Bring etcd support for bucket DNS federation

- Supports centralized `config.json` - Supports centralized `bucket` service records for client lookups - implement a new proxy forwarder
2026-08-06 15:51:14 +03:00 · 2018-02-02 18:18:52 -08:00
parent 7872c192ec
commit 853ea371ce
144 changed files with 77684 additions and 81 deletions
@@ -0,0 +1,201 @@
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@@ -0,0 +1,48 @@
+package msg
+
+import (
+	"path"
+	"strings"
+
+	"github.com/coredns/coredns/plugin/pkg/dnsutil"
+
+	"github.com/miekg/dns"
+)
+
+// 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, prefix 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{"/" + prefix + "/"}, l...)...)
+}
+
+// Domain is the opposite of Path.
+func Domain(s string) string {
+	l := strings.Split(s, "/")
+	// start with 1, to strip /skydns
+	for i, j := 1, len(l)-1; i < j; i, j = i+1, j-1 {
+		l[i], l[j] = l[j], l[i]
+	}
+	return dnsutil.Join(l[1 : len(l)-1])
+}
+
+// PathWithWildcard ascts as Path, but if a name contains wildcards (* or any), 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, prefix 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 == "*" || k == "any" {
+			return path.Join(append([]string{"/" + prefix + "/"}, l[:i]...)...), true
+		}
+	}
+	return path.Join(append([]string{"/" + prefix + "/"}, l...)...), false
+}
@@ -0,0 +1,203 @@
+// Package msg defines the Service structure which is used for service discovery.
+package msg
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/miekg/dns"
+)
+
+// Service defines a discoverable service in etcd. It is the rdata from a SRV
+// record, but with a twist.  Host (Target in SRV) must be a domain name, but
+// if it looks like an IP address (4/6), we will treat it like an IP address.
+type Service struct {
+	Host     string `json:"host,omitempty"`
+	Port     int    `json:"port,omitempty"`
+	Priority int    `json:"priority,omitempty"`
+	Weight   int    `json:"weight,omitempty"`
+	Text     string `json:"text,omitempty"`
+	Mail     bool   `json:"mail,omitempty"` // Be an MX record. Priority becomes Preference.
+	TTL      uint32 `json:"ttl,omitempty"`
+
+	// When a SRV record with a "Host: IP-address" is added, we synthesize
+	// a srv.Target domain name.  Normally we convert the full Key where
+	// the record lives to a DNS name and use this as the srv.Target.  When
+	// TargetStrip > 0 we strip the left most TargetStrip labels from the
+	// DNS name.
+	TargetStrip int `json:"targetstrip,omitempty"`
+
+	// Group is used to group (or *not* to group) different services
+	// together. Services with an identical Group are returned in the same
+	// answer.
+	Group string `json:"group,omitempty"`
+
+	// Etcd key where we found this service and ignored from json un-/marshalling
+	Key string `json:"-"`
+}
+
+// RR returns an RR representation of s. It is in a condensed form to minimize space
+// when this is returned in a DNS message.
+// The RR will look like:
+//	1.rails.production.east.skydns.local. 300 CH TXT "service1.example.com:8080(10,0,,false)[0,]"
+//                      etcd Key              Ttl               Host:Port          <   see below   >
+// between parens: (Priority, Weight, Text (only first 200 bytes!), Mail)
+// between blockquotes: [TargetStrip,Group]
+// If the record is synthesised by CoreDNS (i.e. no lookup in etcd happened):
+//
+//	TODO(miek): what to put here?
+//
+func (s *Service) RR() *dns.TXT {
+	l := len(s.Text)
+	if l > 200 {
+		l = 200
+	}
+	t := new(dns.TXT)
+	t.Hdr.Class = dns.ClassCHAOS
+	t.Hdr.Ttl = s.TTL
+	t.Hdr.Rrtype = dns.TypeTXT
+	t.Hdr.Name = Domain(s.Key)
+
+	t.Txt = make([]string, 1)
+	t.Txt[0] = fmt.Sprintf("%s:%d(%d,%d,%s,%t)[%d,%s]",
+		s.Host, s.Port,
+		s.Priority, s.Weight, s.Text[:l], s.Mail,
+		s.TargetStrip, s.Group)
+	return t
+}
+
+// NewSRV returns a new SRV record based on the Service.
