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package se.leap.bitmaskclient.providersetup.connectivity;
import static java.net.InetAddress.getByName;
import android.util.Log;
import androidx.annotation.NonNull;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import de.blinkt.openvpn.core.VpnStatus;
import okhttp3.Dns;
import okhttp3.HttpUrl;
import okhttp3.OkHttpClient;
import okhttp3.dnsoverhttps.DnsOverHttps;
import se.leap.bitmaskclient.base.models.Provider;
import se.leap.bitmaskclient.base.models.ProviderObservable;
import se.leap.bitmaskclient.base.utils.IPAddress;
public class DnsResolver implements Dns {
OkHttpClient dohHttpClient;
boolean preferDoH;
public DnsResolver(OkHttpClient dohHttpClient, boolean preferDoH) {
this.dohHttpClient = dohHttpClient;
this.preferDoH = preferDoH;
}
@NonNull
@Override
public List<InetAddress> lookup(@NonNull String hostname) throws UnknownHostException {
Log.d("DNS", "trying to resolve DNS for " + hostname);
List<InetAddress> list = null;
if (preferDoH) {
if ((list = tryLookupDoH(hostname)) == null) {
list = tryLookupSystemDNS(hostname);
}
} else {
if ((list = tryLookupSystemDNS(hostname)) == null) {
list = tryLookupDoH(hostname);
}
}
if (list != null) {
return list;
}
Log.d("DNS", "try hard coded IPs");
// let's check if there's an hard-coded IP we can use
ProviderObservable observable = ProviderObservable.getInstance();
Provider currentProvider;
if (observable.getProviderForDns() != null) {
currentProvider = observable.getProviderForDns();
} else {
currentProvider = observable.getCurrentProvider();
}
String ip = currentProvider.getIpForHostname(hostname);
if (!ip.isEmpty()) {
VpnStatus.logWarning("[API] Normal DNS resolution for " + hostname + " seems to be blocked. Circumventing.");
ArrayList<InetAddress> addresses = new ArrayList<>();
addresses.add(InetAddress.getByAddress(hostname, IPAddress.asBytes(ip)));
return addresses;
} else {
VpnStatus.logWarning("[API] Could not resolve DNS for " + hostname);
throw new UnknownHostException("Hostname " + hostname + " not found");
}
}
private List<InetAddress> tryLookupSystemDNS(@NonNull String hostname) throws RuntimeException, UnknownHostException {
try {
Log.d("DNS", "trying to resolve " + hostname + "with system DNS");
return Dns.SYSTEM.lookup(hostname);
} catch (UnknownHostException e) {
e.printStackTrace();
return null;
}
}
private List<InetAddress> tryLookupDoH(@NonNull String hostname) throws UnknownHostException {
DnsOverHttps njallaDoH = new DnsOverHttps.Builder().client(dohHttpClient)
.url(HttpUrl.get("https://dns.njal.la/dns-query"))
.bootstrapDnsHosts(getByName("95.215.19.53"), getByName("2001:67c:2354:2::53"))
.build();
try {
Log.d("DNS", "DoH via dns.njal.la");
return njallaDoH.lookup(hostname);
} catch (UnknownHostException e) {
e.printStackTrace();
Log.e("DNS", "DoH via dns.njal.la failed");
}
DnsOverHttps quad9 = new DnsOverHttps.Builder().client(dohHttpClient)
.url(HttpUrl.get("https://dns.quad9.net/dns-query"))
.bootstrapDnsHosts(getByName("9.9.9.9"), getByName("149.112.112.112"), getByName("2620:fe::fe"), getByName("2620:fe::9"))
.build();
try {
Log.d("DNS", "DoH via dns.quad9.net");
return quad9.lookup(hostname);
} catch (UnknownHostException e) {
e.printStackTrace();
Log.e("DNS", "DoH via dns.quad9.net failed");
}
DnsOverHttps cloudFlareDoHClient = new DnsOverHttps.Builder().client(dohHttpClient)
.url(HttpUrl.get("https://1.1.1.1/dns-query"))
.bootstrapDnsHosts(getByName("1.1.1.1"), getByName("1.0.0.1"))
.build();
try {
Log.d("DNS", "DoH via cloudflare 1.1.1.1");
return cloudFlareDoHClient.lookup(hostname);
} catch (UnknownHostException e) {
e.printStackTrace();
Log.e("DNS", "DoH via cloudflare failed");
}
return null;
}
}
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