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service.go
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service.go
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package main
// source: https://github.com/grandcat/zeroconf
// The MIT License (MIT)
// Copyright (c) 2016 Stefan Smarzly
// Copyright (c) 2014 Oleksandr Lobunets
// Note: Copyright for portions of project zeroconf.sd are held by Oleksandr
// Lobunets, 2014, as part of project bonjour. All other copyright for
// project zeroconf.sd are held by Stefan Smarzly, 2016.
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
import (
"fmt"
"net"
"sync"
)
// ServiceRecord contains the basic description of a service, which contains instance name, service type & domain
type ServiceRecord struct {
Instance string `json:"name"` // Instance name (e.g. "My web page")
Service string `json:"type"` // Service name (e.g. _http._tcp.)
Subtypes []string `json:"subtypes"` // Service subtypes
Domain string `json:"domain"` // If blank, assumes "local"
// private variable populated on ServiceRecord creation
serviceName string
serviceInstanceName string
serviceTypeName string
}
// ServiceName returns a complete service name (e.g. _foobar._tcp.local.), which is composed
// of a service name (also referred as service type) and a domain.
func (s *ServiceRecord) ServiceName() string {
return s.serviceName
}
// ServiceInstanceName returns a complete service instance name (e.g. MyDemo\ Service._foobar._tcp.local.),
// which is composed from service instance name, service name and a domain.
func (s *ServiceRecord) ServiceInstanceName() string {
return s.serviceInstanceName
}
// ServiceTypeName returns the complete identifier for a DNS-SD query.
func (s *ServiceRecord) ServiceTypeName() string {
return s.serviceTypeName
}
// NewServiceRecord constructs a ServiceRecord.
func NewServiceRecord(instance, service string, domain string) *ServiceRecord {
service, subtypes := parseSubtypes(service)
s := &ServiceRecord{
Instance: instance,
Service: service,
Domain: domain,
serviceName: fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
}
for _, subtype := range subtypes {
s.Subtypes = append(s.Subtypes, fmt.Sprintf("%s._sub.%s", trimDot(subtype), s.serviceName))
}
// Cache service instance name
if instance != "" {
s.serviceInstanceName = fmt.Sprintf("%s.%s", trimDot(s.Instance), s.ServiceName())
}
// Cache service type name domain
typeNameDomain := "local"
if len(s.Domain) > 0 {
typeNameDomain = trimDot(s.Domain)
}
s.serviceTypeName = fmt.Sprintf("_services._dns-sd._udp.%s.", typeNameDomain)
return s
}
// LookupParams contains configurable properties to create a service discovery request
type LookupParams struct {
ServiceRecord
Entries chan<- *ServiceEntry // Entries Channel
stopProbing chan struct{}
once sync.Once
}
// NewLookupParams constructs a LookupParams.
func NewLookupParams(instance, service, domain string, entries chan<- *ServiceEntry) *LookupParams {
return &LookupParams{
ServiceRecord: *NewServiceRecord(instance, service, domain),
Entries: entries,
stopProbing: make(chan struct{}),
}
}
// Notify subscriber that no more entries will arrive. Mostly caused
// by an expired context.
func (l *LookupParams) done() {
close(l.Entries)
}
func (l *LookupParams) disableProbing() {
l.once.Do(func() { close(l.stopProbing) })
}
// ServiceEntry represents a browse/lookup result for client API.
// It is also used to configure service registration (server API), which is
// used to answer multicast queries.
type ServiceEntry struct {
ServiceRecord
HostName string `json:"hostname"` // Host machine DNS name
Port int `json:"port"` // Service Port
Text []string `json:"text"` // Service info served as a TXT record
TTL uint32 `json:"ttl"` // TTL of the service record
AddrIPv4 []net.IP `json:"-"` // Host machine IPv4 address
AddrIPv6 []net.IP `json:"-"` // Host machine IPv6 address
}
// NewServiceEntry constructs a ServiceEntry.
func NewServiceEntry(instance, service string, domain string) *ServiceEntry {
return &ServiceEntry{
ServiceRecord: *NewServiceRecord(instance, service, domain),
}
}