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Code Issues Releases Wiki Activity

BIMI: check DMARC policy

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This commit is contained in:
M66B 2021-07-18 13:38:13 +02:00
parent 76ed2d766d
commit 273d7e0dd2
2 changed files with 40 additions and 13 deletions
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37
app/src/main/java/eu/faircode/email/Bimi.java
View file

@ -53,11 +53,12 @@ import java.security.cert.TrustAnchor;
import java.security.cert.X509CertSelector;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
@ -72,6 +73,10 @@ public class Bimi {
private static final int READ_TIMEOUT = 15 * 1000; // milliseconds
private static final String OID_BrandIndicatorforMessageIdentification = "1.3.6.1.5.5.7.3.31";
private static final List<String> DMARC_POLICIES = Collections.unmodifiableList(Arrays.asList(
"quarantine", "reject"
));
static Pair<Bitmap, Boolean> get(
Context context, String domain, String selector, int scaleToPixels)
throws IOException {
@ -85,27 +90,18 @@ public class Bimi {
DnsHelper.DnsRecord[] records;
try {
String txt = selector + "._bimi." + domain;
Log.i("BIMI fetch TXT=" + txt);
Log.i("BIMI fetch TXT " + txt);
records = DnsHelper.lookup(context, txt, "txt");
if (records.length == 0)
return null;
Log.i("BIMI got TXT=" + records[0].name);
Log.i("BIMI got TXT " + records[0].name);
} catch (Throwable ex) {
Log.i(ex);
return null;
}
// Decode DNS record
Map<String, String> values = new HashMap<>();
String[] params = records[0].name.split(";");
for (String param : params) {
String[] kv = param.split("=");
if (kv.length != 2)
continue;
values.put(kv[0].trim().toLowerCase(), kv[1].trim());
}
// Process DNS record
Map<String, String> values = MessageHelper.getKeyValues(records[0].name);
List<String> tags = new ArrayList<>(values.keySet());
Collections.sort(tags); // process certificate first
for (String tag : tags) {
@ -297,6 +293,21 @@ public class Bimi {
cpv.validate(path.getCertPath(), pparams);
Log.i("BIMI valid domain=" + domain);
// Get DMARC record
String txt = "_dmarc." + domain;
Log.i("BIMI fetch TXT " + txt);
records = DnsHelper.lookup(context, txt, "txt");
if (records.length == 0)
throw new IllegalArgumentException("DMARC missing");
Log.i("BIMI got TXT " + records[0].name);
Map<String, String> dmarc = MessageHelper.getKeyValues(records[0].name);
String policy = dmarc.get("p");
if (policy == null ||
!DMARC_POLICIES.contains(policy.toLowerCase(Locale.ROOT)))
throw new IllegalArgumentException("DMARC invalid policy=" + policy);
verified = true;
} catch (MalformedURLException ex) {
Log.i(ex);

16
app/src/main/java/eu/faircode/email/MessageHelper.java
View file

@ -3001,4 +3001,20 @@ public class MessageHelper {
return true;
}
static Map<String, String> getKeyValues(String value) {
Map<String, String> values = new HashMap<>();
if (TextUtils.isEmpty(value))
return values;
String[] params = value.split(";");
for (String param : params) {
String[] kv = param.split("=");
if (kv.length != 2)
continue;
values.put(kv[0].trim().toLowerCase(), kv[1].trim());
}
return values;
}
}