+func (s *Service) NewSRV(name string, weight uint16) *dns.SRV {
+	host := targetStrip(dns.Fqdn(s.Host), s.TargetStrip)
+
+	return &dns.SRV{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeSRV, Class: dns.ClassINET, Ttl: s.TTL},
+		Priority: uint16(s.Priority), Weight: weight, Port: uint16(s.Port), Target: dns.Fqdn(host)}
+}
+
+// NewMX returns a new MX record based on the Service.
+func (s *Service) NewMX(name string) *dns.MX {
+	host := targetStrip(dns.Fqdn(s.Host), s.TargetStrip)
+
+	return &dns.MX{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeMX, Class: dns.ClassINET, Ttl: s.TTL},
+		Preference: uint16(s.Priority), Mx: host}
+}
+
+// NewA returns a new A record based on the Service.
+func (s *Service) NewA(name string, ip net.IP) *dns.A {
+	return &dns.A{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: s.TTL}, A: ip}
+}
+
+// NewAAAA returns a new AAAA record based on the Service.
+func (s *Service) NewAAAA(name string, ip net.IP) *dns.AAAA {
+	return &dns.AAAA{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: s.TTL}, AAAA: ip}
+}
+
+// NewCNAME returns a new CNAME record based on the Service.
+func (s *Service) NewCNAME(name string, target string) *dns.CNAME {
+	return &dns.CNAME{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: s.TTL}, Target: dns.Fqdn(target)}
+}
+
+// NewTXT returns a new TXT record based on the Service.
+func (s *Service) NewTXT(name string) *dns.TXT {
+	return &dns.TXT{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: s.TTL}, Txt: split255(s.Text)}
+}
+
+// NewPTR returns a new PTR record based on the Service.
+func (s *Service) NewPTR(name string, target string) *dns.PTR {
+	return &dns.PTR{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: s.TTL}, Ptr: dns.Fqdn(target)}
+}
+
+// NewNS returns a new NS record based on the Service.
+func (s *Service) NewNS(name string) *dns.NS {
+	host := targetStrip(dns.Fqdn(s.Host), s.TargetStrip)
+	return &dns.NS{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: s.TTL}, Ns: host}
+}
+
+// Group checks the services in sx, it looks for a Group attribute on the shortest
+// keys. If there are multiple shortest keys *and* the group attribute disagrees (and
+// is not empty), we don't consider it a group.
+// If a group is found, only services with *that* group (or no group) will be returned.
+func Group(sx []Service) []Service {
+	if len(sx) == 0 {
+		return sx
+	}
+
+	// Shortest key with group attribute sets the group for this set.
+	group := sx[0].Group
+	slashes := strings.Count(sx[0].Key, "/")
+	length := make([]int, len(sx))
+	for i, s := range sx {
+		x := strings.Count(s.Key, "/")
+		length[i] = x
+		if x < slashes {
+			if s.Group == "" {
+				break
+			}
+			slashes = x
+			group = s.Group
+		}
+	}
+
+	if group == "" {
+		return sx
+	}
+
+	ret := []Service{} // with slice-tricks in sx we can prolly save this allocation (TODO)
+
+	for i, s := range sx {
+		if s.Group == "" {
+			ret = append(ret, s)
+			continue
+		}
+
+		// Disagreement on the same level
+		if length[i] == slashes && s.Group != group {
+			return sx
+		}
+
+		if s.Group == group {
+			ret = append(ret, s)
+		}
+	}
+	return ret
+}
+
+// Split255 splits a string into 255 byte chunks.
+func split255(s string) []string {
+	if len(s) < 255 {
+		return []string{s}
+	}
+	sx := []string{}
+	p, i := 0, 255
+	for {
+		if i <= len(s) {
+			sx = append(sx, s[p:i])
+		} else {
+			sx = append(sx, s[p:])
+			break
+
+		}
+		p, i = p+255, i+255
+	}
+
+	return sx
+}
+
+// targetStrip strips "targetstrip" labels from the left side of the fully qualified name.
