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Merge pull request #17 from gonzojive/refactor-zone

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Refactor mdns.MDNSService API in zone.go.
This commit is contained in:
Armon Dadgar 2014-11-03 12:07:28 -08:00
commit 827e8b390b
3 changed files with 190 additions and 113 deletions
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5
server_test.go
View File

@ -15,10 +15,7 @@ func TestServer_StartStop(t *testing.T) {
}
func TestServer_Lookup(t *testing.T) {
s := makeService(t)
s.Service = "_foobar._tcp"
s.Init()
serv, err := NewServer(&Config{Zone: s})
serv, err := NewServer(&Config{Zone: makeServiceWithServiceName(t, "_foobar._tcp")})
if err != nil {
t.Fatalf("err: %v", err)
}

175
zone.go
View File

@ -2,10 +2,11 @@ package mdns
import (
"fmt"
"github.com/miekg/dns"
"net"
"os"
"strings"
"github.com/miekg/dns"
)
const (
@ -16,80 +17,113 @@ const (
// Zone is the interface used to integrate with the server and
// to serve records dynamically
type Zone interface {
// Records returns DNS records in response to a DNS question.
Records(q dns.Question) []dns.RR
}
// MDNSService is used to export a named service by implementing a Zone
type MDNSService struct {
Instance string // Instance name (e.g. host name)
Service string // Service name (e.g. _http._tcp.)
HostName string // Host machine DNS name
Port int // Service Port
Info string // Service info served as a TXT record
Instance string // Instance name (e.g. "hostService name")
Service string // Service name (e.g. "_http._tcp.")
Domain string // If blank, assumes "local"
Addr net.IP // @Deprecated. Service IP
ipv4Addr net.IP // Host machine IPv4 address
ipv6Addr net.IP // Host machine IPv6 address
HostName string // Host machine DNS name (e.g. "mymachine.net.")
Port int // Service Port
IPs []net.IP // IP addresses for the service's host
TXT []string // Service TXT records
serviceAddr string // Fully qualified service address
instanceAddr string // Fully qualified instance address
}
// Init should be called to setup the internal state
func (m *MDNSService) Init() error {
// Setup default domain
if m.Domain == "" {
m.Domain = "local"
// validateFQDN returns an error if the passed string is not a fully qualified
// hdomain name (more specifically, a hostname).
func validateFQDN(s string) error {
if len(s) == 0 {
return fmt.Errorf("FQDN must not be blank")
}
if s[len(s)-1] != '.' {
return fmt.Errorf("FQDN must end in period: %s", s)
}
// TODO(reddaly): Perform full validation.
return nil
}
// NewMDNSService returns a new instance of MDNSService.
//
// If domain, hostName, or ips is set to the zero value, then a default value
// will be inferred from the operating system.
//
// TODO(reddaly): This interface may need to change to account for "unique
// record" conflict rules of the mDNS protocol. Upon startup, the server should
// check to ensure that the instance name does not conflict with other instance
// names, and, if required, select a new name. There may also be conflicting
// hostName A/AAAA records.
func NewMDNSService(instance, service, domain, hostName string, port int, ips []net.IP, txt []string) (*MDNSService, error) {
// Sanity check inputs
if m.Instance == "" {
return fmt.Errorf("Missing service instance name")
if instance == "" {
return nil, fmt.Errorf("missing service instance name")
}
if m.Service == "" {
return fmt.Errorf("Missing service name")
if service == "" {
return nil, fmt.Errorf("missing service name")
}
if m.Port == 0 {
return fmt.Errorf("Missing service port")
if port == 0 {
return nil, fmt.Errorf("missing service port")
}
// Get host information
hostName, err := os.Hostname()
if err == nil {
m.HostName = fmt.Sprintf("%s.", hostName)
// Set default domain
if domain == "" {
domain = "local."
}
if err := validateFQDN(domain); err != nil {
return nil, fmt.Errorf("domain %q is not a fully-qualified domain name: %v", domain, err)
