64 lines
1.3 KiB
Go
64 lines
1.3 KiB
Go
package resolvers
|
|
|
|
import (
|
|
"time"
|
|
|
|
"github.com/miekg/dns"
|
|
)
|
|
|
|
// UDPResolver represents the config options for setting up a Resolver.
|
|
type UDPResolver struct {
|
|
client *dns.Client
|
|
server string
|
|
}
|
|
|
|
// UDPResolverOpts holds options for setting up a Classic resolver.
|
|
type UDPResolverOpts struct {
|
|
IPv4Only bool
|
|
IPv6Only bool
|
|
Timeout time.Duration
|
|
}
|
|
|
|
// NewUDPResolver accepts a list of nameservers and configures a DNS resolver.
|
|
func NewUDPResolver(server string, opts UDPResolverOpts) (Resolver, error) {
|
|
client := &dns.Client{
|
|
Timeout: opts.Timeout,
|
|
}
|
|
|
|
client.Net = "udp"
|
|
if opts.IPv4Only {
|
|
client.Net = "udp4"
|
|
}
|
|
if opts.IPv6Only {
|
|
client.Net = "udp6"
|
|
}
|
|
return &UDPResolver{
|
|
client: client,
|
|
server: server,
|
|
}, nil
|
|
}
|
|
|
|
// Lookup prepare a list of DNS messages to be sent to the server.
|
|
// It's possible to send multiple question in one message
|
|
// but some nameservers are not able to
|
|
func (r *UDPResolver) Lookup(questions []dns.Question) ([]Response, error) {
|
|
var (
|
|
messages = prepareMessages(questions)
|
|
responses []Response
|
|
)
|
|
|
|
for _, msg := range messages {
|
|
in, rtt, err := r.client.Exchange(&msg, r.server)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
rsp := Response{
|
|
Message: *in,
|
|
RTT: rtt,
|
|
Nameserver: r.server,
|
|
}
|
|
responses = append(responses, rsp)
|
|
}
|
|
return responses, nil
|
|
}
|