+func targetStrip(name string, targetStrip int) string {
+	if targetStrip == 0 {
+		return name
+	}
+
+	offset, end := 0, false
+	for i := 0; i < targetStrip; i++ {
+		offset, end = dns.NextLabel(name, offset)
+	}
+	if end {
+		// We overshot the name, use the orignal one.
+		offset = 0
+	}
+	name = name[offset:]
+	return name
+}
@@ -0,0 +1,33 @@
+package msg
+
+import (
+	"net"
+
+	"github.com/miekg/dns"
+)
+
+// HostType returns the DNS type of what is encoded in the Service Host field. We're reusing
+// dns.TypeXXX to not reinvent a new set of identifiers.
+//
+// dns.TypeA: the service's Host field contains an A record.
+// dns.TypeAAAA: the service's Host field contains an AAAA record.
+// dns.TypeCNAME: the service's Host field contains a name.
+//
+// Note that a service can double/triple as a TXT record or MX record.
+func (s *Service) HostType() (what uint16, normalized net.IP) {
+
+	ip := net.ParseIP(s.Host)
+
+	switch {
+	case ip == nil:
+		return dns.TypeCNAME, nil
+
+	case ip.To4() != nil:
+		return dns.TypeA, ip.To4()
+
+	case ip.To4() == nil:
+		return dns.TypeAAAA, ip.To16()
+	}
+	// This should never be reached.
+	return dns.TypeNone, nil
+}
@@ -0,0 +1,15 @@
+package dnsutil
+
+import "github.com/miekg/dns"
+
+// DuplicateCNAME returns true if r already exists in records.
+func DuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {
+	for _, rec := range records {
+		if v, ok := rec.(*dns.CNAME); ok {
+			if v.Target == r.Target {
+				return true
+			}
+		}
+	}
+	return false
+}
@@ -0,0 +1,12 @@
+package dnsutil
+
+import "github.com/miekg/dns"
+
+// Dedup de-duplicates a message.
+func Dedup(m *dns.Msg) *dns.Msg {
+	// TODO(miek): expensive!
+	m.Answer = dns.Dedup(m.Answer, nil)
+	m.Ns = dns.Dedup(m.Ns, nil)
+	m.Extra = dns.Dedup(m.Extra, nil)
+	return m
+}
@@ -0,0 +1,2 @@
+// Package dnsutil contains DNS related helper functions.
+package dnsutil
@@ -0,0 +1,82 @@
+package dnsutil
+
+import (
+	"fmt"
+	"net"
+	"os"
+
+	"github.com/miekg/dns"
+)
+
+// ParseHostPortOrFile parses the strings in s, each string can either be a address,
+// address:port or a filename. The address part is checked and the filename case a
+// resolv.conf like file is parsed and the nameserver found are returned.
+func ParseHostPortOrFile(s ...string) ([]string, error) {
+	var servers []string
+	for _, host := range s {
+		addr, _, err := net.SplitHostPort(host)
+		if err != nil {
+			// Parse didn't work, it is not a addr:port combo
+			if net.ParseIP(host) == nil {
+				// Not an IP address.
+				ss, err := tryFile(host)
+				if err == nil {
+					servers = append(servers, ss...)
+					continue
+				}
+				return servers, fmt.Errorf("not an IP address or file: %q", host)
+			}
+			ss := net.JoinHostPort(host, "53")
+			servers = append(servers, ss)
+			continue
+		}
+
+		if net.ParseIP(addr) == nil {
+			// No an IP address.
+			ss, err := tryFile(host)
+			if err == nil {
+				servers = append(servers, ss...)
+				continue
+			}
+			return servers, fmt.Errorf("not an IP address or file: %q", host)
+		}
+		servers = append(servers, host)
+	}
+	return servers, nil
+}
+
+// Try to open this is a file first.
+func tryFile(s string) ([]string, error) {
+	c, err := dns.ClientConfigFromFile(s)
+	if err == os.ErrNotExist {
+		return nil, fmt.Errorf("failed to open file %q: %q", s, err)
+	} else if err != nil {
+		return nil, err
+	}
+
+	servers := []string{}
+	for _, s := range c.Servers {
+		servers = append(servers, net.JoinHostPort(s, c.Port))
+	}
+	return servers, nil
+}
+
+// ParseHostPort will check if the host part is a valid IP address, if the
+// IP address is valid, but no port is found, defaultPort is added.
