feat: Multiple resolvers continued
This commit is contained in:
Karan Sharma
parent
b46b64c1ae
commit
53e7f2e59c
11 changed files with 253 additions and 214 deletions
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@ -2,7 +2,6 @@ package resolvers
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import (
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"bytes"
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"errors"
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"fmt"
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"io/ioutil"
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"net/http"
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@ -14,34 +13,30 @@ import (
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// DOHResolver represents the config options for setting up a DOH based resolver.
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type DOHResolver struct {
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client *http.Client
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servers []string
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client *http.Client
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server string
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}
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type DOHResolverOpts struct {
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Timeout time.Duration
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}
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// NewDOHResolver accepts a list of nameservers and configures a DOH based resolver.
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func NewDOHResolver(servers []string, opts DOHResolverOpts) (Resolver, error) {
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if len(servers) == 0 {
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return nil, errors.New(`no DOH server specified`)
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// NewDOHResolver accepts a nameserver address and configures a DOH based resolver.
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func NewDOHResolver(server string, opts DOHResolverOpts) (Resolver, error) {
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// do basic validation
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u, err := url.ParseRequestURI(server)
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if err != nil {
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return nil, fmt.Errorf("%s is not a valid HTTPS nameserver", server)
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}
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for _, s := range servers {
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u, err := url.ParseRequestURI(s)
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if err != nil {
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return nil, fmt.Errorf("%s is not a valid HTTPS nameserver", s)
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}
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if u.Scheme != "https" {
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return nil, fmt.Errorf("missing https in %s", s)
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}
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if u.Scheme != "https" {
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return nil, fmt.Errorf("missing https in %s", server)
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}
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httpClient := &http.Client{
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Timeout: opts.Timeout,
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}
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return &DOHResolver{
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client: httpClient,
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servers: servers,
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client: httpClient,
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server: server,
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}, nil
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}
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@ -57,34 +52,32 @@ func (d *DOHResolver) Lookup(questions []dns.Question) ([]Response, error) {
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if err != nil {
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return nil, err
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}
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for _, srv := range d.servers {
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now := time.Now()
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// Make an HTTP POST request to the DNS server with the DNS message as wire format bytes in the body.
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resp, err := d.client.Post(srv, "application/dns-message", bytes.NewBuffer(b))
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("error from nameserver %s", resp.Status)
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}
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rtt := time.Since(now)
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// extract the binary response in DNS Message.
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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err = msg.Unpack(body)
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if err != nil {
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return nil, err
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}
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rsp := Response{
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Message: msg,
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RTT: rtt,
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Nameserver: srv,
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}
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responses = append(responses, rsp)
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now := time.Now()
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// Make an HTTP POST request to the DNS server with the DNS message as wire format bytes in the body.
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resp, err := d.client.Post(d.server, "application/dns-message", bytes.NewBuffer(b))
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("error from nameserver %s", resp.Status)
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}
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rtt := time.Since(now)
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// extract the binary response in DNS Message.
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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err = msg.Unpack(body)
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if err != nil {
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return nil, err
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}
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rsp := Response{
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Message: msg,
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RTT: rtt,
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Nameserver: d.server,
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}
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responses = append(responses, rsp)
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}
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return responses, nil
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}
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@ -1,21 +1,15 @@
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package resolvers
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import (
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"net"
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"time"
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"github.com/miekg/dns"
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)
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const (
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// DefaultTLSPort specifies the default port for a DNS server connecting over TCP over TLS
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DefaultTLSPort = "853"
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)
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// TCPResolver represents the config options for setting up a Resolver.
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type TCPResolver struct {
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client *dns.Client
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servers []string
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client *dns.Client
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server string
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}
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// TCPResolverOpts represents the config options for setting up a TCPResolver.
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@ -26,31 +20,10 @@ type TCPResolverOpts struct {
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}
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// NewTCPResolver accepts a list of nameservers and configures a DNS resolver.
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func NewTCPResolver(servers []string, opts TCPResolverOpts) (Resolver, error) {
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func NewTCPResolver(server string, opts TCPResolverOpts) (Resolver, error) {
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client := &dns.Client{
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Timeout: opts.Timeout,
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}
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var nameservers []string
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// load list of nameservers to the config
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if len(servers) == 0 {
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ns, err := getDefaultServers()
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if err != nil {
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return nil, err
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}
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nameservers = ns
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} else {
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// load the list of servers that user specified.
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for _, srv := range servers {
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if i := net.ParseIP(srv); i != nil {
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// if no port specified in nameserver, append defaults.
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nameservers = append(nameservers, net.JoinHostPort(srv, DefaultTLSPort))
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} else {
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// use the port user specified.
