chore: refactor doh

dns/dns.go

@@ -59,7 +59,7 @@ func customLookup(host string, port string, domain string) (string, error) {
 
 	response, _, err := c.Exchange(msg, dnsServer)
 	if err != nil {
-		return "", errors.New("couldn not resolve the domain(custom)")
+		return "", errors.New("could not resolve the domain(custom)")
 	}
 
 	for _, answer := range response.Answer {
@@ -76,7 +76,7 @@ func systemLookup(domain string) (string, error) {
 	systemResolver := net.Resolver{PreferGo: true}
 	ips, err := systemResolver.LookupIPAddr(context.Background(), domain)
 	if err != nil {
-		return "", errors.New("couldn not resolve the domain(system)")
+		return "", errors.New("could not resolve the domain(system)")
 	}
 
 	for _, ip := range ips {
@@ -89,18 +89,22 @@ func systemLookup(domain string) (string, error) {
 func dohLookup(domain string) (string, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()
-	log.Debug("[DoH] ", domain, " resolving with dns over https")
 
-	dnsUpstream := util.GetConfig().DnsAddr
-	client := GetDoHClient(*dnsUpstream)
-	resp, err := client.Resolve(ctx, domain, []uint16{dns.TypeA, dns.TypeAAAA})
-	if err == nil {
-		if len(resp) == 0 { // yes this happens
-			return "", errors.New("no record found(doh)")
-		}
+	client := GetDOHClient(*util.GetConfig().DnsAddr)
 
-		return resp[0], nil
+	msg := new(dns.Msg)
+	msg.SetQuestion(dns.Fqdn(domain), dns.TypeA)
+
+	response, err := client.Exchange(ctx, domain, msg)
+	if err != nil {
+		return "", errors.New("could not resolve the domain(doh)")
 	}
 
-	return "", errors.New("could not resolve the domain(doh)")
+	for _, answer := range response.Answer {
+		if record, ok := answer.(*dns.A); ok {
+			return record.A.String(), nil
+		}
+	}
+
+	return "", errors.New("no record found(system)")
 }

dns/doh.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -12,18 +13,17 @@ import (
 	"time"
 
 	"github.com/miekg/dns"
-	log "github.com/sirupsen/logrus"
 )
 
-type DoHClient struct {
+type DOHClient struct {
 	upstream string
-	c        *http.Client
+	client   *http.Client
 }
 
-var client *DoHClient
+var client *DOHClient
 var clientOnce sync.Once
 
-func GetDoHClient(upstream string) *DoHClient {
+func GetDOHClient(upstream string) *DOHClient {
 	clientOnce.Do(func() {
 		if client == nil {
 			if !strings.HasPrefix(upstream, "https://") {
@@ -47,9 +47,9 @@ func GetDoHClient(upstream string) *DoHClient {
 				},
 			}
 
-			client = &DoHClient{
+			client = &DOHClient{
 				upstream: upstream,
-				c:        c,
+				client:   c,
 			}
 		}
 	})
@@ -57,7 +57,7 @@ func GetDoHClient(upstream string) *DoHClient {
 	return client
 }
 
-func (d *DoHClient) doGetRequest(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
+func (d *DOHClient) query(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
 	pack, err := msg.Pack()
 	if err != nil {
 		return nil, err
@@ -72,53 +72,40 @@ func (d *DoHClient) doGetRequest(ctx context.Context, msg *dns.Msg) (*dns.Msg, e
 	req = req.WithContext(ctx)
 	req.Header.Set("Accept", "application/dns-message")
 
-	resp, err := d.c.Do(req)
+	resp, err := d.client.Do(req)
 	if err != nil {
 		return nil, err
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		log.Debug("[DoH] Error while resolving ", url, " : ", resp.Status)
+		return nil, errors.New("doh status error")
 	}
 
 	buf := bytes.Buffer{}
-	buf.ReadFrom(resp.Body)
-
-	ret_msg := new(dns.Msg)
-	err = ret_msg.Unpack(buf.Bytes())
+	_, err = buf.ReadFrom(resp.Body)
 	if err != nil {
 		return nil, err
 	}
 
-	return ret_msg, nil
-}
-
-func (d *DoHClient) Resolve(ctx context.Context, domain string, dnsTypes []uint16) ([]string, error) {
-	var ret []string
-
-	for _, dnsType := range dnsTypes {
-		msg := new(dns.Msg)
-		msg.SetQuestion(dns.Fqdn(domain), dnsType)
-
-		resp, err := d.doGetRequest(ctx, msg)
-		if err != nil {
-			return nil, err
-		}
-
-		if resp.Rcode != dns.RcodeSuccess {
-			continue
-		}
-
-		for _, answer := range resp.Answer {
-			if t, ok := answer.(*dns.A); ok {
-				ret = append(ret, t.A.String())
-			}
-			if t, ok := answer.(*dns.AAAA); ok {
-				ret = append(ret, t.AAAA.String())
-			}
-		}
+	resultMsg := new(dns.Msg)
+	err = resultMsg.Unpack(buf.Bytes())
+	if err != nil {
+		return nil, err
 	}
 
-	return ret, nil
+	return resultMsg, nil
+}
+
+func (d *DOHClient) Exchange(ctx context.Context, domain string, msg *dns.Msg) (*dns.Msg, error) {
+	res, err := d.query(ctx, msg)
+	if err != nil {
+		return nil, err
+	}
+
+	if res.Rcode != dns.RcodeSuccess {
+		return nil, errors.New("doh rcode wasn't successful")
+	}
+
+	return res, nil
 }