+func ParseHostPort(s, defaultPort string) (string, error) {
+	addr, port, err := net.SplitHostPort(s)
+	if port == "" {
+		port = defaultPort
+	}
+	if err != nil {
+		if net.ParseIP(s) == nil {
+			return "", fmt.Errorf("must specify an IP address: `%s'", s)
+		}
+		return net.JoinHostPort(s, port), nil
+	}
+
+	if net.ParseIP(addr) == nil {
+		return "", fmt.Errorf("must specify an IP address: `%s'", addr)
+	}
+	return net.JoinHostPort(addr, port), nil
+}
@@ -0,0 +1,19 @@
+package dnsutil
+
+import (
+	"strings"
+
+	"github.com/miekg/dns"
+)
+
+// Join joins labels to form a fully qualified domain name. If the last label is
+// the root label it is ignored. Not other syntax checks are performed.
+func Join(labels []string) string {
+	ll := len(labels)
+	if labels[ll-1] == "." {
+		s := strings.Join(labels[:ll-1], ".")
+		return dns.Fqdn(s)
+	}
+	s := strings.Join(labels, ".")
+	return dns.Fqdn(s)
+}
@@ -0,0 +1,68 @@
+package dnsutil
+
+import (
+	"net"
+	"strings"
+)
+
+// ExtractAddressFromReverse turns a standard PTR reverse record name
+// into an IP address. This works for ipv4 or ipv6.
+//
+// 54.119.58.176.in-addr.arpa. becomes 176.58.119.54. If the conversion
+// fails the empty string is returned.
+func ExtractAddressFromReverse(reverseName string) string {
+	search := ""
+
+	f := reverse
+
+	switch {
+	case strings.HasSuffix(reverseName, v4arpaSuffix):
+		search = strings.TrimSuffix(reverseName, v4arpaSuffix)
+	case strings.HasSuffix(reverseName, v6arpaSuffix):
+		search = strings.TrimSuffix(reverseName, v6arpaSuffix)
+		f = reverse6
+	default:
+		return ""
+	}
+
+	// Reverse the segments and then combine them.
+	return f(strings.Split(search, "."))
+}
+
+func reverse(slice []string) string {
+	for i := 0; i < len(slice)/2; i++ {
+		j := len(slice) - i - 1
+		slice[i], slice[j] = slice[j], slice[i]
+	}
+	ip := net.ParseIP(strings.Join(slice, ".")).To4()
+	if ip == nil {
+		return ""
+	}
+	return ip.String()
+}
+
+// reverse6 reverse the segments and combine them according to RFC3596:
+// b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2
+// is reversed to 2001:db8::567:89ab
+func reverse6(slice []string) string {
+	for i := 0; i < len(slice)/2; i++ {
+		j := len(slice) - i - 1
+		slice[i], slice[j] = slice[j], slice[i]
+	}
+	slice6 := []string{}
+	for i := 0; i < len(slice)/4; i++ {
+		slice6 = append(slice6, strings.Join(slice[i*4:i*4+4], ""))
+	}
+	ip := net.ParseIP(strings.Join(slice6, ":")).To16()
+	if ip == nil {
+		return ""
+	}
+	return ip.String()
+}
+
+const (
+	// v4arpaSuffix is the reverse tree suffix for v4 IP addresses.
+	v4arpaSuffix = ".in-addr.arpa."
+	// v6arpaSuffix is the reverse tree suffix for v6 IP addresses.
+	v6arpaSuffix = ".ip6.arpa."
+)
@@ -0,0 +1,20 @@
+package dnsutil
+
+import (
+	"errors"
+
+	"github.com/miekg/dns"
+)
+
+// TrimZone removes the zone component from q. It returns the trimmed
+// name or an error is zone is longer then qname. The trimmed name will be returned
+// without a trailing dot.
+func TrimZone(q string, z string) (string, error) {
+	zl := dns.CountLabel(z)
+	i, ok := dns.PrevLabel(q, zl)
+	if ok || i-1 < 0 {
+		return "", errors.New("trimzone: overshot qname: " + q + "for zone " + z)
+	}
+	// This includes the '.', remove on return
+	return q[:i-1], nil
+}