From 762edcd74014a1565797aa8c86079deb10abd9ee Mon Sep 17 00:00:00 2001
From: M66B <M66B@users.noreply.github.com>
Date: Sat, 14 Aug 2021 12:49:05 +0200
Subject: [PATCH] Quick setup: use similar host name from certificate

---
 .../eu/faircode/email/EntityCertificate.java  | 26 +++++++++++++++++++
 .../eu/faircode/email/FragmentQuickSetup.java | 12 +++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/eu/faircode/email/EntityCertificate.java b/app/src/main/java/eu/faircode/email/EntityCertificate.java
index a684b230f7..820a8985ce 100644
--- a/app/src/main/java/eu/faircode/email/EntityCertificate.java
+++ b/app/src/main/java/eu/faircode/email/EntityCertificate.java
@@ -41,6 +41,7 @@ import org.json.JSONException;
 import org.json.JSONObject;
 
 import java.io.ByteArrayInputStream;
+import java.net.InetAddress;
 import java.security.NoSuchAlgorithmException;
 import java.security.cert.CertificateEncodingException;
 import java.security.cert.CertificateException;
@@ -216,6 +217,31 @@ public class EntityCertificate {
         return result;
     }
 
+    static String getSimilarDnsName(X509Certificate certificate, @NonNull String host) {
+        if (certificate == null)
+            return null;
+
+        try {
+            InetAddress haddr = InetAddress.getByName(host);
+            List<String> names = getDnsNames(certificate);
+            for (String _name : names)
+                try {
+                    String name = (_name.startsWith("*.") ? _name.substring(2) : _name);
+                    InetAddress naddr = InetAddress.getByName(name);
+                    Log.i("host=" + host + " name=" + _name + "" +
+                            " haddr=" + haddr + " naddr=" + naddr);
+                    if (haddr.equals(naddr))
+                        return name;
+                } catch (Throwable ex) {
+                    Log.w(ex);
+                }
+        } catch (Throwable ex) {
+            Log.w(ex);
+        }
+
+        return null;
+    }
+
     static boolean matches(String server, List<String> names) {
         for (String name : names)
             if (matches(server, name)) {
diff --git a/app/src/main/java/eu/faircode/email/FragmentQuickSetup.java b/app/src/main/java/eu/faircode/email/FragmentQuickSetup.java
index e69b146889..bbd4ccc47b 100644
--- a/app/src/main/java/eu/faircode/email/FragmentQuickSetup.java
+++ b/app/src/main/java/eu/faircode/email/FragmentQuickSetup.java
@@ -309,7 +309,11 @@ public class FragmentQuickSetup extends FragmentBase {
                                 null, null);
                     } catch (EmailService.UntrustedException ex) {
                         imap_certificate = ex.getCertificate();
-                        imap_fingerprint = EntityCertificate.getKeyFingerprint(imap_certificate);
+                        String similar = EntityCertificate.getSimilarDnsName(imap_certificate, provider.imap.host);
+                        if (similar == null)
+                            imap_fingerprint = EntityCertificate.getKeyFingerprint(imap_certificate);
+                        else
+                            provider.imap.host = similar;
                         iservice.connect(
                                 provider.imap.host, provider.imap.port,
                                 AUTH_TYPE_PASSWORD, null,
@@ -373,7 +377,11 @@ public class FragmentQuickSetup extends FragmentBase {
                                 null, null);
                     } catch (EmailService.UntrustedException ex) {
                         smtp_certificate = ex.getCertificate();
-                        smtp_fingerprint = EntityCertificate.getKeyFingerprint(smtp_certificate);
+                        String similar = EntityCertificate.getSimilarDnsName(smtp_certificate, provider.smtp.host);
+                        if (similar == null)
+                            smtp_fingerprint = EntityCertificate.getKeyFingerprint(smtp_certificate);
+                        else
+                            provider.smtp.host = similar;
                         iservice.connect(
                                 provider.smtp.host, provider.smtp.port,
                                 AUTH_TYPE_PASSWORD, null,