msb-public
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FairEmail
mirror of https://github.com/M66B/FairEmail.git
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Code Issues Projects Releases Wiki Activity

DNS: process cnames

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pull/214/head
M66B 8 months ago
parent 56a053f6be
commit c5dd3b0260
1 changed files with 37 additions and 9 deletions
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46
app/src/main/java/eu/faircode/email/DnsHelper.java
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@ -42,6 +42,7 @@ import org.minidns.hla.ResolverApi;
import org.minidns.hla.ResolverResult;
import org.minidns.record.A;
import org.minidns.record.AAAA;
import org.minidns.record.CNAME;
import org.minidns.record.Data;
import org.minidns.record.MX;
import org.minidns.record.NS;
@ -53,6 +54,7 @@ import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import java.util.Set;
@ -68,6 +70,7 @@ public class DnsHelper {
private static final String DEFAULT_DNS = "84.200.69.80";
private static final int CHECK_TIMEOUT = 5; // seconds
private static final int LOOKUP_TIMEOUT = 15; // seconds
private static final int MAX_FOLLOW = 5; // cnames
static void checkMx(Context context, Address[] addresses) throws UnknownHostException {
if (addresses == null)
@ -78,17 +81,35 @@ public class DnsHelper {
String domain = UriHelper.getEmailDomain(email);
if (domain == null)
continue;
lookup(context, domain, "mx", CHECK_TIMEOUT, false);
lookup(context, domain, "mx", CHECK_TIMEOUT, MAX_FOLLOW, false);
}
}
@NonNull
static DnsRecord[] lookup(Context context, String name, String type) {
return lookup(context, name, type, LOOKUP_TIMEOUT, false);
return lookup(context, name, type, LOOKUP_TIMEOUT, MAX_FOLLOW, false);
}
@NonNull
private static DnsRecord[] lookup(Context context, String name, String type, int timeout, boolean require_authentic) {
private static DnsRecord[] lookup(Context context, String name, String type, int timeout, int max_depth, boolean require_authentic) {
DnsRecord[] records = _lookup(context, name, type, timeout, require_authentic);
if (records.length == 0 &&
max_depth > 0 &&
!"ns".equals(type)) { // mx is not allowed, but used in practice anyway
DnsRecord[] cnames = _lookup(context, name, "cname", timeout, require_authentic);
List<DnsRecord> followed = new ArrayList<>();
for (DnsRecord cname : cnames) {
DnsRecord[] r = lookup(context, cname.response, type, timeout, max_depth - 1, require_authentic);
followed.addAll(Arrays.asList(r));
}
return followed.toArray(new DnsRecord[0]);
}
return records;
}
@NonNull
private static DnsRecord[] _lookup(
Context context, String name, String type, int timeout, boolean require_authentic) {
String filter = null;
int colon = type.indexOf(':');
if (colon > 0) {
@ -116,6 +137,9 @@ public class DnsHelper {
case "aaaa":
clazz = AAAA.class;
break;
case "cname":
clazz = CNAME.class;
break;
default:
throw new IllegalArgumentException(type);
}
@ -132,7 +156,7 @@ public class DnsHelper {
public DnsQueryResult query(DnsMessage query, InetAddress address, int port) throws IOException {
Semaphore sem = new Semaphore(0);
DnsResolver resolver = DnsResolver.getInstance();
Log.i("Android DNS query=" + query);
Log.i("DNS Android query=" + query);
resolver.rawQuery(
null,
query.toArray(),
@ -182,7 +206,7 @@ public class DnsHelper {
}
if (ex == null) {
Log.i("Android DNS answer=" + result);
Log.i("DNS Android answer=" + result);
return result;
} else {
Log.i(ex);
@ -209,6 +233,7 @@ public class DnsHelper {
}
});
Log.i("DNS query name=" + type + ":" + name);
ResolverResult<? extends Data> data = resolver.resolve(name, clazz);
data.throwIfErrorResponse();
@ -224,7 +249,7 @@ public class DnsHelper {
Set<? extends Data> answers = data.getAnswers();
if (answers != null)
for (Data answer : answers) {
Log.i("Answer=" + answer);
Log.i("DNS answer=" + answer);
if (answer instanceof NS) {
NS ns = (NS) answer;
result.add(new DnsRecord(ns.getTarget().toString()));
@ -261,6 +286,9 @@ public class DnsHelper {
} else if (answer instanceof AAAA) {
AAAA aaaa = (AAAA) answer;
result.add(new DnsRecord(aaaa.getInetAddress()));
} else if (answer instanceof CNAME) {
CNAME cname = (CNAME) answer;
result.add(new DnsRecord(cname.target.toString()));
} else
throw new IllegalArgumentException(answer.getClass().getName());
}
@ -346,8 +374,8 @@ public class DnsHelper {
log(lookup(context, "gmail.com", "mx"));
log(lookup(context, "_imaps._tcp.gmail.com", "srv"));
log(lookup(context, "gmail.com", "txt"));
log(lookup(context, "gmail.com", "a"));
log(lookup(context, "gmail.com", "aaaa"));
log(lookup(context, "outlook.office365.com", "a"));
log(lookup(context, "outlook.office365.com", "aaaa"));
log(lookup(context, "posteo.de", "a"));
log(lookup(context, "non.existent.tld", "a"));
log(lookup(context, "rubbish", "a"));
@ -355,7 +383,7 @@ public class DnsHelper {
static void log(DnsRecord[] records) {
if (records.length == 0)
Log.w("No records");
Log.w("DNS no records");
for (DnsRecord record : records)
Log.w("DNS " + record);
}

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