mirror of
https://github.com/linka-cloud/grpc.git
synced 2025-06-22 17:22:26 +00:00
add registry base interface, mdns, noop implementations, add resolver, client
This commit is contained in:
309
registry/mdns/zone.go
Normal file
309
registry/mdns/zone.go
Normal file
@ -0,0 +1,309 @@
|
||||
package mdns
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"net"
|
||||
"os"
|
||||
"strings"
|
||||
"sync/atomic"
|
||||
|
||||
"github.com/miekg/dns"
|
||||
)
|
||||
|
||||
const (
|
||||
// defaultTTL is the default TTL value in returned DNS records in seconds.
|
||||
defaultTTL = 120
|
||||
)
|
||||
|
||||
// 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. "hostService name")
|
||||
Service string // Service name (e.g. "_http._tcp.")
|
||||
Domain string // If blank, assumes "local"
|
||||
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
|
||||
TTL uint32
|
||||
serviceAddr string // Fully qualified service address
|
||||
instanceAddr string // Fully qualified instance address
|
||||
enumAddr string // _services._dns-sd._udp.<domain>
|
||||
}
|
||||
|
||||
// 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 instance == "" {
|
||||
return nil, fmt.Errorf("missing service instance name")
|
||||
}
|
||||
if service == "" {
|
||||
return nil, fmt.Errorf("missing service name")
|
||||
}
|
||||
if port == 0 {
|
||||
return nil, fmt.Errorf("missing service port")
|
||||
}
|
||||
|
||||
// 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)
|
||||
}
|
||||
|
||||
// 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(trimDot(hostName))
|
||||
if err != nil {
|
||||
// Try appending the host domain suffix and lookup again
|
||||
// (required for Linux-based hosts)
|
||||
tmpHostName := fmt.Sprintf("%s%s", hostName, domain)
|
||||
|
||||
ips, err = net.LookupIP(trimDot(tmpHostName))
|
||||
|
||||
if err != nil {
|
||||
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)
|
||||
}
|
||||
}
|
||||
|
||||
return &MDNSService{
|
||||
Instance: instance,
|
||||
Service: service,
|
||||
Domain: domain,
|
||||
HostName: hostName,
|
||||
Port: port,
|
||||
IPs: ips,
|
||||
TXT: txt,
|
||||
TTL: defaultTTL,
|
||||
serviceAddr: fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
|
||||
instanceAddr: fmt.Sprintf("%s.%s.%s.", instance, trimDot(service), trimDot(domain)),
|
||||
enumAddr: fmt.Sprintf("_services._dns-sd._udp.%s.", trimDot(domain)),
|
||||
}, nil
|
||||
}
|
||||
|
||||
// trimDot is used to trim the dots from the start or end of a string
|
||||
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.enumAddr:
|
||||
return m.serviceEnum(q)
|
||||
case m.serviceAddr:
|
||||
return m.serviceRecords(q)
|
||||
case m.instanceAddr:
|
||||
return m.instanceRecords(q)
|
||||
case m.HostName:
|
||||
if q.Qtype == dns.TypeA || q.Qtype == dns.TypeAAAA {
|
||||
return m.instanceRecords(q)
|
||||
}
|
||||
fallthrough
|
||||
default:
|
||||
return nil
|
||||
}
|
||||
}
|
||||
|
||||
func (m *MDNSService) serviceEnum(q dns.Question) []dns.RR {
|
||||
switch q.Qtype {
|
||||
case dns.TypeANY:
|
||||
fallthrough
|
||||
case dns.TypePTR:
|
||||
rr := &dns.PTR{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: q.Name,
|
||||
Rrtype: dns.TypePTR,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
Ptr: m.serviceAddr,
|
||||
}
|
||||
return []dns.RR{rr}
|
||||
default:
|
||||
return nil
|
||||
}
|
||||
}
|
||||
|
||||
// serviceRecords is called when the query matches the service name
|
||||
func (m *MDNSService) serviceRecords(q dns.Question) []dns.RR {
|
||||
switch q.Qtype {
|
||||
case dns.TypeANY:
|
||||
fallthrough
|
||||
case dns.TypePTR:
|
||||
// Build a PTR response for the service
|
||||
rr := &dns.PTR{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: q.Name,
|
||||
Rrtype: dns.TypePTR,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
Ptr: m.instanceAddr,
|
||||
}
|
||||
servRec := []dns.RR{rr}
|
||||
|
||||
// Get the instance records
|
||||
instRecs := m.instanceRecords(dns.Question{
|
||||
Name: m.instanceAddr,
|
||||
Qtype: dns.TypeANY,
|
||||
})
|
||||
|
||||
// Return the service record with the instance records
|
||||
return append(servRec, instRecs...)
|
||||
default:
|
||||
return nil
|
||||
}
|
||||
}
|
||||
|
||||
// serviceRecords is called when the query matches the instance name
|
||||
func (m *MDNSService) instanceRecords(q dns.Question) []dns.RR {
|
||||
switch q.Qtype {
|
||||
case dns.TypeANY:
|
||||
// Get the SRV, which includes A and AAAA
|
||||
recs := m.instanceRecords(dns.Question{
|
||||
Name: m.instanceAddr,
|
||||
Qtype: dns.TypeSRV,
|
||||
})
|
||||
|
||||
// Add the TXT record
|
||||
recs = append(recs, m.instanceRecords(dns.Question{
|
||||
Name: m.instanceAddr,
|
||||
Qtype: dns.TypeTXT,
|
||||
})...)
|
||||
return recs
|
||||
|
||||
case dns.TypeA:
|
||||
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: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
A: ip4,
|
||||
})
|
||||
}
|
||||
}
|
||||
return rr
|
||||
|
||||
case dns.TypeAAAA:
|
||||
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
|
||||
}
|
||||
|
||||
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: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
AAAA: ip16,
|
||||
})
|
||||
}
|
||||
}
|
||||
return rr
|
||||
|
||||
case dns.TypeSRV:
|
||||
// Create the SRV Record
|
||||
srv := &dns.SRV{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: q.Name,
|
||||
Rrtype: dns.TypeSRV,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
Priority: 10,
|
||||
Weight: 1,
|
||||
Port: uint16(m.Port),
|
||||
Target: m.HostName,
|
||||
}
|
||||
recs := []dns.RR{srv}
|
||||
|
||||
// Add the A record
|
||||
recs = append(recs, m.instanceRecords(dns.Question{
|
||||
Name: m.instanceAddr,
|
||||
Qtype: dns.TypeA,
|
||||
})...)
|
||||
|
||||
// Add the AAAA record
|
||||
recs = append(recs, m.instanceRecords(dns.Question{
|
||||
Name: m.instanceAddr,
|
||||
Qtype: dns.TypeAAAA,
|
||||
})...)
|
||||
return recs
|
||||
|
||||
case dns.TypeTXT:
|
||||
txt := &dns.TXT{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: q.Name,
|
||||
Rrtype: dns.TypeTXT,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: atomic.LoadUint32(&m.TTL),
|
||||
},
|
||||
Txt: m.TXT,
|
||||
}
|
||||
return []dns.RR{txt}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
Reference in New Issue
Block a user