[client] Eliminate upstream server strings in dns code (#4267)

client/android/client.go

@@ -4,6 +4,7 @@ package android
 
 import (
 	"context"
+	"slices"
 	"sync"
 
 	log "github.com/sirupsen/logrus"
@@ -112,7 +113,7 @@ func (c *Client) Run(urlOpener URLOpener, dns *DNSList, dnsReadyListener DnsRead
 	// todo do not throw error in case of cancelled context
 	ctx = internal.CtxInitState(ctx)
 	c.connectClient = internal.NewConnectClient(ctx, cfg, c.recorder)
-	return c.connectClient.RunOnAndroid(c.tunAdapter, c.iFaceDiscover, c.networkChangeListener, dns.items, dnsReadyListener)
+	return c.connectClient.RunOnAndroid(c.tunAdapter, c.iFaceDiscover, c.networkChangeListener, slices.Clone(dns.items), dnsReadyListener)
 }
 
 // RunWithoutLogin we apply this type of run function when the backed has been started without UI (i.e. after reboot).
@@ -138,7 +139,7 @@ func (c *Client) RunWithoutLogin(dns *DNSList, dnsReadyListener DnsReadyListener
 	// todo do not throw error in case of cancelled context
 	ctx = internal.CtxInitState(ctx)
 	c.connectClient = internal.NewConnectClient(ctx, cfg, c.recorder)
-	return c.connectClient.RunOnAndroid(c.tunAdapter, c.iFaceDiscover, c.networkChangeListener, dns.items, dnsReadyListener)
+	return c.connectClient.RunOnAndroid(c.tunAdapter, c.iFaceDiscover, c.networkChangeListener, slices.Clone(dns.items), dnsReadyListener)
 }
 
 // Stop the internal client and free the resources
@@ -235,7 +236,7 @@ func (c *Client) OnUpdatedHostDNS(list *DNSList) error {
 		return err
 	}
 
-	dnsServer.OnUpdatedHostDNSServer(list.items)
+	dnsServer.OnUpdatedHostDNSServer(slices.Clone(list.items))
 	return nil
 }
 

client/android/dns_list.go

@@ -1,23 +1,34 @@
 package android
 
-import "fmt"
+import (
+	"fmt"
+	"net/netip"
 
-// DNSList is a wrapper of []string
+	"github.com/netbirdio/netbird/client/internal/dns"
+)
+
+// DNSList is a wrapper of []netip.AddrPort with default DNS port
 type DNSList struct {
-	items []string
+	items []netip.AddrPort
 }
 
-// Add new DNS address to the collection
-func (array *DNSList) Add(s string) {
-	array.items = append(array.items, s)
+// Add new DNS address to the collection, returns error if invalid
+func (array *DNSList) Add(s string) error {
+	addr, err := netip.ParseAddr(s)
+	if err != nil {
+		return fmt.Errorf("invalid DNS address: %s", s)
+	}
+	addrPort := netip.AddrPortFrom(addr.Unmap(), dns.DefaultPort)
+	array.items = append(array.items, addrPort)
+	return nil
 }
 
-// Get return an element of the collection
+// Get return an element of the collection as string
 func (array *DNSList) Get(i int) (string, error) {
 	if i >= len(array.items) || i < 0 {
 		return "", fmt.Errorf("out of range")
 	}
-	return array.items[i], nil
+	return array.items[i].Addr().String(), nil
 }
 
 // Size return with the size of the collection

client/android/dns_list_test.go

@@ -3,20 +3,30 @@ package android
 import "testing"
 
 func TestDNSList_Get(t *testing.T) {
-	l := DNSList{
-		items: make([]string, 1),
+	l := DNSList{}
+
+	// Add a valid DNS address
+	err := l.Add("8.8.8.8")
+	if err != nil {
+		t.Errorf("unexpected error: %s", err)
 	}
 
-	_, err := l.Get(0)
+	// Test getting valid index
+	addr, err := l.Get(0)
 	if err != nil {
 		t.Errorf("invalid error: %s", err)
 	}
+	if addr != "8.8.8.8" {
+		t.Errorf("expected 8.8.8.8, got %s", addr)
+	}
 
+	// Test negative index
 	_, err = l.Get(-1)
 	if err == nil {
 		t.Errorf("expected error but got nil")
 	}
 
+	// Test out of bounds index
 	_, err = l.Get(1)
 	if err == nil {
 		t.Errorf("expected error but got nil")