Refactor mdns.MDNSService API in zone.go.
- Change API for constructing an MDNSService: use NewMDNSService func instead of creating an MDNSService struct and calling its Init method. - Allow full specification of the host name and IP addresses of an MDNSService instead of relying on the net package to infer them from the OS. - Remove deprecated Addr member of MDNSService. - Modify tests to comply with new API.
This commit is contained in:
Red Daly
parent
6f752e8251
commit
e39d11792c
@ -15,10 +15,7 @@ func TestServer_StartStop(t *testing.T) {
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}
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func TestServer_Lookup(t *testing.T) {
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s := makeService(t)
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s.Service = "_foobar._tcp"
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s.Init()
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serv, err := NewServer(&Config{Zone: s})
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serv, err := NewServer(&Config{Zone: makeServiceWithServiceName(t, "_foobar._tcp")})
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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175
zone.go
175
zone.go
@ -2,10 +2,11 @@ package mdns
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import (
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"fmt"
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"github.com/miekg/dns"
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"net"
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"os"
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"strings"
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"github.com/miekg/dns"
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)
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const (
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@ -16,80 +17,113 @@ const (
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// Zone is the interface used to integrate with the server and
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// to serve records dynamically
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type Zone interface {
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// Records returns DNS records in response to a DNS question.
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Records(q dns.Question) []dns.RR
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}
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// MDNSService is used to export a named service by implementing a Zone
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type MDNSService struct {
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Instance string // Instance name (e.g. host name)
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Service string // Service name (e.g. _http._tcp.)
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HostName string // Host machine DNS name
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Port int // Service Port
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Info string // Service info served as a TXT record
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Instance string // Instance name (e.g. "hostService name")
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Service string // Service name (e.g. "_http._tcp.")
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Domain string // If blank, assumes "local"
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Addr net.IP // @Deprecated. Service IP
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ipv4Addr net.IP // Host machine IPv4 address
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ipv6Addr net.IP // Host machine IPv6 address
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HostName string // Host machine DNS name (e.g. "mymachine.net.")
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Port int // Service Port
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IPs []net.IP // IP addresses for the service's host
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TXT []string // Service TXT records
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serviceAddr string // Fully qualified service address
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instanceAddr string // Fully qualified instance address
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}
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// Init should be called to setup the internal state
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func (m *MDNSService) Init() error {
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// Setup default domain
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if m.Domain == "" {
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m.Domain = "local"
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// validateFQDN returns an error if the passed string is not a fully qualified
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// hdomain name (more specifically, a hostname).
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func validateFQDN(s string) error {
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if len(s) == 0 {
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return fmt.Errorf("FQDN must not be blank")
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}
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if s[len(s)-1] != '.' {
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return fmt.Errorf("FQDN must end in period: %s", s)
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}
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// TODO(reddaly): Perform full validation.
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return nil
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}
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// NewMDNSService returns a new instance of MDNSService.
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//
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// If domain, hostName, or ips is set to the zero value, then a default value
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// will be inferred from the operating system.
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//
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// TODO(reddaly): This interface may need to change to account for "unique
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// record" conflict rules of the mDNS protocol. Upon startup, the server should
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// check to ensure that the instance name does not conflict with other instance
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// names, and, if required, select a new name. There may also be conflicting
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// hostName A/AAAA records.
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func NewMDNSService(instance, service, domain, hostName string, port int, ips []net.IP, txt []string) (*MDNSService, error) {
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// Sanity check inputs
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if m.Instance == "" {
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return fmt.Errorf("Missing service instance name")
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if instance == "" {
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return nil, fmt.Errorf("missing service instance name")
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}
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if m.Service == "" {
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return fmt.Errorf("Missing service name")
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if service == "" {
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return nil, fmt.Errorf("missing service name")
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}
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if m.Port == 0 {
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return fmt.Errorf("Missing service port")
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if port == 0 {
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return nil, fmt.Errorf("missing service port")
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}
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// Get host information
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hostName, err := os.Hostname()
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if err == nil {
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m.HostName = fmt.Sprintf("%s.", hostName)
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// Set default domain
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if domain == "" {
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domain = "local."
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}
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if err := validateFQDN(domain); err != nil {
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return nil, fmt.Errorf("domain %q is not a fully-qualified domain name: %v", domain, err)
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}
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addrs, err := net.LookupIP(m.HostName)
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// Get host information if no host is specified.