}
addrs, err := net.LookupIP(m.HostName)
// Get host information if no host is specified.
if hostName == "" {
var err error
hostName, err = os.Hostname()
if err != nil {
return nil, fmt.Errorf("could not determine host: %v", err)
}
hostName = fmt.Sprintf("%s.", hostName)
}
if err := validateFQDN(hostName); err != nil {
return nil, fmt.Errorf("hostName %q is not a fully-qualified domain name: %v", hostName, err)
}
if len(ips) == 0 {
var err error
ips, err = net.LookupIP(hostName)
if err != nil {
// Try appending the host domain suffix and lookup again
// (required for Linux-based hosts)
tmpHostName := fmt.Sprintf("%s%s.", m.HostName, m.Domain)
tmpHostName := fmt.Sprintf("%s%s.", hostName, domain)
addrs, err = net.LookupIP(tmpHostName)
ips, err = net.LookupIP(tmpHostName)
if err != nil {
return fmt.Errorf("Could not determine host IP addresses for %s", m.HostName)
return nil, fmt.Errorf("could not determine host IP addresses for %s", hostName)
}
}
}
for _, ip := range ips {
if ip.To4() == nil && ip.To16() == nil {
return nil, fmt.Errorf("invalid IP address in IPs list: %v", ip)
}
}
for i := 0; i < len(addrs); i++ {
if ipv4 := addrs[i].To4(); ipv4 != nil {
m.ipv4Addr = addrs[i]
} else if ipv6 := addrs[i].To16(); ipv6 != nil {
m.ipv6Addr = addrs[i]
}
}
} else {
return fmt.Errorf("Could not determine host")
}
// Create the full addresses
m.serviceAddr = fmt.Sprintf("%s.%s.",
trimDot(m.Service), trimDot(m.Domain))
m.instanceAddr = fmt.Sprintf("%s.%s",
trimDot(m.Instance), m.serviceAddr)
return nil
return &MDNSService{
Instance: instance,
Service: service,
Domain: domain,
HostName: hostName,
Port: port,
IPs: ips,
TXT: txt,
serviceAddr: fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
instanceAddr: fmt.Sprintf("%s.%s.%s.", instance, trimDot(service), trimDot(domain)),
}, nil
}
// trimDot is used to trim the dots from the start or end of a string
@ -97,6 +131,7 @@ func trimDot(s string) string {
return strings.Trim(s, ".")
}
// Records returns DNS records in response to a DNS question.
func (m *MDNSService) Records(q dns.Question) []dns.RR {
switch q.Name {
case m.serviceAddr:
@ -126,7 +161,7 @@ func (m *MDNSService) serviceRecords(q dns.Question) []dns.RR {
}
servRec := []dns.RR{rr}
// Get the isntance records
// Get the instance records
instRecs := m.instanceRecords(dns.Question{
Name: m.instanceAddr,
Qtype: dns.TypeANY,
@ -157,42 +192,46 @@ func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
return recs
case dns.TypeA:
// Only handle if we have a ipv4 addr
ipv4 := m.Addr.To4()
if ipv4 != nil {
m.ipv4Addr = ipv4
} else if m.ipv4Addr == nil {
return nil
}
a := &dns.A{
var rr []dns.RR
for _, ip := range m.IPs {
if ip4 := ip.To4(); ip4 != nil {
rr = append(rr, &dns.A{
Hdr: dns.RR_Header{
Name: m.HostName,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: defaultTTL,
},
A: m.ipv4Addr,
A: ip4,
})
}
return []dns.RR{a}
}
return rr
case dns.TypeAAAA:
// Only handle if we have a ipv6 addr
ipv6 := m.Addr.To16()
if ipv6 != nil && m.Addr.To4() == nil {
m.ipv6Addr = ipv6
} else if m.ipv6Addr == nil && m.Addr.To4() != nil {
return nil
var rr []dns.RR
for _, ip := range m.IPs {
if ip.To4() != nil {
// TODO(reddaly): IPv4 addresses could be encoded in IPv6 format and
// putinto AAAA records, but the current logic puts ipv4-encodable
// addresses into the A records exclusively. Perhaps this should be
// configurable?
continue
}
a4 := &dns.AAAA{
if ip16 := ip.To16(); ip16 != nil {
rr = append(rr, &dns.AAAA{
Hdr: dns.RR_Header{
Name: m.HostName,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: defaultTTL,
},
AAAA: m.ipv6Addr,
AAAA: ip16,
})
}
return []dns.RR{a4}
}
return rr
case dns.TypeSRV:
// Create the SRV Record
@ -231,7 +270,7 @@ func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
Class: dns.ClassINET,
Ttl: defaultTTL,
},
Txt: []string{m.Info},
Txt: m.TXT,
}
return []dns.RR{txt}
}

