Refactoring

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -2013,6 +2013,20 @@ public class MessageHelper {
                 return signers;
 
             for (String header : headers) {
+                String signer = verifySignatureHeader(context, header, DKIM_SIGNATURE, amessage);
+                if (signer != null && !signers.contains(signer))
+                    signers.add(signer);
+            }
+
+            Log.i("DKIM signers=" + TextUtils.join(",", signers));
+        } catch (Throwable ex) {
+            Log.e("DKIM", ex);
+        }
+
+        return signers;
+    }
+
+    private String verifySignatureHeader(Context context, String header, String name, MimeMessage amessage) {
         Map<String, String> kv = getKeyValues(MimeUtility.unfold(header));
 
         String a = kv.get("a");
@@ -2027,7 +2041,7 @@ public class MessageHelper {
         } else {
             // TODO: Ed25519
             Log.i("DKIM a=" + a);
-                    continue;
+            return null;
         }
 
         try {
@@ -2036,7 +2050,7 @@ public class MessageHelper {
             Log.i("DKIM lookup " + dns);
             DnsHelper.DnsRecord[] records = DnsHelper.lookup(context, dns, "txt");
             if (records.length == 0)
-                        continue;
+                return null;
 
             Log.i("DKIM got " + records[0].name);
             Map<String, String> dk = getKeyValues(records[0].name);
@@ -2062,7 +2076,7 @@ public class MessageHelper {
             if (!from)
                 throw new IllegalArgumentException("from missing: " + hs);
 
-                    keys.add(DKIM_SIGNATURE);
+            keys.add(name);
 
             Map<String, Integer> index = new Hashtable<>();
             for (String key : keys) {
@@ -2072,7 +2086,7 @@ public class MessageHelper {
                 idx = (idx == null ? 1 : idx + 1);
                 index.put(_key, idx);
 
-                        String[] values = (DKIM_SIGNATURE.equals(key)
+                String[] values = (name.equals(key)
                         ? new String[]{header}
                         : amessage.getHeader(key));
                 if (values == null || idx > values.length) {
@@ -2083,7 +2097,7 @@ public class MessageHelper {
                 }
 
                 String value = values[values.length - idx];
-                        if (DKIM_SIGNATURE.equals(key)) {
+                if (name.equals(key)) {
                     int b = value.lastIndexOf("b=");
                     int s = value.indexOf(";", b + 2);
                     value = value.substring(0, b + 2) + (s < 0 ? "" : value.substring(s));
@@ -2091,7 +2105,7 @@ public class MessageHelper {
                     Log.i("DKIM " + key + "=" + value.replaceAll("\\r?\\n", "|"));
 
                 if ("simple".equals(c[0])) {
-                            if (DKIM_SIGNATURE.equals(key))
+                    if (name.equals(key))
                         head.append(key).append(": ").append(value);
                     else {
                         // Find original header/name (case sensitive)
@@ -2115,7 +2129,7 @@ public class MessageHelper {
                 } else
                     throw new IllegalArgumentException(c[0]);
 
-                        if (!DKIM_SIGNATURE.equals(key))
+                if (!name.equals(key))
                     head.append("\r\n");
             }
             Log.i("DKIM head=" + head.toString().replace("\r\n", "|"));
@@ -2162,7 +2176,7 @@ public class MessageHelper {
 
             String pubkey = dk.get("p");
             if (pubkey == null)
-                        continue;
+                return null;
 
             String p = pubkey.replaceAll("\\s+", "");
             Log.i("DKIM pubkey=" + p);
@@ -2174,7 +2188,7 @@ public class MessageHelper {
 
             String hash = kv.get("b");
             if (hash == null)
-                        continue;
+                return null;
             String s = hash.replaceAll("\\s+", "");
             Log.i("DKIM signature=" + s);
 
@@ -2188,20 +2202,13 @@ public class MessageHelper {
                     " dns=" + dns +
                     " from=" + formatAddresses(getFrom()));
 
-                    if (verified &&
-                            !signers.contains(signer))
-                        signers.add(signer);
-                } catch (Throwable ex) {
-                    Log.e("DKIM", ex);
-                }
-            }
-
-            Log.i("DKIM signers=" + TextUtils.join(",", signers));
+            if (verified)
+                return signer;
         } catch (Throwable ex) {
             Log.e("DKIM", ex);
         }
 
-        return signers;
+        return null;
     }
 
     Address[] getMailFrom(String[] headers) {