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if hostName == "" {
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var err error
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hostName, err = os.Hostname()
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if err != nil {
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return nil, fmt.Errorf("could not determine host: %v", err)
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}
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hostName = fmt.Sprintf("%s.", hostName)
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}
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if err := validateFQDN(hostName); err != nil {
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return nil, fmt.Errorf("hostName %q is not a fully-qualified domain name: %v", hostName, err)
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}
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if len(ips) == 0 {
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var err error
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ips, err = net.LookupIP(hostName)
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if err != nil {
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// Try appending the host domain suffix and lookup again
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// (required for Linux-based hosts)
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tmpHostName := fmt.Sprintf("%s%s.", m.HostName, m.Domain)
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tmpHostName := fmt.Sprintf("%s%s.", hostName, domain)
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addrs, err = net.LookupIP(tmpHostName)
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ips, err = net.LookupIP(tmpHostName)
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if err != nil {
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return fmt.Errorf("Could not determine host IP addresses for %s", m.HostName)
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return nil, fmt.Errorf("could not determine host IP addresses for %s", hostName)
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}
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}
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}
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for _, ip := range ips {
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if ip.To4() == nil && ip.To16() == nil {
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return nil, fmt.Errorf("invalid IP address in IPs list: %v", ip)
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}
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}
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for i := 0; i < len(addrs); i++ {
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if ipv4 := addrs[i].To4(); ipv4 != nil {
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m.ipv4Addr = addrs[i]
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} else if ipv6 := addrs[i].To16(); ipv6 != nil {
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m.ipv6Addr = addrs[i]
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}
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}
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} else {
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return fmt.Errorf("Could not determine host")
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}
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// Create the full addresses
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m.serviceAddr = fmt.Sprintf("%s.%s.",
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trimDot(m.Service), trimDot(m.Domain))
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m.instanceAddr = fmt.Sprintf("%s.%s",
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trimDot(m.Instance), m.serviceAddr)
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return nil
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return &MDNSService{
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Instance: instance,
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Service: service,
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Domain: domain,
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HostName: hostName,
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Port: port,
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IPs: ips,
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TXT: txt,
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serviceAddr: fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
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instanceAddr: fmt.Sprintf("%s.%s.%s.", instance, trimDot(service), trimDot(domain)),
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}, nil
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}
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// trimDot is used to trim the dots from the start or end of a string
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@ -97,6 +131,7 @@ func trimDot(s string) string {
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return strings.Trim(s, ".")
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}
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// Records returns DNS records in response to a DNS question.
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func (m *MDNSService) Records(q dns.Question) []dns.RR {
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switch q.Name {
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case m.serviceAddr:
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@ -126,7 +161,7 @@ func (m *MDNSService) serviceRecords(q dns.Question) []dns.RR {
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}
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servRec := []dns.RR{rr}
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// Get the isntance records
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// Get the instance records
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instRecs := m.instanceRecords(dns.Question{
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Name: m.instanceAddr,
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Qtype: dns.TypeANY,
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@ -157,42 +192,46 @@ func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
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return recs
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case dns.TypeA:
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// Only handle if we have a ipv4 addr
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ipv4 := m.Addr.To4()
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if ipv4 != nil {
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m.ipv4Addr = ipv4
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} else if m.ipv4Addr == nil {
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return nil
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}
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a := &dns.A{
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var rr []dns.RR
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for _, ip := range m.IPs {
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if ip4 := ip.To4(); ip4 != nil {
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rr = append(rr, &dns.A{
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Hdr: dns.RR_Header{
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Name: m.HostName,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: defaultTTL,
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},
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A: m.ipv4Addr,
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A: ip4,
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})
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}
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return []dns.RR{a}
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}
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return rr
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case dns.TypeAAAA:
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// Only handle if we have a ipv6 addr
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ipv6 := m.Addr.To16()
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if ipv6 != nil && m.Addr.To4() == nil {
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m.ipv6Addr = ipv6
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} else if m.ipv6Addr == nil && m.Addr.To4() != nil {
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return nil
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var rr []dns.RR
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for _, ip := range m.IPs {
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if ip.To4() != nil {
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// TODO(reddaly): IPv4 addresses could be encoded in IPv6 format and
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// putinto AAAA records, but the current logic puts ipv4-encodable
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// addresses into the A records exclusively. Perhaps this should be
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// configurable?
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continue
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}
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a4 := &dns.AAAA{
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if ip16 := ip.To16(); ip16 != nil {
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rr = append(rr, &dns.AAAA{
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Hdr: dns.RR_Header{
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Name: m.HostName,
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Rrtype: dns.TypeAAAA,
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Class: dns.ClassINET,
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Ttl: defaultTTL,
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},
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AAAA: m.ipv6Addr,
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AAAA: ip16,
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})
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}
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return []dns.RR{a4}
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}
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return rr
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case dns.TypeSRV:
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// Create the SRV Record
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@ -231,7 +270,7 @@ func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
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Class: dns.ClassINET,
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Ttl: defaultTTL,
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},
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Txt: []string{m.Info},
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Txt: m.TXT,
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}
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return []dns.RR{txt}
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}
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99
zone_test.go
99
zone_test.go
@ -2,25 +2,65 @@ package mdns
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import (
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"bytes"
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"github.com/miekg/dns"
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"net"
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"reflect"
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"testing"
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"github.com/miekg/dns"
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)
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func makeService(t *testing.T) *MDNSService {
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m := &MDNSService{
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Instance: "hostname.",
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Service: "_http._tcp.",
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Port: 80,
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Info: "Local web server",
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Domain: "local.",
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}
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if err := m.Init(); err != nil {
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return makeServiceWithServiceName(t, "_http._tcp")
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}
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func makeServiceWithServiceName(t *testing.T, service string) *MDNSService {
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m, err := NewMDNSService(
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"hostname",
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service,
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"local.",
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"testhost.",
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80, // port
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[]net.IP{net.IP([]byte{192, 168, 0, 42}), net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")},
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[]string{"Local web server"}) // TXT
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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return m
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}
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func TestNewMDNSService_BadParams(t *testing.T) {
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for _, test := range []struct {
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testName string
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hostName string
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domain string
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}{
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{
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"NewMDNSService should fail when passed hostName that is not a legal fully-qualified domain name",
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"hostname", // not legal FQDN - should be "hostname." or "hostname.local.", etc.
