micro/router/dns/dns.go

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package dns
import (
"fmt"
"net"
"strconv"
"github.com/micro/go-micro/v2/router"
)
// NewRouter returns an initialized dns router
func NewRouter(opts ...router.Option) router.Router {
options := router.DefaultOptions()
for _, o := range opts {
o(&options)
}
if len(options.Network) == 0 {
options.Network = "micro"
}
return &dns{options, &table{options}}
}
type dns struct {
options router.Options
table *table
}
func (d *dns) Init(opts ...router.Option) error {
for _, o := range opts {
o(&d.options)
}
d.table.options = d.options
return nil
}
func (d *dns) Options() router.Options {
return d.options
}
func (d *dns) Table() router.Table {
return d.table
}
func (d *dns) Advertise() (<-chan *router.Advert, error) {
return nil, nil
}
func (d *dns) Process(*router.Advert) error {
return nil
}
func (d *dns) Lookup(opts ...router.QueryOption) ([]router.Route, error) {
return d.table.Query(opts...)
}
func (d *dns) Watch(opts ...router.WatchOption) (router.Watcher, error) {
return nil, nil
}
func (d *dns) Close() error {
return nil
}
func (d *dns) String() string {
return "dns"
}
type table struct {
options router.Options
}
func (t *table) Create(router.Route) error {
return nil
}
func (t *table) Delete(router.Route) error {
return nil
}
func (t *table) Update(router.Route) error {
return nil
}
func (t *table) List() ([]router.Route, error) {
return nil, nil
}
func (t *table) Query(opts ...router.QueryOption) ([]router.Route, error) {
options := router.NewQuery(opts...)
// check to see if we have the port provided in the service, e.g. go-micro-srv-foo:8000
host, port, err := net.SplitHostPort(options.Service)
if err == nil {
// lookup the service using A records
ips, err := net.LookupHost(host)
if err != nil {
return nil, err
}
p, _ := strconv.Atoi(port)
// convert the ip addresses to routes
result := make([]router.Route, len(ips))
for i, ip := range ips {
result[i] = router.Route{
Service: options.Service,
Address: fmt.Sprintf("%s:%d", ip, uint16(p)),
}
}
return result, nil
}
// we didn't get the port so we'll lookup the service using SRV records. If we can't lookup the
// service using the SRV record, we return the error.
_, nodes, err := net.LookupSRV(options.Service, "tcp", t.options.Network)
if err != nil {
return nil, err
}
// convert the nodes (net services) to routes
result := make([]router.Route, len(nodes))
for i, n := range nodes {
result[i] = router.Route{
Service: options.Service,
Address: fmt.Sprintf("%s:%d", n.Target, n.Port),
Network: t.options.Network,
}
}
return result, nil
}