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sd.go
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sd.go
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package dnsclient
import (
"fmt"
"github.com/miekg/dns"
"github.com/syslab-wm/adt/set"
"github.com/syslab-wm/functools"
)
/*
type ServiceBrowserDomain struct {
Name string // domainname
IsDefault bool
IsLegacy bool
}
func (sbd *ServiceBrowserDomain) String() string {
return fmt.Sprintf("{name: %q, default: %t, legacy: %t}", sbd.Name, sbd.IsDefault, sbd.IsLegacy)
}
*/
func GetServiceBrowserDomains(c Client, domain string) ([]string, error) {
var sbds []string
browserDomain := fmt.Sprintf("b._dns-sd._udp.%s", domain)
resp, err := c.Query(browserDomain, dns.TypePTR)
if err != nil {
return nil, err
}
if resp.Rcode != dns.RcodeSuccess {
return nil, fmt.Errorf("DNS query returned error: %s", dns.RcodeToString[resp.Rcode])
}
ptrRRs := functools.Filter(resp.Answer, func(rr dns.RR) bool {
_, ok := rr.(*dns.PTR)
return ok
})
if len(ptrRRs) == 0 {
return nil, fmt.Errorf("DNS query did not return any PTR records")
}
for _, rr := range ptrRRs {
ptr := rr.(*dns.PTR)
sbds = append(sbds, ptr.Ptr)
}
return sbds, nil
}
func GetDefaultServiceBrowserDomain(c Client, domain string) (string, error) {
browserDomain := fmt.Sprintf("db._dns-sd._udp.%s", domain)
resp, err := c.Query(browserDomain, dns.TypePTR)
if err != nil {
return "", err
}
if resp.Rcode != dns.RcodeSuccess {
return "", fmt.Errorf("DNS query returned error: %s", dns.RcodeToString[resp.Rcode])
}
ptrRRs := functools.Filter(resp.Answer, func(rr dns.RR) bool {
_, ok := rr.(*dns.PTR)
return ok
})
if len(ptrRRs) == 0 {
return "", fmt.Errorf("DNS query did not return any PTR records")
}
if len(ptrRRs) > 1 {
return "", fmt.Errorf("DNS query returned multiple PTR records")
}
ptr := ptrRRs[0].(*dns.PTR)
return ptr.Ptr, nil
}
func GetLegacyServiceBrowserDomain(c Client, domain string) (string, error) {
browserDomain := fmt.Sprintf("lb._dns-sd._udp.%s", domain)
resp, err := c.Query(browserDomain, dns.TypePTR)
if err != nil {
return "", err
}
if resp.Rcode != dns.RcodeSuccess {
return "", fmt.Errorf("DNS query returned error: %s", dns.RcodeToString[resp.Rcode])
}
ptrRRs := functools.Filter(resp.Answer, func(rr dns.RR) bool {
_, ok := rr.(*dns.PTR)
return ok
})
if len(ptrRRs) == 0 {
return "", fmt.Errorf("DNS query did not return any PTR records")
}
if len(ptrRRs) > 1 {
return "", fmt.Errorf("DNS query returned multiple PTR records")
}
ptr := ptrRRs[0].(*dns.PTR)
return ptr.Ptr, nil
}
func GetAllServiceBrowserDomains(c Client, domain string) ([]string, error) {
sbdSet := set.New[string]()
browsers, errb := GetServiceBrowserDomains(c, domain)
if errb == nil {
sbdSet.Add(browsers...)
}
defaultBrowser, errdb := GetDefaultServiceBrowserDomain(c, domain)
if errdb == nil {
sbdSet.Add(defaultBrowser)
}
legacyBrowser, errl := GetLegacyServiceBrowserDomain(c, domain)
if errl == nil {
sbdSet.Add(legacyBrowser)
}
if sbdSet.Size() == 0 {
// TODO: use errors.Join to include info from errb, errdb, and errdl,
// if non-nil
return nil, fmt.Errorf("failed to find any service browsing domains")
}
return sbdSet.Items(), nil
}
func EnumerateServices(c Client, domain string) ([]string, error) {
var services []string
fauxDomain := fmt.Sprintf("_services._dns-sd._udp.%s", domain)
resp, err := c.Query(fauxDomain, dns.TypePTR)
if err != nil {
return nil, err
}
if resp.Rcode != dns.RcodeSuccess {
return nil, fmt.Errorf("DNS query returned error: %s", dns.RcodeToString[resp.Rcode])
}
ptrRRs := functools.Filter(resp.Answer, func(rr dns.RR) bool {
_, ok := rr.(*dns.PTR)
return ok
})
if len(ptrRRs) == 0 {
return nil, fmt.Errorf("DNS query did not return any PTR records")
}
for _, rr := range ptrRRs {
ptr := rr.(*dns.PTR)
services = append(services, ptr.Ptr)
}
return services, nil
}
func EnumerateServiceInstances(c Client, domain, service string) ([]string, error) {
var instances []string
fauxDomain := fmt.Sprintf("%s.%s", service, domain)
resp, err := c.Query(fauxDomain, dns.TypePTR)
if err != nil {
return nil, err
}
if resp.Rcode != dns.RcodeSuccess {
return nil, fmt.Errorf("DNS query returned error: %s", dns.RcodeToString[resp.Rcode])
}
ptrRRs := functools.Filter(resp.Answer, func(rr dns.RR) bool {
_, ok := rr.(*dns.PTR)
return ok
})
if len(ptrRRs) == 0 {
return nil, fmt.Errorf("DNS query did not return any PTR records")
}
for _, rr := range ptrRRs {
ptr := rr.(*dns.PTR)
instances = append(instances, ptr.Ptr)
}
return instances, nil
}
func GetServiceInstanceInfo(c Client, domain string) error {
// Perform a SRV query on name
// Perform a TXT query on name
// Aggreage the results
return nil
}