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"local.", // legal
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},
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{
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"NewMDNSService should fail when passed domain that is not a legal fully-qualified domain name",
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"hostname.", // legal
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"local", // should be "local."
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},
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} {
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_, err := NewMDNSService(
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"instance name",
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"_http._tcp",
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test.Domain,
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test.hostName,
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80, // port
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[]net.IP{net.IP([]byte{192, 168, 0, 42})},
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[]string{"Local web server"}) // TXT
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if err == nil {
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t.Fatalf("%s: error expected, but got none", test.testName)
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}
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}
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}
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func TestMDNSService_BadAddr(t *testing.T) {
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s := makeService(t)
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q := dns.Question{
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@ -40,35 +80,32 @@ func TestMDNSService_ServiceAddr(t *testing.T) {
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Qtype: dns.TypeANY,
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}
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recs := s.Records(q)
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if len(recs) != 5 {
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t.Fatalf("bad: %v", recs)
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if got, want := len(recs), 5; got != want {
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t.Fatalf("got %d records, want %d: %v", got, want, recs)
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}
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ptr, ok := recs[0].(*dns.PTR)
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if !ok {
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t.Fatalf("bad: %v", recs[0])
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if ptr, ok := recs[0].(*dns.PTR); !ok {
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t.Errorf("recs[0] should be PTR record, got: %v, all records: %v", recs[0], recs)
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} else if got, want := ptr.Ptr, "hostname._http._tcp.local."; got != want {
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t.Fatalf("bad PTR record %v: got %v, want %v", ptr, got, want)
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}
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if _, ok := recs[1].(*dns.SRV); !ok {
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t.Fatalf("bad: %v", recs[1])
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t.Errorf("recs[1] should be SRV record, got: %v, all reccords: %v", recs[1], recs)
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}
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if _, ok := recs[2].(*dns.A); !ok {
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t.Fatalf("bad: %v", recs[2])
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t.Errorf("recs[2] should be A record, got: %v, all records: %v", recs[2], recs)
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}
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if _, ok := recs[3].(*dns.AAAA); !ok {
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t.Fatalf("bad: %v", recs[3])
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t.Errorf("recs[3] should be AAAA record, got: %v, all records: %v", recs[3], recs)
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}
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if _, ok := recs[4].(*dns.TXT); !ok {
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t.Fatalf("bad: %v", recs[4])
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}
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if ptr.Ptr != s.instanceAddr {
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t.Fatalf("bad: %v", recs[0])
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t.Errorf("recs[4] should be TXT record, got: %v, all records: %v", recs[4], recs)
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}
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q.Qtype = dns.TypePTR
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recs2 := s.Records(q)
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if !reflect.DeepEqual(recs, recs2) {
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t.Fatalf("no match: %v %v", recs, recs2)
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if recs2 := s.Records(q); !reflect.DeepEqual(recs, recs2) {
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t.Fatalf("PTR question should return same result as ANY question: ANY => %v, PTR => %v", recs, recs2)
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}
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}
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@ -136,7 +173,7 @@ func TestMDNSService_InstanceAddr_A(t *testing.T) {
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if !ok {
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t.Fatalf("bad: %v", recs[0])
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}
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if !bytes.Equal(a.A, s.ipv4Addr) {
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if !bytes.Equal(a.A, []byte{192, 168, 0, 42}) {
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t.Fatalf("bad: %v", recs[0])
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}
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}
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@ -155,7 +192,11 @@ func TestMDNSService_InstanceAddr_AAAA(t *testing.T) {
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if !ok {
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t.Fatalf("bad: %v", recs[0])
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}
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if !bytes.Equal(a4.AAAA, s.ipv6Addr) {
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ip6 := net.ParseIP("2620:0:1000:1900:b0c2:d0b2:c411:18bc")
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if got := len(ip6); got != net.IPv6len {
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t.Fatalf("test IP failed to parse (len = %d, want %d)", got, net.IPv6len)
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}
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if !bytes.Equal(a4.AAAA, ip6) {
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t.Fatalf("bad: %v", recs[0])
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}
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}
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@ -174,7 +215,7 @@ func TestMDNSService_InstanceAddr_TXT(t *testing.T) {
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if !ok {
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t.Fatalf("bad: %v", recs[0])
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}
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if txt.Txt[0] != s.Info {
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t.Fatalf("bad: %v", recs[0])
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if got, want := txt.Txt, s.TXT; !reflect.DeepEqual(got, want) {
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t.Fatalf("TXT record mismatch for %v: got %v, want %v", recs[0], got, want)
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}
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}
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Block a user