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nameservers = append(nameservers, srv)
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}
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}
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}
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client.Net = "tcp"
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if opts.IPv4Only {
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@ -60,8 +33,8 @@ func NewTCPResolver(servers []string, opts TCPResolverOpts) (Resolver, error) {
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client.Net = "tcp6"
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}
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return &TCPResolver{
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client: client,
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servers: nameservers,
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client: client,
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server: server,
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}, nil
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}
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@ -75,19 +48,17 @@ func (r *TCPResolver) Lookup(questions []dns.Question) ([]Response, error) {
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)
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for _, msg := range messages {
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for _, srv := range r.servers {
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in, rtt, err := r.client.Exchange(&msg, srv)
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if err != nil {
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return nil, err
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}
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msg.Answer = in.Answer
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rsp := Response{
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Message: msg,
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RTT: rtt,
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Nameserver: srv,
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}
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responses = append(responses, rsp)
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in, rtt, err := r.client.Exchange(&msg, r.server)
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if err != nil {
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return nil, err
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}
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msg.Answer = in.Answer
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rsp := Response{
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Message: msg,
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RTT: rtt,
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Nameserver: r.server,
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}
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responses = append(responses, rsp)
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}
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return responses, nil
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}
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@ -1,23 +1,15 @@
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package resolvers
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import (
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"net"
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"time"
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"github.com/miekg/dns"
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)
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const (
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// DefaultUDPPort specifies the default port for a DNS server connecting over UDP
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DefaultUDPPort = "53"
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//DefaultResolvConfPath specifies path to default resolv config file on UNIX.
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DefaultResolvConfPath = "/etc/resolv.conf"
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)
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// UDPResolver represents the config options for setting up a Resolver.
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type UDPResolver struct {
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client *dns.Client
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servers []string
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client *dns.Client
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server string
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}
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// UDPResolverOpts holds options for setting up a Classic resolver.
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@ -28,31 +20,10 @@ type UDPResolverOpts struct {
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}
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// NewUDPResolver accepts a list of nameservers and configures a DNS resolver.
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func NewUDPResolver(servers []string, opts UDPResolverOpts) (Resolver, error) {
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func NewUDPResolver(server string, opts UDPResolverOpts) (Resolver, error) {
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client := &dns.Client{
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Timeout: opts.Timeout,
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}
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var nameservers []string
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// load list of nameservers to the config
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if len(servers) == 0 {
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ns, err := getDefaultServers()
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if err != nil {
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return nil, err
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}
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nameservers = ns
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} else {
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// load the list of servers that user specified.
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for _, srv := range servers {
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if i := net.ParseIP(srv); i != nil {
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// if no port specified in nameserver, append defaults.
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nameservers = append(nameservers, net.JoinHostPort(srv, DefaultUDPPort))
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} else {
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// use the port user specified.
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nameservers = append(nameservers, srv)
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}
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}
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}
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client.Net = "udp"
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if opts.IPv4Only {
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@ -62,34 +33,31 @@ func NewUDPResolver(servers []string, opts UDPResolverOpts) (Resolver, error) {
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client.Net = "udp6"
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}
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return &UDPResolver{
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client: client,
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servers: nameservers,
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client: client,
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server: server,
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}, nil
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}
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// Lookup prepare a list of DNS messages to be sent to the server.
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// It's possible to send multiple question in one message
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// but some nameservers are not able to
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func (c *UDPResolver) Lookup(questions []dns.Question) ([]Response, error) {
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func (r *UDPResolver) Lookup(questions []dns.Question) ([]Response, error) {
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var (
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messages = prepareMessages(questions)
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responses []Response
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)
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for _, msg := range messages {
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for _, srv := range c.servers {
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in, rtt, err := c.client.Exchange(&msg, srv)
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if err != nil {
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return nil, err
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}
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msg.Answer = in.Answer
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rsp := Response{
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Message: msg,
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RTT: rtt,
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Nameserver: srv,
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}
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responses = append(responses, rsp)
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in, rtt, err := r.client.Exchange(&msg, r.server)
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if err != nil {
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return nil, err
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}
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rsp := Response{
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Message: *in,
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RTT: rtt,
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Nameserver: r.server,
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}
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responses = append(responses, rsp)
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}
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return responses, nil
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}
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@ -1,11 +1,6 @@
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package resolvers
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import (
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"errors"
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"fmt"
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"net"
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"runtime"
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"github.com/miekg/dns"
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)
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@ -23,26 +18,3 @@ func prepareMessages(questions []dns.Question) []dns.Msg {
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}
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return messages
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}
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func getDefaultServers() ([]string, error) {
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if runtime.GOOS == "windows" {
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// TODO: Add a method for reading system default nameserver in windows.
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return nil, errors.New(`unable to read default nameservers in this machine`)
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}
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// if no nameserver is provided, take it from `resolv.conf`
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cfg, err := dns.ClientConfigFromFile(DefaultResolvConfPath)
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if err != nil {
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return nil, err
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}
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servers := make([]string, 0, len(cfg.Servers))
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for _, s := range cfg.Servers {
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ip := net.ParseIP(s)
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// handle IPv6
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if ip != nil && ip.To4() != nil {
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servers = append(servers, fmt.Sprintf("%s:%s", s, cfg.Port))
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} else {
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servers = append(servers, fmt.Sprintf("[%s]:%s", s, cfg.Port))
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}
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}
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return servers, nil
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}
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