Merge pull request #40 in DNS/adguard-dns from feature/347 to master

* commit 'ff86d6b7dc31e463651c11f02330630e35676e05':
  Set default servers to tls://1.1.1.1 and tls://1.0.0.1

config.go

@@ -56,7 +56,7 @@ type filter struct {
 	LastUpdated time.Time `json:"last_updated" yaml:"-"`
 }
 
-var defaultDNS = []string{"1.1.1.1", "1.0.0.1"}
+var defaultDNS = []string{"tls://1.1.1.1", "tls://1.0.0.1"}
 
 // initialize to default values, will be changed later when reading config or parsing command line
 var config = configuration{

control.go

@@ -506,16 +506,25 @@ func handleStatsTop(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func httpError(w http.ResponseWriter, code int, format string, args ...interface{}) {
+	text := fmt.Sprintf(format, args...)
+	http.Error(w, text, code)
+}
+
 func handleSetUpstreamDNS(w http.ResponseWriter, r *http.Request) {
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
 		errortext := fmt.Sprintf("Failed to read request body: %s", err)
 		log.Println(errortext)
-		http.Error(w, errortext, 400)
+		http.Error(w, errortext, http.StatusBadRequest)
 		return
 	}
 	// if empty body -- user is asking for default servers
-	hosts := parseIPsOptionalPort(string(body))
+	hosts, err := sanitiseDNSServers(string(body))
+	if err != nil {
+		httpError(w, http.StatusBadRequest, "Invalid DNS servers were given: %s", err)
+		return
+	}
 	if len(hosts) == 0 {
 		config.CoreDNS.UpstreamDNS = defaultDNS
 	} else {
@@ -584,17 +593,10 @@ func handleTestUpstreamDNS(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func checkDNS(host string) error {
-	host = appendPortIfMissing(host)
-	{
-		h, _, err := net.SplitHostPort(host)
-		if err != nil {
-			return err
-		}
-		ip := net.ParseIP(h)
-		if ip == nil {
-			return fmt.Errorf("Invalid DNS server field: %s", h)
-		}
+func checkDNS(input string) error {
+	input, err := sanitizeDNSServer(input)
+	if err != nil {
+		return err
 	}
 
 	req := dns.Msg{}
@@ -603,45 +605,91 @@ func checkDNS(host string) error {
 	req.Question = []dns.Question{
 		{"google-public-dns-a.google.com.", dns.TypeA, dns.ClassINET},
 	}
-	resp, err := dns.Exchange(&req, host)
-	if err != nil {
-		return fmt.Errorf("Couldn't communicate with DNS server %s: %s", host, err)
+
+	prefix, host := splitDNSServerPrefixServer(input)
+
+	c := dns.Client{
+		Timeout: time.Minute,
 	}
+	switch prefix {
+	case "tls://":
+		c.Net = "tcp-tls"
+	}
+
+	resp, rtt, err := c.Exchange(&req, host)
+	if err != nil {
+		return fmt.Errorf("Couldn't communicate with DNS server %s: %s", input, err)
+	}
+	trace("exchange with %s took %v", input, rtt)
 	if len(resp.Answer) != 1 {
-		return fmt.Errorf("DNS server %s returned wrong answer", host)
+		return fmt.Errorf("DNS server %s returned wrong answer", input)
 	}
 	if t, ok := resp.Answer[0].(*dns.A); ok {
 		if !net.IPv4(8, 8, 8, 8).Equal(t.A) {
-			return fmt.Errorf("DNS server %s returned wrong answer: %v", host, t.A)
+			return fmt.Errorf("DNS server %s returned wrong answer: %v", input, t.A)
 		}
 	}
 
 	return nil
 }
 
-func appendPortIfMissing(input string) string {
+func sanitiseDNSServers(input string) ([]string, error) {
+	fields := strings.Fields(input)
+	hosts := []string{}
+	for _, field := range fields {
+		sanitized, err := sanitizeDNSServer(field)
+		if err != nil {
+			return hosts, err
+		}
+		hosts = append(hosts, sanitized)
+	}
+	return hosts, nil
+}
+
+func getDNSServerPrefix(input string) string {
+	prefix := ""
+	switch {
+	case strings.HasPrefix(input, "dns://"):
+		prefix = "dns://"
+	case strings.HasPrefix(input, "tls://"):
+		prefix = "tls://"
+	}
+	return prefix
+}
+
+func splitDNSServerPrefixServer(input string) (string, string) {
+	prefix := getDNSServerPrefix(input)
+	host := strings.TrimPrefix(input, prefix)
+	return prefix, host
+}
+
+func sanitizeDNSServer(input string) (string, error) {
+	prefix, host := splitDNSServerPrefixServer(input)
+	host = appendPortIfMissing(prefix, host)
+	{
+		h, _, err := net.SplitHostPort(host)
+		if err != nil {
+			return "", err
+		}
+		ip := net.ParseIP(h)
+		if ip == nil {
+			return "", fmt.Errorf("Invalid DNS server field: %s", h)
+		}
+	}
+	return prefix + host, nil
+}
+
+func appendPortIfMissing(prefix, input string) string {
+	port := "53"
+	switch prefix {
+	case "tls://":
+		port = "853"
+	}
 	_, _, err := net.SplitHostPort(input)
 	if err == nil {
 		return input
 	}
-	return net.JoinHostPort(input, "53")
-}
-
-func parseIPsOptionalPort(input string) []string {
-	fields := strings.Fields(input)
-	hosts := []string{}
-	for _, field := range fields {
-		_, _, err := net.SplitHostPort(field)
-		if err != nil {
-			ip := net.ParseIP(field)
-			if ip == nil {
-				log.Printf("Invalid DNS server field: %s\n", field)
-				continue
-			}
-		}
-		hosts = append(hosts, field)
-	}
-	return hosts
+	return net.JoinHostPort(input, port)
 }
 
 func handleGetVersionJSON(w http.ResponseWriter, r *http.Request) {

helpers.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 	"path"
 	"runtime"
 	"sort"
@@ -259,5 +260,5 @@ func trace(format string, args ...interface{}) {
 	if len(text) == 0 || text[len(text)-1] != '\n' {
 		buf.WriteRune('\n')
 	}
-	fmt.Print(buf.String())
+	fmt.Fprint(os.Stderr, buf.String())
 }