97
zone_test.go
View File

@ -2,25 +2,65 @@ package mdns
import (
"bytes"
"github.com/miekg/dns"
"net"
"reflect"
"testing"
"github.com/miekg/dns"
)
func makeService(t *testing.T) *MDNSService {
m := &MDNSService{
Instance: "hostname.",
Service: "_http._tcp.",
Port: 80,
Info: "Local web server",
Domain: "local.",
return makeServiceWithServiceName(t, "_http._tcp")
}
if err := m.Init(); err != nil {
func makeServiceWithServiceName(t *testing.T, service string) *MDNSService {
m, err := NewMDNSService(
"hostname",
service,
"local.",
"testhost.",
80, // port
[]net.IP{net.IP([]byte{192, 168, 0, 42}), net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")},
[]string{"Local web server"}) // TXT
if err != nil {
t.Fatalf("err: %v", err)
}
return m
}
func TestNewMDNSService_BadParams(t *testing.T) {
for _, test := range []struct {
testName string
hostName string
domain string
}{
{
"NewMDNSService should fail when passed hostName that is not a legal fully-qualified domain name",
"hostname", // not legal FQDN - should be "hostname." or "hostname.local.", etc.
"local.", // legal
},
{
"NewMDNSService should fail when passed domain that is not a legal fully-qualified domain name",
"hostname.", // legal
"local", // should be "local."
},
} {
_, err := NewMDNSService(
"instance name",
"_http._tcp",
test.domain,
test.hostName,
80, // port
[]net.IP{net.IP([]byte{192, 168, 0, 42})},
[]string{"Local web server"}) // TXT
if err == nil {
t.Fatalf("%s: error expected, but got none", test.testName)
}
}
}
func TestMDNSService_BadAddr(t *testing.T) {
s := makeService(t)
q := dns.Question{
@ -40,35 +80,32 @@ func TestMDNSService_ServiceAddr(t *testing.T) {
Qtype: dns.TypeANY,
}
recs := s.Records(q)
if len(recs) != 5 {
t.Fatalf("bad: %v", recs)
if got, want := len(recs), 5; got != want {
t.Fatalf("got %d records, want %d: %v", got, want, recs)
}
ptr, ok := recs[0].(*dns.PTR)
if !ok {
t.Fatalf("bad: %v", recs[0])
if ptr, ok := recs[0].(*dns.PTR); !ok {
t.Errorf("recs[0] should be PTR record, got: %v, all records: %v", recs[0], recs)
} else if got, want := ptr.Ptr, "hostname._http._tcp.local."; got != want {
t.Fatalf("bad PTR record %v: got %v, want %v", ptr, got, want)
}
if _, ok := recs[1].(*dns.SRV); !ok {
t.Fatalf("bad: %v", recs[1])
t.Errorf("recs[1] should be SRV record, got: %v, all reccords: %v", recs[1], recs)
}
if _, ok := recs[2].(*dns.A); !ok {
t.Fatalf("bad: %v", recs[2])
t.Errorf("recs[2] should be A record, got: %v, all records: %v", recs[2], recs)
}
if _, ok := recs[3].(*dns.AAAA); !ok {
t.Fatalf("bad: %v", recs[3])
t.Errorf("recs[3] should be AAAA record, got: %v, all records: %v", recs[3], recs)
}
if _, ok := recs[4].(*dns.TXT); !ok {
t.Fatalf("bad: %v", recs[4])
}
if ptr.Ptr != s.instanceAddr {
t.Fatalf("bad: %v", recs[0])
t.Errorf("recs[4] should be TXT record, got: %v, all records: %v", recs[4], recs)
}
q.Qtype = dns.TypePTR
recs2 := s.Records(q)
if !reflect.DeepEqual(recs, recs2) {
t.Fatalf("no match: %v %v", recs, recs2)
if recs2 := s.Records(q); !reflect.DeepEqual(recs, recs2) {
t.Fatalf("PTR question should return same result as ANY question: ANY => %v, PTR => %v", recs, recs2)
}
}
@ -136,7 +173,7 @@ func TestMDNSService_InstanceAddr_A(t *testing.T) {
if !ok {
t.Fatalf("bad: %v", recs[0])
}
if !bytes.Equal(a.A, s.ipv4Addr) {
if !bytes.Equal(a.A, []byte{192, 168, 0, 42}) {
t.Fatalf("bad: %v", recs[0])
}
}
@ -155,7 +192,11 @@ func TestMDNSService_InstanceAddr_AAAA(t *testing.T) {
if !ok {
t.Fatalf("bad: %v", recs[0])
}
if !bytes.Equal(a4.AAAA, s.ipv6Addr) {
ip6 := net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")
if got := len(ip6); got != net.IPv6len {
t.Fatalf("test IP failed to parse (len = %d, want %d)", got, net.IPv6len)
}
if !bytes.Equal(a4.AAAA, ip6) {
t.Fatalf("bad: %v", recs[0])
}
}
@ -174,7 +215,7 @@ func TestMDNSService_InstanceAddr_TXT(t *testing.T) {
if !ok {
t.Fatalf("bad: %v", recs[0])
}
if txt.Txt[0] != s.Info {
t.Fatalf("bad: %v", recs[0])
if got, want := txt.Txt, s.TXT; !reflect.DeepEqual(got, want) {
t.Fatalf("TXT record mismatch for %v: got %v, want %v", recs[0], got, want)
}
}