Fix DNS resolution for routes on iOS (#2378)

client/internal/routemanager/dynamic/route_ios.go

@@ -0,0 +1,55 @@
+//go:build ios
+
+package dynamic
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/miekg/dns"
+
+	nbdns "github.com/netbirdio/netbird/client/internal/dns"
+
+	"github.com/netbirdio/netbird/management/domain"
+)
+
+const dialTimeout = 10 * time.Second
+
+func (r *Route) getIPsFromResolver(domain domain.Domain) ([]net.IP, error) {
+	privateClient, err := nbdns.GetClientPrivate(r.wgInterface.Address().IP, r.wgInterface.Name(), dialTimeout)
+	if err != nil {
+		return nil, fmt.Errorf("error while creating private client: %s", err)
+	}
+
+	msg := new(dns.Msg)
+	msg.SetQuestion(dns.Fqdn(string(domain)), dns.TypeA)
+
+	startTime := time.Now()
+
+	response, _, err := privateClient.Exchange(msg, r.resolverAddr)
+	if err != nil {
+		return nil, fmt.Errorf("DNS query for %s failed after %s: %s ", domain.SafeString(), time.Since(startTime), err)
+	}
+
+	if response.Rcode != dns.RcodeSuccess {
+		return nil, fmt.Errorf("dns response code: %s", dns.RcodeToString[response.Rcode])
+	}
+
+	ips := make([]net.IP, 0)
+
+	for _, answ := range response.Answer {
+		if aRecord, ok := answ.(*dns.A); ok {
+			ips = append(ips, aRecord.A)
+		}
+		if aaaaRecord, ok := answ.(*dns.AAAA); ok {
+			ips = append(ips, aaaaRecord.AAAA)
+		}
+	}
+
+	if len(ips) == 0 {
+		return nil, fmt.Errorf("no A or AAAA records found for %s", domain.SafeString())
+	}
+
+	return ips, nil
+}