From 6ad580827e85380fb1d905d454967bb51c33b3ee Mon Sep 17 00:00:00 2001
From: M66B <M66B@users.noreply.github.com>
Date: Sat, 10 Feb 2024 07:52:53 +0100
Subject: [PATCH] Try secondary ip4 addresses first when ip4 preferred

---
 .../main/java/eu/faircode/email/EmailService.java  | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/eu/faircode/email/EmailService.java b/app/src/main/java/eu/faircode/email/EmailService.java
index 854478a0d3..dc9a851676 100644
--- a/app/src/main/java/eu/faircode/email/EmailService.java
+++ b/app/src/main/java/eu/faircode/email/EmailService.java
@@ -67,6 +67,7 @@ import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
@@ -617,6 +618,8 @@ public class EmailService implements AutoCloseable {
         crumb.put("port", Integer.toString(port));
         crumb.put("auth", Integer.toString(auth));
 
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+
         InetAddress main = null;
         boolean require_id = (purpose == PURPOSE_CHECK &&
                 auth == AUTH_TYPE_OAUTH &&
@@ -627,8 +630,6 @@ public class EmailService implements AutoCloseable {
             //    throw new MailConnectException(
             //            new SocketConnectException("Debug", new IOException("Test"), host, port, 0));
 
-            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
-
             String key = "dns." + host;
             try {
                 main = DnsHelper.getByName(context, host, dnssec);
@@ -748,6 +749,15 @@ public class EmailService implements AutoCloseable {
                             " ip4=" + ip4 + " max4=" + MAX_IPV4 + " has4=" + has46[0] +
                             " ip6=" + ip6 + " max6=" + MAX_IPV6 + " has6=" + has46[1]);
 
+                    boolean prefer_ip4 = prefs.getBoolean("prefer_ip4", true);
+                    if (prefer_ip4)
+                        Arrays.sort(iaddrs, new Comparator<InetAddress>() {
+                            @Override
+                            public int compare(InetAddress a1, InetAddress a2) {
+                                return -Boolean.compare(a1 instanceof Inet4Address, a2 instanceof Inet4Address);
+                            }
+                        });
+
                     for (InetAddress iaddr : iaddrs) {
                         EntityLog.log(context, EntityLog.Type.Network, "Address resolved=" + iaddr);