s.domain + "."})
case ip.To16() != nil:
extra = append(extra, &dns.AAAA{Hdr: dns.RR_Header{Name: serv.UUID + "." + s.domain + ".", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: serv.TTL}, AAAA: ip.To16()})
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 10, Weight: weight, Port: serv.Port, Target: serv.UUID + "." + s.domain + "."})
default:
panic("skydns: internal error")
}
}
// Append matching entries in different region than requested with a higher priority
labels := dns.SplitDomainName(key)
pos := len(labels) - 4
if len(labels) >= 4 && labels[pos] != "*" {
region := labels[pos]
labels[pos] = "*"
// TODO: This is pretty much a copy of the above, and should be abstracted
additionalServices := make([]msg.Service, len(services))
additionalServices, err = s.registry.Get(strings.Join(labels, "."))
if err != nil {
return
}
weight = 0
if len(additionalServices) <= len(services) {
return
}
weight = uint16(math.Floor(float64(100 / (len(additionalServices) - len(services)))))
for _, serv := range additionalServices {
// Exclude entries we already have
if strings.ToLower(serv.Region) == region {
continue
}
// TODO: Dynamically set priority and weight
// TODO(miek): same as above: abstract away
ip := net.ParseIP(serv.Host)
switch {
case ip == nil:
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 20, Weight: weight, Port: serv.Port, Target: serv.Host + "."})
continue
case ip.To4() != nil:
extra = append(extra, &dns.A{Hdr: dns.RR_Header{Name: serv.UUID + "." + s.domain + ".", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: serv.TTL}, A: ip.To4()})
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 20, Weight: weight, Port: serv.Port, Target: serv.UUID + "." + s.domain + "."})
case ip.To16() != nil:
extra = append(extra, &dns.AAAA{Hdr: dns.RR_Header{Name: serv.UUID + "." + s.domain + ".", Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: serv.TTL}, AAAA: ip.To16()})
records = append(records, &dns.SRV{Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: serv.TTL},
Priority: 20, Weight: weight, Port: serv.Port, Target: serv.UUID + "." + s.domain + "."})
default:
panic("skydns: internal error")
}
}
}
return
}
func (d dnsAPI) ServiceLookup(w dns.ResponseWriter, req *dns.Msg) {
qName := req.Question[0].Name
qType := req.Question[0].Qtype
name := strings.TrimSuffix(strings.ToLower(dns.Fqdn(qName)), d.Domain)
labels := dns.SplitDomainName(name)
tcp := isTCP(w.RemoteAddr())
res := &dns.Msg{}
res.Authoritative = true
res.Compress = true
res.RecursionAvailable = len(d.Recursors) > 0
res.SetReply(req)
defer func() {
if res.Rcode == dns.RcodeSuccess && qType == dns.TypeSOA {
// SOA answer if requested. at the end of the request to ensure we didn't hit NXDOMAIN
res.Answer = []dns.RR{d.soaRecord()}
}
if len(res.Answer) == 0 {
// Add authority section with SOA if the answer has no items
res.Ns = []dns.RR{d.soaRecord()}
}
w.WriteMsg(res)
}()
nxdomain := func() { res.SetRcode(req, dns.RcodeNameError) }
var service string
var proto string
var instanceID string
var leader bool
switch {
case len(labels) == 1:
// normal lookup
service = labels[0]
case len(labels) == 2 && strings.HasPrefix(labels[0], "_") && strings.HasPrefix(labels[1], "_"):
// RFC 2782 request looks like _postgres._tcp
service = labels[0][1:]
proto = labels[1][1:]
case len(labels) == 3 && labels[2] == "_i":
// address lookup for instance in RFC 2782 SRV record
service = labels[1]
instanceID = labels[0]
case len(labels) == 2 && labels[0] == "leader":
// leader lookup
leader = true
service = labels[1]
default:
nxdomain()
return
}
var instances []*discoverd.Instance
if !leader {
a, err := d.GetStore().Instances(service)
if err != nil {
log.Printf("discoverd: dns: cannot retrieve instances: %s", err)
nxdomain()
return
} else if a == nil {
nxdomain()
return
}
instances = a
}
if leader || instanceID != "" {
// we're doing a lookup for a single instance
var resInst *discoverd.Instance
if leader {
sl, err := d.GetStore().ServiceLeader(service)
if err != nil {
log.Printf("discoverd: dns: cannot retrieve service leader: %s", err)
nxdomain()
return
}
resInst = sl
} else {
for _, inst := range instances {
if inst.ID == instanceID {
resInst = inst
break
}
}
}
if resInst == nil {
nxdomain()
return
}
addr := parseAddr(resInst)
if qType != dns.TypeA && qType != dns.TypeAAAA && qType != dns.TypeANY && qType != dns.TypeSRV ||
addr.IPv4 == nil && qType == dns.TypeA ||
addr.IPv6 == nil && qType == dns.TypeAAAA {
// no results if we're looking up an record that doesn't match the
// request type or the type is incorrect
return
}
res.Answer = make([]dns.RR, 0, 2)
if qType != dns.TypeSRV {
res.Answer = append(res.Answer, addrRecord(qName, addr))
}
if qType == dns.TypeSRV || qType == dns.TypeANY {
res.Answer = append(res.Answer, d.srvRecord(qName, service, addr, false))
}
if tcp && qType == dns.TypeSRV {
res.Extra = []dns.RR{addrRecord(qName, addr)}
}
return
}
if qType == dns.TypeSOA {
// We don't need to do any more processing, as NXDOMAIN can't be reached
// beyond this point, the SOA answer is added in the deferred function
// above
return
}
addrs := make([]*addrData, 0, len(instances))
added := make(map[string]struct{}, len(instances))
for _, inst := range instances {
if proto != "" && inst.Proto != proto {
continue
}
addr := parseAddr(inst)
if _, ok := added[addr.String]; ok {
continue
}
if addr.IPv4 == nil && qType == dns.TypeA || addr.IPv6 == nil && qType == dns.TypeAAAA {
// Skip instance if we have an IPv6 address but want IPv4 or vice versa
continue
}
if qType != dns.TypeSRV {
// skip duplicate IPs if we're not doing an SRV lookup
added[addr.String] = struct{}{}
}
addrs = append(addrs, addr)
}
if len(addrs) == 0 {
// return empty response
return
}
shuffle(addrs)
// Truncate the response if we're using UDP
if !tcp && len(addrs) > maxUDPRecords {
addrs = addrs[:maxUDPRecords]
}
res.Answer = make([]dns.RR, 0, len(addrs)*2)
for _, addr := range addrs {
if qType == dns.TypeANY || qType == dns.TypeA || qType == dns.TypeAAAA {
res.Answer = append(res.Answer, addrRecord(qName, addr))
}
}
for _, addr := range addrs {
if qType == dns.TypeANY || qType == dns.TypeSRV {
res.Answer = append(res.Answer, d.srvRecord(qName, service, addr, true))
}
}
if qType == dns.TypeSRV && tcp {
// Add extra records mapping instance IDs to addresses
res.Extra = make([]dns.RR, len(addrs))
for i, addr := range addrs {
res.Extra[i] = addrRecord(d.instanceDomain(service, addr.ID), addr)
}
}
}
